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•
INTEGRATED PEST MANAGEMENT APPROACH FOR THE SORGHUM SHOOT FLY,
ATHERIGONA SOCCATA RONDANI (DIPTERA: MUSCIDAE), IN BURKINA FASO
by
Joanny O. Zongo
• A thesis submitted to the Faculty of Graduate Studies and Research
in partial fulfilment of the requirements for the degree of
Doctor of Philosophy (Ph.D.)
Department of Entomology
McGill University
Montréal, Québec
Canada August 1992
~ cJoanny O. Zongo
Nationallibraryof Canada
Bibliothèque nationaledu Canada
Acquisitions and Direction des acquisitions elBibliographie Services Branch des services bibliograplliques
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ISBN 0-315-87849-5
Canada
Short title
Integrated pest management approach for the sorghum shoot fly
Joanny O. Zongo
• i i
ABSTRACT
Ph.D. Joanny O. Zongo Entomology
•
•
A four-year (1988 to 1991 inclusive) field and laboratory study
was undertaken to determine and select the components that could be
integrated to control the sorghum shoot fly, Atherigona soccata Rondani
(Diptera: Muscidae), in 8urkina Faso, West Africa. Nine approaches
were investigated: 1) monitoring adult shoot fl ies: 2) sequential
sampling based on egg and dead heart counting: 3) cultural practices
(sowing dates and plant densities, intercropping sorghum-cowpea): 4)
use of resistant cultivars: 5) use of natural insecticide from the neem
tree Azadirachta indica A. Juss. (Meliaceae): 6) effects of
intercropping sorghum-cowpea on the natural enemi~~ of the shoot fly:
7) spider fauna in pure sorghum and intercropped sorghum-cowpea: 8)
parasitism of the shoot fly by a larval parasitoid, Neotrichoporoides
nyemitawus Rohwer; and 9) the biology of an egg parasitoid,
Trichogrammatoidea simmondsi Nagaraja. These nine approaches were
divided into four main components: 1) monitoring populations, 2)
cultural practices, 3) natural and chemical pesticides, and 4)
biological control that could be integrated to control the shoot fly.
Among these components, monitoring populations (egg sampling), cultural
practices, and use of natural pesticides could be util ised at the
farmer level •
•Doctorat
RËSUMË
Joanny O. Zongo Entomologie
iii
•
.'
Approche de Lutte Intégrée Pour la Mouche des Pousses du Sorgho,
Atherigona soccata Rondani (Diptère: Muscidae), au Burkina Faso.
Quatre années d'études au champ et au l aboratoi re (1988-1991
inclus) ont été effectuées en vue de déterminer et de sélectionn~r des
composantes de lutte intégrée pour la mouche des pousses du sorgho,
Atherigona soccata Rondani (Diptère: Muscidae), dans les conditions du
Burkina Faso. Neuf approches ont été examinées: 1) dépistage des
mouches adultes, 2) échantillonnage séquentiel basé sur le comptage des
oeufs et des coeurs morts, 3) les pratiques culturales (dates et
densités de semis, culture associée sorgho-niébé), 4) utilisation de
cultivars résistants, 5) utilisation des extraits naturels du neem,
Azadirachta indica A. Juss. (Meliaceae), 6) effets de la culture
associée sorgho-niébé sur les ennemis naturels de la mouche, 7) la
faune aranéologique en culture pure du sorgho et en culture associée
sorgho-niébé, 8) parasitisme de la mouche par un endoparasitoïde
larvaire, Neotrichoporoides nyemitawus Rohwer, et 9) la biologie d'un
parasitoïde des oeufs, Trichogrammatoidea simmondsi Nagaraja. Ces neuf
approches ont été divisées en quatre principales composantes: 1)
dépistage des populations, 2) pratiques culturales, 3) pesticides
naturels et chimiques, et 4) lutte biologique. Parmi ces composantes,
le dépistage des populations (échantillonnage des oeufs), les pratiques
culturales et l'utilisation des extraits du neem pourraient être
utilisés en milieu paysan.
•
•
•
;v
Suggested short t; t le: Integrated pest management approach for the
sorghum shoot fly.
Joanny O. Zongo
•
•
•
DEDICATIDN
TD
My wife Rasmata Minoungou~
my sons, Jean-Eudes Wendintoin,
and Héribert Guétawendé,
for their great patience.
v
•
•
•
vi
ACKNOWLEDGEMENTS
Project Supervision
l wish to express my great admiration and gratitude to my two
supervisors: 1) Dr. R.K. Stewart, whose help, support, knowledge, and
hospitality have been invaluable. His whole being inspires confidence.
2) Dr. C. Vincent, for his creative ideas, active participation in
field work and his kind hospitality. l appreciated his attention in
the preparation of the project and his dil igence in reviewing the
thesis.
Staff Members
l express my gratitude to Dr. J.E. McFarlane, Chairman of the
Department of Entomology, who allowed me to transfer from the M.Sc. to
the Ph.D. program; Dr. S.B. Hill, Dr. W.N. Yule, Dr. P.M. Sanborne, Dr .
D.J. Lewis and Dr. 6.B. Dunphy for their constructive guidance during
my training. Special thanks to Dr. S.B. Hill who commented on chapter
6. Special thanks to Alan Godfrey for his help in teaching me English
and Dr. Shahrokh Khanizadeh for statistical advices.
l also thank Pierre Langlois for advice on computer programs and
other technical aspects; Monique Verrette, Marie J. Kubecki and Diane
King for their excellent guidance en administrative policies. Special
thanks to Marie J. Kubecki for her diligence in typing the thesis.
External Scientists
l am particularly indebted to Mr. J.C. Deeming, National Museum
of Wales, Cardiff, U.K., who taught me the art and science of shoot
fly identification at Cardiff. He described and named a new species of
shoot fly that l identified. l also appreciated his kind hospitality.
Dr. B. Pintureau, INRA-INSA, Villeurbanne, Lyon, France, who
taught me how to identify and rear Trichwgrammatidae species and for
•
•
•
vii
his great hospitality. l also appreciated the kind hospitality of Dr.
B. Delobel at Lyon.
In Paris, l had helpful discussions with Dr. A. Delobel, ORSTOM,
who gave me reprints of his publ ished papers and his thesis in
microfilm format on the sorghum shoot fly.
Dr. R.A. Humber, from USDA Plant Protection Research, US Plant,
Soil & Nutrition Lab., Ithaca, New York, USA, for fungal
identification.
Dr. K.F. Nwanze formerly at ICRISAT, Hyderabad, India, furnished
t:1e model for the ICRISAT trap.
Dr. C. Dondale Biosystematic Research Center, Ottawa, Canada, and
Dr. R. Jocqué, Musée Royal de L'Afrique Centrale, Tervuren, Belgium,
for their help in spider identification.
Dr. L. Pedigo, Dept. Entomology, Iowa State University, USA,
commented on the second chapter.
Dr. M.B. Isman, Dept. of Plant Science, University of British
Columbia, Vancouver, Canada, for assessing azadirachtin content.
Colleagues and Friends
1) Canada
Special thanks are expressed to the following (in no particular
order):
Marie-Claude Larivière for advice on my transfer to the Ph.D.
level and teaching me WordPerfect on the IBM microcomputer.
Graham Thurston for his help and advice on my Comprehensive Exam,
and teaching me SAS,
Dr. Gérald Lafleur for general advice before my studies.
Mr. François Fournier for commenting on chapter 4.
Ed Zaborski for advice on SAS.
•
•
•
viii
Christine Noronha for her advice on my Comprehensive Exam,
Dr, Mohammad Javahery and Sue Johnson for advice and assistance
on my first English seminar,
Georges-Marie Momplaisir, Tarik Kassay, Mrs, Wanga. Jean-Piel're
Delond and Maria, François Genier, Alexander Yaku, Getano. Yacine and
Andrew Frowd, François Fournier, and Doulaye Traoré for their pleasant
company.
2) Burkina Faso
Dr. Dona Dakouo, INERA, Farako-Bâ, for suggestions on my first
field work,
Dr. Da Sansan, INERA, Farako-Bâ, for providi ng l ocal sorghum
cultivars,
Blaise K. Kaboré for providing local sorghum cultivars and
encouragements,
Napon Marcellin, INERA, Farako-Bâ, for allowing trap installation
in a sorghum field in 1988,
Dr. M. Muleba, IITA/SAFGRAD, Ouagadougou, for his help in
assessing yields of intercropped sorghum-cowpea,
Mr. Jérémy Ouédroago, IITA/SAFGRAD, Ouagadougou, furnished seeds
of cowpea,
Dr. Luc Couture and Célestin Kaboré for fungi and bacteria
isolation,
My technician Tou Fadoua Malick and the field workers Ouattara
Salif, Ouédraogo Boukary, Yabré Seydou, Tiemtoré Marcel, longo
François, and longo Oumarou for their help in collecting data,
Da Angèle and Solange Dabiré for typing my project,
My family-in-law, particularly my mother-in-law; Noelie Yerbanga,
Hubert R. longo, Mathieu and Adrienne Ramdé, Seydou loma, Blaise K.
•
•
.'
ix
Kaboré, Joanny B. Ouattara, Dominique Compaoré, Adama Sanou, Pierre
Yaméogo, Aimé Zongo, Pascal Zongo and Apollinaire Zongo for their
constant attention to my family,
Zongo Tanga, and all my bothers, sisters, parents, and friends in
Koudougou, Ouagadougou, and Bobo-Dioulasso, for their attention.
Institutions
This research is part of a Plant Protection Project funded by the
Canadian International Development Agency (CIDA 960325) managed by
Agriculture Canada Research Station at Saint-Jean-sur-Richelieu,
Québec, Canada.
l would like to express my gratitude to the personnel of Saint
Jean-sur-Richel ieu Research Station and in particular to its former
Director, Dr. Claude B. Aubé, the current Director Dr. Denis Demars,
Dr. Pierre Martel, formerly Directeur of CIDA Plant Protection Project
in Burkina Faso, G. Benharrosh, senior administrator of the project in
Burkina Faso, Dr. Guy Boivin, Jacques Daneau, Ian Wallace, L-G. Simard
and Benoit Rancourt for their various assistance. Special thanks to
Dr. Pierre Martel who, as interim Director of the project, accepted
with sound judgment my transfer to the Ph.D. level.
The International Institute of Entomology, London, U.K.
identified insect specimens.
Biosystematic Research Center, Ottawa, Canada, and Musée Royal de
L'Afrique Centrale, Tervuren, Belgium, for accepting voucher specimens.
INRA-INSA, Villeurbanne, Lyon, France, for allowing me to use
their laboratory facilities. '
Thanks are also extended to the personnel of the Plant Protection
Laboratory in Bobo-Dioulasso, Burkina Faso, for the facilities,
•
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x
Special thanks to Burkina Faso government through Blaise Kaboré,
Amidou Ouédraogo, (Chiefs of Plant Protection Laboratory, Bobo
Dioulasso), Combari Abdoulaye and Blaise T. Ouédraogo (Directors of
Plant Protection and Conditioning, Ouagadougou), for allowing the time
to complete this study.
Finally, l wish to express my great gratitude and love to my
wife, Rasmata Minoungou, my sons, Jean-Eudes Wendintoin, and Héribert
Guétawendé, to whom l dedicate this work. Without Rasmata's support,
understanding and love, this work could not have been completed .
•
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•
xi
CLAIH5 TD DRIGINALITY
1. A new species of shoot fly, Atherigona zongoi Deeming, was
discovered and described.
2. Thirteen shoot fly species were found new to Burkina Faso.
3. First record of Trichogrammatoidea simmondsi Nagaraja, an egg
parasitoid of shoot fly.
4. First record of a new predator of shoot fly eggs, Tapinoma sp.
(Hymenoptera: Formicidae).
5. First record of fungus, Fusarium sp., attacking the shoot fly eggs.
6. First record of bacterium, Corynebacterium sp., attacking the shoot
fly eggs.
7. First record of Bracon sp. (Hymenoptera: Braconidae) attacking the
shoot fly larvae.
B. First record of Hockeria sp. (Hymenoptera: Chalcididae) attacking
the shoot fly larvae.
9. A complex of spiders (families, genera and species) associated with
shoot flies was found and listed for the first time.
10. This is the first study on the effects of the neem seed extracts,
a natural pesticide on shoot fly egg and larval mortality.
Il. A sequential sampli ng based on dead heart and egg counti ng was
established.
12. This is the first study on the behavior of Neotrichoporoides
nyemitawus Rohwer, a parasitoid of shoot fly larvae.
13. Amethod was developed to rear Neotrichoporoides nyemitawus Rohwer
for the first time.
14. First demonstration tiGt Neotrichoporoides nyemitawus Rohwer cannot
prevent dead heart formation.
•
•
•
xii
15. First demonstration that second instar of the shoot fly is more
parasitized than first and third instars by Neotrichoporoides
nyemitawus Rohwer.
16. First demonstration that shoot fly eggs less than 24 h old are more
parasitized than > 24 old eggs by Trichogrammatoidea simmondsi
Nagaraja.
17. A simple method was developed to rear Trichogrammatoidea simmondsi
Nagaraja for the first time.
18. Thi sis the fi rst study on the biology of Trichogrammatoidea
simmondsi Nagaraja, an egg parasitoid of shoot fly.
19. First record of superparasitism on shoot fly eggs by
Trichogrammatoidea simmondsi Nagaraja.
20. First demonstration of the beneficial effect of intercropped
sorghum-cowpea on Neotrichoporoides nyemitawus.
21. First demonstration of the" beneficial effect of intercropped
sorghum-cowpea on Meioneta prosectes Locket, and Steatoda badia Roewer.
22. A new trap (Multi-Pher) was found to be effective in catching the
shoot flies for the first time.
23. Local sorghum cultivars in the Province of Houet (Bobo-Dioulas~o,
Burkina Faso) were found to be susceptible to the shoot fly for the
first time.
24. Overall, this is the first practical IPM approach for ~ontrol of
the shoot fly in Burkina Faso .
•
•
•
TABLE OF CONTENTS1
Abstract
Résumé .
Suggested Short Title
Dedication ..
Acknowledgments
Claims to Originality
List of Figures
List of Tables
1. Introduction
2. Literature Review
2.1. "Importance of Sorghum in Burkina Faso
2.2. Constraints to Sorghum Production
2.3. Insect Pests of Sorghum
2.4. The Sorghum Shoot Fly .
2.4.1. Origin and Distribution
2.4.2. Taxonomy .....
2.4.2.1. Nomenclature
2.4.2.2. Classification
2.4.2.3. Identification
2.4.3. Biology and Ecology
2.4.3.1. Egg.
2.4.3.2. Larva
2.4.3.3. Pupa
2.4.3.4. Adult
l Papers published or submitted to Journals are indicated.
xiii
Page
i i
i i i
iv
• v
vi
xi
xx
xxi
1
6
7
7
8
10
10
10
10
11
11
12
12
14
14
15
• 2.4.3.5. Life cycle and voltinism ..
xiv
16
2.4.3.6. Population growth regulators 17
2.4.6.1. Cultural control 19
2.4.6.1.1. Planting time 19
2.4.6.1.2. Sanitation and plant density 20
2.4.6.1.3. Crop diversity 20
•
2.4.3.6.1. Abiotic factors
2.4.3.6.2. Biotics factors
2.4.4. Host-Plants .
2.4.4.1. Food-Plants
2.4.4.2. Damage
2.4.5. Rearing
2.4.6. Control
2.4.6.1.4. Fertilization
17
17
17
17
18
19
19
20
2.4.6.1.5. Host-plant resistance 21
2.4.6.1.5.1. Mechanisms of resistance 21
2.4.6.1.5.2. Bases of resistance 21
2.4.6.2. Biological control
2.4.6.3. Chemical control
2.4.6.4.
CONNECTING STATEMENT . . . .
Monitoring and surveying
22
23
24
25
3. Monitoring Adult Sorghum Shoot Fly, Atherjgona soccata
Rondani (Diptera: Muscidae), and Related Species in Burkina Faso 26
3.1. Abstract .. 27
3.2. Introduction 28
3.3. Materials and Methods 29
• 3.4. Resul ts . 30
3.5. Discussion 32
4. Time-sequential Sampling of Sorghum Shoot Fly,
Atherigana saccata Rondani (Diptera: Muscidae), in Burkina Faso 45
4.1. Abstract . . 46
4.2. Introduction 47
4.3. Materials and Methods 48
4.4. Results . 51
4.5. Discussion 52
4.6. References 55
4.7. Tables. . 58
CONNECTING STATEMENT 65
•
•
•
3.6. References
3.7. Tables ..
CONNECTING STATEMENT
5. Influence of Cultural Practices on Sorghum Yields
and Incidence of Sorghum Shoot Fly, Atherigana saccata Rondani
(Diptera: Muscidae), in Burkina Faso
5.1. Abstract ..
5.2. Introduction
5.3. Materials and Methods
5.3.1. Experimental Series A
5.3.2. Experimental Series B
5.4. Results ....
5.4.1. Series A
5.4.1. Series B
5.5. Discussion
5.6. References
5.7. Tables and Figure 1.
CONNECTING STATEMENT • . . . .
xv
35
38
44
66
67
68
69
69
71
72
72
72
73
76
80
86
•
•
•
6. Screening of Local Cultivars for Resistance to Sorghum
Shoot Fly, Atherigona soccata Rondani (Diptera: Muscidae)
6.1. Abstract .
6.2. Introduction
6.3. Materials and Methods
6.4. Results
6.5. Discussion
6.6. References
6.7. Tables ..
CONNECTING STATEMENT
7. Effects of Neem Seed Kernel Extracts on Egg and Larval
Survival of the Sorghum Shoot Fly, Atherigona soccata Rondani
(Diptera: Muscidae)
7.1. Abstract
7.2. Introduction
7.3. Materials and Methods
7.3.1. Field experiments
7.3.2. Laboratoryexperiments
7.4. Results .
7.4.1. Field experiments
7.4.2. Laboratoryexperiments
7.5. Discussion
7.6. References
7.7. Tables and Figure 2
CONNECTING STATEMENT . . . . •
xvi
87
88
89
90
91
92
95
97
100
101
102
103
104
104
106
108
108
108
109
113
117
122
•
•
•
8. Effects of Intercropping Sorghum-Cowpea on Natural
Enemies of the Sorghum Shoot Fly, Atherigona soccata Rondani
(Diptera: Muscidae), in Burkina Faso
8.1. Abstract ..
8.2. Introduction
8.3. Materials and Methods
8.3.1. Egg parasitoid sampling
8.3.2. Larval and pupal parasitoids sampling
8.3.3. Fungi and bacteria sampling
8.4. Results .
8.4.1. Shoot fly complex
8.4.2. Egg natural enemies
8.4.3. Larval and pupal parasitoids
8.5. Discussion
8.6. References
8.7. Tables and Figure 3
CONNECTING STATEMENT . . . . .
9. Spider Fauna in Pure Sorghum and Intercropped
Sorghum-Cowpea in Burkina Faso
9.1. Abstract ..
9.2. Introduction
9.3. Materials and Methods
9.4. Results .
9.5. Discussion
9.6. References
9.7. Tables and Figure 4
CONNECTING STATEMENT . . . . .
xvi i
123
124
125
125
126
127
127
128
128
128
129
130
135
139
144
145
146
147
148
149
151
154
158
163
•
•
•
10. Parasitism of the sorghum shoot fly, Atherigona soccata
Rondani (Diptera: Muscidae), by Neotrichoporoides nyemitawus
Rohwer (Hymenoptera: Eulophidae)
10.1. Abstract
10.2. Introduction
10.3. Materials and Methods
10.4. Results .
10.5. Discussion
10.6. References
10.7. Tables
CONNECTING STATEMENT
Il. Biology of Trichogrammatoidea simmondsi Nagaraja
(Hymenoptera: Trichogrammatidae) on sorghum shoot fly,
Atherigona soccata Rondani (Diptera: Muscidae) eggs
11.1. Abstract
11. 2. Introduction
11.3. Materials and Methods
11. 4. Results .
11. 5. Discussion
11. 6. References
11. 7. Tables
xviii
164
165
166
167
169
170
173
176
179
180
181
182
183
184
~85
187
188
•
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•
xix
12. General Discussion and Conclusion 191
13. References .... . . . . . 198
Appendix 1. Manuscripts and Presentations Based on this Thesis 227
Appendix 2. Atherigona zongoi: trifoliate process
and hypopygial prominence; morphological characters
used for identification 230
Appendix 3. Sorghum shoot fly, Atherigona soccata: adult,
immature stages and damage........•.•...... 231
Appendix 4. Copyright waiver of "Monitoring Adult Sorghum
Shoot Fly Atherigona soccata Rondani (Diptera: Muscidae)
and Related Species in Burkina Faso"
by Zongo et a7. (1991) 233
• xx
LIST OF FIGURES
Page
l. Spatial arrangement of sorghum and cowpea rows
in five cropping systems . . . . . . . · . 85
2. Shoot fly eggs decomposed 24 h after treatment
with neem aqueous extracts . . . . . . · . 121
3. Percentages of egg and larval parasitism due to
Neotrichoporoides nyemitawus and Trichogrammatoidea
simmondsi in two cropping systems in Burkina Faso ..... 143
4. Total spider numbers (spiderlings and adults) per five
•
•
rows in three cropping systems in Burkina Faso
5. Approaches to sorghum shoot fly 1PM investigated
in this thesis ...•.•.........
· . . . 162
197
• xxi
LIST OF TABLES
Page
l. Major insect pests of sorghum of economic importance
in the world . . . . . . . . . . . . . . . . . . 9
2. Atherigona spp. catches in four trap models in Burkina Faso
1988 and 1989 . . . . . . . . . . . . . . . . . . . . 39
3. Sorghum shoot fly Atherigona soccata (male + female)
catches in four trap models in Burkina Faso 1988, 1989 .. 40
4. Relative abundance of Atherigona and Acritochaeta males
•
captured in Burkina Faso, 1988, 1989
5. Time required to collect and count shoot flies from
four trap models in the field, Burkina Faso, 1988
6. Adult shoot flies (Atherigona spp.) monthly captures,
rainfall and relative humidity in southwestern
Burkina Faso
41
42
43
7. Endemie (m,) and (m,) outbreak population
configurations of Atherigona spp. eggs. (n= 30)
and dead hearts (n= 100), Burkina Faso ... ••...• 59
8. Sorghum shoot fly egg distribution on leavesin
three localities, Burkina Faso, (1988 and 1989 data pooled) 60
9. Mean (n= 30), variance, and dispersion characteristics
of Atherigona spp. eggs on sorghum in three localities,
••
Burkina Faso
10. Mean (n= 100), variance, and dispersion characteristics
of dead hearts caused on sorghum by Ahterigona spp.
in three localities, Burkina Faso ..••.••
Il. Time-sequential sampling plan based on egg counts of
sorghum shoot fly Atherigona soccata . . . .
. . 61
62
63
•
•
•
xxii
12. Time-sequential sampling plan based on dead heart counts
caused by the sorghum shoot fly, Atherigona soccata . 64
13. Yields and Land Equivalent Ratio (LER) for intercropped
sorghum-cowpea, in 1988 at Matourkou, Burkina Faso . . . . 81
14. Yields and Land Equivalent Ratio (LER) for intercropped
sorghum-cowpea, in 1989 at Matourkou, Burkina Faso .. , 82
15. Average number of eggs laid, percentage of plants
with eggs and percentage of dead hearts due to
A. soccata in four cropping systems in Burkina Faso . . . . 83
16. Effect of sowing dates on yield and % head hearts caused
by the sorghum shoot fly Atherigona soccata at
Matourkou, Burkina Faso, in 1988 and 1989 . . . . . . . . . 84
17. Mean number of shoot fly eggs/ 10 plants and mean
percentage of dead hearts observed in 54 cultivars
of sorghum at Matourkou, Burkina Faso . . . . 98
18. Mean number of eggs and mean percentage of dead hearts
observed in 9 cultivars of sorghum, Matourkou, 1990, 1991 99
19. Effect of neem se~J kernel extracts on egg survival and
dead heart formation due to A. soccata at Matourkou,
Burkina Faso . . . . . . . . . . . . . . • . . . . . . , . 118
20. Effect of neem seed kernel extracts on the egg
mortality of A. soccata in laboratory conditions,
Burkina Faso . • . .. .. .. . 119
21. Effect of aqueous neem seed kernel extracts on larval
mortality of A. soccata in 1991, Burkina Faso.. . ... 120
22. Abundance of shoot flies species (male and female)
emerging from larvae collected from sorghum shoots
at Matourkou, Burkina Faso .... . . . . . . . . . . . . 140
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xxiii
23. Average percent parasitism due to Neotrichoporoides
nyemitawus and Trichogrammatoidea simmondsi on sorghum
shoot fly eggs and larvae in intercropped
sorghum-cowpea in Burkina Faso .. . 141
24. Total number of shoot fly parasitoid species
collected in Burkina Faso . • • . . ..•... 142
?5. Mean number of spiders (spiderlings and adults,
all species confounded) per five rows collected
in two cropping systems in Burkina Faso . . . . 159
26. Total number of spider species (spiderlings and adults)
collected in two cropping systems in Burkina Faso
in 1990 and 1991 (n = 156, identified to at least genus) . 160
27. Relative abundance of spider families and species
collected in three cropping system in Burkina Faso
in 1990 and 1991 ••..•..... ' .... 161
28. Mean percentage of larval parasitism in relation to
period of exposure to Neotrichoporoides nyemitawus 177
29. Ouration of l ife-cycle parameters of Neotrichoporoides
nyemitawus in the laboratory {26 (± 1) 0 C,
75% R.H, (± 2) and 12:12 (LlO) ..•. • 178
30. Percentage of A. soccata eggs parasitized by
T. simmondsi and number of exit holes per egg •.•••.. 189
31. Relative size of T. simmondsi immature stages
•
(2~ C, 60-65% R.H.) • • • • . • . • 190
•
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1 INTRODUCTION
1
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2
The sorghum shoot fly, Atherigona soeeata Rondani (Diptera:
Muscidae), is a key pest of sorghum, Sorghum bieo7or L. (Moench) in
Burkina Faso (Bonzi 19B1, Nwanze 1988). In 1986, the National Sorghum
- Millet - Maize Board (SOMIMA) recommended that more studies be
undertaken on the shoot fly, particularly in areas where sorghum
production is important. The Province of Houet, whose Bobo-Dioulasso
is the administrative center, produces over 9% of the national sorghum
production (Ministère de l'Agriculture et l'Elevage 1988).
It has been well established that a single method approach to
control any agricultural insect pest is usually inadequate and leads to
fail ures. Integrated Pest Management (IPM), defined in a practi cal
context as "The farmer's best mix of control tactics in comparison with
yields, profits and safety of alternatives" (Iles and Sweetmore 1991),
is the ideal approach to control the shoot fly (Jotwani 1981). To
apply IPM, various tactics have to be investigated and sel ected
according to local conditions.
The hypothesis examined here was that it is possible to develop
an Integrated Pest Management program for the shoot fly in Burki na
Faso. The present work, based on a four-year (1988 to 1991 inclusive)
field and laboratory study, was done to determine the components that
may be integrated to control the shoot fly in Burkina Faso conditions.
Nine chapters presented here, deal with (in order of appearance)
monitoring adult shoot flies; time-sequential sampling based on egg and
dead heart counting; influence of cultural practices; use of resistant
cultivars; use of natural insecticide from the neem tree Azadirachta
il'/die~ A. Juss. (Mel iaceae); effccts of intc:-croppin; sorghum-cowpea en
the natural enemies of the shoot fly; spider fauna in pure sorghum and
intercropped sorghum-cowpea; parasitism of the shoot fly by
•
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3
Neotrichoporoides nyemitawus Rohwer; and the biology of
Trichogrammatoidea simmondsi Nagaraja.
The present thesis format, accepted by the Faculty of Graduate
Studies and Research and the Department of Entomology, Macdonald Campus
of McGill University, requires a full citation of a section B, 2
(Manuscri pts and Authorshi p), of the Guidel ines Concerni ng Thesi s
Preparation of the Faculty of Graduate Studies and Research. "The
candidate has the option, subject to the approval of their Department,
of including as part of the thesis the text, or duplicated published
text, of an original paper or papers.
- Manuscript-style theses must still conform to all other requirements
explained in the Guidelines Concerning Thesis Preparation.
- Additional material (procedural and design data as well as
descriptions of equipment) must be provided in sufficient detail (eg.
in appendices) to allow clear and precise judgement to be made of the
important and originality of the research report.
- The thesis should be more tllan a mere collection of manuscripts
published or to be published. It must include a general abstracto a
full introduction and literature review and a final overall conclusion.
Connecting texts which provide logical bridges between different
manuscripts are usually desirable in the interest of cohesion.
It is acceptable for theses to include, as chapters, authentic copies
of papers already published, provided these are duplicated clearly and
bound as an integral part of the thesis. In such instances. connecting
texts are mandatory and supplementary explanatory material is al ways
necessary.
- Photographs or other materials which do not duplicate well must be
included in their original form.
•
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4
While the inclusion of manuscripts co-authored by the candidate and
others is acceptable, the candidate is reguired ta make an explicit
statement in the thesis of who contributed ta such work and ta what
extent, and supervisors must attest ta the accuracy of the claims at
the Ph.D. Oral Defense. Since the task of the Examiners is made more
difficult in these cases, it is in the candidate's interest ta make the
responsibil ities of authors perfectly clear".
l followed the rules of scientific writing given in the CBE Style
Manual (1983) and the MLA Handbook for Writers of Research Papers
(Gibaldi and Achtert 1988). l wrote each chapter ta be presented ta a
specific scientific journal according ta the requirements of that
journal. The first chapter (Monitoring Adult Sorghum Shoot Fly
Atherigona soccata Rondani (Diptera: Muscidae) and Related Species in
Burkina Faso) was published in Tropical Pest Management (Vol. 37: 235
239) whose copyright waiver is enclosed (appendix 4). Chapter 4 (Ti me
sequential Sampl ing of Sorghum Shoot Fly Atherigona soccata Rondani
(Diptera: Muscidae) in Burkina Faso) is In Press in Insect Science and
its Application (Kenya), chapter 7 (Effects of Neem Seed Kernel
Extracts on Egg and Larval Survival of the Sorghum Shoot Fly,
Atherigona soccata Rondani (Diptera: Muscidae)) is In Press in Journal
of Applied Entomology (Germany), chapter 8 (Effects of Intercropping
Sorghum-Cowpea on Natural Enemies of the Sorghum Shoot Fly, Atherigona
soccata Rondani (Diptera: Muscidae) in Burkina Faso) is In Press in
Biological Agriculture &Horticulture (U.K.), while chapters ID and Il
have already been submitted ta Insect Science and its Application
(Kenya), and Entomophaga (France) respectively. All chapters were
reviewed by my supervisors, Dr. R.K. Stewart and Dr. C. Vincent, and by
the editorial committee of Agriculture Canada, Research Station, Saint-
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5
Jean-sur-Richelieu. Sorne chapters were cowmented on by certain
scientists when available. All papers were coauthored by my
supervisors.
1 used SuperANOVA (version 1.1 for the Macintosh Computer)
(Abacus Concepts Inc., 1989), and SAS (version 6.03 for IBM PC) (SAS
Institute Inc., 1988) for the statistical analysis of the data.
The acknowledgement sections were pooled at the beginning of the
thesis whereas references were also pooled at the end of the thesis.
1 deposited voucher specimens in the following institutions:
point mounted specimens and wet collections in the Lyman Museum,
Macdonald Campus of McGill University, Sainte-Anne de Bellevue, Québec,
Canada, the Biosystematic Research Center, Ottawa, Canada, Musée Royal
de L'Afrique Centrale, Tervuren, Belgium, and in the Plant Protection
Laboratory, Bobo-Dioul asso, Burkina Faso. The exi stence of voucher
specimens was mentioned in each chapter whenever appropriate.
This study constitutes the first practical investigation on IPM
components that could be applied to control the shoot fly in Burkina
Faso .
•
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2 LITERATURE REVIEW
6
•
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7
2.1. Importance of 50rghum in Burkina Faso
In Burkina Faso, sorghum is the most importance cereal crop. Its
production represents 51.31% of total cereal production (FAD, 1991).
Sorghum production in Burkina Faso represents 7.17% of the total
cereals produced in Africa, putting Burkina Faso as the first producer
in the Sahelian regions (FAD, 1991).
Sorghum is grown mainly in central and southern regions and has
a wide range of uses: human food (the main dish being locally called
"To"), beer (locally called "Dolo"), fuel for cooking and, to a lesser
extent fences, baskets and livestock feeding.
2.2. Constraints ta 50rghum Production
Constraints on sorghum production are numerous in Burkina Faso.
They range from cl imatic constraints (poor water resources) ta low soil
fertility, poor sail management, lack of infrastructures, diseases and
insect pests which often cause very severe damage. Overall,
constraints may be summarized into technical, economic and
sociological.
Technicàl constraints are insufficiency of research, and low
level of education of farmers (illiteracy).
Economic constraints range from lack of local organized markets,
low income, to lack of a world market.
Sociological constraints are that peasant farmers are in general
traditional and conservative, sa sorghum production technology shows a
low rate of adoption. Other social constraints include the lack of
united action from farmers and the insufficiency of cooperation between
researchers .
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8
2.3. Insect Pests of Sorghum
Although over 100 insect species are known to be pests of
sorghum, only some of these are presently of economic importance and
belong to the Orders Di ptera, Lepidoptera, and Hemi ptera (Nwanze,
1985). In an International Sorghum Entomology workshop, sorghum insect
pests from Eastern Africa (Seshu Reddy and Omolo, 1985), West Africa
(Nwanze, 1985), India (Srivastava, 1985), South East Asia (Meksongsee
and Chawanapong, 1985), Australia (Passlow et al., 1985), U.S.A.
(Pitre, 1985), Mexico (Castro, 1985), Central America (Reyes, 1985) and
8razil (Viana, 1985) were reviewed. From these reviews, it appears
that shoot flies, grain midges, stored grain weevils, stem borers, head
bugs, aphids, mites are the major pests. The economic importance of
each key pest varies with the region .
Young and Teetes (1977) and Doggett (1988) reviewed sorghum
insects pests while Teetes et al. (1983) furnished practical
identification handbook with excellent coloured photographs. Major
widespread pests of economic importance are given in Table 1•
• 9
Table 1. Major insect pests of sorghum of economic importance in the world.
Sorghum Latin namepart attacked (common name) Damage Lasses (%)
Seedling Atherigona soccata Dead heart 60-90'(Sorghum shoot fly)
Stem Busseola fusca Fuller Dead heart, NilChi10 spp. perfored stems
10' , 83'(Stem borers)
Earhead Contarinia sorghicola Tiny 25"45'Coq. shrunken Seeds(Sorghum midge)
Grain Sitophilus oryzae L. Seed and 61.3'(Rice weevil) grain destruction
Tribolium castaneum NAHerbst(Red flour beetle)
•Rhyzopertha dominica
Fab•(Lesser grain borer)
Sitotroga cereallelaOlivier(Angoumois math)
Ephestia cautellaWal k.(Almond math)
NA
NA
NA
•
= Rai et al. (1978); 'a Harris (1985); , a Jotwani et al. (1971); •• Youngand Teetes (1977); '. Leuschner and Sharma (1983); '. Venkatarao et al.(1958), NA = Not available .
•
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. '
10
2.4. The Sorghum Shoot Fly
2.4.1. Origin and Distribution
Atherigona soccata Rondani was first reported from Italy and
named by Rondani in 1871. About 43 years later, its injury to sorghum
seedl i ngs was fi rst reported by Fl etcher (1914) and by Ba11 ard and
Ramachandra Rao (1924) in India.
The outbreak areas of A. soccata are widespread in Africa, South
and South East Asia. However, it may also be found in Mediterranean
Europe and in the Middle East. The present regions of shoot fly
distribution in Africa and Asia contain three fourth of the sorghum
cultivated area and produce only one third of the sorghum grain crop
(FAO, 1975).
2.4.2. Taxonomy
There are excellent revi ews of the taxonomy of the Afri can
(Deeming 1971, 1972; Dike 1989a, 1989b) and Oriental (Pont 1972)
species of Atherigona. The genus Atherigona comprises 168 known
species, five subspecies and one variety (Deeming 1971, 1978).
2.4.2.1. Nomenclature
The sorghum shoot fly has been described under different names.
This is probably due to its wide distribution. The following names have
been reported.
Atherigona soccata Rondani 1871
A. indica Malloch 1923
A. indica ssp. infuscata Emden 1940
A. varia ssp. soccata Rondani, Hennig 1961
A. excisa Thomson, Avidov 1961
A. varia Meigen, Yathom 1967•
A survey of the literature shows that there still remains some
•
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11
difference of opinion as to whether soccata is a subspecies of varia,
or a distinct species. However, it is quite definite that A. soccata
remains the most predominant species attacking the plants of the genus
sorghum.
2.4.2.2. Classification
The systematic position of the sorghum shootfly A. soccata
is as follow:
Super order Mecopteroid
Order Diptera
Suborder________________________ Brachycera
Superfamily MuscoideaFamily Muscidae
Subfamily Atherigoninae
Genus Atherigona
Species soccata
2.4.2.3. Identification
The female has head and thorax pale grey, abdomen yellowish with
paired brown patches. The male is blacker than the female. The main
morphological characters used to identify A. soccata may be divided in
two groups : those used for the mal e, and those for the female. The
shape of the trifoliate process and the hypopygial prominence is useful
in identifying male species (Deeming 1971, Pont 1972).
The characters used to identify females are the terminalia and
especially the form of the eighth tergite (Deemimg 1971, Clearwater
1981).
To identify both sexes, the relative position of the three
sterno-pleural bristles and the position of anterior cross vein on the
discal cell are valuable. Clearwater (1981) found that the sixth and
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12
seventh ovipositon tergites are val uabl e taxonomic characters, and
therefore May be added to those descri bed by Deemi ng (1971). The
markings on seventh tergite are particularly valuable for identifying
female A. soccata (Clearwater 1981).
A key for the identification of male species in the Afrotropical
Region was first constructed by van Emden (1940). Further keys to the
species of this region were constructed by Deeming (1971) and Dike
(l989a). Since 1971, several new species of Atherigona have been
described by Deeming (1971, 1972, 1975, 1978, 1979, 1981, 1987) and
Dike (1989a, 1989b).
2.4.3. Biology and Ecology
Ramachandra Rao and Ballard (1924) were the first
entomologists to work on the biology of A. soccata. Their research was
the first step, and a bench mark in a long series of investigations
that have continued until the present time on the biology and control
of this important pest (Young 1981).
2.4.3.1. f9.9i
The eggs are usually laid singly on the underside of the leaves
of sorghum seedling, or on young tillers (Kundu and Kishore 1970, Barry
1972). The eggs are white, elongate with a raised flattened,
longitudinal ridge (Barry 1972). The following sizes have been
recorded.
1.3 mm long and 0.33 mm wide (Kundu and Kishore 1970)
1.3 mm n n 0.6 mm n (Barry 1972)
1.5 mm " "0.30 mm n (Rao and Rao 1956)
Ogwaro and Kokwaro (1981) using l ight and scanning el ectron
microscopy found that the egg measured 1.3 mm and its ventral surface
had longitudinal ridges allowing the eggs to be attached to its
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13
substrate. Incubation periods vary from 2-3 days (Raina, 1981a) to 2-5
days (Barry 1972). Before hatching, the anterior end of the egg becomes
yellowish. Eclosion takes place by a rupturing of the dorsal side first
below the tip of the egg shell and its duration is 2-3 minutes (Kundu
and Kishore 1970). The number of eggs laid per female depends on the
diet used to feed females (Meksongsee et al., 1978, Unnithan and
Mathenge, 1983). Meksongsee et al., (1978) reported 440 eggs using dry
yeast, sugar, and water to feed females. A maximum of 715 eggs were
laid by a female shootfly when fed on Baker's yeast, sugar and water
and kept at 3~ C (Unnithan and Delobel, unpubl. cited in Unnithan and
Mathenge 1983).
Temperature and humidity influence the development of the eggs
(Swaine and Wyatt 1954, Nye 1960, Barry 1972, Delobel 1983a, 1983b,
Doharey et al. 1977). The optimal temperature for the egg lies between
20 and 3~C (Del obel 1983a, Doharey et al. 1977). Del obel (l983a)
pointed out that the mortality of eggs is high at 1~ C and 3~ C, and no
hatching occurs at 1~ C, while embryomic development is inhibited at
37.5" C.
Low humidity (30%) increases the duration of egg development
(Del obel , 1983b) and decreases egg survival (Doharey et al., 1977,
Delobel, 1983b).
The distribution of the eggs in field is random (Del obel 1981,
Zongo et al. 1991). In field and laboratory, Delobel (1981) found that
eggs among sorghum stems were randomly distributed or slightly
aggregated. Raina (1981b) found that the female shoot fly uses a marker
pheromone to deter repeated oviposition on one sorghum plant .
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14
2.4.3.2. Larva
The larva represents the hazardous stage for sorghum plants. It
measures about 10 mm long and 1.3 mm wide. At hatching, it is white
and then becomes light yellow and gradually turns yellowish-brown
(Barry 1972).
Swaine and Wyatt (1954), Nye (1960) and Rao and Rao (1956)
recorded three larval instars, whereas Kundu and Kishore (1970)
reported 4 larval instars. Ogwaro and Kokwaro (1980) using a scanning
electron microscope described three instars. The three larval instars
are similar in general appearance but can be distinguished by the size
and shape of the cephalopharyngeal skeleton, spiracular process and
general coloration (Ogwaro and Kokwaro 1980).
Total' larval period ranges between 8-10 days and there is
generally one larva per stem (Swaine and Wyatt, 1954, Nye, 1960, Kundu
and Kishore, 1970, 8arry, 1972, Raina, 1981a).
Temperature and relative humidity affect the duration of larval
development (Del obel 1983a, Delobel and Unnithan 1983, Doharey et al.
1977). The optimal temperature for a rapid development of the shoot fly
preimaginal stages (egg, larval and pupal) is 30 0 C (Del obel 1983,
Doharey et al. 1977).
2.4.3.3. Pupa
The shoot fly pupa is initially light brown, but it becomes dark
with age (Barry, 1972). It measures 3.38 to 4.03 mm in length and 1.17
to 1.3 mm in width (Kundu and Kishore, 1970); 3.6 mm long and 1.2 mm
diameter (Barry, 1972); 4.8 mm x 1.53 mm (Ogwaro and Kokwaro, 1980).
The puparium is barrel shaped. Its posterior end is tapered
while the anterior is concave bearing two anterior spiracles (Kundu and
Kishore, 1970). Ten segments (Kundu and Kishore, 1970) or nine (Ogwaro
•
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15
and Kokwaro, 1981) remain visible. Pupation takes place inside the
stem or rarely in the soil. The pupal period takes an average of 10.4
days (Barry, 1972), eight to ten days (Kundu and Kishore, 1970).
Temperature influences pupal development (Kundu and Kishore 1970,
Delobel 1983a) whereas the R.H. has little effect (Kundy and Kishore
1970). Pupal weight decreases with increasing temperature (Del obel
1983a). The optimal temperature is 30 • C (Kundu and Kishore 1970,
Del obe1 1983a).
2.4.3.4. Adult
The adult shoot fly appears simil ar to the house fly Musca
domestica Linné, but it is smaller (Barry 1972). The shoot fly
measures 4.42 mm to 5.2 mm in length. It is generally diurnal (Raina
(1982). Studying the daily rhythms of oviposition, egg hatching and
adult eclosion, Raina (1982) found no eggs laid during the scotophase.
However, Swaine and Wyatt (1954) and Barry (1972) found that eggs were
laid at night as well as during the day.
In Burkina Faso, the sex ratio male:female was 1:2.84-1:4 (Bonzi,
1981), 1:2.66; 1:4.45 (Zongo et a7., 1991). In Sénégal, Gahukar (1987)
collected 80-97% of females using fish meal traps. However, when shoot
flies were reared from sorghum plants with dead hearts, the sex ratio
was one male for three females (Gahukar, 1985). Clearwater (1981)
collected 90% females in Kenya whereas Seshu Reddy and Davies (1978)
collected 90-99% females in India.
The longevity of both male and female depends on environmental
conditions (Barry 1972, Kundu and Kishore 1970) and particularly the
diet (Meksongsee et a7.1978, Ogwaro 1978a, Unnithan and Mathenge 1983).
Adult flies survived for 32.6 days on brewer's yeast, glucose and water
(Ogwaro 1978a), 33.0 days on sorghum aphid honeydew (Unnithan and
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16
Mathenge 1983). Male and female survived 39 and 26 days respectively on
ordinary sugar and water (Meksongsee et al. 1978).
The flies are attracted by fish meal (Starks 1970). As already
mentioned, the temperature and humidity have an effect on the
development of A. soccata.
At 15·C there is no mating or ovipositon (Del obel 1983a). The
combination of 30·C and 90% R.H. is the most favourable condition for
the rapid development and multipl ication of the sorghum shoot fly
(Doharey et al. 1977).
Shoot fly adult females usually do not mate more than once, but
males mate several times with virgin females (Unnithan 1981). Unnithan
(1981) also found that enough sperm is transferred and stored by the
female at the first mating and thus multiple mating is not required for
egg fertilization.
2.4.3.5. Life-cycle and voltinism
The literature shows little variation on the biological cycle of
A. soccata. The life-cycle ranges between three and four weeks.
The foll owing development times from egg to adult have been
reported : 16.8 days at 27.22 Oc and unknown relative humidity (Swaine
and Wyatt 1954), 17 to 21 days at 32.6 Oc and 50% relative humidity
(Kundu and Kishore 1970), 26.7 days at 28.1 Oc and unknown relative
humidity (Barry 1972), 21 to 34 days at unknown temperature and
relati~"'~iiÛmidity (Ogwaro and Kogwaro 1981).
A. soccata is multivoltine. Three generations have been recorded
in a three month period by Soto and Laximarayan (1971). Gahukar (1987)
found that a l ife-cycle of 3 - 4 weeks allowed A. soccata to produce up
to ten generations per year. In China, seven (Shiang-Lin 1977) and ten
to Il (SHiand-Lin et al. 1981) generations per year have been recorded.
• 2.4.3.6. Population growth regulators
17
•
•
2.4.6.1. Abiotic factors
Density independent factors influencing the mortality, longevity,
fertility of A. soccata are temperature, R.H., and rainfall patterns
(Doharey et a7. 1977, Dubey and Yadad 1980, Jotwani et a7. 1970,
Delobel 1983a). Jotwani et a7. 1970, pointed out that temperatures >
3~ C and < 1& C, and continuous rainfall are fatal to the shoot fly.
2.4.6.2. Biotic factors
Little is known about exact effects of biotic factors on A.
soccata. Several natural enemies of eggs (Deeming 1971, Pont 1972,
Taley and Takhare 1979, Jotwani 1978, Reddy and Davies 1978) have been
reported. Other natural enemies such as birds and spiders (Del obel and
Lubega 1983) playon important part in the reduction of adult flies .
2.4.4. Host-Plants
2.4.4.1. Food - Plants
The shoot fly has many food-plants. In addition to
sorghum, it also attacks other crop plants such as maize and millet
(Nye, 1960) and several wild graminaceaous plants in various parts of
Africa (Deeming, 1971), India (Davies and Seshu Reddy, 1980 a) and
China (Shiamp-Lin et a7. 1981). For instance in India, Davies and Seshu
Reddy (1980a) reared the shoot fly from 21 species of Gramineae.
Delobel and Unnithan (1981) and Singh and Raina (1986) found that the
wild sorghum and grasses act as reservoir particularly during the dry
season .
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18
2.4.4.2. Damage
Damage done by the shoot fly is very apparent on sorghum
seedlings. After hatching, the maggot slowly moves downwards, enters
the central shoot and feeds on the growing point causing a typical
damage named 'dead heart' (Barry, 1972, Kundu and Prem Kishore, 1970).
Raina (1981a) found that the 'dead heart' is caused by cutting the base
of the central shoot and that very little damage is done to the growing
point by the first instar. The first and the second instars are mainly
involved in cutting leaf tissues, whereas the third instar feeds on
dead and decaying tissues (Raina 1981a).
Dead heart formation is evident within two to three days of pest
attack (Barry 1972, Gahukar 1987). The most suceptible stage of the
sorghum for infestation was found to be within 21 days after
germination (Kundu et al. 1971 and Jotwani et al. 1970). After shoot
fly attack, small seedlings may be killed outright whereas larger
seedlings may continue to produce tillers that in turn are attacked
(Young 1981). Sometimes plants tiller excessively and produce less
grain. Losses in yield result from a reduced stand and a reduction in
tiller size (Jotwani et al. 1970).
Little is known about economic thresholds (E. T.) or economic
injury levels (E.I.L.). Rai et al. (1978a, 1978b) estimated the EIL of
shoot fly infestation on the basis of the cost of protection with
carbofuran seed treatment and disulfoton granules as soil application.
These two insecticides implied economic grain threshold values of 133
Kg and 337 Kg respectively. The EIL ranged from 3.8 to 15 dead hearts
on three sorghum cultivars (CSHl, CSH5 and Swarma).
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19
2.4.5. Rearing
A. soccata may be reared using sorghum seedl ings as wel1 as
artificial diet, the main food requirements being protein and
carbohydrate. Unnithan (1981) found that free amino acids were more
important than proteins in stimulating vitellogenesis in the shoot fly.
Seedlings of a susceptible cultivar have been used to rear A.
soccata (Soto 1972, Soto and Laxminarayana 1971, Gahukar 1985).
Several artificial diets have been developed to rear the shoot
fly (Dang et al. 1971, Soto and Laxminarayana 1971, Soto 1972, Moorty
and Soto 1978, Meksongsee et al. 1978, Unnithan 1981, Unnithan and
Mathenge 1983, Singh et al. 1983). From these diets it has been
revealed that sugar is indispensable for female survival and also for
the maturation of the eggs •
2.4.6. Control
A survey of l iterature shows that the more promising control
measures that received the greatest research emphasis include cultural
control, chemical control (use of systemic insecticides) and the
development of high yielding resistant cultivars.
2.4.6.1. Cultural control
2.4.6.1.1. Planting time
Many workers (i.e. Brenière 1972, Shri Ram et al. 1976, Gandhale
et al. 1983, Gahukar 1987) found that shoot fly damage was lower with
early planting times than later ones. However, in China, damage
caused by the first generation of the shoot fly was the heaviest and
early sown sorghum suffered from serious damage (Shiang-Lin et al.
1981). Synchronous planting times are recommended to avoid or to reduce
A. soccata damage. Young (1981) pointed out that continuous cropping
over several months favors population build-up and fly injury.
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20
2.4.6.1.2. Sanitation and plant density
In Kenya, A. soccata survives the off season by living in sorghum
stubble and wild sorghum. Removal and destruction of these plants after
harvest would disrupt the carry-over of the pest (Unnithan et al.
1985). Removal and destruction of dead heart injured plants from
infested fields are effective practices to reduce the population of the
sorghum shoot fly (Ponnaiya 1951, Delobel 1982). The use of high
seedling rates (40 Kg/ha) and thinning of infested plants is also an
effective control practice (Ponnaiya 1951, Young 1981). This method is
based on the fact that A. soccata laids its eggs randomly (Delobel,
1981, Zongo et al., 1992) and that a sorghum shoot can sustain only a
single instar larva (Meksongsee et al., 1981). Delobel (1982) found
that in low density plots (22 plants/m2), plants received 3.35 times
more eggs than plants in higher density plots (704 plants/m2).
2.6.6.1.3. Crop diversity
Little work has been done on crop diversity and reseach results
seem to be not useful in field conditions. Raina and Kibuka (1983)
studied the effect of intercropped maize and sorghum on the oviposition
and survival of the sorghum shoot fly and found that no more than 6% of
the maize plants received eggs compared with 61% of the sorghum plants.
Venugopal and Palanippan (1976) reported that A. soccata damage was
more severe when sorghum was intercropped with groundnut.
2.4.6.1.4. Fertilization
Phosphorus fertilization reduced shootfly incidence in rainfed
sorghum (Bangar 1985). He also found that the incidence of dead hearts
was inversely proportional to the application of graded levels of
Phosphorus. The lowest incidence of dead hearts was observed where
Phosphorus was placed 50 Kg P20s/ha in the vicinity of available soil
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21
moisture.
Appl ication of nitrogenous fertil izers at 50 kg No/ha, reduced the
incidence of the shoot fly (Reddy and Rao 1975, Mote and Kadam 1983).
2.4.6.1.5. Host-plant resistance
2.4.6.1.5.1. Mechanisms of resistance
First screening of a sizable world sorghum collection for A.
soccata resistance was made by Ponnaiya in October 1944 (Young 1981).
In South India, Ponnaiya (1951) screened 214 sorghum cultivars and
found that only 15 cultivars were tolerant to the shoot fly attack and
that the percentage of healthy seedlings ranged from la to 84. In 1951,
he noted the presence of silica bodies in the third and fourth leaf
sheaths of tolerant cultivars and concluded that these silica bodies
were the mechanism of resistance. After this work, a long series of
research has been undertaken. Today, i t i s we11 known that the main
mechanisms of resistance are non-preference for oviposition (Jain and
Bhatnagar, 1962, Blum, 1967, Jotwani et al. 1971, Singh and Jotwani
1980a), antibiosis (Soto, 1972, 1974, Singh and Jotwani 1980b, Raina et
al., 1981), and tolerance or recovery resistance (Doggett and Majisu,
1965, 1966 , Doggett et al., 1970, Singh and Jotwani 1980c, Doggett
1988).
2.4.6.1.5.2. Bases of resistance
The main bases of resistance are physico-morphological, and
biochemical factors.
- Physico-morphological factors
These factors deter penetration of the young l arvae or egg
laying. The main physico-morphological factors are silica bodies
(Ponnaiya 1951), small prickly hairs on the abaxial epidermis (Blum
1967, 1968), glossy appearance (shining leaves) in the seedling stage
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(Jotwani et al. 1971, Maiti et al. 1980, Singh and Jotwani 1980d), long
and narrow leaves and fast seedling growth, seedling weight and
toughness of leaf sheaths (Singh and Jotwani 1980c, 1980d), col our,
texture and shape of leaves (Raina 1982), and presence of trichomes on
the abaxial surface of leaves (Maiti and Bidinger 1979).
- Biochemical factors
Very little is known about the biochemical basis of resistance.
Singh and Rana (1986) found that the presence of certain compounds such
as hordenine, an alkaloid, and dhurrin, a cyanogenic glucoside in the
sorghum plants may act as toxins, feeding stimulants or deterrents in
the recognition of the host by the female shoot fly. High nitrogen
content (Singh and Narayana 1978) phosphorus (Khurana and Verma 1983)
in sorghum plants, and lysine content in leaf sheath (Singh and Jotwani
1980c) is correlated with shoot fly susceptibility.
2.4.6.2. Biological control
Biological control of A. soccata remains the most unexplored
control strategy. However, the shoot fly has,a wide range of natural
enemi es incl udi ng egg paras i toi ds [Tri chogramma evanescens Westwood
(Trichogrammatidae), Trichogramma spp.] (Pont 1972, Taley and Thakare
1979, Deeming 1971, Delobel 1983c), larval parasitoids [Tetrastichus
nyemitawus Rohwer (Eulophidae), Aprostocetus sp. (Eulophidae),
Cal1itula sp. (Chalcididae), Trichosteresis sp., (Ceraphrontidae)]
(Kundu and Kishore 1972, Pont 1972, Taley and Thakare 1979, Del obel
1983c), pupal parasitoids, [Alysia sp. (Braconidae), Pachyneuron sp.
(Pteromalidae) Exoristobia deemingi Subba Rao (Encyrtidae) and
Syrphophilus bizonarius Gravenhorst (Ichneumonidae)] (Deeming 1971,
Taley and Thakare 1979), and unidentifiedbirds and spiders species
(Del obel and Lubega 1984). Deeming (1983) found that the most common
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prey of the wasp Dasyproctus bipunctatus Lepeletier and Brullé
(Sphecidae), are Atherigona spp. adults. Delobel and Lubega (1984)
mentioned that unidentified birds and spiders are an important group of
natural enemies of the sorghum shoot fly. Reddy and Davies (1978) found
a predacious mite, Abro7ophus sp. feeding on A. soccata eggs in 1ndia.
ln India, parasitism due to Aprostocetus sp. reached 15% in
September 1975 and 35% in August 1977 (Jotwani 1978).
2.4.6.3. - Chemical control
Earlier workers (Swaine and Wyatt 1954, Rao and Rao 1956, Davies
and Jowett 1966, Vedamoorthy et a7. 1965) obtained unsatisfactory
results using D.D.T. and BHC sprayed on the foliage of seedlings at
weekly intervals. Application of systemic insecticides such as phorate,
disyston and carbofuran granules in the furrow of seed at planting time
gave effective effects in reducing dead-hearts (Young 1981).
Many others insecticides such as chlorfenvinphos, oncol,
dicrotophos, dimethoate, isofenphos, phosalone also gave a positive
effect for the control of the sorghum shoot fly (Jadhaw and Jotwani
1982, Shivpuje and Thombare 1983, Mote an Kadam 1984).
Carbofuran seed treatment proved to be the most practical
effective and economic chemical method to control A. soccata compared
to any other insecticides and insecticidal applications (Jotwani et a7.
1972, Shivpuje and Thombare 1983, Mote and Kadam 1984). However this
insecticide is more hazardous to handle and the treatment has to be
done under strict technical supervision, which limits its use on large
scale (Mote and Kadam 1984).
The literature reveals no report of A. soccata resistance to any
of the insecticides evaluated and recommended for the control of this
pest.
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2.4.6.4. - Monitoring and surveying
Fish meal attracted shoot flies (Starks 1970) and was first used
in traps to monitor A. soccata (Seshu Reddy and Davies 1978). The trap
consisted of a square pan galvanized metal ( 60 x 60 x 7,5 cm) with a
lid; fishmeal was placed in a dispenser kept at the center of the trap.
The trap was then filled with water (201) to which a small quantity of
detergent (100 g) is added. Fishmeal and water are periodically
replaced.
The square pan metal trap has been replaced by a plastic traps
which is simple and easy to handle (Taneja and Leuschner 1986). It
consisted of one liter plastic jar with fly entry holes on the sides.
The top of the jar contained a fish meal dispenser and a vial
containing a volatile insecticide. The bottom was filled with a plastic
funnel whose outlet is attached to a collecting jar. The fermented fish
meal may remain attractive for a week .
Zongo et a7. (1991) compared the previous traps with two others
(Multi-Pher and Conical) and concluded that the ICRISAT (Taneja and
Leuschner 1986) and Multi-Pher are more appropriate. Mohan and Prasad
(1991) developed a fish meal powder formulated with three insecticides
(fenthion 80 EC, quinalphos 40 EC and propoxur 1%) and found that
propoxur formulation reduced si9nificantly shoot fly damage.
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CONNECTING STATEMENT
Modern pest management cannot operate without estimates of pest
population densities (Ruesink and Kogan 1982). To estimate pest
population densities, three main methods are used, namely absolute
methods, relative methods and population indices (Ruesink and Kogan
1982). Shoot fly population densities are usually estimated using
relative methods (Bonzi 1981, Bonzi and Gahukar 1983, Gahukar 1987) as
these techniques are easier than absolute ones (Ruesink and Kogan
1982). Monitoring shoot fly adults may generate useful information for
improving control strategies. For example, knowing the outbreak periods
during a cropping season may help to schedule planting times and
screening programs. Chapter 3 deals with how to monitor shoot fly
populations using different traps. The main goal of this chapter iS,to
determine the shoot fly species array and to investigate the
possibility of using more efficient traps than those previously
recommended to monitor shoot flies .
.. 26
3 Monitoring Adult Sorghum Shoot Fly, Atherigona soccata Rondani
(Diptera: Muscidae), and Related Speices in Burkina Faso•
•
Published in Tropical Pest Management, 37: 321-235 [1991]
Authors: J.O. ZONGO, C. VINCENT, and R.K. STEWART.
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3.1. AB5TRACT
Fish meal was used as attractant in four trap types for assessing the
rel ati ve abundance and speci es composi ti on of sorghum shoot fl i es.
which are major pests in the wetter southern zones of Burkina Faso.
Trapping was carried out in 1988 and 1989 during the rainy season in
Bobo-Dioulasso. Three trap models were effective in catching Atherigona
soccata: 1) water trap, 2) Multi-Pher and 3) ICRISAT (International
Crops Research Institute for 5emi-Arid Tropics) traps. Multi-Pher and
water traps were the most efficient. The advantages and disadvantages
of each trap model are discussed. Identification of male shoot flies
demonstrated the presence of 34 species of the subgenus Atherigona and
two species of the subgenus Acritochaeta, with Atherigona soccata, A.
occidenta7is Deeming and A. tomentigera van Emden being predominant .
Thirteen species were new records to Burkina Faso: A. aberrans Malloch,
A. africana Deeming, A. fi7i7oba Deeming, A. gabonensis Deeming, A.
gi7vifo7ia van Emden, A. griseiventris van Emden, A. hya7inipennis van
Emden, A. med7eri Deeming, A. nigrapica7is Deeming, A. pu77a Wiedemann,
A. ruficornis Stein, Acritochaeta yorki Deeming. A new species
Atherigona (s.s.) sp. n. will be described elsewere' .
1 The species was described and named as Atherigona zongoi, see appendix 2.
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3.2. INTRODUCTION
The sorghum shoot fly, Atherigona soccata Rondani (Diptera:
Muscidae), is one of the most destructive and widely distributed pest
of sorghum in Africa and Asia (Young, 1981). In Burkina Faso it is a
key limiting factor of Sorghum bicolor (Linné, Moench) production in
the wetter southern zones, particularly when rainfall dictates delayed
planting (Brenière, 1972; Bonzi, 1981; Nwanze, 1988).
Several shoot fly species are injurious to sorghum seedlings the
most destructive being A. soccata (Deeming, 1971; Baliddawa and Lyon,
1974; Davies et al., 1980; Gahukar, 1985). In Burkina Faso, high shoot
fly damage (15-46% of head hearts) has been recorded in farmers' fields
(Nwanze, 1988). Bonzi (1981) Bonzi and Gahukar (1983), respectively,
found 22 and 24 species of Atherigona, including the subgenus
Acritochaeta. Among the species so far collected in Burkina Faso, A.
soccata accounted for 14% of the seasonal captures and A. marginifolia,
36% (Bonzi and Gahukar, 1983).
To monitor shoot fly adults, two types of trap have been
recommended: the water trap (Seshu Reddy and Davies, 1978) and the
ICRIS~~~(lnternatinal Crops Research Institute for Semi-Arid Tropics)
trap (Taneja a:'d Leuschner, 1986). Both traps use fi sh meal as an
attractant (Starks, 1970). _
The present investigations were undertaken to study the relative
proportion of sorghum shoot fly species in Burkina Faso and ta test
whether another effective trap could be used to monitor adult sorghum
shoot fly .
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3.3. MATERJALS AND HETHODS
The experiments were conducted in 1988 at Farako-Bâ and in 1989
at Matourkou, both located ca. la km south of Bobo-Dioulasso (11· ll'N,
4· lS'W). Four types of traps were used during the rainy season: (l)
Multi-Pher (Jobin, 1985); (2) ICRISAT insecticide trap (Taneja and
Leuschner, 1986); (3) conical (Eckenrode and Arn, 1972): and (4) water
trap . The traps were placed 20 m apart in a sorghum fields (3 ha in
1988, 0.5 ha in 1989) in a Latin-square design at 50 cm above ground
level. The local cultivar 'Gnofing', known to be susceptible to sorghum
shoot fly (Brenière, 1972; Zongo, 1987), was used in both fields. The
Multi-Pher ICRISAT and conical traps were held with an iron stake. The
water trap consisted of a plate (26 cm diameter) containing 500 ml
water and detergent and placed in a circular hole in a 50 cm high
table. The ICRISAT trap was made with rubber tubing and a plastic
funnel.
Apl ast i c bag was fill ed wi th 25 9 fi sh me..1 saturated wi·th
water. The bait was placed in the traps 24 h later. The plastic bag was
perforated around the upper part so that the fish meal odour could
escape. A rubber band was used to hold the fish meal in the Multi-Pher
trap whereas paper clips were used in the ICRISAT and conical· traps.
One gram of a (18,6% Vapona'") dichlorvos strip was placed in the
Multi-Pher, ICRISAT and conical traps to kill trapped insects. The
dichlorvos strip was taped to the Hulti-Pher and conical traps, and was
held in a plastic capsule in the ICRISAT trap. Water and fish meal
were replaced in the water trap twice a week, whereas in the Multi~
Pher, ICRISAT and conical traps, fish meal was changed weekly and the
insecticide fortnightly •
The traps were placed la days after sowing. The trapping
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experiment lasted from 21 July to 17 November 1988 at Farako-Bâ and
from 1 August to 17 November 1989 at Matourkou. Flies were collected
every 3-4 days for each trap model. Flies were then placed in vials
containing 70% alcohol until identification in the laboratory.
In 1988 we calculated the time required to empty the traps on two
occasions. On the first occasion the time (in minutes) required to
collect all insects captured, including Atherigona spp. was recorded
twice for each trap model. On the second occasion the time required
for collecting only Atherigona spp. from each trap model was recorded
four times. These data also allowed estimation of the selectivity of
each trap model.
At each date of trapping, and for each trap model, a maximum of
100 flies (males and females) were randomly retained for
identification. The specimens were kept in 3% potassium hydroxide
overnight before idenfication with Deeming's (1971, 1972, 1978, 1981)
and Clearwater's (1981) keys. Data were analysed using LSD test (Steel
and Torrie, 1980). Voucher specimens of most species were deposited at
the Biosystematics Reseal'ch Center (Agriculture Canada), Ottawa.
3.4. RESULTS
In 1988 the number of Atherigona spp. caught in the water, Multi
Pher, ICRISAT and conical traps was 32 161, 25 336, 14 978, and 4459
respectively (Table 2). The number of A. soccata (males + females) was
1214, 891, 740, and 386 in Multi-Pher trap, water trap, ICRISAT trap.
and conical trap respectively (Table 3). In 1989, similar results were
found but captures of both Atherigona spp. and A. soccata were fewer.
Of the total number of Atherigona spp. (76 934, all trap models pooled)
captured in 1988, 17 190 specimens were identified representing 22.34%
of the total specimens captured. The sex ratio was one male for five
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31
females. In 1989 the number of keyed specimens was 6139, representin9
49.76% of the total number 12 337. The sex ratio (male:female) was 1:4.
In 1988, A. soccata was the predominant species, representin9 32%
of males captured followed by A. occidenta7is (14.85%), A. budongoana
(7.51%), A. tomentigera (5.63%), A. 7ineata (4.75%), A. truncata
(4.03%), A. marginifo7ia (3.59%), A. secrecauda (3.23%), A. peduncu7ata
(3.16%), A. mirabi7is (2.65%) and other species. In 1989, A.
occidenta7is was the most numerous species (29.97%), followed by A.
soccata (19.63%), A. tomentigera (18.22%) and A. 7ineata (4.74%) (Table
4).
Thirteen species are new records to Burkina Faso. Anew species,
Atherigona (s.s) sp. n., has been found and will be described elsewhere
by J.C. Deeming (National Museum of Wales, Cardiff U.K.) from material
in our collection and that of R.J. Gahukar (J.C. Deeming, personal
communication).
In 1988 and 1989 the sex ratio (male:female) of A. soccata were
1:2.66 and 1:4.45, respectively. Of the total number of species
examined in 1988 and 1989 for all trap models pooled, A. soccata (males
and females) represented 18.79% and 19.90% respectively.
The time required for collecting only Atherigona spp. in conical,
ICRISAT, Multi-Pher and water traps was respectively 4, 9, 28 and 32
min (Table 5). The time required to count both Atherigona spp. and
other insects caught was 5, 13, 43 and 80 min for conical, ICRISAT,
Multi-Pher and water traps respectively (Table 5) .
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32
3.5. DISCUSSION
The fish meal proved to be an effective bait for monitoring shoot
fl ies. Simil ar resul ts have been found by Bonzi (1981), Bonzi and
Gahukar (1983), Taneja and Leuschner (1986), Doumbia and Gahukar
(1986), Gahukar (1987). However, fish meal was not a specific
attractant, hence increasing the time of collection. The four trap
models captured six times more shoot flies in 1988 than in 1989. This
might be due to factors such as climatic conditions, as Doharey et a7.
(1977) observed that high relative humidity is an important factor for
sorghum shoot fly development. Rainfall and relative humidity were
higher in 1988 than in 1989 (Table 6). Heavy rainfall at the onset and
during the cropping period may enhance the growth of grasses and wild
sorghum, which are known to be important hosts of shoot flies (Deeming,
1971; Bonzi and Gahukar, 1983; Gahukar, 1985, 1987).
The advantages of the ICRISAT trap have been listed by Taneja and
Leuschner (1986) as simplicity, handiness, light weight, low
operational costs, and the ability to capture live flies for various
purposes. High selectivity by calibration of holes may also be added
(Table 5). In the course of our experiment, ants climbed up the iron
stake, ate the fish meal or damaged the flies caught. In both Multi
Pher, ICRISAT and conical traps, a ring of insect adhesive
(Tangletrap~) applied to the iron stake solved the problem.
The Multi-Pher trap showed similar advantages to those of the
ICRISAT. However, its efficacy in catching live flies is reduced
because its openings are large and may let the flies e~cape. Although
Multi-Pher trap showed the highest selectivity (82.04%), it also
captured many other fl ies such as Ca77iphoridae, Sarcophagidae and
Ch7oropidae. Unlike the ICRISAT trap it cannot be made of local
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33
material.
The water trap was the most efficient model for capturing
Atherigona spp., but it required more time to empty the trap, largely
due to wet conditions in which the flies are collected. Water traps
also captured many other insects including Ca77iphoridae,
Sarcophagidae, Ch7oropidae, and Scarabaeidae. As Taneja and Leuschner
(1986) pointed out, the fish meal and water must be replaced frequently
in water traps. During collection, more precautions were required to
keep the specimens intact. Furthermore, the specimens started to rot
after a few days.
The conical trap was the least efficient model. Destruction of
fish meal by rodents and ants occurred frequently. The trap needs to be
refined concerning the location of fish meal. However, it allowed the
collector to work in dry conditions and to obtain good material for
identification.
Atherigona is a large genus: 168 known species, five subgenera
and one variety have been described (Deeming 1971, 1978). The subgenus
Atherigona is the largest and contains all the species destructive to
graminaceous crops (Deeming, 1978). In Burkina Faso 41 species (39
species of the subgenus Atherigona, two species of the subgenus
Acritochaeta) including the species here reported have been collected
so far from sorghum and millet fields. The present study revealed 13
species new to Burkina Faso (Table 4). Among the most predominant
species captured both in 1988 and 1989, A. soccata, A. tomentigera and
A. 7ineata are known to be found in sorghum seedlings (Deeming, 1971).
Other species have also bee~found in sorghum shoots. Seshu Reddy and
Davies (1978) listed 13 species in India, while Deeming (1971) and
Gahukar (1985) listed nine and seven in Nigeria and Sénégal,
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34
respectively.
A. occidenta7is was predominantly captured in 1989 and second in
importance in 1988, but larvae have not bean found in sorghum shoots.
Females, that were more attracted than males to fish meal bait,
represented 73% and 82% of A. soccata captured respectively in 1988 and
1989. Similar results have been found by Bonzi (1981) in Burkina Faso,
Clearwater (1981) in Kenya, Gahukar (1987) in Sénégal. The greatest
(90-99%) proportion of females has been recorded in India by Seshu
Reddy and Davies (1978) using fish meal-baited water traps.
Peak captures of both Atherigona spp. and A. soccata were
recorded in August and September, confirming the results of Bonzi and
Gahukar (1983). In general, these months coincide with heavy rainfall
in Burkina Faso. Gahukar (1987) pointed out that the shoot flies abound
when rainfall is abundant, while Delobel and Unnithan (1983) stressed
the negative effect of heavy rainfall.
In conclusion the water trap, Multi-Pher and ICRISAT types might
be useful in monitoring and assessing sorghum shoot fly populations.
However, for systematic and hi stol ogical studies that require high
quality of specimens, ICRISAT and Multi-Pher traps are more
appropriate. Although Natarajan and Chelliah (1983) recommended the
ICRISAT type at a rate of 12-15 traps per ha, Gahukar (1987) found that
the efficiency of fish meal traps in timing control methods for sorghum
shoot fly is questionable. Further work is needed to clarify these
conflicting statements.
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35
3.6. REFERENCES
BALI DDAWA , C.W. and LYON, W.F., 1974. Sorghum shoot fly species and
their control in Uganda. Proceedings of the Academy of Natural
Sciences, 20, 20-22.
BONZI, S.M., 1981. Fl uctuati ons sai sonnières des popul ations de la
mouche des pousses de sorgho en Haute-Volta. Insect Science and
its Application, 2, 59-62.
BONZI, S.M. and GAHUKAR, R.T., 1983. Répartition de la population
d'Atherigona soccata Rondani (Diptère: Muscidae) et des espèces
alliées pendant la saison pluvieuse en Haute-Volta. Agronomie
Tropicale, 38, 331-334.
BRENIERE, J., 1972. Sorghum shoot fly in West Africa. In Control of
Sorghum Shoot Fly, (M.G. Jotwani. and W.L. Young, Eds). (Oxford
and I.B.M., New Delhi), pp. 129-135.
CLEARWATER, J.R., 1981. Practical identification of the female of five
species of Atherigona Rondani (Diptera: Muscidae) in Kenya.
Tropical Pest Management, 27, 303-312.'
DAVIES, J.C., SESHU REDDY, K.V. and REDDY, Y.V., 1980. Species of shoot
flies reared from sorghum in Andhra Pradesh, India. Tropical Pest
Management, 26, 258-261.
DEEMING, J.C., 1971. Some species of Atherigona Rondani (Diptera:
Muscidae) from northern Nigeria, with special reference ta those
injurious ta cereal crops. Bulletin of Entomological Research,
61, 133-190.
DEEMING, J.C., 1972. Two remarkable new species of Atherigona Rondani
(Dipt., Muscidae) from Nigeria and Cameroun. Entomologist's
Monthly Magazine, 108, 3-6 •
DEEMING, J.C., 1978. New and l ittle known species of Atherigona
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Rondani (Dipt., Muscidae) from Nigeria and Cameroun.
Entomologist's Monthly Magazine, 114, 31-52.
DEEMING, J.C., 198!. New and little known African species of
Atherigona Rondani (Dipt., Muscidae). Entomologist's Monthly
Magazine, 117, 99-113.
DELOBEL, A.G.L. and UNNITHAN, G., 1983. Influence des températures
constantes sur les caractéristiques des populations d'Atherigona
soccata (Diptères, Muscidae). Acta Oecologia and Applicata, 4,
351-368.
DOHAREY, K. L., SRIVASTAVA, B.G., YOUNG, M.G. and DANG, K., 1977.
Effect of temperature and humidity on the development of
Atherigona soccata Rondani. Indian Journal of Entomology;39,
211-215
DOUMBIA, Y.O. and GAHUKAR, R.T., 1986. Atherigona soccata Rondani et
autres mouches nuisibles au sorgho au Mali. Agronomie Tropicale,
41, 170-172.
ECKENRDDE, C.J. and ARN, H., 1972. Trapping cabbage maggots with plant
bait and allyl'isothiocyanate. Journal of 'Economie Entomology,
65, 1343-13~5.
GAHUKAR, R.T., 1985. Some species of Atherigona (Diptera: Muscidae)
reared from Gramineae in Sénégal. Annals of Applied Biology, 106,
399-403.
GAHUKAR, R.T., 1987. Population dynamics of sorghum shoot fly,
Atherigona soccata (Diptera: Muscidae) in Sénégal. Environmental
Entomology, 16, 910-916
JOBIN, L.J., 1985. Development of a large capacity Pheromone trap for
Monitoring forest insect pest populations. In Proceeding of the
CANUSA Spruce Budworm Research Symposium, (C.J. Sanders, R.W.
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Stark, E.J. Mullins and J. Murphy, (Eds.), Bangor, Maine,
September 16-20, 1984, pp. 243-245.
NATARAJAN, K. and S. CHELLIAH, 1983. A new method to control sorghum
shoot fly. Pesticides, 17, 37.
NWANZE, K.F., 1988. Distribution and seasonal incidence of some major
insect pests of sorghum in Burkina Faso. Insect Science and its
Application, 9, 313-321.
SESHU REDDY, K. V. and DAVIES, J .C., 1978. Attractant traps for the
assessment of sorghum shoot fly, Atherigona soccata Rondani
populations. Bulletin of Entomology, 19, 48-51
STARKS, K.J., 1970. Increasing infestation of the sorghum shoot fly in
experimental plots. Journal of Economie Entomology, 63, 1715·
1716 .
STEEL, R.G.D. and TORRIE, J.H. 1980. Principles and procedures of
statistics, A biometrical approach, McGrall-Hill Book Company,
New York, 633 pp.
TANEJA, S.L. and LEUSCHNER, K., 1986. A simple trap for monitoring
sorghum shoot fly. Indian Journal of Plant Protection, 14, 83
86.
YOUNG, W.R., 1981. Fifty-five years of research on the sorghum shoot
fly. Insect Science and its Application, 2, 3-9.
ZONGO, O.J., 1987. Entomologie du sorgho et mil. In Rapport de
synthèse de la campagne 1986. M.A.E., D.A. Service Protection
des Végétaux, (Burkina Faso: Laboratoire de Recherches Bobo
Dioulasso), pp. 1-3 .
•
•
•
3.7. TABLES
38
• 39
Table 2. Atherigona spp. catches in four trap models in Burkina Faso, 1988 and1989
Trap Farako-Bâ, 1988 Matourkou, 1989model
No. shoot flies Mean' No. shoot fl ies Mean'
Water trap 32161 8040' 10028 2507'
Multi-Pher 25336 6334' 1511 377'
• ICRISAT 14978 3745' 449 112'
Conical 4459 1115' 349 87'
1 L.S.O ~1547; , L.S.O- 178; P ~ 0.05.; means with the same letter are not
significantly different .
•
.. 40
Table 3. Sorghum shoot fly Atherigona soccata (male + female) catches in four
trap models in Burkina Faso 19BB, 19B9
Trap Farako-Bâ 1988 Matourkou 1989
model
No. A. soccata Mean' No. A. soccata Mean'
• Water trap 891 223' 718 180'
Multi-Pher 1214 304' 340 85'
ICRISAT 740 185' 113 28'
Conical 386 97' 51 13'
1 L.S.O .74; 'L.S.O • 43; p. 0.05; means with the sameletter are not
significantly different .
•
• 41
Table 4. Relative abundance of Atherigona and Acritochaeta males captured inBurkina Faso 1988, 1989
Percentage of total seasonal captures
Sor9hum shootfly species
Farako-Bâ 1988New
Matourkou 1989 Mention inBurkina Faso
Atherigona aberrans Malloch 2.10 1.24 yesAtherigona africana Deeming 0.36 l.rsAtherigona albistyla Deeming 2.28 2.36Atherigona bimaculata Stein 0.98 1
Atherigona budongoana van Emden 7.51 1.58 1.:
Atherigona fililoba Deemin~ 0.76 0.18 yesAtherigona gabonensis Deemlng 0.08 yesAtherigona gilvifolia van Emden 0.03 yesAtherigona hriseiventris van Emâ&n 0.03 yesAtherigona ancocki van Emden 0.32 0.70 ..'Atherigona hyalinipennis van Emden 0.47 0.52 yesAtherigona insignis Deeming 1.19 1.84 •Atherigona lineata Adams 4.75 4.74 1.'Atherigona longifolia van Emden 0.65 2.12 1Atherigona marrinifolia van Emden 3.59 2.80 1.'Atherigona med eri Deeming 0.08 r.~s• Atherigona mirabilis Deeming 2.65 1.32Atherigona naqvii Steyskal 0.69 0.70 1
Atherigona nigeriensis Deeming 0.03 •Atherigona nigr~iCalis Deeming 0.52 yesAtherigona occi entalis Deeming 14.85 29.97 1
Atherigona pallidipleura Deeming 2.79 0.62 1.'Atherigona pedunculata van Emden 3.16 0.08 1.'Atherigona ponti Deeming 0..03 0.78Atherigona pulla Wiedemann 0.39 0.26 r.~sAtherigona rubricornis Stein 0.29 0.18Atherigona ruficornis Stein 0.03 r.~sAtherigona samaruensis Deeming 1.77 0.36Atherigona secrecauda Séguy 3.23 7.02 1.'Atherigona soccata Rondani 32.0 19.63 1.'Atherigona tomentigera van Emden 5.63 18.22 1.-Atherigona truncata van Emden 4.03 0.62 1.'Atherigona valida Adams 0.07 1.'Atherigona (s.s.) sp. n. 0.76 0.08 r.~sAcritochaeta orientalis Schiner 2.10 1.24Acritochaeta yorki Deeming 0.03 yes
Total 2753 1141
l Mentioned in Bonzi and Gahukar (1983) •• Mentioned in Bonzi (1981)
••
• 42
Table 5. Time required to collect and count shoot flies from four trap modelsin the field, Burkina Faso, 1988
Ti me (min.) for counting
Trap Without1 Counting' Total insects Atherigonamodel counting all insects captured spp.
Atherigona spp. includingAtherigona spp.
Water trap 32 80 1315 40.22• Multi-Pher 28 43 606 82.04
1CR15AT 9 13 221 80.54
Coni cal 4 5 48 56.25
Mean of four counts.
Mean of two counts .
•
• 43
Table 6. Adult shoot f1 ies (Atherigona spp.) monthly captures, rainfall and
relative humidity in southwestern Burkina Faso.
Farako-Bâ 1988 Matourkou 1989
Month Rainfail R.H. No. Rainfall R.H. No.
(mm) (%) shoot- (mm) (%) shoot-
flies flies
captured captured
January 25.2 29.2
February 18.9 15.3
March 3.8 31.5 25.1 27.1
April 56 48.4 10 46.6
May 83 56 59.4 51.0• June 98.5 69 126.3 63.9
July 193.8 77.4 840' 155.1 73.7
August 195.8 80.43 22218 365.6 90.3 3951
September 305.3 78.3 40745 144.2 77 .1 6824
Octaber 62.5 64.8 12446 40.8 65.6 1449
November 50 685' n.a. n.a. 124'
,Catches of 1 week.
Catches of 2 weeks
•
n.a. E Not available .
•
•
•
44
CONNECTING STATEMENT
Appropriate sampl ing techniques are essential to IPM programs
because they provide informati en on the crop. and insect pest under
study and allowing recommendations for intervention (Boivin and Vincent
1983). In chapter 3, adult shoot fly population densities were
evaluated by trapping with defined peak captures. It is well
established that damage caused by the shoot fly is a function of its
population densities (Gahukar 1987). Knowing the fluctuation of adult
shoot fly populations, it becomes necessary to assess eggs by sampling
in order to improve recommendations in controll ing the pest before-~
damage. Sequential sampling is an important technique in IPM prograll)s,
allowing time and money saving (Krebs 1989). Time-sequential sampling,
a new use of sequential sampling, allows timely decisions and reduces
trips to the field (Pedigo and van Schaik 1984). This chapter deals
,with time-sequential sampling for the sorghum'shoot fly based on egg
and dead heart counting •
.---'
•
•
•
45
4 TIME-SEQlIENTIAL SAMPLING OF SORGHUM SHOOT FLY. ATHERIGONA SOCCATA
RONOANI (DIPTERA: MUSCIDAE). IN BURKINA FASO.
In press in Insect Science and its Application
Authors: Joanny O. ZONGO. Charles VINCENT. and Robin K. STEWART
•
•
•
46
4.1. ABSTRACT
Field experiments were conducted in 1988 and 1989 in sorghum
fields at three localities near 80bo-Dioulasso (Burkina Faso), West
Africa. Eggs and dead hearts were sampled every fifth day starting 10
days after sowing. The second and third leaves of sorghum plants were
preferred for oviposition. The maximum number of eggs laid per plant
and per leaf were three and two, respectively. The distribution of
eggs was random in most (38 out of 39) sampling dates. Pooling data by
year (n = 16), the coefficients of correlation between average egg
number and average dead hearts were r = 0.89, 0.87, and 0.80 at
Matourkou, Sogossagasso, and Darsalamy, respectively. A time
sequential sampling plan based on the POISSON distribution was
establ ished for the sorghum shoot fly, Atherigona soccata Rondani
(Diptera: Muscidae) using eggs and dead hearts.
•
•
••
47
4.2. INTRODUCTION
The sorghum shoot fly, Atherigona soccata Rondani (Diptera:
Muscidae), is a key limiting factor of sorghum, Sorghum bic%r (Linné,
Moench), production in the wetter southern zones of Burkina Faso,
particularly when rainfall dictates delay planting (Brenière 19ï2;
Bonzi 1981). In southern Burkina Faso, high shoot fly damage (15-46%
dead hearts) has been recorded in farmers' fields (Nwanze, 1988).
Sorghum shoot fly research focused on various management
practices, including the use of systemic insecticides, cultural
control, and the release of high yielding resistant varieties (Young
1981). However, a complete Integrated Pest Management (IPM) program
is yet to be developped.
Sequential sampling is an important step forward in the
development of IPM programs (Boivin and Vincent 1983). In sequential
sampling schemes, sample size is not fixed in advance, resulting in
considerable savings in time and money (Krebs 1989). The number of
samples required may thus be reduced by 47-63% (Wald 1947) or, in sorne
cases, up to 79% (Pieters and Sterl ing 1974). Sequential sampl ing
plans have been published for many pests (Pieters 1978). Pedigo and van
Schaik (1984), developed and used a time-sequential sampling plan based
on the fact that number of insects have characteristic distributions in
time, as well as in space. This approach is valuable in studying
populations which may be sporadic, or build up rapidly, and decl ine
before the end of the season. It allows decisions to be made as to
when to sample in the season,' and when to el iminate entire sampl ing
periods. Compared to a fixed program of nine sampling periods, Pedigo
and van Schaik (1984) found savings of 44 to 67% of resources for the
green cloverworm, P7athypena scabra (F.), whose outbreaks occur
•
•
•
48
sporadically in Iowa, U.S.A..
Sorghum shoot fly populations and damage vary with environmental
factors, plant varieties, and plant phenological stage (Bonzi 1981,
Brenière 1972, Gahukar 1987, Jotwani et al. 1970, Nwanze 1988, Rai et
al. 1978, Zongo et al. 1991). Shoot fly damage is usually low « 10%)
for early sowings in Burkina Faso (Nwanze 1988) making A. soccata a
sporadic pest at this time. Therefore, time-sequential sampling is
appropriate for this pest. Delobel (1981) worked on the distribution
of sorghum shoot fly eggs in the laboratory and in field conditions
using small plots at Nairobi and Mbita, Kenya. He found, on 21 sample
occasions, that the distribution of eggs within the field was
consistentlya POISSON, although about half of these distributions also
agreed with the Negative Binomial.
No sequent i al sampli ng plans have been yet publ i shed for the
sorghum shoot fly, and the present investigations were undertaken to
establish a time-sequential sampling plan for this pest.
4.3. MATERIALS AND METHODS
Experiments were conducted in 1988 and 1989 at Matourkou,
Darsalamy and Sogossagasso in sorghum fields (60 x 40 m) located ca. 10
, 15 and 35 km from Bobo-Dioul asso (11°11 'N, 4°18'W), respectively.
At Darsalamy and Sogossagasso farmers' fields were used while the
field at Matourkou was located in a research station. The local.
sorghum variety "Gnofing" was sown on 12, 13 and 14 July, one month
after normal planting dates-respectively, at Matourkou, Sogossagasso
and Darsalamy. Inter-row and intra-row were 0.80 m and 0.40 m,
respectively. Fields were fertilized with 200 kg/ha of NPK (15-15-15)
appl ied in two occasions, (namely 100 kg/ha at sowing time, '-...-.1""
100kg/ha 30 days after sowing). Fifty kg/ha of urea (46%) were applied
•
•
•
49
45 days after sowing.
In each field, samples were taken on eight occasions, every fifth
day, starting 10 days after planting. On each occasion, sorghum shoot
fly eggs were counted on 30 randomly selected plants. Each plant was
carefully inspected; the position of each egg and the number of leaves
were noted from top to bottom. The number of eggs per leaf was also
recorded. Dead hearts were counted on 100 randomly selected plants.
Departure from a random dispersion was tested for each local ity and
year by using the following method:
ID= S2 (n-1)/X,
where ID is the index of dispersion,
where S2 = variance, n is the number of samples, and X= mean number of
eggs or dead hearts (Krebs 1989). The Chi-square x2 (with n-1 df) was
used to test the observed dispersion. There were 29 df for eggs and 99
for dead hearts. If a data set followed the 'POISSON distribution, the
value of ID lied within the limits /0.975 and /0.D25.The standardized
Morisita index of dispersion (Ip ) (Smith-Gill 1975) ranging from -1.0
to +1.0, with 95% confidence limits was used to calculate the
di spersi on when a val ue of ID l ay outside the l imits defined previ ously.
Arandom pattern gave Ip of zero. Aggregated and regul ar pattern occured
when Ip was above and below zero respectively (Krebs 1989).
To calculate the time-sequential sampling parameters, data of all
local ities were pooled. The main parameters required for POISSON
distribution were:
hl = log [ B1(1 - a) ]
h2 = log [(1 - BI) a];
•
•
•
50
where h, and h2 are intercepts, llIoi = mean number of the eggs or dead
hearts expected in the i th sample of an endemic population, m'i= mean
number of the eggs or dead hearts expected in the i th sampl e of an
outbreak population, bt is a slopelike parameter, Wi is a weighting
coefficient, dt is a weighted cumulative number of eggs or dead hearts
observed, ri is the number of eggs or dead hearts in the i~ sample, Q
is probability of calling a population endemic when it is outbreak, and
B is probability of calling a population outbreak when it is endemic.
The boundaries of the decision zones after the t~sample are calculated
as follows:
d't= h,+ bt (lower limit)
d2t = h2+ bt (upper limit)
The class limits (m., m,) on each sampling data describing endemic and
outbreak populations were determined using pooled data from the three
localities and the two years. Because economic injury levels vary from
one cultivar to another (Rai et a7. 1978), and that no formal economic
injury level has yet been published for sorghum growing in West African
conditions, we used a nominal threshold based on unpublished work that
we conducted at Matourkou, Bobo-Dioulasso from 1988 to 1990 (Table 7).
The level of acceptable error was set at 0.1 for both Q and B, as
recommended by Waters (1955).
•
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51
4.4. RESULTS
Sorghum shoot fly females laid their eggs mostly on the second
(40.48%) and third (50.28%) leaves (Table 8). The maximum number of
eggs laid per plant and per leaf were three and two, respectively.
Seasonal average number of eggs per plant and percent of dead
hearts were greater in 1988 than in 1989 at Matourkou and Sogossagasso
(Table 9, 10). Four times out of S, the peak number of eggs and the
average peak of dead hearts coincided on the same sampling date. In
1989, peak number of eggs and dead hearts occurred on the 7th sampling
date in all localities (Table 9, 10).
The distribution pattern of eggs was random in most (38 times
over 39) sampling dates. An aggregated pattern occurred at Matourkou
on August 6th, 1989 (Table 9). The dispersion patterns of dead hearts
were random (38 times over 42), and regular (4 times over 42) (Table
10). In Sogossagasso, the dispersion pattern of both eggs and dead
hearts was consistently random in 1988 and in 1989 (Table 9, 10). In
Darsalamy, the dispersion pattern of eggs was random, whereas dead
hearts were randomly distributed on six sampling dates and regularly
distributed on one occasion (Table 9, 10). Using pooled data (by date)
of the two years, the distribution of eggs was random in the three
localities, whereas dead hearts were randomly distributed in
Sogossagasso and Darsalamy; and randomly and regularly distributed in
Matourkou.
A positive significant ~ ~ 0.05) correlation (r • 0.87, n- 48,
all years and localities pooled) has been found between egg abundance
and dead hearts, the regression equation being Y • -1.34S7e-2 +
0.9420Sx. The coefficient of correlation and regression equation (n •
IS, all years pooled for each locality) were: r = 0.89, Y= -3.170Se-2
• 52
+ 1.0487x for Matourkou; r = 0.87, Y = -6.1350e-3 + 0.87603x for
Sogossagasso, and r = 0.80 , Y= 6.9524e-3 + 0.76155x for Darsalamy.
We chose a tabular presentation (Table 11, 12) for the time
sequential sampling plan as Pedigo and van Schaik (1984) found this
format most convenient.
4.5. DISCUSSION
The second and third leaves were preferred for oviposition. Our
results agree with Ogwaro (1978), who found that 28.5 and 54.1% of
total eggs were deposited on the second and thir~ leaves, respectively.
After hatching, the first instar larva takes one to six hours to reach
the base of the leaf sheath (Doggett 1988). Because eggs are
•
•
preferentially laid on second and third leaves, first instar larvae are
near the site of penetration in the main shoot; this reduces exposure
to natural enemies and adverse climatic conditions. Although Ogwaro
(1978) recorded a few eggs on the sixth and the seventh leaves, we
found no eggs when the sorghum plants had more than five leaves.
Ogwaro (1978) pointed out that the lower leaf surfaces were preferred
for oviposition, which we also observed.
Our results on egg distribution confirm Delobel's (1981) finding
that the distribution of sorghum shoot fly eggs is random or slightly
aggregated. Aggregated distribution occurred occasiorally when many
plants bore more than one egg. The biological consequence of such a
distribution is that many larvae hatching from these eggs will perish
as usually only one larva develops in a single shoot (Delobel, 1981).
Dead hearts caused by the sorghum shoot fly were frequently
randomly distributed and, on few occasions, regularly. In 1988, average
dead hearts were higher in Matourkou (research station) than in
Sogossagasso and in Darsalamy. ICRISAT (1983, 1984) and Nwanze (1988)
•
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.'
53
found similar differences in infestation level and pointed out that
this is due to different varieties and sowing dates. However, in 1989
the percentage of dead hearts was higher in Darsalamy (31%) than in
Matourkou (14%). We observed 22% dead hearts in Sogossagasso on August
17th, 1988 whereas Nwanzc (1988) found 26% in the same locality
(unknown sampling date). However, the percentage of dead hearts were
much lower (6%) in 1989 at Sogossagasso.
Rainfall and relative humidity are important factors for sorghum
shoot fly population outbreaks (Naitam and Sukhani 1985, Gahukar 1987).
Zongo et al. (1991) noted that rainfall and relative humidity were
higher in 1988 than in 1989 with, as a consequence, a higher shoot fly
infestation level in 1988. The seasonal variation in oviposition and
dead heart prevalence observed in our study is thus partly due to
climatic conditions. Similar seasonal variation in oviposition and
dead heart have been reported by Gahukar (1987), and Jotwani et al.
(1970).
Time-sequential sampling is intended to address the problem of
when samples should be taken in the season (Pedigo and van Schaik
1984). For the sorghum shoot fly, sampl ing efforts should coyer the
early stage of sorghum seedlings, as Rai et al. (1978) found that early
attack leads to complete destruction of the plar.ts. In addition,
Jotwani et al., (1970) found that the most susceptible stage for
infestation is within 21 days after germination.
Sampling dead hearts as an early detection method does not allow. -
enough time to plan and implementcontrol actions in due time. However,
our sequential sampling plan may prove to be useful for rapid survey of
shoot fly damage. In general, control measures should be taken before
dead hearts formation. Therefore, egg sampling is most appropriate in
•
e
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54
an IPM context. This approach allows sufficient time to undertake
controi actions as Barry (1972) found that eggs hatch within 2-5 days
after oviposition and dead heart formation occurs 2-3 days after
hatchi ng. An effect ive management program of the sorghum shoot fly
should be adapted to local conditions. Whatever the agronomie
conditions, egg sampling should be used as a monitoring technique to
alert farmers of threatening population levels.
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55
4.6. REFERENCES
Barry, D. 1972. Notes on life history of a sorghum shoot fly,
Atherigona varia soccata. Ann. Entomo7. Soc. Am. 65, 586-589.
Boivin, G. and Vincent, C. 1983. Sequential samplin9 for pest control
programs. Agriculture Canada, Technical Bulletin 1983-14Ei
Agriculture Canada, Research station, Saint-Jean-sur-Richelieu,
Québec, Canada. 29 p.
Bonzi, S.M. 1981 Fluctuations saisonnières des populations de la
mouche des pousses de sorgho en Haute-Volta. Insect Sei. App7ic.
2, 59-62.
Brenière, J. 1972. Sorghum shoot fly in West Africa, pp. 129-135, In
Contro7 of sorghum shoot f7y, (Jotwani, M.G. and W.L. Young
Eds). Oxford and I.B.M., New Delhi .
Delobel, A.G.L. 1981. The distribution of the eggs of the sorghum
shootfly, Atherigona soccata Rondani (Diptera: Muscidae). Insect
Sei. App7ic. 2, 63-66.
Doggett, H. 1988. Sorghum. Longman Scientific &Technical, Harlow U.K.
pp. 301-306.
Gahukar R.T. 1987. Population dynamics of sorghum shoot fly, Atherigona
soccata Rondani (Diptera: Muscidae), in Senegal. Environ.
Entomo7. 16, 910-916.
International Crops Research Institute for the Semi-Arid Tropics
(ICRISAT) 1983. Annua7 Report 1982, International Cooperation,
Patancheru, India, pp. 363-365.
International Crops Research Institute for the Semi-Arid Tropics
(ICRISAT) 1984. Sahe7ian Center Annua7 Report 1983, Entomo7ogy,
ICRISAT Niamey, Niger, pp. 31-37 .
Jotwani, M.G., Marwaha, K.K., Srivastava, K.M. and Young, W.R. 1970.
•
•
•
56
Seasonal incidence of shootfly (Atherjgona varja soccata Rond.)
in jowar hybrids at Delhi. Indjan. J. Ent. 32, 7-15
Krebs, C.J. 1989. Ecological methodology. Harper &Row Publishers, New
York. 654 p.
Nait"m, N.R. and Sukhani, T.R. 1985. Ovipisition behavior of the
sorghum shootfly Atherjgona soccata Rondani under different soil,
plant and weather parameters. Indjan J. Ent. 47, 195-200
Nwanze, K.F. 1988. Distribution and seasonal incidence of sorne major
insect pests of sorghum in Burkina Faso. Insect Scj. App7jc. 9,
313-321.
Ogwaro, K. 1978. Ovipositional behaviour and host-plants preference of
the sorghum shootfly, Atherjgona soccata (Diptera: Anthomyiidae).
Entom07. exp. app7. 23, 189-199 .
Pedigo, L.P. and van Schaik, J.W. 1984. Time-sequential sampling: Anew
use of the sequential probability ratio test for pest management
decisions. Bu77. Ent. Soc. Am. 3D, 32-36.
Piet<;lrs, E. P. 1978. Bibliography of sequential sampling plans for
insects. Bu77. Ent. Soc. Am. 24, 372-374.
Pieters, E. P. and Sterling, W.L. 1974. Asequential sampling plan ~or
the cotton leafhopper, Pseudatomosce7js' serjatus. Envjron.
Entom07. 3, 102-106.
Rai, S., Jotwani, M.G. and Jha, D. 1978. Economic injury level of
shootfly, Atherjgona soccata (Rondani) on sorghum. Indjan J.
Ent. 40, 126-133.
Smith-Gill, S.J. 1975. Cytophysiolog~ca1 basis of disruptive pigmentary
patterns in the leopard frog Rana pjpjens II. Wild type and
mutant cell specific patterns. J. Morph. 146, 35-54 •
Wald, A. 1947. Sequential analysis. Dover Publications, INC. New York.
•
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57
212 p.
Waters, W.E. 1955. Sequential sampling in forest insect surveys. For.
Sci. l, 68-79.
Young, W.R. 1981. Flfty-five years of research on the sorghum shoot
fly. Inseet Sei. App7ie. 2, 3-9.
Z.:Jngo, J.O., Vincent, C. and Stewart, R.K. 1991. Monitoring adult
sorghum shoot fly Atherigona soeeata (Rondani) (Di ptera:
Muscidae), and related species in Burkina Faso. Trop. Pest
Manag. 37, 231-235 .
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•
4.7. TABLES
58
• 59
Table 7. Endemie (~) and (m,) outbreak population configurations of Atherigona
spp. eggs (n=30) and dead hearts (n=100), Burkina Faso.
Sample Days Eggs Dead heartsdate after
sowingm• m, m. m,
• 1 10 2 6 4 102 15 3 8 7 123 20 5 10 10 144 25 7 13 12 175 30 9 15 13 196 35 12 17 15 207 40 13 19 16 21B 45 5 7 B 15
••
•
•
Table 8. Sorghum shoot fly egg distribution on leaves in three 10ca1ities,
1 Number of times eggs were deposited on the leaf •
60
• 62
Tabl e 10. Mean (n= 100), vari ances , and di spersi on characteri st i cs of deadhearts caused on sorghum by Atherigona spp. in three localities, BurkinaFaso.
LocalitySamplingperiod
Matourkou
x
1988
10 x
1989
10
•
July 22 0.00July 27 0.00August 1 0.03August 6 0.15August Il 0.45August 16 0.58August 21 0.37August 26 0.07
Sogossagasso
July 23 0.01July 2B 0.00August 2 0.01August 8 0.12August 12 0.18August 17 0.22August 22 0.08August 27 0.02
Darsalamy
0.000.000.0290.1280.2500.2400.2300.062
0.0100.000.0100.1020.1440.1680.0720.019
0.000.0095.04'84.15'54.45"40.59"61.38"87.12'
99'0.0099'84.15'79.20'75.24'89.10'94.05"
0.000.000.020.040.060.080.14
. 0.05
0.010.020.030.020.050.040.060.02
0.000.000.0190.0360.0520.072O.lIs0.044
0.100.0190.0290.0190.0440.0360.0520.019
0.000.0094.05"89.10"85.14'89.10'81.18'87.12'
99'94. os"95.04'94. os"87.12'75.24'85.14'94.05'
July 24July 29AU9ust 3AU9ust 8August 13August 18August 23August 28
0.020.040.020.060.130.120.140.05
0.0190.0360.0190.0520.1080.102O.lIs0.044
94. OS'89.10'94. OS'85.14'82.17'84.5'81.18'87.12'
0.000.010.030.030.050.260.310.26
0.000.0100.0290.0290.0440.1940.2160.194
0.0099'9s.0s"9s.0s"87.12"73.95'68.31'"73.95'
•, POISSON distribution as 10 lies within the limits 73.46 (/0.915) and 128.31(/o.m)for 99 df.
" Tests with 10 indicated that these data were not a Poisson distribution; Iptests suggested a regular pattern as Ip wa$ -1 in ~latourkou and ·-0.25 inDarsalamy.
••
•
.Tab
leIl
.T
ime-
sequ
entia
lsa
mpl
ing
plan
base
don
egg
coun
tsof
sorg
hum
shoo
tfl
yA
ther
igon
aso
ccat
a.
ab
cd
Sam
ple
Num
ber
Wei
ghtin
gW
eigh
ted
Low
erT
otal
ofU
pper
li/l
lit
num
ber
coun
ted
fact
orco
unt
lim
itw
eigh
ted
coun
t
1e
0.47
71St
op3.
05C
ontin
ue4.
95St
op2
0.42
59sa
mpl
ing
4.05
sam
plill
g5.
95an
d3
0.30
104.
055.
95ap
ply
40.
2688
3.05
4.95
trea
tmen
t5
0.22
183.
054.
956
0.15
124.
055.
957
0.16
485.
056.
958
0.14
611.
052.
95
Dir
ecti
ons:
Sam
plin
gsh
ould
best
arte
dfro
mat
leas
t10
days
afte
rso
win
gun
til
40da
ysaf
ter
sow
ing.
Sam
ples
are
tobe
take
nev
ery
fift
hda
y.Th
enu
mbe
rof
eggs
coun
ted
(e)
isre
cord
edin
colu
mn
aan
dth
enm
ulti
plie
dby
the
wei
ghtin
gfa
ctor
(col
umn
b).
Thi
snu
mbe
ris
reco
rded
inco
lum
nsc
and
d,an
dco
mpa
red
toth
elo
wer
orth
eup
per
lim
it.
Ifth
enu
mbe
rin
colu
mn
dex
ceed
sth
eup
per
lim
it,
stop
sam
plin
gan
dap
ply
trea
tmen
t.If
the
num
ber
isbe
low
the
low
erli
mit
,st
opsa
mpl
ing.
Ifth
enu
mbe
rex
ceed
sth
elo
wer
lim
lt,
cont
inue
sam
plin
g.
63
••
•
Tab
le12
.T
lme-
sequ
entla
lsa
mpl
lng
plan
base
don
dead
hear
tco
unts
caus
edby
the
sorg
hum
shoo
tfl
y,A
ther
igon
aso
ccat
a. ab
cd
Sam
ple
Num
ber
Wel
ghtln
gW
elgh
ted
low
erT
otal
ofU
pper
llm
ltnu
mbe
rco
unte
dfa
ctor
coun
tlI
mlt
wel
ghte
dco
unt
1e
0.39
79En
dem
ie5.
05C
ontin
ue6.
95O
utbr
eak
20.
2340
popu
latio
n4.
05sa
mpl
lng
5.95
popu
latio
n3
0.14
613.
054.
954
0.15
124.
055.
955
0.16
485.
056.
956
0.12
494.
055.
957
0.11
804.
055.
958
0.13
463.
054.
95
Dir
ecti
ons:
Sam
plln
gsh
ould
best
arte
dfro
mat
leas
t10
days
afte
rso
wln
g.Sa
mpl
esar
eto
beta
ken
ever
yfl
fth
day
untl
l40
days
afte
rso
wln
g.Th
enu
mbe
rof
dead
hear
tsco
unte
d(e
)Is
reco
rded
lnco
lum
na
and
then
mul
tlpl
led
byth
ew
elgh
tlng
fact
or(c
olum
nb)
.T
his
num
ber
Isre
cord
edln
colu
mns
can
dd
and
com
pare
dto
the
low
eror
the
uppe
rll
mlt
.If
the
num
ber
lnco
lum
nd
exce
eds
the
uppe
rll
mlt
,th
epo
pula
tion
lndl
cate
san
outb
reak
.If
the
num
ber
Isbe
low
the
low
erll
mlt
,th
epo
pula
tion
Isen
dem
lc.
64
•
•
••
65
CONNECTING STATEMENT
In Chapter 3, the relative abundance and species composition of
shoot flies in the field were assessed while chapter 4 provided
information on the emergence pattern of shoot fly eggs and damage with
a subsequent time-sequential sampling scheme. It is essential to
investigate whether changes in shoot fly abundance can be linked with
particular cultural practices. Cultural controls, the oldest methods
for managing insect pest populations are preventive rather than
curative (Knipling 1979, Hill 1989). They are important in IPM
programs, particularly in developing countries where the technical and
educational level of farmers is low. Cultural practices such as
manipulating sowing dates or intercropping could help to escape attack
by the shoot fly. The goal of this chapter is to answer questions on
when to sow sorghum to escape heavy shoot fly damage. Another
hypothesis investigated was whether intercropping sorghum-cowpea could
reduce shoot fly damage •
•
•
•
5 Influence of Cultural Practices on Sorghum Yields and
Incidence of Sorghum Shoot Fly, Atherigona soccata
Rondani (Diptera: Muscidae), in Burkina Faso•
To be submitted to Sahel Phytoprotection, August 1992.
Authors: ZONGO, J.O., STEWART, R.K., VINCENT, C.
66
•
•
•
67
5.1. ABSTRACT
Field experiments were conducted in 1988, 1989 and 1991 in a
sorghum field at Matourkou, Bobo-Dioulasso (Burkina Faso), to determine
plant spacing arrangements for intercropping sorghum-cowpea, Sorghum
bicolor [L.] (Moench)-Vigna unguiculata [L.] Walp., and the most
suitable sowing dates and plant densities for avoidance and reduction
of yield 10~ses caused by the shoot fly, Atherigona soccata Rondani
(Diptera: Ml!~cidae). Observations were recorded on eggs and dead hearts
17 and 28 days after plant emergence respectively. In both 1988 and
1989, intercropping systems gave a LER (Land Equivalent Ratio) higher
than one. In 1988 and 1991, no significant differences were observed
with respect to the number of eggs laid, the percentage of plants
bearing eggs and the percentage of dead hearts. In 1989, significant
differences were only observed with respect to dead heart incidence.
Sowi ng dates between June 20 and 30 were acceptable whereas sowi ng
dates after June 30 should be avoided. Plant densities were not
significant with respect to damage. Significant negative correlation
existed between the percentage of dead hearts and the yi~ld in all the
five sowing dates, between the yield and the sowing dates, and between
the yield and the numbers of tillers .
•
•
•
68
5.2. INTRODUCTION
The shoot fly, Atherigona soeeata Rondani (Diptera: Muscidae),
is an important pest of sorghum, Sorghum bieo7or (Linné, Moench), in
West Africa (Nwanze 1985, Gahukar 1990), including Burkina Faso (Bonzi
1981, Nwanze 1988).
Several species of shoot fly are injurious to sorghum (Deeming,
1971) but in Burkina Faso, A. soeeata accounted for over 96% of the
flies reared from sorghum shoots (Nwanze, 1988). Several control
strategies have been suggested including insecticide applications, the
use of resistant varieties, cultural practices (Young, 1981) and
sequential sampiing (Zongo et a7. 1992).
Mixed cropping represents 80% of the cultivated area in West
Africa (Steiner, 1984). This practice may decrease insect pest
populations (Vandermeer, 1989). Compiling the results from 150
publ i shed studi es on the effect of di versi fying agroecosystems on
insect pest populations, Risch et a7. (1983) found that 53% of insect
pest species (n = 198) were less abundant in the more diversified
system, 18% were more abundant in the diversified system, 9% showed no
difference, and 20% showed a variable response. Intercropping sorgh~m
cowpea, Vigna unguieu7ata [L.] Walp. is widely practiced by Burkina
Faso farmers, the main advantages being the rational use of land,
labour saving and diversified food supply. Cowpea is usually harvested
before sorghum and serves as a food supply before regul ar harvest
periods.
In India, sorghum shoot fly damage was severe when sorghum was
intercropped with ground nuts (Venugopal and Palanippan, 1976). In
Kenya, Raina and Kibuka (1983) found that intercropping sorghum-maize
in different planting holes or in the same hole did not significantly
•
•
•
69
affect shoot fly oviposition on either crop.
Modifying planting dates is also one of the most widely used
methods to cause asynchrony between crops and insect pests. In Burkina
Faso, Brenière (1972) evaluated shoot fly damage for three different
sowing dates in the west central region (i.e. 5aria, Koudougou) and
found that sorghum seedlings were less damaged with early sowing dates.
In India, several authors from different localities have studied the
effects of sowing dates and seed rates on the incidence of the shoot
fly and found that early sowing helped to avoid and reduce damage (Ram
et al. 1976, Gandhale et al. 1982, Mote, 1983).
To implement sound IPM programs, various tactics have to be
investigated. The present investigations were undertaken to determine
plant spatial arrangements and the most suitable sowing date and
optimum seed rate to avoid losses caused by the shoot fly and to obtain
good yields under Burkinabè conditions.
5.3. MATERIAlS AND METHODS
The st~dy was carried out in 1988 and 1989 at Matourkou, located
ca. 10 km from Bobo-Dioulasso (l1°lI'N, 4°18'W), Burkina Faso, West
Africa.
5.3.1. Experimental Series A: Intercropping
Five cropping systems we'"e appl ied in a randomized complete
block design with four replicates: 1) 5" pure sorghum; 2) 52' one row
of sorghum + one row of cowpea; 3) 53' two rows of sorghum + two rows
of cowpea; 4) 5., two rows of cowpea + three rows of sorghum; 5) 55'
pure cowpea (Fig. 1). Each plot measured 7.5 x 5 m and contained 10
rows. Row spaci ngs were 0.75 min all plots whereas i ntra-row spaC'ings
were 0.25 and 0.20 mfor sorghum and cowpea respectively. One and two
seedlings were maintained per hill for cowpea and sorghum respectively.
•
•
•
70
Ten tons/ha of cow dung were applied at plowing time. Plots were
fertilized with 200 kg/ha of NPK (15 15 15) applied on two occasions,
i.e. 100 kg/ha at sowing time, and 100kg/ha 30 days after sowing. Fifty
kg/ha of urea (46%) were applied 45 days after sowing.
Cowpea plants were treated with Decise (Procida/Roussel Uclaf,
Abidjan, Côte d'Ivoire), deltamethrin EC, 12 9 a.i/ha at 30 and 40 days
after sowing to control thrips and pod sucking bugs. The treatment was
done with a hand operated sprayer.
Weeding was done as required, and earthing-up was carried out at
30 and 45 days after sowing on cowpea and sorghum respectively.
Numbers of eggs and dead hearts were recorded at 17 and 28 days
after plant emergence respectively. In pure sorghum, observed rows
were the fifth and sixth rows. In intercropped sorghum cowpea, they
were the second and third rows for 52 and 53' and the third and fourth
for 5. (Fig. 1). On these rows, the total number of plants, plants
bearing eggs, eggs, and dead hearts were recorded.
At harvest, the first and the last hills on a row of sorghum were
discarded. In cowpea rows, 50 cm of row were left on each extremity.
Harvesting was do ne on observed rows only. The weight of grain from
each plot was recorded.
To assess yields from intercropping, the Land-Equivalent-Ratio
(LER) (Mead, 1980, 1986) was used.
The experiments were repeated in 1991 to augment 1988 and 1989
results on sorghum shoot fly incidence. Both crops were sown on July
26th. No cow dung was applied. The parameters observed were: the
number of plants bearing eggs, the number of eggs laid at 17 days after
pl ant emergenceand the percentage of dead hearts at 28 days after
plant emergence.
•
•
. '
71
5.3.2. Experimental Series B: Sowing dates and plant densities
Each year (1988, 1989) the local sorghum variety "Gnofing" was
sown on five dates at la day intervals, on 20, 30 June and on la, 20,
30 July. The experimental design was a split-plot with four replicates,
the main plots being sowing dates and the sub-plots, plant densities.
The seeds had been treated with K-Othrine~ (Deltamethrin, 50 g/100 kg
of seed) to prevent damage by stored grain pests. Each plot measured
3.20 x 4m and contained four rows. Row spacings were 0.80 m in all
densities whereas intra-row spacings were 0.50 m (25,000 hills /ha),
0.40 m (31,250 hills /ha, the recommended density in Burkina Faso),
0.30 m (41,666 hills/ha), 0.20 m (62,500 nills/ha), and 0.10 m (125,000
hills/ha) for densities l, 2, 3, 4 and 5, respectively. Two seedlings
were maintained per hill in all plots. Plots were fertilized with 200
kg/ha of NPK (15 15 15) appl ied on two occasions, i.e. 100 kg/ha at
sowing time, and 100kg/ha 30 days after sowing. Fifty kg/ha of urea
(46%) were applied 45 days after sowing.
Observations were recorded on the plants of the two central rows
twenty eight days after seedling emergence. The number of plants, dead
hearts, tillers, dead hearts on tillers were counted. At harvest time,
the number of plants, main earheads, earheads on tillers and weight of
grain were recorded from each plot.
Data of both experiments were transformed to arcsin values and
analysed using Scheffe's test, SuperAnova (version 1.1 for the
Macintosh computer) Abacus Concepts Inc. (1989) .
•
•
•
72
5.4. RESULTS
5.4.1. Series A
In both 1988 and 1989, intercropping systems gave a LER higher
than 1.00 (Table 13, 14). A value of > 1.00 indicates an agronomic
advantage for intercropping. In 1988, the LER was 1.48, 1.30 and 1.28
in 52, 53, S. respectively (Table 13). In 1989, the LER was 1.42, 1.23
and 1.06 in 52, 53, S. respectively (Table 14).
In 1988, no significant differences were observed with respect to
the number of eggs laid, the percentage of plants bearing eggs and the
percentage of dead hearts (Table 15). In 1989, significant differences
were only observed with respect to dead heart incidence (F = 4.37, df=
3,12, P < 0.026) (Table 15). In 1991, no significant differences were
observed with respect to all measured parameters (Table 15) .
5.4.2. Series B
Shoot fly damage ranged from 6.47 to 66.89% dead hearts in 1988,
and from 10.20 to 45.38% in 1989 (Table 16). Si9nificant differences
were observed among sowin9 dates. No signifi cant di fferences were
observed for plant density and for the interaction of sowing dates
plant density. In 1988 the percentage of dead hearts was higher than in
1989 (Table 16). There were significant negative correlations between
the yield and the percentage of dead hearts in all the five sowin9
dates, the yield and the sowing dates, and between the yield and the
numbers of tillers. The regression equations for yields (y) versus
dead hearts (x) were (n = 100, all sowing dates pooled) y = - 0.033x +
2.83 (r = 0.78), and y = - 0.019x + 1.40 (r = 0.72) in 1988 and in 1989
respectively. The regression equations for yields (y) and sowing
dates (x, expressed in Julian calendar) were y = - 0.99x + 1 (r =0.89)
in 1988 and y = - 0.87x + 1 (r = 0.69) in 1989 respectively. The
•
•
•
73
regression equations for yield (y) and tillers (x) were y : - 0.71x +
1 (r : 0.69), y : - 0.74x + 1 (r : 0.71), in 1988 and in 1989
respectively.
Few plants (32 of 3730 plants in 1988 and Il of 2236 plants in
1989) bore more than one earhead and no earheads were recorded on
tillers.
5.5. DISCUSSION
Our results on the LER values suggest an agronomic compatibility
between the local sorghum cultivar "Gnofing" and the cowpea cultivar
TVx 3236. At Farako-Bâ (c~ 2 km from Matourkou), Muleba (1984, 1985)
reported a LER value of 0.95 and 1.02 in 1984 and 1985 respectively in
the intercropping sorghum (cultivar "Framida") and cowpea (Cultivar TVx
3236). He found that the LER varied according ta cowpea cultivars and
that yields of bath sorghum and cowpea were significantly reduced in
certain cultivars. He also noted that cowpea was more competitive than
sorghum in using sail nutrients.
Our 1988 and 1991 results on shoot fly incidence are similar ta
those of Dissemond and Hindorf (1990) who did not find significant
differences between pure sorghum and intercropped sorghum-cowpea sown
in intra-row spacings. Shoot fly infestation was higher in 1988 than in
1989. This may be due ta more favorable climatic conditions for the
shoot fly in 1988 (Zongo et al. 1991).
Our results suggest that intercropping sorghum-cowpea has no
significant effect in reducing shoot fly damage. This confirms Raina
and Kibuka's (1983) conclusion that crops such as cowpea which sustain
high aphid populations constitute a poor choice for intercropping with
sorghum. However, intercropping systems.should not only be based on
pest. control objectives but should also focus on obtaining good yields.
•
•
•
74
Steiner (1984) described typical traditional cropping systems and
reviewed the agronomic and socio-economic aspects of intercropping in
West Africa. He concluded that intercropping has a positive impact in
small holder farming systems, but recommendations cannot be formulated
as easily as for single crops because of the complexity of
intercropping.
Our results on the incidence of the shoot fly, indicated an
increased infestation with later sowing dates. Our observations are
similar to those of Brenière (1972), Gandhale et a7. (1982), and Mote
(1983). Brenière (1972) pointed out that the earliest sown plants
escaped severe damage but this would change according to the year.
The significant negative correlation between grain yields and
dead hearts here reported are in agreement with those of Rai et a7 .
(1978) and Mote (1988). Mote (1983) observed that for each per cent
increase in dead hearts, a reduction in grain yield of 32.28, 65.56,
62.06 kg/ha is obtained in early, normal and delayed sowing
respectively. Rai et a7. (1978) and Mote (1988) found that the
reduction in grain yield is dependent on the sorghum varieties.
Our results on the effects of plant density (seed rates) on the
incidence of the shoot fly are similar to those of Sukhani and Jotwani
(1980), and Mote (1983). However, they are in strong contradiction to
those of Ayyar (1932) and Ponnaiya (1951) who recommended control of
the shoot fly by using high seed rates and then removing and destroying
damaged plants. Brenière (1972) also recommended this method in west
Africa. In Burkina Faso, this technique of removing and destroying
damaged plants may entail much labor particularly at the beginning of
the rainy season. Although it may be practiced, it is unsuitable
because farmers have a time c~mmitment to other crops (such as cash
•
•
•
75
crops) at that period.
Delobel (1984) and Blum (1972) indicated that some sorghum
varil:ties such as CSH-1 produce ti11ers that may bear earheads and so
compensate for the shoot fly attack . Our results on the local cultivar
"Gnofing" are not in agreement with these observations as no tillers
bearing earheads were produced and there was a negative correlation
between yield and number of tillers. This confirms Panchabhavi et al.
(1989) finding that tiller formation does not compensate for grain and
fodder yield losses.
In Burkina Faso, the economic situation dictates that pest
control approaches be based on practices easily understood and carried
out by farmers. Sowing sorghum at the beginning of the rainy season
results in. reduced shoot fly damage. Sowing dates prior to June 20
could be preferable. Sowing dates between 20- 30 June may also be
practiced. To be more effective, this simple cultural practice requires .
united.acti on by a11 farmers from the same l ocal ity. Young (1981)
recommended that the sorghum crop should be sown within a period of 2-3
weeks in any defined area.
•
•
•
76
5.6. REFERENCES
Abacus Concepts Inc. 1989. SuperANOVA, Accessible General Linear
Modeling, Berkeley, California, 316 p.
Ayyar, T.V.R. 1932. Entomology of the sorghum plant in south India.
Madras Agricultural Journal, 20: 50.
8lum, A. 1972. Sorghum breeding for shoot fly resistance in Israel, pp.
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W.R. (eds.). Proceeding of International Symposium 1-3 November
1971, Hyderabad. Oxford &IBH Publ. India, New Delhi.
Bonzi, S.M. 1981. Fluctuations saisonnières des populations de la
mouche des pousses de sorgho en Haute-Volta. Insect Science and
its Application, 2: 59-62.
8renière, J. 1972. Sorghum shoot fly in West Africa. pp. 129-135, In
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Deeming, J. C. 1971. Some species of Atherigona Rondani (Diptera:
Muscidae) from Northern Nigeria, with special reference to those
injurious to cereal crops. Bulletin of Entomological Research,
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Delobel, A. 1984. Une méthode d'estimation des pertes de récolte
attribuables à la mouche du sorgho, Atherigona soccata Rondani.
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Dissemond A., Hindorf H., 1990. Influence of sorghum/maize/cowpea
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Jotwani, M.G. 1981. Integrated approach to the control of the sorghum
•
•
.'
77
shootfly. Insect Science and its Application, 2: 123-127.
Mead R., 1980. The concept of a 'Land Equivalent Ratio' and advantages
in yields from intercropping. Exp. Agric., 16: 217-228.
Mead R., 1986. Statistical Methods for multiple cropping. In Multiple
cropping systems, FRANCIS (ed.). MacMillan Pub1ishing Company,
New York, p.317-350.
Mi ni stère de l' Agri cul ture et de l' Ei evage du Burkina Faso 1988.
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Mote, U.N. 1983. Relation between the shootfly damage and sorghum
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Atherigona soccata Rondani and the yield of sorghum hybrids .
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Nwanze, K.F. 1985. Sorghum insect pesis in West africa pp. 37-43, In
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Nwanze, K.F. 1988. Distribution and seasonal incidence of sorne major
insect pests of sorghum in Burkina Faso. Insect Science and its
Application, 9: 313-321.
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•
78
Nwanze K.F., 1988. Distribution and seasonal incidence of sorne major
insect pests of sorghum in Burkina Faso. Ins. Sci. Appl ic., 9:
313-321.
Panchabhavi, K.S., K.A. Ku1karni, P.C. Hieremath and R.K. Hegde 1989.
A study on the yield compensation by tillers caused by shootfly
in sor~hum. Karnataka Journa7 of Agricu7tura7 Science, 2: 338
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Ponnaiya, B.W.X. 1951. Studies on the genus sorghum. 1. Field
observations on sorghum resistance to the insect pest.
Atherigona indica M., Madras University Journa7, 21: 203-217.
Raina A.K., Kibuka J.G., 1983. Dviposition and survival of the sorghum
shootfly on intcrcropped maize and sorghum. Ento. exp. appl. 34:
107-110 .
Ram, S., D.P. Handa and M.P. Gupta 1976. Effects of planting dates of
fodder sorghum on the incidence of shootfly, Atherigona soccata
Rond. Indian Journa7 of Entomo7ogy, 38: 290-293.
Risch S. J., Andow D., Altieri M.A., 1983. Agroecosystem diversity and
pest control: data, tentative conclusions and new research
directions. Environ. Entomol., 12: 625-626.
Sukhani, T.R. and M.G. Jotwani 1980. Comparison of cultural and
chemical methods for the control of sorghum shoot fly.
Entomo7ogy, 5: 291-294.
Vandermeer J. H., 1989. The ecology of intercropping. Cambridge
University Press, New York, 237 p.
Venugopal M.S., Pal anippan S., 1976. Infl uence of intercropping sorghum
on the incidence of sorghum shoot fly. Madras Agric. J., 83:
572-573 .
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79
Young, W.R. 1981. Fifty-five years of research on the sorghum shootfly.
Insect Science and its Application, 2: 3-9.
Zongo J.O., Vincent C., Stewart R. K. 1991. Monitoring adult sorghum
shoot fly Atheri gona soccata Rondani (Di ptera: Muscidae) and
related species in Burkina Faso. Tropical Pest Management, 37:
231-235.
Zongo, J.O., Vincent, C. and Stewart, R.K. 1992. Time-sequential
sampl ing of the sorghum shoot fly, Atherigona soccata Rondani
(Diptera: Muscidae), in Burkina Faso. Insect Science and its
Application. (In press).
•
•
•
TABLES AND FIGURE 1.
80
••
•
Tab
le13
.Y
ield
san
dLa
ndE
quiv
alen
tR
atio
(LER
)fo
rin
terc
ropp
edso
rghu
m-c
owpe
ain
1988
atM
atou
rkou
,8u
rkin
aFa
so.
Cro
ppin
gSy
stem
'Y
ield
stl
haSo
rghu
mCo
wpe
aLE
RSo
rghu
mLE
RCo
wpe
aLE
RIn
terc
ropp
ing
S,1.
87(0
.76)
'S,
1.14
(0.6
5)0.
60(0
.19)
'0.
600.
881.
48S,
0.83
(0.6
2)0.
59(0
.13)
0.44
0.86
1.30
S.1.
07(0
.87)
0.48
(0.1
9)0.
570.
711.
28S,
-0.
68(0
.11)
See
Fig.
1fo
rpl
otde
sign
.St
anda
rdde
viat
ion
base
don
four
repl
icat
es.
81
••
•
Tab
le14
.Y
ield
san
dLa
ndE
quiv
alen
tR
atio
(LER
)fo
rin
terc
ropp
edso
rghu
m-c
owpe
ain
1989
at11
atou
rkou
,B
urki
naFa
so.
Cro
ppin
gSy
stem
'Y
ield
st/
haSo
rghu
mCo
wpe
aLE
RSo
rghu
mLE
RCo
wpe
aLE
RIn
terc
ropp
ing
S,1,
47(0
,36)
'S,
1,23
(0,8
6)0,
55{0
,16)
'0,
830,
591,
42S,
0,96
(0,5
2)0,
54(0
,11)
0,65
0,58
1,23
S.0,
78(0
,53)
0,49
(0,1
1)0,
530,
531,
06S,
-0,
92(0
,21)
See
Fig.
1fo
rpl
otde
sign
.St
anda
rdde
viat
ion
base
don
four
repl
icat
es.
82
•if // li il " \\ 1 ,i
••
Tab
le15
.A
vera
genu
mbe
rof
eggs
laid
,pe
rcen
tage
ofpl
ants
wlth
eggs
and
perc
enta
geof
dead
hear
tsdu
eto
A.so
ccat
.In
four
crop
plng
syst
ems
lnB
urki
nafa
so.
1988
19B9
1991
Cro
ppln
gsy
stem
,;P
lant
s',;
Pla
nts'
,;P
lant
s'11
0.eg
g<,;
Oea
dH
eart
s11
0.eg
gs,;
Oea
dH
earts
110.
eggs
%Oe
adlI
e.rt
s
S,4.
461
•4.
46'
38.2
0'5.
75'
8.49
'30
.3gb
12.0
0'27
.43'
31.9
5'
S215
.11'
8.40
'45
.86'
6.75
'10
.36'
19.7
1'Il
.00'
25.7
4'43
.32'
S39.
37'
15.1
1'47
.36'
4.75
'B
.07'
24.6
S'b
17.0
0'32
.27'
38.9
9'
S,8.
40'
8.40
'29
.48'
6.75
'11
.11'
27.7
6'b
6.25
'23
.36'
36.9
0'
%P
lant
sbe
arln
geg
gs
•H
eans
wlth
lna
colu
mn
wlth
the
sam
ele
tter
are
notsignlfl~antly
dlff
eren
tP
•0.
05,
Sch
effé
'ste
st.
83
1.'")
••
•
Tab
le16
.E
ffec
tof
sow
ing
date
son
yiel
dan
d%
dead
hear
tsca
used
byth
eso
rghu
msh
oot
fly
Ath
erig
ona
socc
ata
inM
atou
rkou
,B
urki
naFa
so,
in19
88an
din
1989
.
1988
1989
Sow
ing
Dat
es%
Dea
dhe
arts
Yie
ld(t
/ha)
%D
ead
hear
tsY
ield
(t/h
a)
June
ZO6.
47"-
Z.9
1"10
.20"
1.80
Z"
June
30Z
O.O
I"Z
.58"
13.6
8"1.
228b
July
1023
.57"
1.5
9b17
.61"
b1.
004b
July
ZO6
0.4
8b
0.80
0<30
.13bc
0.49
1<
July
306
6.8
9b0.
277
d4
5.3
8bc0.
319<
-M
eans
with
the
sam
ele
tter
are
not
sign
ific
antl
ydi
ffer
ent,
P=
0.0
5,
Sch
effé
s's
test
.
84
85
Figure 1. Spatial arrangement of sorghum and cowpea rows in five
cropping systems.
•
•
•
•en en en en en
0U1 .... W N -
en I!f#$ fi*;9 '1 "' 1.....0cC::rc=3 Nep; eM e 4 i
Lji D 1(,)
li Il Il I~
• 1 Il è ; Il len :-'en3
li ;; • Il Il le>C'>0
il MN Il Ai 1'"-1lt>0>
Il 10)
1 lco
0cr 1.....'"lt> 0<!l!-a::l
~ .. ..Gl
en3
•
•
•
•
86
CONNECTING STATEMENT
In chapter 5, appropriate sorghum sowing dates have been proposed
to avoid and reduce yield losses caused by the shoot fly. These sowing
dates would be more effective if attention is paid to the choice of a
suitable sorghum cultivar. In IPM, the choice of plant cultivar is
important as growi ng pl ant cul tivars resi stant to insects attack
confers na~ural control. The use of resistant cultivars is one of the
most desirable and compatible control method in IPM programs for many
agricultural insect pests (Kogan 1982). To choose an appropriate
cultivar, effective screening techniques should be applied. Artificial
and natural screening methods have been used to select sorghum
cultivars resistant to the shoot fly (Singh and Rana 1986). In Chapter
6, l use natural methods to determine which local cultivars of sorghum
are resistant to the shoot fly in Burkina Faso.
•
•
•
6 Screening of Local Cultivars for Resistance to Sorghum Shoot Fly,
Atherigona soccata Rondani (Diptera: Muscidae), in Burkina Faso
To be submitted to Sahel Phytoprotection, August 1992.
Authors: ZONGO, J.O., VINCENT, C., STEWART, R.K .
87
•
•
•
88
6.1. Abstract
Experiments were conducted at Matourkou, Burkina Faso, using
natural screening techniques to screen 52 local sorghum cultivars for
resistance to sorghum shoot fly, Atherigona soccata Rondani (Diptera:
Muscidae). The 52 local cultivars were compared to one resistant
cultivar (15 2123) and one susceptible cultivar (C5H-l) introduced from
India. Experiments were conducted in 19B8 and 1989 for 52 local
cultivars and in 1990 and 1991 for eight local cultivars. Criteria used
to assess the cultivars were the number of shoot fly eggs per 10 plants
and the percentage of dead hearts per cultivar. Using t tests (Least
5ignificant Difference), significant differences were observed with
respect to the number of eggs per 10 plants and to dead heart
incidence. In all years, none of local cultivars received 'significantly
fewer eggs and dead hearts than the resistant cultivar 15 2123. The
results indicated that damage to cultivars varied with the shoot fly
population levels. Overall, none of the 52 Burkinabè sorghum cultivars
was resistant ta shoot fly attack.
•
•
•
89
6.2. Introduction
Sorghum, Sorghum bico 7or (L. Moench), i s the most important
cereal crop in Burkina Faso. Traditionally the crop is used as human
food, beverages, animal feed and for fence construction.
Among the factors reducing sorghum yields are insect pests, the
important groups being those attacking stored grain, seedling foliage,
and the head and stem of growing plants (Nwanze 1985). The shoot fly,
Atherigona soccata Rondani (Diptera: Muscidae), is one of the most
important seedling pests in Burkina Faso (Bonzi 1981, Nwanze 1988).
One of the strategies for reducing shoot fly damage is to use
resi stant cul ti vars. Sorghum cul ti vars resi stant to shoot fly were
first reported in India by Ponnaiya (1951), who screened 212 genotypes
and found 15 to be less damaged. Taneja and Leuschner (1985) listed 42
cultivars as less susceptible over five seasons with five germplasm
lines which were quite stable at different locations. The main factors
associ ated with shoot fly resi stance are physi co-morphol ogi cal
(seedling vigor, glossiness, silica bodies, presence of hairs on the
epidermi s) and bi ochemi cal factors (presence of compounds such as
hordenine, alkaloid, dhurrin, cyanogenic glucoside, lysine, nitrogen
and phosphorous content) (Singh and Rana 1986). The mechanisms of
resistance found to interfere with the shoot fly are non-preference or
antixenosis, antibiosis, and tolerance or recovery resistance (Singh.
and Rana 1986).
In Burkina Faso, Brenière (1972) screened eight and six cultivars
at Sari a (Koudougou) and Boni respectively and foundsuscepti bi li ty
differences between cultivars.
Local cultivars are adapted to each environmental site in Burkina
Faso as differences between rainfall are well pronounced. Therefore,
•
•
•
90
the choice of a given cultivar should take into account these rainfall
di fferences. The present study was carri ed out to screen 52 l ocal
sorghum cultivars commonly used in the western region based on the
number of eggs laid and the percentage dead hearts per cultivar.
6.3. Materials and Methods
Experiments were conducted at Matourkou located about 10 km from
Bobo-Dioulasso (11 0 Il'N, 40 18'W), Burkina Faso, West Africa.
In 1988 and 1989, 52 local cultivars from the National
Agricultural Research Institute (INERA), one resistant (IS 2123 from
the USA) and one susceptible (CSH-l) cultivar from the International
Crops Research Institute for the Semi-Arid Tropics (ICRISAT) India were
used.
In 1990 and 1991, eight local cultivars selected from 1988 and
1989 screening and the resistant cultivar IS 2123 were used. These
cultivars were retained because they received less than 50% dead hearts
and fewer dead hearts than the susceptible CSH-l in 1988. The local
cultivar "Gnofing" was used as a check.
The experimental design was a randomized complete block with four
repl icates. Each year, sowing was done on 20 July, one month after
normal sowing dates to increase the l ikel ihood of high shoot fly
infestation. Each cultivar was sown in a 4 m row. Row and intra-row
spacings were 0.80 mand 0.10 mrespectively. One plant was maintained
perhill.
Natural screening techniques (Singh and Rana 1986) were used.
The cultivar "Gnofing" was sown in two border rows between the blocks
and on each side of each block to act as reservoir of shoot fly
populations. These border rows were 1 m away from cultivars being
scre.ened. Row and intra-row spacings were 0.80 and 0.20 ni
•
•
•
91
respectively. Two plants were maintained per hill in these border rows.
The distance between blocks was 2.80 m.
One week after border row plant emergence, 100 g/4 mrow of fish
meal, purchased in a local market, was spread by hand to attract shoot
flies. In 1990 and 1991, border rows were not used. One week after
experimental cultivar emergence, 100 9 of fish meal was used per row
for each cultivar. Fish meal was spread between 8.00 and 9.00 h
adjacent to plants on both sides of each row. Thinning was done 15 days
after sowing.
Visual observations were made between 7.00 and 10.00 h, 13 and 28
days after plant emergence for egg and dead heart numbers respectively.
Egg counting was done on ten randomly selected plants per row for each
cultivar. Dead heart counting was done per row for each cultivar. The
total numbers of plants, and plants bearing dead hearts were recorded.
Data were analyzed using t tests (LSD) of the software SAS
(version 6.03 for the IBM PC) (SAS Institute Inc. 19BB).
6.4. Results
Significant differences w~re observed with respect to the number
of eggs per 10 plants and to dead heart incidence in all years (Ta~le
17, 18).
In 1988, the mean number of eggs varied from 0.25 (IS 2123) to
7.75 (CVS 606) (Table 17). None of local cultivars received
significantly fewer eggs than the susceptible CSH-l. Mean percentage
of dead hearts ranged from 0.80% (IS 2123) to 78.8% (CVS.631) (Table
17). Ten local cultivars (CVS 578, CVS 586, CVS 606, CVS 611, CVS 617,
CVS 628, CVS 633, CVS 638, CVS 643, CVS 644) showed significantly fewer
dead hearts than CSH-l. None of the 54 cultivars was immune to shoot
fly attack.
•
•
•
92
In 1989, shoot fly infestation was low. The mean number of e9gs
and percentage of dead hearts ranged from zero (IS 2123) to 2.75 (CVS
600) and from 1.49 (IS 2123) to 27.49% (CVS 641) respectively. The
cult i vars IS 2123 and CVS 625 showed absol ute non-preference for
oviposition by the shoot fly (Table 17).
In 1990, the mean number of eggs per 10 plants varied from 0.00
(IS 2123) to 3.5 (Gnofing and CVS 586), whereas dead heart incidence
ranged from 0.00 (IS 2123) to 33.59% (CVS 611) (Table 18). IS 2123
showed absolute resistance to the shoot fly.
Although less shoot fly damage was recorded in 1991, egg numbers
were higher than in 1990. The mean number of eggs varied from 0.00 (IS
2123) to 14.67 (Gnofing) and percentage of dead hearts ranged from 0.20
(IS 2123) to 10.55% (CVS 643).
6.5. Discussion
Our results on shoot fly incidence indicated that damage to
cultivars varied with years and degree of infestation. These findings
have also been found by many authors i.e. Ponnaiya (1951), Singh et al.
(1978), Sharma and Rana (1583), Taneja and Leuschner (1985), and Singh
and Rana (1986). Highers number of eggs and percentage dead hearts were
recorded in 1988 than in 1989. This may be due to more favorable
climatic conditions for the shoot fly in 1988 (Zongo et al. 1991)
None of the local cultivars was resistant to shoot fly attack.
Brenière (1972), using six cultivars in 1964 in Boni (western part of
Burkina Faso), also observed that hybrid cultivars (originating from
crosses between American and Burkina Faso cultivars) were less
susceptible to the shoot fly attack than their local parents although
he concluded that this observation needs to be confirmed. Our results
strongly support his observation.
•
•
•
93
Although no local sorghum cultivars showed resistance to shoot
fly in Burkina Faso, resistant cultivars have been found from various
countri es. Taneja and Leuschner (1985) li sted 42 l ess suscept ibl e
sorghum cultivars among which 32 originated from 1ndia, 5 from Sudan,
3 from the USA, and one each from Ni geri a and South Afri ca, whereas
Singh and Rana (1986) reported 73 resistant cultivars from various
screening programmes. Singh and Rana (1986) mentioned that resistant
sorghum cultivars found in various screening programmes are not
generally good agronomic types because they are susceptible to lodging,
photosensitive, late maturing, and low yielding. Singh et al. (1978)
found that dead heart incidence in resistant cultivars changed over the
seasons but never beyond 42.64% in 1ndia. Jotwani and Srivastava (1970)
reported that under artificial screening conditions, some moderately
resistant cultivars showed from 26.3% to 64.2% dead hearts, whereas
susceptible ones recorded up to 91.6% dead heart. Our results on local
cultivars indicated a maximum percentage dead heart of 78.80% in 1988.
The cultivar IS 2123, originating from the USA, showed high
resistance and stability compared with the local cultivars. Taneja and
Leuschner (1986) also found that IS 2123 showed moderate stability and
has been used as a source of resistance in 1ndia. The resistance of IS
2123 tG shoot fly attack observed in our study was due to the non
preference for oviposition, as less than 1.00 egg per ten plants were
recorded during the four-year screening. This confirms Blum's (1967)
and Jotwani et al. 's (1971) results that under field conditions,
resistance -is primarily due to non-preference for oviposition. IS 2123
also showed antibiosis against the shoot fly (Singh and Narayana 1978).
Although no resistant Burkinabè cultivars to shoot fly were found
in our study, screening of other local cultivars should be pursued.
•
•
. '
94
The cultivar 15 2123 might be a good source of resistance in developing
local sorghum cultivars resistant to shoot fly. This suggests that a
close liaison should be established between entomologist and breeder.
The recommendation that may be made at the present time concerning the
use of local cultivars is to practice early sowing dates, as Zongo et
a7. (unpublished data) found that sowing sorghum at the beginning of
the rainy season resulted in reduced shoot fly damage .
•
•
•
95
6.6. References
Blum, A. 1967. Varietal resistance of sorghum to the sorghum shootfly
(Atherigona varia var. soccata). Crop Sei. 7: 461-462.
Bonzi, S.M. 1981. Fluctuations saisonnières des populations de la
mouche des pousses de sorgho en Haute-Volta. Insect Sei. Applic.
2: 59-62.
Brenière, J. 1972. Sorghum shoot fly in West Africa, pp. 129-135, In
Control of sorghum shoot fly, (Jotwani, M.G. &W.L. Young Eds).
Oxford and I.B.M., New Delhi.
Jotwani, M.G., Sharma, G.C., Srivastava, B.G. and Marwaha, K.K. 1971.
Oviposi tional response of shootfly. Atherigona varia soccata
(Rondani) on sorne promising resistant lines of sorghum. In
Pradhan, S. (ed.) Investigations on Insect Pests of Sorghum and
Millets (1965-70), pp. 119-122. Final Technical Report,
Division of Entomology, IARI, New Delhi.
Jotwani, M.G. and Srivastava, K.P. 1970. Studies on sorghum lines
resistant against shootfly, Atherigona varia soccata (Rondani).
Indian J. Entomol. 32: 1-3.
Nwanze, K.F. 1985. Sorghum insect pests in West Africa, pp. 37-43, In
International Crops Research Institute for the Semi-Arid Tropics
(ICRISAT). Proceedings of the International Sorghum Entomology
Workshop, 15-21 July 1984. Texas A & M University, College
Station, TX, USA. Patancheru, A.P. 502324 India: ICRISAT.
Nwanze, K.F. 1988. Distribution and seasonal incidence of sorne major
insect pests of sorghum in Burkina Faso. Insect Sei. Applic. 9:
313-321 .
96
Field
pest.•
•
. '
Ponnaiya, B.W.X. 1951. Studies on the genus Sorghum 1.
observati ons on sorghum res i stance to the insect
Atherigona indiea M. Madras Univ. J. (B) 21: 96-117.
SAS Institute Inc. 1988. SAS Language Guide for Personal Computers:
Release 6.03 Edition. Cary, NC, USA. 558 pp.
Sharma, G.C. and Rana, B.S. 1983. Resistance to the shoot fly,
Atherigona soeeata (Rond.) and selection for antibiosis. J.
Entomol. Res. 7: 133-138.
Singh, R. and Narayana, K.L. 1978. Influence of different varieties of
sorghum on the biology of the sorghum shootfly. Indian J. Agrie.
Sei. 48: 8-12.
Singh, B.U. and Rana, B.S. 1986. Resistance in sorghum to the shootfly,
Atherigona soceata Rondani. Inseet Sei. App7ie. 5: 577-587 .
Singh, S.P., Jotwani, M.G., Rana, B.S. and Rao, N.G.P. 1978. Stability
of host-plant resistance to sorghum shootfly, Atherigona soeeata
(Rondani). Indian J. Entomo7. 40: 376-383.
Taneja, S.L. and Leuschner, K. 1985. Resistance screening and
mechanisms of resistance in sorghum to shoot fly, pp. 115-129. In
International Crops Research Institute for the Semi-Arid Tropics
(ICRISAT). Proceedings of the International Sorghum Entomology
Workshop, 15-21 July 1984. Texas A & M University, College
Station, TX, USA. Patancheru, A.P. 502324 India: ICRISAT.
Zongo, J.O., Vincent, C. and Stewart, R.K. 1991. Monitoring adult
sorghum shoot fly Atherigona soeeata Rondani (Diptera: Muscidae),
and related species in Burkina Faso. Trop. Pest Manag. 37: 231
235 •
•
•
•
6.7. TABLES
97
98
Table 17. Mean number of shoot fly eggs/ 10 plants and mean percentage of deadhearts observed in 54 cultivars of sorghum at Matourkou, Burkina Faso .
• Cultivar 1988 1989
No. Eggs % dead hearts No. Eggs %dead hearts
15 2123 0.25 0.8 0 1.49CVS-608 3.00 60.8 1.75 15.55CVS-625 3.00 63.8 0 18.21CVS-626 3.25 58.8 1.25 16.65Frikan 3.25 60.3 0.5 20.89CVS-574 3.50 57.8 2.25 23.57CVS-587 3.50 60.5 1 16.18CVS-624 3.50 66.0 1.25 22.88CVS-631 3.50 78.8 0.5 25.39CVS-578 3.75 50.3 0.25 16.99CVS-619 3.75 64.5 1.5 12.97CVS-634 3.75 71.5 1.25 19.56CVS-635 3.75 71.5 1.75 14.40CVS-639 3.75 60.3 0.75 18.56CVS-641 3.75 67.3 0.75 27.49Gnofing 3.75 58.8 0.5 21.48CSH-l 4.00 70.5 1.25 17.63CVS-586 4.00 48.8 0.75 5.68CVS-600 4.00 61.0 2.75 22.08CVS-601 4.00 68.5 0.75 20.15CVS-610 4.00 73.0 0.25 17 .84CVS-644 4.00 46.8 2.25 21.50CVS-654 4.00 60.5 0.75 22.60
• CVS-5BO 4.25 57.0 0.75 14.74CVS-589 4.25 65.8 2 14.92CVS-596 4.25 57.5 0.75 12.23CVS-638 4.25 52.3 1.25 13.81CVS-652 4.25 62.0 0.75 22.B3CVS-655 4.25 55.3 1.5 20.85CVS-659 4.25 69.0 1.25 26.53CVS-660 4.25 54.0 1.25 17.44Ouédézouré 4.25 65.3 ·0.75 25.19CVS-576 4.50 72.0 0.25 24.95CVS-6Il 4.50 48.0 0.5 13.82CVS-633 4.50 45.8 1.5 13.50CVS-643 4.50 49.0 0.75 13.87CVS-653 4.50 58.0 0.75 17 .81CVS-602 4.75 60.5 0.5 12.99CVS-620 4.75 56.3 1.25 9.31CVS-646 4.75 54.8 2 18.09CVS-617 5.00 47.0 2 11.90CVS-582 5.25 55.5 0.5 17 .67CVS-618 5.25 58.3 0.75 17.88CVS-613 5.50 55.8 0.25 18.04CVS-630 5.50 . 74.0 1 20.50CVS-575 5.75 65.3 0.75 Il.51CVS-584 5.75 60.3 1.75 21.49CVS-623 5.75 64.3 0.75 15.31CVS-594 6.00 66.0 1.25 9.36CVS-614 6.25 64.5 1 14.82CVS-593 6.50 53.5 1 11.15CVS-629 6.50 57.3 1 16.88CVS-628 7.00 48.3 0.75 19.4B• CVS-606 7.75 52.0 1.25 20.34LSO' 3.19 17.81 1.43 12.95
Least Slgnlflcant Olfference at 5% level
•99
Tabl e 18. Mean nurnber of eggs and rnean percentage of dead hearts observed in 9
cultivars of sorghurn, Matourkou, 1990, 1991.
Cultivar 1990 1991
No. Eggs %dead hearts No. Eggs %dead hearts
rs 2123 0.00 0.00 0.00 0.20
CVS6Il 2.75 33.59 5.33 4.28
CVS643 3.00 25.08 4.67 rO.55
CVS644 3.00 15.43 6.33 7.49
• CVS628 3.25 24.35 8.00 4.02
CVS617 3.25 27.90 5.67 5.31
CVS633 3.25 24.09 8.33 4.12
CVS586 3.50 24.99 3.00 2.45
Gnofing 3.50 25.04 14.67 5.51
LSD' 2.39 13.21 4.32 7.16
• Least Significant Difference at 5% level •
•
•
•
•
100
CONNECTING STATEMENT
Insect pest control has generally been obtained through the use
of chemicals. As a result of the problems (e.g. toxicity to non target
organisms, high prices, environmental contamination) associated with
the use of synthetici nsect icides, l ocally obtainable products and
socioeconomically sustainable plant protection tactics are being sought
in developing countries. Among these is the use of natural pl ant
extracts such as those from the neem tree Azadirachta indica A. Juss.
(Meliaceae)". Neem pesticidal properties have been discussed at three
international conferences held in Germany and Africa (Kenya)
(Schmutterer et a7. 1981, Schmutterer and Ascher 1984, 1987). In
Burkina Faso, the tree grows well in any part of the country and is
widely used for building materials (fence posts), and traditional
medicine. Neem tree products could be an alternative insect control
material for peasant farmers. Chapter 7 deals with the use of neem tree
extracts as techni cally acceptabl e components of an IPM program to
control the shoot fly.
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7 Effects of Neem Seed Kernel Extracts on Egg and Larval Survival of
the Sorghum Shoot Fly, Atherigona soccata Rondani (Diptera: Muscidae) .
In press in Journal of Applied Entomology
Authors: ZDNGO, J.O., VINCENT, C., STEWART, R.K•
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7 .1. ABSTRACT
A two-year study was conducted to evaluate the effects of neem
extracts on egg and larval mortality of the sorghum shoot fly,
Atherigona soccata Rondani (Diptera: Muscidae). Field experiments were
conducted in 1990 and 1991 in a sorghum field at Matourkou (Burkina
Faso, West Africa). The following treatments were applied: 1)
carbofuran S G, 2) 20 kg/ha neem seeds/SOO L water, 3) 20 kg/ha neem
seeds/SOO L water + 2. S L/ha adhesol, 4) 30 kg/ha neem seeds/SOO L
water + 2.S L/ha adhesol, S) 2.S l/ha adhesol, 6) control (untreated
plots). Significant differences among treatments were observed in the
number of eggs laid, and the percentage of dead hearts. Significantly
fewer eggs and dead hearts were observed in plots treated with neem
extracts compared with adhesol and the control. In the laboratory, the
treatments were: 1) commercial neem oil containing 0.63% azadirachtin,
2) local neem oil, 3) 40 9 seed kernels/L water, 4) 40 9 seed kernels/L
water + 5 ml adhesol, S) 60 9 seed kernels/L water + S ml adhesol, 6)
S ml adhesol/L water, 7) control (untreated eggs). All neem seed
extracts gave a significant lower percentage of egg hatching than the
adhesol and control treatments. In larval survival experiments,
commercial and local neem oil were not used. All treatments showed a
significantly higher larval mortality compared with the controls .
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7.2. INTRODUCTION
Sorghum, Sorghum bicolor (Linné, Moench), ranks first among the
staple-crops in Burkina Faso. Its production is limited by a complex
of insect pests among which the sorghum shoot fly, Atherigona soccata
Rondani (Diptera: Muscidae), is an important one in the wetter southern
zones (Nwanze, 1988). Shoot fly larvae feed on the central shoot of
sorghum seedlings, causing a typical symptom called "dead heart". To
control the shoot fly, systemic insecticides such as carbofuran are
used to treat seeds (Mote, 1985). In practice however, the peasants of
Burkina Faso do not have the capital and training to use chemical
pesticides.
Neem tree, Azadirachta indica A. Juss. (Meliaceae), products are
known to have strong insecticidal properties (Schmutterer et al. 1981,
Schmutterer and Ascher 1984, 1987, Jacobson, 1986) and could be
alternative pest control strategies for the farmers of Sahelian
countries. The tree grows well in the Sahel and produces fruit, wood
and leaves, all of which are used for a variety of purposes by peasant
farmers. About 57 different chemical substances have been isolated from
various parts of the neem tree (Jones et al. 1989). The most important
active ingredient, azadirachtin (C"H"O.., see Jones et al. 1989), is
mostly concentrated in the seeds (Saxena 1981, cited in Stoll 1986).
In Burkina Faso, a survey done in 1986 and 1987 revealed that th~
leaves were traditionally used in warehouses to control stored grain
pests (Zongo, unpubl ished data). Ahmed and Graigne (1985) reported
that neem extracts can control up to 100 species of insects, mites and
nematodes. Today, more than 200 insect species are reported to be
control1ed by the pesticides derived from the neem tree (Hamilton,
1992). Although neem products are effective against many insect
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species, few papers have been published on their effect on the sorghum
shoot fly. Abdul Kareen et al. (1974) pointed out that neem kernel
extracts caused 27% and 20% l ess shoot fly damage than an unsprayed
control at a rate of 10 and 5 kg kernel s/ha (unknown azadi racht in
content) respectively. Chundurwar and Karanjkar (Parbhani) (19S0)
concluded that neem oil decreased the percentage of plants bearing dead
hearts compared with unsprayed plots (data not presented). No work has
been yet published on the effects of neem extracts on egg and larval
mortality of the sorghum shoot fly. This paper reports the results of
a two-year study conducted in the laboratory and in the field on the
effects of neem extracts on egg and larval mortality.
7.3. MATERIALS AND METHODS
7.3.1. Field experiments
The experiments were conducted in 1990 and in 1991 at Matourkou,
located 10 km from Bobo-Dioulasso (11° lI'N, 4° lS'W), Burkina Faso.
Each year, the local sorghum variety "Gnofing" was sown on 30 June in
a randomized complete block design with four replicates. The seeds
were treated with benomyl (Benlate 50% WP, Du Pont De Nemours,
Switzerland) at a rate of 5 g/kg to prevent fungus attack.
Each plot measured 3.20 x 4 m and contained four rows. Row and
intra-row spacings were O.SO and 0.40 m respectively. Two seedlings
were maintained per hill in all plots. The plots were fertilized with
200 kg/ha of NPK (15-15-15) applied on two occasions, 100 kg/ha at
sowing_ time and 100 kg/ha 15 days after sowing. Fifty kg/ha of urea
(46%) were applied 45 days after sowing.
Neem seed kernels originated from Koudougou (120 43'N, 4°40'W),
a city located in the central western part ,of Burkina Faso. In June and
JulY,1990, and in May and June 1991, fallen fruits were collected
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underneath neem trees. The flesh was removed from the seed and any
remaining shreds were washed away with water. The seeds were then
she11ed and dried one week in the sun. After drying, the good seed
kernels were sorted and then stored at room temperature.
In July of each year, a sample of dried seed kernels was shipped
to Canada for azadi rachtin content analysi s. To assess azadi racht in
content, one 9 of ground seed kernels or seed oil was mixed with 10 ml
of distilled water (i.e. 10% aqueous solutions). These were allowed to
sit at room temperature for 24 h, then stored at S' C for a further 48
h before analysis. The azadirachtin content was determined using
reverse phase gradient HPLC as described in Isman et al. (1990).
Seeds were ground with a blender at high speed. The required
adhesol quantity (5 ml/L water) was added to the seeds at grinding
time. After grinding, 5 L of water was added to the ground seeds which
were then a11 owed to stand 24 h. The sol ut ion was then si eved and
filtered through fine muslin.
Six treatments were applied: 1) at sowing time, carbofuran 5 G
(Procida/Roussel Uclaf, Abidjan, Côte d'Ivoire) was applied by hand at
a rate of 1.5 g/m of row adjacent to the hills, 2) 20 kg/ha of neem
seed kernels diluted in 500 L of water/ha, 3) 20 kg/ha of neem seed
kernels in 500 L of water and mixed with 2.5 L/ha of adhesol EC
(SOFACO/Roussel Uclaf, Abidjan, Côte d'Ivoire), 4) 30 kg/ha of neem
seed kernels diluted with 500 L of water and mixed with 2.5 L/ha of
adhesol EC, 5) adhesol EC, 2.5 L/ha diluted with 500 L/ha of water
(adhesol is an emulsifiable concentrate containing condensate ethylene
oxyde and non ionic terpene) and 6) the control plots (untreated).
Neem seed kernel extracts were appl ied weekly starting after
plant emergence for five weeks. One hand operated sprayer was used per
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plot with the preloaded appropriate treatment of neem seed kernel
extracts and adhesol. Spraying was done between 8.00 - 10.00 h on whole
plants and individual leaves for 40 sec per plot (i.e. 10 sec per row).
This procedure allowed about 16 ml of spray/second.
Observations were made on eight occasions every fifth day,
starting 10 days after sowing. Egg counting was done on the two
central rows of each plot. The number of eggs and dead hearts was
recorded and the number of plants per plot noted. On each sampli ng
occasion, the plants showing dead heart symptoms were flagged with a
piece of red cloth to avoid repeated counting.
7.3.2. Laboratoryexperiments
In 1990 and in 1991, shoot fly eggs were collected between 8.00
10.00 h from untreated field plots sown at weekly intervals. The eggs
were detached from the leaves using small scissors and were transferred
to Petri dishes containing wet filter paper. The eggs were examined
under a bi nocul ar mi croscope and parasit ized or damaged eggs were
discarded. Eggs showing black-head formation before hatching were
also discarded. Thirty eggs per treatment were used in a randomized
compl ete bl ock desi gn repli cated four t imes. Seven treatments were
applied: 1) control (untreated eggs), 2) commercial neem oil (Safer
LTD, Victoria, B.C., Canada) containing 0.63% azadirachtin, 3) local
neem oil, traditionally extracted by pressing seed kernels, 4) 40 9
seed kernels/L water, 5) 40 9 seed kernels/L water + 5 ml adhesol, 6)
60 9 seed kernels/L water + 5 ml adhesol, 7) 5 ml adhesol/L water.
Five pl of each neem seed kernel extracts and adhesol were topically
applied with a micro-pipette (Micromane Model M50). Five pl of 0.63%
azadirachtin and local neem oil were spread on fil ter papers. A few
seconds later, the eggs were removed from the pieces of leaf and placed
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on the treated part of the filter paper. All eggs were then
transferred into a rearing room at 26 Oc (± 1), 68-75% R.H., and a
photoperiod of 12:12 (L/D). Observations were made daily on the number
of eggs hatched until one week after treatments.
To study the effects of neem extracts on larval survival, five
first-instar larvae obtained from mass rearing were used per treatment
in a randomized complete block design replicated four times. A. soccata
adults were obtained from third instar larvae identified using
Deeming's (1971), and Raina's (1981) description. Five treatments were
applied including 1) control (treated with distilled water), 2) 40 9
seed kernels/L water, 3) 40 9 seed kernels/L water + 5 ml adhesol, 4)
60 9 seed kernels/L water + 5 ml adhesol, 5) 5 ml adhesol/L water.
The analytical methods previously described were used to assess
azadirachtin content.
About 500 ml of solution of each treatment was used in a small
operated hand sprayer (8erthoud F2) that allowed a flow of 30 ml during
15 sec of spraying on five plants. Care was taken to ensure that the
solution reached the central shoot of the plants. Fifteen minutes after
treatment, a fine camel brush was used to transfer each larva into the
central shoot of a 14 day-old plant from sowing, grown in a plastic
pot. After transferring the larvae, each pot was put in a cage (40 x 40
x 40 cm) placed in an insectarium. One week after treatment, all plants
were dissected to count living larvae.
Data on the percentage of dead hearts and egg hatch ing was
transformed to arcsin values. All data were analyzed using Scheffé's
test of the software SuperANOVA (version 1.1 for the Macintosh
Computer) (Abacus Concepts Inc. 1989) .
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7.4. RESULTS
In 1990, seed kernels and seed oil contained 447 ppm and 93 ppm of
azadirachtin in solution respectively, whereas in 1991 they yielded 508
ppm and 100 ppm respectively.
7.4.1. Field experiments
In both 1990 and 1991, significant differences among treatments
were observed in the number of eggs laid (F= 55.22, df= 5,15 p= 0.0001
in 1990 ; F= 31.06, df= 5, 15; p= 0.0001 in 1991) and the percentage of
dead hearts (F= 101.03, df= 5,15; p= 0.0001 in 1990; F= 74.96, df=
5,15; p= 0.0001 in 1991) (Table 19). In both 1990 and 1991, fewer eggs
were laid in plots treated with neem extracts compared with carbofuran,
adhesol and control plots. The average number of eggs and dead hearts
(all data pooled per year) was higher in 1990 (31.91 eggs, 23.45% dead
hearts) than in 1991 (17.66 eggs, 22.78% dead hearts) (Table 19)
In 1990, there were no significant differences between neem seed
extracts (20 kg seed kernels/ha + 2.5 L adhesol/ha, 30 kg seed
kernels/ha + 2.5 L adhesol/ha, and carbofuran in reducing dead heart
formation. In 1991, the carbofuran treatment was significantly superior
to all neem seed extracts in reducing dead heart formation. In 1990 and
in 1991, all neem extracts gave a lower percentage of dead hearts than
adhesol and controls.
7.4.2. Laboratory experiments
Significant differences were obtained on the rate of hatching (F=
71.87; df= 6,18; p= 0.0001 in 1990; F= 60.48, df= 6,18, p= 0.0001 in
1991) (Table 20). All neem seed extracts gave a higher percentage of
egg mortality than the adhesol and control treatments (Table 20). The
treatment with adhesol had an egg mortality significantly higher than
that observed in the control. There were no significant differences
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between neem extracts and neem oil ( 0.63% azadirachtin, and local neem
oil) in causing egg mortal ity. Most of the unhatched eggs were
compl etely decomposed 24 h after the treatment wi th neem aqueous
extracts (Fig. 2) while they collapsed with neem oil .
All treatments showed significantly higher larval mortality
compared with the controls (F= 8.95, df= 4,12; p= 0.0007) (Table 21).
7.5. DISCUSSION
The di fferent concentrat ions of azadi rachti n found in our samples
confirm Ermel et al. (1984) and Isman et al. (1990) results who found
that azadirachtin content may vary according to the tree From which
seeds were collected, the environmental conàitions, the year and the
geographical area. In studying the azadirachtin content of 12 neem oil
samples, Isman et al. (1990) reported a variation of azadirachtin From
50 to 4000 ppm with a subsequent variation in bioactivity From 72 to
90%. The variations of the number of eggs laid, the percentage of egg
hatching and dead hearts between 1990 and 1991 (Table 19, 20) could be
due to the qualitative difference recorded in azadirachtin content.
The neem seed extracts proved to be effective in reducing egg
numbers in the field. This might be due to either an antiovipositional
action or an ovicidal effect. The antiovipositional action of neem
extracts has been observed on various insect pests by several authors
including Das (1986), Hellpap and Mercado (1986), Bowry et al. (1986),.
Rice et al. (1985), Saxena et al. (1981). For instance, AZT -VR-K, an
enriched formulated neem seed kernel extract, gave 100% repellence at
a concentration of 0.02% against the sheep blowfly, Lucilia sericata
(Rice et al. 1985).
Although little data are available on the ovicidal effect of neem
extracts, our results indicated a strong effect on the shoot Fly eggs.
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110
Mong and Sudderuddin (1978) found that high concentrations of ethanolic
and aqueous neem extracts reduced the hatching rate of the diamondback
moth, P7ute77a xy7oste77a L., eggs. Saxena et a7. (1981) obtained
similar results by dipping the eggs of the rice leaffolder,
Cnapha7ocrocis medina7is (Guenée), into neem oil at different
concentrations (12, 25, 50%). But Schmutterer (1990) pointed out that
these results were probab1y due to the choking effect of the neem oi1,
as other vegetable oi1s (such as groundnut) will do, rather than the
growth regu1ating properties of the neem ingredients. A partial
suffocating effect cou1d have a1so occurred in our experiment as eggs
were deposited on the fil ter paper parts treated with neem oil.
Rovesti and Deseo (1991) reported inconsistent effects of neem extracts
on egg morta1ity of the 1eafminer Leucoptera ma7ifo7ie77a Costa and
suggested that this was probab1y due to qua1 itative differences
between the kerne1s stored for different times.
The decomposition of eggs observed in laboratory conditions,
mi9ht a1so have occurred in field conditions. But this wou1d not have
happened without a uniform spraying of the neem extracts on the
underside of the sorghum 1eaves where eggs are laid. Neem application
shou1d be done in the morning after dew disappearance. Applications
shou1d be done at least one hour after the rain. Schmutterer (1990)
discussed the practica1 prob1ems of neem app1 ication and mentioned that
the residua1 effect of neem products f~~g~ most1y from five to seven
days. Consequently, he recommended that extensi on personnel exp1 ain
we11 the de1ayed effect of neem products to farmers in order to avoid
disapointments or premature wrong conclusions.
The carbofuran treatment did not reduce egg 1aying. However, it .
a110wed plants to deve10p well and to escape from heavy shoot f1y
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III
damage. Sukhani and Jotwani (1982) found simil ar results and noted
that the maximum number of eggs (31.75 eggs per 25 plants) were laid in
plots treated with carbofuran (3G at a rate of 1.5 g/m row) compared
with untreated checks (18.25 eggs per 25 plants).
In the laboratory, adhesol caused 61.5% and 51.5% egg mortality
in 1990 and in 1991 respectively. However, in field conditions, it
neither prevented egg laying nor dead heart formation. In 1990 field
experiments, it increased the potency of the solution in reducing dead
heart formation when added to neem extracts.
The reduct i on of dead heart format ion here reported, confi rms
Abdul-Kareem et a7. ' s (1974) results that were 27% and 20% of
reduction of dead heart using 10 and 5 Kg kernels/ha respectively.
Using neem oil at 0.6%, Chundurwar and Karanjkar (Parbhani) (1980) also
noted a reduction in dead heart formation compared with the control.
Our results on the effect of neem extracts on the shoot fly
l arvae suggested that there was an antifeedant effect. Raina (1981)
suggested that the movement of the first-instar larvae to the base of
the sorghum plant shoot could be due to a chemical attractant present
in or around the growing point of the central shoot. The neem aqueo~s
extracts and adhesol spread so that the solution could reach the
sorghum central shoot, might alter this chemical attractant and cause
a deterrent effect on shoot fly larvae. Many authors (e.g. Olâifa and
Akingbohungbe 1987, Raffa 1987, Jacobson 1986, Saxena and Khan. 1986)
have showed outstanding antifeedant properties of neem extract products
against several pests. Gill and Lewis (1971) pointed out that an
effective antifeedant.must be persistent, absorbed and translocated to
the growing point of the treated plants. Otherwise selective attack by
insect pests will occur on the new growths of the plants while the
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112
older treated parts remain distasteful. More investigations are
required in the case of the sorghum shoot fly larvae.
In view of the low education level of Burkina Faso farmers and
Sahelian farmers in general, their low agricultural income, the cost of
pesticides and the local availability of the neem tree, neem products
coul d be a techni cally acceptabl e component of an Integrated Pest
Management approach to control the shoot fly.
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7.6. REFERENCES
Abacus Concepts Inc. 1989. SuperANOVA, Accessible General Linear
Modeling, Berkeley, California, 316 p.
Abdul Kareen, A., Sadakathulla, S., Venugopal, M.S. and Subramaniam,
T.R. 1974. Efficacy of two organotin compounds and neem
extracts against the sorghum shoot fly. Phytoparasitica 2, 127
129.
Admed, S. and Grainge, M. 1985. The use of indigenous plant resources
in rural development. Potential of the neem tree. International
Journal for Development Technology 3, 123-130.
Bowry, S.K., Pandey, N.D. and Tripathi, R.A. 1986. Evaluation of
certain ail seed cake powder as grain protection against
Sitophilus oryzae L. Indian J. Entomol. 46, 196-200 .
Chundurwar, R.D. and Karanjkar (Parbhani), R.R. 1980. Control of
sorghum shootfly with neemoil and Decamethrin. Sorghum
Newsletter 23, 82.
Das, G.P. 1986. Effect of different concentrations of neemoil on the
adult mortality and oviposition of Callosobruchus chinensis L.
(Coleoptera: Bruchidae). Indian J. Agri. Sc. 56, 743-744.
Deeming, J. C. 1971. Sorne species of Atherigona Rondani (Diptera:
Muscidae) from Northern Nigeria, with special reference ta those
injurious ta cereal crops. Bull. Entomol. Res. 61, 133-190.
Ermel, K., Pahlich, E. and Schmutterer, H. 1984. Comparison of the
azadirachtin content of neem seeds from ecotypes of Asian and
African origin, pp. 91-93. In Schmutterer, H. and Ascher,
K.R.S. eds. Proc. 2nd Int. Neem Conf. Rauischholzhausen 1983.
Gill, J.S. and Lewis, C.T. 1971. Systemic action of an insect feeding
deterrent. Nature, 232, 402-403
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Hamilton, D.P. 1992. The wonders of the neem tree - Revealed! Science
255, 275.
Hellpap, C. and Mercado, J.C. 1986. Effects of neem on the
oviposition behaviour of the fall armyworm Spodoptera frugiperda
Smith. J. Appl. Entomol. 105, 463-467.
lsman, M.B., Koul, O., Luczynski, A. and Kaminski, J. 1990.
lnsecticidal and antifeedant bioactivities of neem oil and their
realationship to azadirachtin content. J. Agric. Food Chem. 38,
1406-1411.
Jacobson, M. 1986. The neem tree: Natural resistance par excellence,
pp. 220-232. In Green, M.B. and Hedin, P.A., eds. Natural
resistance of plants to pests. Roles of allechemicals. American
Chemical Society Symposium Series No. 296. Washington, D.C. 243
pp.
Jones, R.S., Ley, S.V., Morgan, LD. and Santafianos, 0.1989. The
chemistry of the neem tree, pp. 19-45. In Jacobson, M. (ed.),
1988 Focus on Phytochemical Pesticides, Vol. 1, the Neem tree.
CRC Press, Florida, USA.
Mong, T.T. and Sudderuddin, K.I. 1978. Effects of a neem tree
(Azadirachta indica) extract on diamondback moth (P7ute77a
xy770ste77a L.). Mal. Appl. Biol. 7, 1-6.
Mote, U.N. 1985. Efficacy of mixtures of carbofuran treated and
untreated sorghum seed for the control of shootfly. J.
Maharashtra agric. Univ. 10, 36-38.
Nwanze, K.F. 1988. Distribution and seasonal incidence of some major
insect pests of sorghum in Burkina Faso. lnsect Sei. Applic. 9,
313-321 .
Olaifa, J.l. and Akingbohungbe, A.E. 1987. Antifeedant and
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insecticidal effects of extracts of Azadirachta indica, Petiveria
a77iacea and Piper quineense on the variegated grasshopper,
Zonocerus variegatus, pp. 405-418. In Schmutterer, H. and
Ascher, K.R.S. eds. Proc. 3rd Int. Neem Conf. Nairobi, Kenya
1986.
Raffa, K.F. 1987. Influence of host plant on deterrence by
azadirachtin of feeding by fa" armyworm larvae (Lepidoptera:
Noctuidae). J. Econ. Entomol. 80, 384-387.
Raina, A.K. 1981. Movement, feeding behaviour and growth of larvae of
the sorghum shoot fly Atherigona soccata. Insect Sci. Applic. 2,
71-81
Rice, M., Sexton, S. and Esmail, A.M. 1985. Antifeedant phytochemical
blocks oviposition by sheep blowfly. J. Aust. Entomol. Soc. 24,
16.
Rovesti, L., and Deseo, K.V. 1991. Effectiveness of neem seed kernel
extract against Leucoptera ma7ifo7ie77a Costa (Lep.,
Lysnetiidae). J. Appl. Entomol. Ill, 231-236.
Saxena, R.C. 1981. Neem seed ail for leaf folder control. Plant Prat.
News (Philippines) 10, 48-50
Saxena, R.C., Waldbauer, G.P., Liquida, N.J. and Puma, B.C.. 1981.
Effects of neem seed ail on the rice leaffolder Cnapha7ocrocis
medina7is, pp. 189-204. In Schmutterer, H., Aschter, K.R.S. and
Rembold, H. (eds.). Natural pesticides from the neem tree
Azadirachta indica A. Juss. Proc. lst Int. Neem Conf.
Rottachegrern, 16-18, June 1980. GTZ 6236 Eschborn 1. 297 pp.
Saxena, R.C. and Khan, Z.R. 1986. Aberrations caused by neem ail
odour in green leafhopper feeding on rice plants. Entomol. Exp .
Appl. 42, 279-284.
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Schmutterer, H. 1990. Properties and potential of natural pesticides
from the neem tree, Azadirachta indica. Annu. Rev. Entomol. 35,
271-297.
Schmutterer, H. and Ascher, K.R.S. 1984. Natural pesticides from the
neem trees Azadirachta indica A. Juss, and other tropical
plants. Proc. 2nd Int. Neem Conf. Rauischholzhausen, 25-28 May,
1983. GTZ, Eschborn 1., 587 pp.
______ . 1987. Natural pesticides from the neem tree Azadirachta indica
A. Juss, and other tropical plants. Proc. 3rd Int. Neem Conf.
Nairobi, Kenya 10-15 July, 1986. GTZ, Eschborn 1. 703 pp.
Schmutterer, H., Aschter, K.R.S. and Rembold, H. 1981. Natural
pesticides from the neem tree Azadirachta indica A. Juss. Proc.
Ist Int. Neem Conf. Rottachegrern, 16-18, June 1980. GTZ,
Eschborn 1., 297 pp.
Stoll, G. 1986. Natural crop protection, based on local resources in
the tropics and subtropics. Josef Margraf, Publisher. Aichtal,
Federal Republic of Germany. 186 pp.
Sukhani, T.R. and Jotwani, M.G. 1982. Spot treatment of granular
insecticides for the control of sorghum shootfly, Atherigona
soccata Rondani. Indian. J. Entomol. 44, 117-120 .
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7.7. TABLES AND FIGURE 2•
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• 119
Table 20. Effect of neem seed kernel extracts on the eg9 mortality of
A. soccata in laboratory conditions, Burkina Faso.
Treatment%Mortality (n- 30)
1990 1991
Neem oil0.63% azadirachtin 87.5a" 88.3a
40 9 of seed kernel/ 87.5a 91.7aL water + adhesol
• 60 9 of seed kernel/ 85.0a 90.8aL water + adhesol
Local neem oil 83.3a 88.3a
40 9 of seed kernel/ 81. Sa 85.84aL water
5 ml of adhesol/ 61.5b 51.5bL water
Control 29.0c 23.4c
" Means within a column with the same letter are not significantly different,P • 0.05, Scheffé's test .
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Table 21. Effect of aqueous neem seed kernel extracts on larval mortality of
A. soccata in 1991, Burkina Faso.
Treatment % Mortality of larvae
40 9 of seed kernel/l 55.0b"water + adhesol
60 9 of seed kernel/l 55.0bwater + adhesol
40 9 of seed kernel/l 50.0b
• water
Adhesol 50.0b5 mll l water
Control O.Oa(Distilled water)
• Mean percentages with the same letter are not significantly different,P • 0.05, Scheffé's test •
. '
121
Figure 2. Shoot fly eggs decomposed 24 h after treatment with neem
aqueous extracts.
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CONNECTING STATEMENT
In the previous chapters, l investigated five shoot fly control
tactics including monitoring, time-sequential sampling, cultural
practices, host plant resistance, and the use of a biopesticide from
the neem tree. An IPM program requires the use of several combined
tacti cs that will signi fi cantly reduce pest damage wi thout harmful
impact on the environment. The use of natural enemies against a given
insect pest should be considered as an important component in IPM
programs (Surn et al. 1987). This tactic, known as biological control,
is a harmless component to human beings and the environment. It implies
research on which natural enemies will provide control, and how to
conserve or augment the number of these natural enemies. In chapters
8 and 9, l will investigate the impact of cultural activies using
intercropping of sorghum and cowpea on biocontrol agents. The main
goal is to identify candidate species which are likely to enhance shoot
fly suppression .
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8 Effects of Intercropping Sorghum-Cowpea on
Natural Enemies of the Sorghum Shoot FlY,
Atherigona soccata Rondani (Diptera: Huscidae). in
Burkina Faso
In press in Biological Agriculture &Horticulture
Authors: ZONGO, J.O" VINCENT, C. STEWART, R.K.
123
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8.1. ABSTRACT
Experiments were conducted in 1990 and 1991 at Matourkou near
Bobo-Di oul asso, Burki na Faso (West Afri ca), to study the effect of
intercroppin9 sor9hum-cowpea, Sorghum bico7or L. (Moench)- Vigna
ingucu7ata (Walp.), on the natural enemies of the sor9hum shoot fly,
Atherigona soccata Rondani (Diptera: Muscidae). Sampl ing was done
weekly, on six occasions starting 10 days after sowing. Natural enemies
of eggs were Trichogrammatoidea simmondsi Nagaraja (Hymenoptera:
Trichogrammatidae), Tapinoma sp. (Hymenoptera: Formicidae), Fusarium
sp. and a bacterium, Corynebacterium sp. Other insect species included
a thysanopteran (Phlaeothripidae, Haplothripinae) and Dicrodiphosis sp.
(Diptera: Cecidomyiidae) which were also associated with the sorghum
shoot fly eggs. No significant differences were observed between the
pure sorghum and the intercropped sorghum-cowpea with rl~spect to T.
simmondsi parasitism. Larval parasitoids were Neotrichoporoides
nyemitawus Rohwer (Hymenoptera: Eulophidae), (6 to 17.50% of
parasitism), Bracon sp. (Hymenoptera: Braconidae), and Hockeria sp.
(Hymenoptera: Chalcididae). One pupal parasitoid was recorded, A7ysia
sp. (Hymenoptera: Braconidae). Significant differences were observed in
the percentage of larval parasitism in 1990 and in 1991 betwee: the
pure sorghum and intercropped sorghum-cowpea. There was about two-fold
and 1.4-fold increased larval parasitism in intercropped sorghum-cowpea
in 1990 and 1991 respectively. Morisita's index of similarity (0.94.
in 1990, 0.98 in 1991) between pure sorghum and intercropped sorghum·~
cowpea (0.9B between 1990 and 1991), indicated that the parasitoid
species composition was independent of both the cropping system and the
year .
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8.2. INTRODUCTION
Intercropping has been defined as growing two or more crops
simultaneously in the same field (Vandermeer 1989). This practice may
increase (Risch et al. 1983, Vandermeer 1989) or decrease (Pimentel
1961, Risch et al. 1983) the abundance of natural enemies of a given
pest. Intercropping sorghum-cowpea is a common practice in Burkina
Faso, the former crop being attacked by the shoot fly, Atherigona
soccata Rondani (Diptera: Muscidae).
A. soccata has a wide range of natural enemies including egg
parasitoids (Pont 1972, Taley and Thakare 1979, Deeming 1971, Delobel
1983, Delobel and Lubega 1984), larval parasitoids (Kundu and Kishore
1972, Pont 1972, Taley and Thakare 1979, Del obel 1983), pupal
parasitoids (Deeming 1971, Taley and Thakare 1979), spiders and birds
(Del obel and Lubega 1984). Deeming (1983) found that the most common
prey of the wasp Dasyproctus bipunctatus Lepeletier and Brullé
(Sphecidae), are adult Atherigona spp. Delobel and Lubega (1984)
stated that unidentified species of spiders and birds are important
natural enemies of the sorghum shoot fly.
Young (1981) noted that research on biological control of the
shoot fly has been neglected. No work has been published so far on the
effect of intercropping on the natural enemies of the sorghum shoot
fly. The hypothesis examined here was that the population density of
egg, larval and pupal parasitoids would be less abundant in a
monoculture than in an intercropped system. We al so recorded other
potential biocontrol agents of the shoot fly.
8.3. MATERIAL5 AND METHOD5
The study was carried out in 1990 and 1991 at Matourkou, located
approximately 10 km from Bobo-Dioulasso (11 0 Il', 40 18'W), Burkina
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Faso, West Africa. Each year, the local sorghum cultivar "Gnofing" and
the cowpea cultivar TVx 3236 were sown on 15 July in a randomized
complete block design with four replicates. Each plot measured 13.5 x
9 m and contained 18 rows. Three cropping systems were established:
pure sorghum, 50% sorghum/50% cowpea sown in alternate rows, and pure
cowpea. Row spacings were 0.75 m in all plots and intra-row spacings
were 0.25 and 0.20 mfor sorghum and cowpea respectively. One and two
seedlings were maintained per hill for cowpea and sorghum respectively.
Plots were fertilized with 200 kg/ha of NPK (15 15 15) applied on
two occasions: 100 kg/ha at sowing, and 100 kg/ha 30 days after sowing.
Fifty kg/ha of urea (46% N) were applied 45 days after sowing.
No pesticides were applied during the study. Sampling was done
weekly, on six occasions starting 10 days after sowing .
8.3.1. Egg parasitoid sampling
In each plot, five rows of sorghum were randomly selected.
Twenty shoot fly eggs were collected between 8.00 and 10.00 h from
randomly selected plants within these rows. ·Pieces of sorghum leaves
with eggs were removed using small scissors. The eggs were then
transferred to Petri dishes containing wet filter paper and brought to
the laboratory. They were examined with a binocular microscope and
damaged eggs were discarded. Undamaged eggs were placed on filter
paper (10 x 80 mm) and transferred to small vials (25 x 95 mm). The
vials were closed with a wet cotton plug and kept under observation for
two weeks in a rearing room set at 26 (± 1) ·C, 75% R.H.(± 2) and 12:12
(L/D) photoperiod.
To feed emerging adults, a diet comprising 1/3 honey and 2/3
distilled water v/v was streaked inside the vial using a fine camel
brush. Observations were recorded daily, and emerging adult parasitoids
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were counted and removed from the vials. Fourteen days after field
collection, all remaining eggs were dissected in Ringer's solution
using two fine pins to detect the presence of unemerged parasitoids.
8.3.2. Larval and pupal parasitoid samplinq
Twenty pl ants showing dead hearts were randomly sel ected and
removed from each plot. In the laboratory, these plants were
dissected. The larvae were removed and transferred individually to
plastic cups (30 ml; from Priee Daxxion, Saint-Laurent, Québec,
Canada). Four holes (2 dia. mm) were eut in the lids. Each larva was
provided with 1 9 of artificial diet (Singh et a7. 1983), which was
repl aced every second day. Pupae were transferred i ndi vidually to
similar plastic cups containing sterilized sand (6 g), which was wetted
every second day with 10 droplets of distilled water. Parasitoid
emergence was recorded daily. Emerged shoot fl ies were kept in 70%
alcohol for identification.
8.3.3. Funqi and bacteria samplinq
All dark eggs collected from the field were retained. These eggs were
disinfected by dipping them in 1% sodium hypochlorite (NaOC1) for one
minute and then rinsing them with distilled water. Isolation was done
on Potato Dextrose Agar (PDA), (DIFCO Inc.) medium. The microorganisms
were then subcultured in legume juice (V8 medium, 200 ml legume juice,
3 9 MgC03 , 15 9 Agar).
Insect species were identified by the International Institute of
Entomology, London, U.K •. Voucher specimens were deposited in the Lyman
Museum, Macdonald Campus of McGill University, Sainte-Anne'de Bellevue,
Québec, and at the Biosystematic Research Center, Ottawa, Canada.
Fungi were identified by USDA Plant Protection Research, US
Plant, Soil &Nutrition Lab., Ithaca, New York, USA. The fungi here
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isolated has been deposited into the USDA-ARS Collection of
Entomopathogenic Fungal Cultures (ARSEF), Boyce Thompson Institute,
Ithaca, New York, USA (Humber, personal ccmmunicat~~n). Bacteria were
identified by MDS Laboratories, Montréal, Québec, Canada.
Data on percentage of parasitism was analyzed using ANOVA
followed by Scheffé's test of the software SuperANOVA (version 1.1 for
the Macintosh Computer) (Abacus Concepts Inc., 1989). Morisita's index
of similarity (MI) (Morisita 1959) was used to compare species
composition between the two crops, and among the two years. The x2 (chi
square) test (Steel and Torrie, 1980) was used to compare total number
of egg, larval and pupal parasitoid individuals between the two crops.
8.4. RESULTS
8.4.1. Shoot fly complex
Species of shoot fly collected from sorghum shoots included A.
soccata, Sco7iophtha7mus micantipennis Duba (Diptera: Chloropidae),
Si7ba pectita J.F. McAlpine (Diptera: Chloropidae) and Diopsis apica7is
Dalman (Diptera: Diopsidae) (Table 22). All specimens of the genus
Atherigona, were A. soccata. A. soccata were significantly (P = 0.05)
more abundant in pure sorghum than in intercropped sorghum-cowpea
(Table 22). Larvae of Sco7iophtha7mus micantipennis were commonly
associated (6 to 9 larvae per sorghum shoot) with the A. soccata larva.
The former were usually smaller in size than the A. soccata larvae and
were found in the upper part of the damaged shoots. They were most
frequent when the damage on the central shoot was well developed.
8.4.2. Egg natural enemies
In both 1990 and 1991, shoot fly eggs were commonly parasitized
by Trichogrammatoidea simmondsi Nagaraja .. Parasitism was recorded from
17 to 38 days after sowing in both cropping systems. Based on pooled
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data each year, rate of parasitism was highest 24 days after sowing in
both cropping systems (Fig. 3). Although the highest rate of egg
parasitism was recorded in intercropped sorghum-cowpea (8.75% in 1990;
12.3% in 1991), no significant differences were observed between the
levels in pure sorghum and the intercropped sorghum-cowpea (Table 23).
The male:female sex ratio of T. simmondsi was 1:1.28 and 1:1.37 in 1990
and 1991, respectively. Among the 305 A. soccata eggs examined, the
numbers of T. simmondsi exit holes per egg were: one (44.92%), two
(53.45%) and three (1.63%).
In the course of laboratory experiments, Tapinoma sp. Forster
(Hymenoptera: Formicidae) was found preying on shoot fly eggs. One
individual was found to destroy up to 18 eggs per day.
Mites such as Suidasia pontifica Oudemans (Astigmata:
Saproglyphidae) and sorne species of the family Histiotomatidae, were
found in association with shoot fly eggs in great numbers (7 to 13 per
sampling date).
A fungus, Fusarium sp. Link ex Fr., and a bacterium,
Corynebacterium sp. Lehmann and Neuman, were isolated from shoot fly
eggs. Technically it was difficult to quantify parasitism by these
microorganisms owing to lack of facilities.
A thysanopteran (Phlaeothripidae, Haplothripinae) and
Dicrodiphosis sp. (Diptera: Cecidomyiidae) were also found associated
with eggs.
8.4.3. larval and pupal parasitoids
Neotrichoporoides nyemitawus Rohwer (Hymenoptera: Eulophidae) was
the most, important endo-larval parasitoid. Significant differences
were found on the percentage of larval parasitism in 1990 (F = 66, df
= 1,3, P < 0.0001) and in 1991 (F = 30, df = 1,3, P = 0.0015) between
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the pure sorghum and intercropped sorghum-cowpea (Table 23). There was
about two-fold and 1.4-fold increase in larval parasitism in
intercropped sorghum-cowpea in 1990 and 1991 respectively. The highest
percentage of larval parasitism was II.75 and 17.50% in 1990 and 1991
respectively. Parasitism was detected from 17 to 45 days after sowing.
In 1990, using pooled data, percentage larval parasitism was found to
be highest 31 days after sowing in both cropping systems (Fig. 3). In
1991, percentages of parasitism were highest 31 and 38 days after
sowing in pure sorghum and intercropped sorghum-cowpea respectively
(Fig. 3). The larval parasitoids Bracon sp. (Hymenoptera: Braconidae)
and Hockeria sp. (Hymenoptera: Chalcididae) were also found emerging
from field collected shoot fly larvae. One pupal parasitoid, A7ysia sp.
(Hymenoptera: Braconidae), was recorded .
Total number of shoot fly parasitoid species collected in 1990
and 1991 is given in Table 24. All shoot fly parasitoids were present
in both years and both cropping systems. Morisita's index of similarity
(MI) between pure sorghum and intercropped sorghum-cowpea was 0.94 and
0.98 in 1990 and 1991 respectively. Using pooled data, MI was found to
be 0.98 between 1990 and 1991.
8.5. DISCUSSION
In both years, A. soccata was the species of the genus Atherigona
attacking sorghum. This confirms the results of Nwanze (1988) who
found up to 96% of A. soccata in sorghum shoots collected both from
farmers and research station fields. A. soccata larva was found in the
same sorghum shoot with larvae of the species Sco7iophtha7mus
micantipennis and Si7ba pectita. We did not find solitary larvae of
these species in the sorghum shoots. However, Deeming (1971) recorded
sol itary l arvae of S. micantipennis destroyi ng young sorghum seedl ings.
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Our observations confirm his more common finding that of about a dozen
S. micantipennis larvae associated with A. soccata larva in the same
shoot. Damage by A. soccata may make sorghum shoots more attractive to
S. micantipennis, which may be considered as an opportunistic pest.
Although sorne species of Diopsis attack undamaged rice plants, those
which attack other grasses, such as Diopsis apica7is, are known to only
attack already damaged plant tissues (I.M. White, personal
communication).
Trichogrammatoidea simmondsi Nagaraja was an important shoot fly
egg parasitoid. This is a first record on A. soccata eggs.
Trichogrammatoidea spp. are mainly egg-parasites of Lepidcptera, and to .
a lesser extent, of few other insect orders (Nagaraja;. 1978). T.
simmondsi has been recorded on rice· pests, such as Chi70 sp.
(Pyralidae), Chi70 parte77us Swinhoe (Lepidoptera: Pyralidae), Sepedon
angu7aris (Diptera: Sciomyzidae), and Diopsis thoracica Westwood
(Diopsidae) (Na9araja, 1978). Feijen and Schulten (1981) recorded T.
simmondsi on the rice stalk-eyed fly Diopsis macrçphtha7ma Dalm (=
thoracica Westwood) in Malawi and concluded that its importance as a
parasitoid was secondary or marginal.
Another species, Trichogrammoidea bactrae Nagaraja, has been
recorded on A. soccata eggs in India (Rao et a7. 1987). Other species
of the genus Trichogramma are also egg parasitoids of the shoot fly.
Deeming (1971) recorded Trichogramma evanescens Westwood in Nigeria,
whereas Taley and Thakare (1979) reported T. austra7icum Girault (=
chi70nis Ishii) in India. Delobel (1983) recorded T. ka7kae in Kenya.
So far, two species (Trichogrammatoidea bactrae and T. simmondsi) of
the genus Trichogrammatoidea and three speci es (Tri chogramma
evanescens, T. ka7kae and T. austra7icum) of the genus Trichogramma are
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known to be egg parasitoids of the sorghum shoot fly.
Our results on the number of exit holes of T. simmondsi indicate
that one (44.92%) or two (53.45%) individuals emerged per host egg.
Nagaraja (1978) found an average of 2 and 2.1 exit holes on O.
macrophtha7ma eggs in fi eld and l aboratory respect ively.
Superparasitism occurred as there were 1.63% eggs with three exit holes
per egg.
Tapinoma sp. was a voraci ous egg predator in the 1aboratory.
Many speci es of the genus Tapinoma are opportuni st i c nesters often
found in tufts of dead grass, plant stems, urban environments and other
local sites (Hôlldobler and Wilson, 1990). Forel (1920) mentioned that
Tapinoma is a large widely distributed and common genus. This suggests
that the Tapinoma sp. here recorded may be a potential shoot fly egg
predator to look for. Tapinoma sp. constitutes a first record on A.
soccata eggs.
Suidisia pontifica individuals were associated in great number
(from 7 to 13 per sampling date) with sorghum shoot fly eggs. These
mites are mycophagous and show various degrees of selectivity in
choosing fungi (Sinha, 1966). Our observations were not conclusive in
fi ndi ng mites as predators of shoot fly eggs. However, Reddy and
Davies (1978) found a predacious mite, Abro7ophus sp. (Acari:
Erythraeidae) feeding on A. soccata eggs in India.
The genus Fusarium has a wide range of insect hosts. Species such
as F. avenaceum (Fries) Saccardo, and F. merismoides Corola, are found
on Lymantria dispar L. (Lepidoptera: Lymantriidae) egg mass (Humber and
Soper 1986).
Corynebacterium sp. is a bacterium widely distributed in nature
in the animal kingdom, sorne species being found in birds and insects
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(Buchanan and Gibbons, 1974).
So far, no microbial control agent has been found on shoot fly
e9gs. Therefore, Fusarium sp. and Corynebacterium sp. are the first
'record on the sorghum shoot fly e99s. They could be potential microbial
control agents.
Other suspected predators such as Dicrodiphosis sp. and
Haplothipinae (Thysanoptera: Phlaeothripidae) were associated with
shoot fly eggs. Larvae of Dicrodiplosis species are usually predators
on mealy bugs (K.M. Harris, personal communication). More
investigation are needed to confirm the real status of these insects on
the sorghum shoot fly eggs.
The most important endo-larval parasitoid was N. nyemitawus. In
our study, the percentage parasitization ranged from 6.00 to 17.50%.
Taley and Thakare (1979) recorded 1.59 to 8.33% parasitism due to N.
nyemitawus, whereas Rawat and Sahul (1968) reported 22 to 30% in India.
Our highest numbers (11.75 in 1990, 17.50% in 1991) of parasitized
shoot fly l arvae was recorded in intercropped sorghum-cowpea. This
shows that i ntercroppi ng sorghum-cowpea had a benefi ci al effect in
increasing N. nyemitawus populations.
Bracon sp. and Hockeria sp. were present in sma11 numbers'. They
constitute a first record on A. soccata larvae. Hockeria Walker is a
worldwide genus and contains about thirty described species (Halstead,.
1990).
Although other larval-pupal parasitoids such as Spalangia endius
Wal ker, Trichopria sp., Opius sp., and pupal parasitoids such as
Monelata sp., and Rhoptromeris sp. have been recorded in India (Taley
and Thakara, 1979), Alysia sp. was the only pupal parasitoid in our
study. Deeming (1971) also recorded Alysia sp. in Nigeria.
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No parasitism due to T. simmondsi and N. nyemitawus occured on
the 10 th day after sowing. This was due to the lack of shoot fly eggs
and larvae at that period. In 1988 and 1989, longo et al. (1992) also
recorded no shoot fly eggs ten days after sowing at Matourkou. The
most susceptible stage of sorghum for shoot fly attack is within 21
days after germination (Jotwani et al., 1970). The fluctuation of
parasitism suggests that T. simmondsi could reduce shoot fly
populations better than N. nyemitawus within the susceptible stage of
sorghum.
Our results on the shoot fly parasitoid species composition
indicated that there was a high similarity between the two cropping
systems and between the years. High Morisita similarity index values
(0.94 in 1990 and 0.98 in 1991 between pure sorghum and intercropped
sorghum-cowpea, 0.98 between 1990 and 1991) here reported indicated
that the parasitoid species composition was independent of the cropping
system and of the year.
Although the intercropped sorghum-cowpea did not show significant
differences compared with pure sorghum with respect to egg parasitism,
it could increase N. nyemitawus populations and also give ;: good
combined yield of sorghum and cowpea as longo et al. (unpubl ished
data) found an agronomie advantage of practicing this cropping system.
longo et al. (1992) recommended that control measures be taken against
the shoot fly before dead heart formation. Further to this
recommendation, egg natural enemies such as Trichogrammatoidea
simmondsi, T. bactrae, Trichogramma spp., Tapinoma sp., Abrolophus sp.,
Fusarium sp., Corynebacterium sp., may be the appropriate biological or
microbial control agents to look for inimplementing any biological
control strategy.
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sampl ing of the sorghum shoot fly, Atherigona SGccata Rondani
(Diptera: Muscidae), in Burkina Faso. Insect Science and its
Application, (In press) .
•
•
•
8.7. TABLES AND FIGURE 3.
139
••
•
Tab
le22
.A
bund
anee
ofsh
oot
fIle
ssp
eele
s(m
ale
and
fem
a1e)
emer
ged
from
1arv
aeeo
llee
ted
from
sorg
hum
shoo
tsat
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ourk
ou,
Bur
kina
Faso
.
Shoo
tf1
ysp
eele
s19
90
Sorg
hum
Sor9
hum
-Cow
pea
x'P
-val
ues
1991
Sorg
hum
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hum
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pea
x'P
-val
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socc
ata
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mus
mie
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penn
is
Sflb
ap
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la
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psis
apfc
alis
Tot
al
35 55 4 94
13 43 6 62
10.0
S'
1.46
fiS'
0.40
fiS
<0.
005
0.10
<P
<0.
25
0.5
<P
<0
.75
41 63 7 111
17 56 5 SS
9.93
'
0.41
Ils
0.33
fiS
flAb
<0.
005
0.5<
P<
0.75
0.5<
P<
0.75
Si9
nifl
eant
,P
•0.
05,
x't
est
•N
otsi
gnif
ican
t,P
=0.
05,
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st
bN
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ble
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dno
tbe
perf
orm
eddu
eto
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hran
'sre
stri
ctio
n(i
.e.
expe
cted
freq
uenc
y<
5).
140
•(
\ U
••
Tab
le23
.A
vera
gepe
rcen
tpar~~Îtism
due
taT
rich
ogra
mm
atoi
dea
sim
mon
dsi
and
lIeo
tric
hop
oroi
des
nyem
itaw
uson
sorg
hum
shoo
tfl
yeg
gsan
dla
rvae
inin
terc
ropp
ing
sorg
hum
-cow
pea
lnB
urkI
naFa
so.
Cro
ppln
gsy
stem
Pure
sorg
hum
Sorg
hum
-cow
pea
P-va
lues
1990
r.si
lMlo
ndsf
7.00
..
8.75
a
0.25
0B
/1.
nyem
itaw
us
6.00
a
11.7
5b
0.00
37
1991
1.si
mm
onds
i
11.8
0a
12.3
0a
0.72
16
1/.
nyem
itaw
us
12.5
0a
17.5
0b
0.00
15
•H
ean
perc
enta
ges
wit
hin
aco
lum
n,w
ithdl
ffer
ent
Jett
ers
are
sign
lflc
antl
ydt
ffer
ent,
.P
=0.
05,
AfiO
VA•
141
••
•
T.b
le24
.T
otal
num
ber
of
shoo
tfl
yp
aras
itoi
dsp
ecie
sco
llec
ted
inB
urki
naF
aso.
Par
asit
oid
spec
ies
1990
1991
Pure
sorg
hum
Sorg
hum
-Cow
pea
x'P
-val
ues
Pure
sorg
hum
Sorg
hum
-Cow
pea
x'
Tric
hogr
amm
atoi
dea
sim
mon
dsi
3539
0.21
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0.5
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7547
490.
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roid
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19·
4510
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<0.
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5070
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con
sp.
32
lIA"
24
liA
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asp
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11
liA
Aly
sl.
sp.
52
liA14
100.
66ilS
Tot
.162
8811
313
3
P·v
alue
s
0.75
<P
<0.
9')
0.05
<P
<0.
10
0.25
<P
<0.
5
• ..S
igni
fie.
nt,
P=
0.05
,x
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t
Ilot
sig
nif
le.n
tP
•0.
05,
x't
est
rial
avai
lab
lc,
x2te
stco
uld
not
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rfor
med
due
toC
ochr
an's
rest
rict
ion
(i.e
.ex
pect
edfr
eque
ncy
<5)
.
142
143
Figure 3. Percentages of egg and larval parasitism due to
Neotrichoporoides nyemitawus and Trichogrammatoidea simmondsi in
two cropping systems in Burkina Faso.
•
•
•
1-0
-P
ure
sorg
hu
m,
Sor
ghum
-cow
pea
140
11
401
1
A)
N.
nyem
ltaw
us,
1990
C)
T.sl
mm
on
ds!
,19
90
3030
2020
5040
3020
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•"
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o
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1991
eu ....
B)
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30J
/\
130
~ 0
2020
1010
Day
sa
fta
rso
win
g
••
•
•
•
•
144
CONNECTING STATEMENT
In an agroecosystem, all potential natural enemies of a given
insect pest should be investigated to identify appropriate candidates
for a biocontrol program. In chapter 8, sorne biocontrol agents
including egg natural enemies (Trichogrammatoidea simmondsi, Tapinoma
sp., Fusarium sp. and Corynebacterium sp.), and the larval parasitoid
(Neotrichoporoides nyemitawus) were identified as potential candidates
against the shoot fly. Baily and Chada (1968) found that spiders are
an important group of predators of sorghum insect pests in Oklahoma
(USA). In Kenya, Delobel and Lubega (1984) pointed out that several
unidentified spider genera and species reduced shoot fly eggs ·in
sorghum fields. Therefore, l decided to investigate spider populations
in Burkina Faso. Because spiders are a complex group of predators with
respect to their numbers, species, ecology, and behaviour, l decided to
separate chapter 9 from the previous one. The main questions asked in
this chapter are: "Which spider species are associated with the shoot
fly, and could intercropping sorghum-cowpea increase spider
populations?"
•
•
•
145
9 Spi der Fauna in Pure Sorghurn and Intercropped Sorghurn-Cowpea in
Burkina Faso .
In press in Journal of Applied Entomology.
Authors: ZONGO, J.O., STEWART, R.K., VINCENT, C.
•
•
•
146
9 .1. ABSTRACT
Atwo-year study was conducted at Matourkou near Bobo-Dioulasso,
Burkina Faso (West Africa), to study spider fauna in pure sorghum and
intercropped sorghum-cowpea, Sorghum bico7or L. (Moench)- Vigna
ingucu7ata (Walp.), associated with the sorghum shoot fly, Atherigona
soccata Rondani (Diptera: Muscidae). Sampling was done weekly, on six
occasions starting 10 days after sowing. Significant differences were
observed with respect to the number of individu1ls in the specific
composition of spider fauna from different cropping systems. Juvenile
spiders represented 84 and 75% of the total number of spiders in 1990
and 1991 respectively. Twelve families and 24 genera were recorded. In
pure sorghum, the most important families were Thomisidae (7.73%) and
Salticidae (4.12%) whereas Araneidae (15.15%), Theridiidae (8.77%)
Thomisidae (8.76%) and Linyphiidae (7.22%) were predominant in sorghum
cowpea. In pure cowpea, Linyphiidae (6.69%), Pisauridae (6.18%), and
Theridiidae (4.63%) were predominant. Four species were identified:
Latrodectus geometricus C.L. Koch, Meioneta prosectes Locket, Pardosa
injucunda O.P. Cbr, and Steatoda badia Roewer. Latrodectus geometricus
and P. injucunda were only recorded in sorghum-cowpea whereas M.
prosectes and S. badia were common to the three cropping systems. Five
species namely Araneus sp., M. prosectes, Misumenops sp., Neoscona
sp. ,and S. badia showed preference for the intercroppfld sorghum
cowpea. The Sorenson's index of similarity between sorghum and sorghum
cowpea, and between cowpea and sorghum-cowpea was 0.75 and 0.66
respectively suggesting that spider species composition was relatively
independent of the cropping system.
•
•
•
147
9.2. INTRODUCTION
Spiders are an important group of terrestrial predators widely
distributed in the world (Nentwig 1987, Nyffeler et al. 1990, Riechert
and Lockley 1984, Nyffeler and Benz 1987). There are about 35,000
described species, belonging to about one hundred families (Platnick
1989). Most of the studies of spiders in agroecosystems have been done
in North America, Europe, Asia and, to a lesser extent Africa and
Australia (Nyffeler and Benz, 1987).
Bailey and Chada (1968) studied spider populations in sorghum
fields at Oklahoma (USA) and concluded that spiders played an important
part in controlling sorghum insect pests.
Information on West African spiders is very limited. For
instance, reviewing 300 papers on the role of spiders in natural pest
control, Nyffeler and Benz (1987) cited only three papers from Egypt
and three from South Africa. Likewise, among the 48 D~pers cited in
Nyffeler et al. 's (1990) review concerning spiders as predators of
insect eggs, none was African. Millot (1941) studied crab spiders
(Thomisidae) in six West African countries including Burkina Faso, Côte
d'Ivoire, Guinée, Mali, Niger and Sénégal. In Côte d'Ivoire, Blandin
(1971, 1972) stud~ed the spider communities in a savanna grassland and
found that peak numbers of both adult and juvenile spiders occurred
during the long rainy season.
In Kenya, Del obel and Lubega (1984) mentioned that several
unidentifieo-'spider genera and species are important predators of the
sorghum shoot fly, Atherigona soccata Rondani (Diptera: Muscidae) eggs.
A. soccata is a key pest of sorghum, Sorghum bicolor L. (Moench), in
West Africa (Nwanze, 1985), including Burkina Faso (Bonzi, 1981,
Nwanze, 1988).
•
•
•
148
Intercropping sorghum-cowpea, Vigna unguicu7ata [L.] Walp. is a
commor. practice in Burkina Faso, and it has been suggested that it may
increase or decrease natural enemies of some insect pests (Vandermeer,
1989).
No work has been published on the effects of intercropping
sorghum-cowpea on spider populations. The present experiments were
undertaken to study the spider fauna associ ated with sorghum duri ng
shoot fly activity and det~rmine if sorghum-cowpea intercropping
increases spider populations.
9.3. MATERIALS AND METHODS
The study was carried out in 1990 and 1991 at Matourkou, located
approximately 10 km from Bobo-Dioulasso, Burkina Faso, West Africa (Il'
11' S, 4' 18'W). Each year, the local sorghum variety "Gnofing" and
the cowpea cultivar TVx 3236 were sown on 15 July in a randomized
complete block design with four replicates. Each plot measured 13.5 x
9 m and contained 18 rows. Three cropping systems were established:
pure sorghum, 50% sorghum/50% cowpea sown in alternate rows, and pure
cowpea. Row spacings were 0.75 m in all plots, whereas intra-row
spacings were 0.25 and 0.20 m for sorghum and cowpea, respectively.
One and two seedlings were maintained per hill for cowpea and sorghum,
respectively.
Plots were fertilized with 200 Kg/ha of NPK (1515 15) applied on
two occasions, namely 100 Kg/ha at sowing time, and 100 Kg/ha 30 days
after sowing. Fifty Kg/ha of urea (46%) were applied 45 days after
sowing. Weeding was done on two occasions, 15 and 30 days after sowing.
No pesticides were applied during the study.
Spider populations were determined by direct observation weekly
on six occasions starting 10 days after sowing. In each plot, five rows
•
•
.'
149
of each crop were randomly selected. The spiders found on these rows
were collected by hand using camel brushes and small vials. They were
transferred to vials containing 70% alcohol until they were sorted and
counted.
Data were analyzed using Scheffé's test of the software
SuperANOVA (version 1.1 for the Macintosh Computer) (Abacus Concepts
Inc., 1989). Sorenson's index of similarity (Sorenson 1948, cited in
Krebs 1989) was used to compare species composition between the two
crops. The x2 (chi-square) test (Steel and Torrie, 1980) was used to
compare the total number of individuals of each species between two
crops.
Voucher specimens of most spider species were deposited at the
Musée Royal de l'Afrique Centrale, Tervuren, Belgium.
9.4. RESULTS
No significant differences of the total number of spiders were
observed between cropping system, and per individual crop in 1990 and
1991 (Table 25). However, significant differences of the number of
individuals per species were observed between cropping systems (Table
26).
The total number of spiders collected (all data pooled) was 221
and 367 in 1990 and 1991, respectively. Several spiders were not
identified to species level because the number of spiderl ings was
higher (84 and 75% in 1990 and 1991 respectively) than adults (16 and
25% in 1990 and 1991 respectively). Consequently, 194 individual s
belonging to 12 families and 24'genera were identified (Table 27). They
represented 33% of the total number of spiders collected in 1990 and
1991. In pure sorghum, the most important families were Thomisidae
(7.73%) and Salticidae (4.12%) whereas Araneidae (15.15%), Theridiidae
•
•
•
150
(8.77%) Thomisidae (8.76%) and Linyphiidae (7.22%) were predominant in
sorghum-cowpea. In pure cowpea, Linyphiidae (6.69%), Pisauridae
(6.18%), and Theridiidae (4.63) were predominant (Table 27). Eleven
genera were common to cowpea versus sorghum-cowpea whereas la were
common to all cropping systems and 12 to sorghum versus sorghum-cowpea
(Table 26). Four species were identified: Latrodectus geometricus C.L.
Koch, Meioneta prosectes Locket, Pardosa injucunda a.p. Cbr, and
Steatoda badia Roewer. Latrodectus geometricus and P. injucunda were
only recorded in sorghum-cowpea whereas M. prosectes and S. badia were
common to the three cropping systems. Araneus sp., M. prosectes,
Misumenops sp., Neoscona sp., and S. badia showed marked preference
for the intercropped sorghum-cowpea (Table 26).
The Sorenson's index of similarity between sorghum and sorghum
cowpea, and between cowpea and sorghum-cowpea was 0.75 and 0.66
respectively. This indicated that species composition of spider
communities was more similar when sorghum was compared with
intercropped sorghum-cowpea than cowpea compared with sorghum-cowpea.
Few spiders were recorded in both cropping systems on the first
sampling occasion (ten days after sowing) (Fig. 4). The spiders started
to substantially colonize each cropping system from 17 to 45 days'after
sowing. In 1990, the peak number of spiders in both cropping systems
was recorded 31 days after sowing (Fig. 4). In 1991, the peak number of,
spiders in pure sorghum èind in sorghum-cowpea was recorded 31 days
after sowing, whereas it was on 38 days aftpr sowing in pure cowpea.
•
•
•
151
9.5. DISCUSSION
Thomisidae were common to both cropping systems. We found five
genera namely Misumenops, Runcinia, Thomisus, Tmarus, and Xysticus.
Millot (1941) described 50 species belonging to 22 genera from six West
African countries (Burkina Faso, Côte d'Ivoire, Guinée, Mali, Niger,
and Sénégal). He found that the genera Thomisus and Tmar'us contained
over 30 and 12 African species respectively. The species Misumenops
rubro-decorata Millot, Runcinia depressa Simon, Runcinia proxima
voltaensis Millot, Thomisus bidentatus Kulczynski and, Thomisus
spinifer Cambridge were collected in Burkina Faso (Millot, 1941).
Little information exists on the biology of the four species here
reported. A survey of the literature from the scientific database
Agricola and Biological Abstracts from 1970 to April 1992 revealed no
paper published on these spider species.
In pure sorghum, we found that Salticidae, Thomisidae, and
Araneidae were predominant. Studying spider populations in grain
sorghum, Bailey and Chada (1968) also found that Lycosidae, Thomisidae,
and Salticidae were the most commonly collected families. In Côte
d'Ivoire, Blandin (1971, 1972) found that Thomisidae populations were
most abundant in a savanna grassland at the beginning of the long rainy
season and also in the short rainy season.
Prey compos i t ion was not q!lanti fi ed. However, i t i s we11 known
that the prey composition varies with the group of spiders (web
builders or hunting) (Bishop and Riechert 1990, Culin and Yeargan 1983,
Nentwig 1988), the agroecosystem (Agnew and Smith 1989, Bishop and
Riechert 1990, Culin and Yeargan 1983, Doane and Dondale 1979, Nyffeler
et al. 1989, Young and Lockley 1985), the geographical zones (Nentwig
1985) and the cultural practices (Buschman et al. 1984). The
•
•
152
intercropped sorghum-cowpea might have influenced prey composition as
different spider species were collected per cropping system.
Del obel and Lubega (1984) found that spiders sucked the shoot fly
egg contents and left conspicuous remman~s of the chorion attached to
the sorghum leaves. Nyffeler et al. (1990) also found examples of
spiders preying upon the eggs of Araneae and Insecta from North and
South America, and Austral ia, largely in agroecosystems and forest
ecosystems. They pointed out that spider species found to be predacious
on insect eggs belonged principally to the families Salticidae,
Oxyopidae, Lycosidae, and Clubionidae which were important families in
our studies.
ln all cropping systems, spider populations increased until 31
days after sowing. This period corresponded to the susceptible stage of
sorghum for shoot fly attack and therefore to high shoot fly activity.
The spider populations at that period might have played an important
part in reducing shoot fly populations.
Although no statistical differences were observed with respect to
the total number of spiders, the intercropped sorghum-cowpea increased
the number of fi ve speci es namely Araneus sp., M. prosectes, Misumen.ops
sp., Neoscona sp.,and S. badia. Studying the bionomics of these species
could help to understand their real impact in intercropping sorghum
cowpea during shoot fly activity.
Conservation and augmentation of predators in a given area is an
important step in biological control as a maximum control effect is
always expected from them (Huffaker and Messenger 1976). Spiders being
important predators, great attention must be paid to measures that
might be taken to conserve and to increase their numbers. In general,
agricultural practices causing high mortal ity to spiders are
•
•
•
153
insecticide applications (Dondale et al. 1979, Pfrimmer 1964, Riechert
and Lockley 1984), annual harvesting and tilling of the vegetation
ground layer (Riechert and Lockley 1984, Nentwig 1988), and mechanical
disturbance (Bultman and Vetz 1982, Riechert and Lockley 1984).
Although more research should be done to understand the effect of
spiders in reducing shoot fly populations, intercropping sorghum-cowpea
could be practiced to increase the number of certain spider species
namely Araneus sp., Meioneta prosectes, Misumenops sp., Neoscona sp.,
and Steatoda badia .
•
•
•
154
9.6. REFERENCES
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modeling. Berkeley, CA., 316 p.
Agnew, C.W. and Smith, Jr. J.W. 1989. Ecology of spiders (Araneae) in
a peanut agroecosystem. Environ. Entomo7. 18: 30-42.
Bailey, C.L. and Chada, H.L. 1968. Spider populations in grain sorghum.
Ann. Entomo7. Soc. Am. 61: 567-571.
Bishop, L. and Riechert, S.E. 1990. Spider colonization of
agroecosystems: mode and source. Environ. Entomo7. 19: 1738-1745
Blandin, P. 1971. Recherches ëcologiques dans la savane de Lamto (Côte
d'Ivoire): observations prëliminaires sur le peuplement
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Blandin, P. 1972. Recherches ëcologiques sur les araignëes de la savane
de Lamto (Côte d'Ivoire): premières donnëes sur les cycles des
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264.
Bonzi, S.M. 1981 Fl uctuations sai sonni ères des popul ati ons de la
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Bultman, T.L.and Vetz, G.W. 1982. Abundance and community structure of
forest floor spi ders fa11 owi ng l itter man i pul at ion. Oeco7ogia 55:
34-41.
Buschman, L.L.; Pitre, H.N. and Hodges, H.F. 1984. Soybean cultural
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Culin,J.D. and Yeargan, K.V. 1983. Comparative study of spider
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spiders. Ann. Entomo7. Soc. Am. 76: 825-831.
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155
Delobel, A.G.L. and Lubega, M.C. 1984. Rainfall as a mortality factor
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Muscidae). Z. ang. Entomol. (J. Appl. Entomol.) 97: 510-516.
Doane, J.F. and Condale, C.D. 1979. Seasonal captures of spiders
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Dondale, C.D.; Parent, B. and Pitre, D. 1979. A6-year study of spiders
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Huffaker, C.B. and Messenger, P.S. 1976. Theory and practice of
biological control. Academic Press, New York, 788 p.
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Millot, M.J. 1941. Les araignées de l'Afrique Occidentale Française:
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Nentwig, W. 1985. Prey analysis of four species of tropical orb-weavi~g
spiders (Aranea: Araneidae) and a comparaison with araneids of
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Nentwig, W. 1987. Ecophysiology of spiders. Springer-Verlag. Berlin,
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Nentwig, W. 1988. Augmentation of beneficial arthropods by strip
management. 1 succession of predacious arthropods and long-term
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a meadow. Oeco7ogia 76: 597-606•
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156
Nwanze, K.F. 1985. Sorghum insect pests in West Africa pp. 37-43, In
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(ICRISAT). Proceeding of the International Sorghum Entomology
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Nwanze, K.F. 1988. Distribution and seasonal incidence of some major
insect pests of sorghum in 8urkina Faso. Insect Science and its
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Nyffeler, M. and Benz. G. 1987. Spiders in natural pest control: A
review. J. App7. Ent. 103: 321-339.
Nyffeler, M., Dean, D.A. and Sterling, W.L. 1989. Prey selection and
predatory importance of orb-weaving spiders (Aranae: Araneidae,
Uloboridae) in Texas cotton. Environ. Entomo7. ~8: 373-380•
Nyffeler, M., Breene, R.G.; Dean, D.A. and Sterling, W.L. 1990. Spiders
as predators of arthropod eggs. J. App7. Ent. 109: 490-501
Pfrimmer, T.R. 1964. Populations of certain insects and spiders on
cotton plants following insecticide application. J. Econ.
Entomo7. 57: 640-644.
Platnick, N.I. 1989. Advances in spider taxonomy 1981-1989: A
suppl ement to Bri gnoli 1 s A catalogue of the Araneae descri bed
between 1940 and 1981. Manchester University Press, New York. 673
pp.
Riechert,S.E. and Lockley, T. 1984. Spiders as biological control
agents. Annu. Rev. Entomo7. 29: 299-320.
Sorenson, T. 1948. A method of establishing groups of equal amplitude
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Dan. Vidensk. Se7sk. Bio7. Skr. 5: 1-34.
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157
Steel, R.G.D. & Torrie, J.H. 1980. Principles and procedures of
statistics, Abiometrical approach, McGraw-Hill Book Company, New
York, 633 pp.
Vandermeer J. H., 1989. The ecology of intercroppi ng. Cambridge
University F~"':,s, New York, 237 p.
Young, a.p. and Lockley, T.C. 1985. The striped lynx spider, Oxyopes
sa lticus (Araneae: axyopidae) in agroecosystems. Entomophaga 30:
329-346 .
•
•
•
9.? TABLES AND FIGURE 4
158
• 159
Table 25. Mean number of spiders (spiderlings and adults, all species
confounded) per five rows collected in two cropping systems in
Burkina Faso.
Crop 1990 1991
Pure Intercropped Pure Intercropped
• •Sorghum 13.50 a 14.00a 23.75 a 24.00a
Cowpea 15.75 a 12.00a 24.00 a 26.00a
•
* Horizontally (pure vs intercropped), mean percentages with same letterswithin the same year are not significantly different, Scheffé's test, P =0.05 .
•.,
••
Tabl
e26
.io
tal
num
ber
ofsp
ider
spec
ies
(spi
derl
ings
and
adul
ts)
coll
ecte
din
two
crop
ping
syst
ems
inB
urki
naFa
soin
1990
and
1991
(n=
156,
iden
tifi
edto
atle
ast
genu
s).
Sorg
hum
tow
pea
Spid
ersp
ecie
s
Pure
Inte
rcro
pped
X2Pu
reIn
terc
ropp
edx2
Aran
eus
sp.
413
4.7
6'
113
101,
28'
Aran
fe71
asp
.-
-1
-NA
Chi
raca
nthf
umsp
.-
1NA
"-
--
C/u
bfon
asp
.3
5NA
25
NAC
yrto
phor
asp
.-
--
1-
NAE
uryo
pis
sp.
--
--
1NA
Hfp
pasa
sp.
-2
NA-
2NA
Latr
odec
tus
geom
ftrfc
us-
1NA
-1
NALe
ucau
gesp
.-
5NA
-5
NAH
eren
nius
sp.
1-
NA-
--
Hef
onet
apr
osec
tes
2Il
6.2
3'
10Il
0.0
4,
Hfsu
men
ops
sp.
Il9
0.2
0,
19
6.40
,N
eosc
ona
sp.
212
7.14
112
6.40
Oxy~pes
sp.
13
NA1
3NA
Pard
osa
fnju
cund
a..
1NA
-1
NAPh
flodr
omus
sp.
11
NA2
lNA
Run
cfni
asp
.-
1NA
,-
1NA
Stea
toda
badf
a1
1310
.28
713
1.8
Than
atus
sp.
12
NA-
2NA
Ther
fdio
nsp
.2
2NA
22
NATh
omfsu
ssp
.1
2NA
-2
NATm
arus
sp.
-3
NA1
3NA
Tyb
aert
ie//
asp
.-
--
3-
NAX
ystic
ussp
.3
2NA
12
NA
*S
igni
fica
nt,
P<
2.0
5,
x2te
st.
**N
otap
plic
able
,X
test
coul
dno
tbe
perf
orm
eddu
eto
Coc
hran
'sre
stri
ctio
n(i
.e.
expe
cted
freq
uenc
y<
5)•
160
• 161
Table 27. Relative abundance of spider families and species collected in threecropping systems in Burkina Faso in 1990 and 1991.
Percenta~e of total capturesfamily)(n- 194, ldentified to at least
Family Pure sorghum Sorghum-cowpea Pure cowpeaSpecies
Araneidae (Orb weavers) 3.09 15.45 2.08Araneus sp. 2.06 6.70 0.52AranieH ~ sp. 0.52Cyrtophora sp. 0.52Leucauge sp. 2.57Neoscona sp. 1.03 6.18 0.52
Clubionidae (foliage spiders) 1.54 3.09 1.03Chiracanthium sp. 0.52C7ubiona sp. 1.54 2.57 1.03
Corinnidae 0.52Merennius sp. 0.52
Gnaphosidae (Ground spiders) 0.52 0.52 0.52Unidentified species 0.52 0.52 0.52
Linyphiidae (Line weaversk 1.03 7.22 6.69Meioneta prosectes Loc et 1.03 5.67 5.15
• Tybaertie77a sp. 1.54Lycodidae (Wolf spiders) 1.55
Hippasa sp. 1.03Pardosa injucunda (O.P. Cbr. ) 0.52
Oxyopidae (Lynx spiders) 0.52 1.54 0.52Oxyopes sp. 0.52 1.54 0.52
Philodomidae (Running crab spiders) 1.04 1.55 1.03Phil odromus sp. 0.52 0.52 1.03Thanatus sp. 0.52 1.03
Pisauridae }NUrsery-web spiders) 1.03 2.57 6.18Unidenti ied species 1.03 2.57 6.18
Salticidae }JUmping spiders) 4.12 1.03 2.57Unidenti ied species 4.12 1.03 2.57
Theridiidae (Comb-footed spiders) 1.55 8.77 4.63Euryopis sp. - 0.52Latrodectus geomitricus C.L.Koch 0.52Steatoda badia Roewer 0.52 6.70 3.60Theridion sp. 1.03 1.03 1.03
Thomisidae (Crab spiders) 7.73 8.76 1.56Misumenops sp. 5.67 4.64 0.52Runcinia sp. 0.52Thomisus sp. 0.52 1.03Tmarus sp. 1.54 0.52Xysticus sp. 1.54 1.03 0.52
% of total captures (n -194) 22.69 50.50 26.81
•
162
Figure 4. Total spider numbers (spiderlings and adults) per five rows
in three cropping systems in Burkina Faso
•
•
•
• 0 Pure sorghum
Sorghum-cowpea~ Pure co ea
60
A) 199050
40en:::0 30:l0-
G)>:;:: 20:l0-G)C.
10en:l0-G)
"C 0.-c.
• en-0 60:l0-G)..c B) 1991E 50~
l::- 40ca-01-
30
20
.L;~~10
0 "10 17 24 31 3B 45
1
• Days after sowing
•
•
•
163
CONNECTING STATEMENT
In biological control, no natural enemy can be used without sorne
knowledge of its biology. Answering important questions such as which
instar of the host is preferred, as well as other aspects of parasitism
may help to implement control tactics. In chapter 8, l suggested that
Neotrichoporoides nyemitawus could reduce shoot fly larval populations.
l also concluded that intercropping sorghum-cowpea would increase N.
nyemitawus populations. Taley and Thakare (1979) studied the life
history of N. nyemitawus in India, but no informati~n exists on how to
rear this par~sitoid and which instar of the shoot fly is preferred.
Therefore, this chapter deals with how to rear N. nyemitawus, with an
emphasis on host stage preference and searching behaviour .
•
•
•
164
10 Parasitism of sorghum shoot fly larvae, Atherigona soccata Rondani
(Diptera: Muscidae), by Neotrichoporoides nyemitawus Rohwer
(Hymenoptera: Eulophidae) •
Submitted to Insect Science and its Application, July 1992.
Authors: ZONGO, J.O., STEWART, R.K., VINCENT, C.
•
•
•
165
10.1. ABSTRACT
Larval parasitism of the sorghum shoot fly, Atherigona soccata
Rondani (Diptera: Muscidae), by Neotrichoporoides nyemitawus Rohwer
(Hymenoptera: Eulophidae) was studied in the laboratory. Ten shoot fly
larvae of each instar (3) and two periods of exposure (24, 48 h) were
used in a factorial design with four replicates. Significant
differences of parasitism were observed with respect to instars,
periods of exposure, and the interaction instar - period of exposure.
The second larval instar was most parasitized (68.75 and 85% of
parasitism after 24 and 48 h respectively) fcllowed by the first instar
(46.25% of parasitism) exposed after 48 h to adult parasitoids. N.
nyemitawus was an effective shoot fly endo-larval parasitoid.
Observations on N. nyemitawus searching sorghum seedlings for shoot fly
larvae are summarized .
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•
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166
10.2. INTRODUCTION
The sorghum shoot fly, Atherigona soccata Rondani (Diptera:
Muscidae), is an important pest of sorghum, Sorghum bico7or (Linne,
Moench), in West African countries (Nwanze 1985, Gahukar 1990) and in
Asia (Young 1981).
Although much work has been done on control strategies for the
shoot fly (Young 1981), biological control remains a relatively
unexplored strategy. The shoot fly has a wide range of natural enemies
including Neotrichoporoides nyemitawus Rohwer (Hymenoptera: Eulophidae)
which is a widespread endo-larval parasitoid. N. nyemitawus was first
described by Rohwer (1921) as Tetrastichus nyemitawus. Under this
name, the parasitoid has been recorded on Atherigona spp. in India
(Rawat and Sahu 1968, Kundu and Kishore 1972, Taley and Thakare 1979)
and in Kenya (Delobel, 1983). In a revision of the European
Tetrastichinae (Hymenoptera: Eulophidae), De V. Graham (1987) replaced
the genus Tetrastichus by Neotrichoporoides Girault. Although Taley
and Thakare (1979) studied the life-history of N. nyemitawus, little
information exists on host stage preference and the parasitoid's
searching behavior.
The present work was undertaken to determine which instar of A.
soccata is preferred for attack and how long the parasitoid takes to
parasitize shoot fly larvae. The searching behavior of N. nyemitawus is
also summarized. Such information could be important for implementing
a biological control program based on N. nyemitawus.
•
•
• '
167
10.3. MATERIALS AND METHODS
The study was carried out in a rearing room set at 26 (± 1) ·C,
75% R.H. (± 2) and 12:12 (L/D). Fourteen day-old sorghum plants from
sowing were grown in 18 cm diameter plastic pots. 8efore transferring
shoot fly larvae and parasitoids to the plants, the pots were covered
with a transparent plastic sheet (40 x 40 cm) held in three places
(upper part of the pot; middle and upper parts of the plastic sheet),
by clamp collars to form a cylindrical cage. The upper part of the
cage was capped with fine muslin. A square hole (10 x 10 cm) was made
on the basal part of the cage to allow diet replacement. Ten shoot fly
larvae of each instar were used in a factorial design with four
replicates. The three instars were defined according to Deeming (1971)
and Raina (1981) descriptions. Larvae of each instar were exposed to
N. nyemitawus adults for two periods of exposure: 24 and 48 h. They
were transferred into the central shoot of the plants with a fine camel
brush. After transferring the larvae, a two day-old mated female adult
N. nyemitawus was placed in each cage. To obtain two day-old female
parasitoids, newly emerged females on the same day were kept in a
separate cage with two > 24 h old males. Adult parasitoids were fed on
a medium consisting of 1/3 honey and 2/3 distilled water. A 5 cm
diameter Petri dish containing cotton with distilled water was also put
in the cage. The diet was replaced every second day. After each
treatment, the sorghum plants were removed and dissected. Each shoot
fly larva was then removed and transferred to 30 ml plastic cups with
perforated lids (model Priee Daxxion, Saint-Laurent, Québec, Canada)
containing 1 9 of Singh's et al. (1983) diet. The diet was replaced
every second day .
Observations were made daily untn the parasitoids emerged.
•
•
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168
Larvae dyi ng in the course of the experiments were di ssected in
Ringer's solution to detect the presence of eggs, larvae or pupac of
the parasitoids.
To study the searching behavior of female N. nyemHawus, one
parasitoid female was placed in a cage containing five sorghum plants
and one to two day-old second instar of shoot fly as follow: 1) five
larvae on each sorghum plant, 2) five larvae placed on the soil
adjacent to the sorghum plants, and 3) five larvae placed on the soil
near a 10 x 20 mm piece of sorghum leaf. Treatments were repeated nine
times. Observations were made for one hour on how the adult female
explored the plant, inserted its ovipositor as well as the time
required to move From one plant to another.
A cage containing up to two day-old N. nyemitawus adults (males
and females) was used to provide material for dissection. Second and
third intars shoot fly larvae were placed on the sorghum plant. After
exposure to adult parasitoid females, larvae were dissected daily ln
Ringer's solution to observe the number of eggs laid, larvae and pupae.
The number of days from 1) the date of infestation to the death of A.
soccata larvae, 2) the date of infestation to the emergence of adult
parasitoids, 3) the time from death of A. soccata larvae to· adult
parasitoid emergence, and 4) the longevity of adult parasitoids were
recorded .
Specimens were identified by Dr. J. Lasalle from the
International Institute of Entomology, London. Voucher specimens were
deposited in the Lyman Museum, Macdonald Campus of McGill University,
Sa inte-Anne de Bellevue, Québec, Canada, and at the Bi osystemat ic
Research Center, Ottawa, Canada.
Data were analyzed using ANOVA two factors and Scheffé's test of
•
•
•
169
the software SuperANOVA (version 1.1 for the Macintosh Computer)
(Abacus Concepts Inc. 1989).
10.4. RESULTS
Significant differences of parasitism were observed with respect
to instars (F = 217; df = 2, 18; P < 0.0001), period of exposure (F =
44.37; df = l, 18; p < 0.0001) and the interaction instars - period of
exposure (F = 34.94; df = 2, 18; P < 0.0001) (Table 28). The second
instar was most heavily parasitized, followed by the first instar
exposed 48 h (Table 28). Table 29 gives the mean number of days from
oviposition to adult emergence; from egg to A. soccata larval death;
from time of A. soccata parasitized larvae dying to adult emergence;
from egg to adult mortality and the life span of adults.
The parasitoid female used its antennae to explore the sorghum
plant. She started to inspect leaves adjacent to the point of exit of
the central shoot. She sometimes entered the central shoot to detect
the presence of a shoot fly l arva. When a l arva was l ocated, the
parasitoid started probing for a host by applying its ovipositor tip to
the plant tissues. She then bent her abdomen and stroked the plant
several times (8 to 13) with her ovipositor. If there was a resistance
to penetration, the female moved the ovipositor around the sorghum
plant stem until she found a suitable penetration site. She then
inserted her ovipositor into the plant tissues. Exploring and
oviposition after plant penetration usually took about 10 minutes and
then the female would relocate. During oviposition, the female held
the plant ~lith all six legs, the fore and middle legs being less mobile'
than the hind legs. Although we did not quantify the time spent by the
female parasitoid on each sorghum plant part, sorghum stems received
more.search time than leaves. Upper leaves were used for resting when
•
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170
the parasitoid fini shed laying an egg. In general, foraging on the
sorghum plant started from top to bottom, the larva being found usually
in the base of the plant. The behavior of N. nyemitawus was
characterized by continuous movements, turning, and exploring the whole
plant from top to bottom with its antennae. This behavior may be
divided in four phases: 1) exploring, 2) ovipositor insertion, 3)
oviposition, and 4) resting.
There was neither attraction nor attack when larvae were exposed
on the soil. When a piece of leaf was put adjacent to a larva, the
female parasitoid flew around but never touched the larvae. Wh en
larvae crawled and entered into the central shoot, the female started
to examine the sorghum plant.
Usually one egg was laid per larva, but two eggs per larva were
observed once in 30 observations. The egg was deposited between the
7th and 8th abdominal segments of the shoot fly larva. No A. soccata
adult emerged from parasitized larvae. Parasitoid pupa occupied the
whole body of the shoot fly larva, leaving about 0.3 to 0.5 mm in each
extremity.
10.5. DISCUSSION
The first and second instars of the shoot fly last 1- 3 days at
30° C (Raina, 1981). This suggests that at 26 ·C, the first and second
instars parasitized would still remain in their instar by the time they
were parasitized. The high rate of parasitism of second and, to a
lesser extent, third instars indicated that the female parasitoid can
distinguish the size ·of its hosto The first-instars are smaller and
more slender than second and third instars (Raina, 1981), and size is
a physical cue used by insect parasitoids in host selection and
location (Vinson, 1985). The lack of attraction to the first instar and
•
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171
the low percentage of parasitism on third instar, suggested that the
size of shoot fly larva is used as a physical cue. Richerson and
DeLoach (1972) also found that different sized beetles influenced the
choice of Peri7itus coccine77ae Schrank (Braconidae). Other physical
cues used by insect paras i toi ds inc1ude sound, vi brat ion, shape,
texture and electromagnetic radiation (Vinson, 19B5). Movements of the
shoot fly larva in the sorghum stem might stimulate the parasitoid in
host attack. Another physical cue might be the sorghum plant itself, as
no larva moving outside the sorghum stem was examined or attacked by N.
nyemitawus. Insects often use environmental cues (abiotic and biotic
factors) to direct their searching when cues from resources cannot be
detected (Bell 1991). For instance, females of Diaeretie77a rapae
Mclntosh (Braconidae), parasitoids of cabbage aphid, Brevicoryne
brassicae L. are attracted by plant odour, and col our, of the leaves
(Bell, 1991). The pieces of leaves here put adjacent to A. soccata
larvae might have stimulated N. nyemitawus searching.
Chemical cues play the greatest role in host location by
parasitoids (Vinson 1985, Vet and Dicke 1992), physical factors being
more important at host examination level (Vinson, 1985). Vet and Dicke
(1992) reviewed the ecology of infochemical used by natural enemies and
stated that herbivores have to feed and defecate, resulting in emission
of volatiles that may attract parasitoids. Although these mechanisms
have not been investigated in this study, a characteristic odor
escaping from the dead heart was noted. More detailed a:ld critical
experimentation is required to determine the nature of both physical
and ehemieal eues in the case of N. nyemitawus. The eharaeteristic odor
from the dead heart might be an important eue to investigate .
The duration of life-eyele. parameters of N. nyemitawus sueh as
•
•
•
172
the mean number of days from oviposition to adult emergence, from egg
to adult mortality and the life span of adults here reported may help
to implement the use of programmed releases i.e. timing of releases.
After the parasitoid laid its eggs, the A. soccata larva took 5
to 12 days (average = 8, n = 30) to die. Taley and Thakare (1979)
reported that the shoot fly larvae became inactive when the parasitoid
larva was in its third or fourth instar. This clearly indicates that
dead heart formation cannot be avoided before or after shoot fly larva
parasitization, as damage is still done by the parasitized larvae.
The cage and the medium were effective in rearing N. nyemitawus
adults as the average life span was 21.65 days. The maximum life span
of an adult female parasitoid was 51 days.
Neotrichoporoides nyemitawus was an effective shoot fly endo
larval parasitoid as no adult shoot flies emerged from parasitized
larvae. Zongo et al. (1992) concluded that shoot fly control methods
should be implemented before dead heart formation. Although N.
nyemitawus cannat prevent dead heart formation, it may be of potential
use in reducing shoot fly populations during a cropping season.
•
•
.'
173
10.6. REFERENCES
Abacus Concepts Inc. (1989) SuperANOVA, Accessible General Linear
Modelin9, Berkeley, California, 316 p.
Bell, W.J. (1991) Searchin9 behaviour. The behavioural ecology of
finding resources. Chapman and Hall, London, 358 pp.
Deeming, J. C. (1971) Sorne species of Atherigana Rondani (Diptera:
Muscidae) from Northern Nigeria, with special reference to those
injurious to cereal crops. B~77. Entama7. Res., 61, 133-190.
Del obel , A. (1983) Etude des facteurs déterminant l'abondance des
populations de la mouche du sorgho, Atherigana saccata Rondani
(Diptères, Muscidae). Thèse de Doctorat d'Etat, Université de
Paris Sud, Centre d'Orsay. ORSTOM, Paris, 127 pp.
De V. Graham, M.W.R. (1987) A reclassification of the European
Tetrastichinae (Hymenoptera: Eulophidae), with a revision of
certain genera. Bu 77 • Brit. Mus. (Natura7 Histary), EntamaI.
Series 55, 55-69.
Gahukar, R.T. (1990) Overview of insect pest management in cereals
crops in sub-Saharan West Africa. Indian J. Entama7. 52, 125
138.
Kundu, G.G. and Kishore, P. (1972) New host record of Atherigana
naqvii Steyskal (Anthomyiidae: Diptera) from India t0gether with
new record of i ts three Hymenopterous paras i tes. l ndi an J.
Entama7. 34, 80-81.
Nwanze, K.F. (1985) Sorghum insect pests in West africa pp. 37-43, In
International Crops Research Institute for the Semi-Arid Tropics
(ICRISAT). Proceedings of the International Sorghum Entomology
Workshop, 15-21 July 1984. Texas A & M University, College'
Station, TX, USA. Patancheru, India.
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174
Raina, A.K. (1981) Movement, feeding behaviour and growth of larvae of
the sorghum shoot fly, Atherigana saeeata. Inseet. Sei. Applie.
2, 77-8l.
Rawat, R.R. and Sahu, H.R. (1968) New records of Tetrastiehus
nyemitawus Rohwer (Hymenoptera: Eulophidae) as a parasite of
Atherigona sp., the wheat stem fly in Madhya Pradesh. Indian J.
Entamai. 3D, 319.
Richerson, J.V. and DeLoach, C.J. (1972) Sorne aspects of hast selection
by Perilitus eaeeinellae. Ann. Entamai. Sac. Am. 65, 834-839.
Rohwer, S.A. (1921) Descriptions of new chalcidid flies from
Coimbatore (S. India). Ann. Mag. Nat. Hist 7, 123-135 [Rev.
Appl. Ent. (A): 136].
Singh, P., Unnithan, G.C. and Delobel, A.G.L. (1983) An artificial
diet for sorghum shoot fly larvae. Entomol. Exp. Appl. 33, 122
124.
Taley, Y.M. and Thakare, K.R. (1979) Biology of seven new
hymenopterous parasitoids of Atherigana soeeata Rondani. Indian
J. agrie. Sei. 49, 344-354.
Vet, L.E.M. and Dicke, M. (1992) Ecology of i nfochemi cal use by
natural enemies in a tritrophic context. Annu. Rev. Entamai. 37,
141-172.
Vinson, S.B. (1985) The behavior of parasitoids, pp. 417-469. III
Kerkut, G.A. and Gilbert, L.I. (eds.). Comprehensive Insect
Physiology Biochemistry and Pharmacology. Vol. 9, Behaviour.
Pergamon Press, New York.
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175
Young, W.R. (1981) Fifty-five years 0; research on the sorghum
shootfly. Inseet Sei. App7ie., 2, 3-9.
Zon90, J.O., Vincent, C. and Stewart, R.K. (1992) Time-sequential
sampl ing of the sorghum shoot fly, Atherigona soeeata Rondani
(Diptera: Muscidae), in Burkina Faso. Inseet Sei. App7ie. (ln
press) .
•
•
•
10.7. TABLES
176
• 177
Table 28. Mean percentages of larval parasitism in relation to period
of exposure to Neotrichoporoides nyemitawus.
First instar24 0.00 0.0048 46.25 5.15
Second instar24 68.75 4.2748 85.00 2.04
Third instar24 17 .50 3.2248 8.75 2.39
•
A. soccata larval stage/time of exposure (h)
% parasitism'(n • 10 larvaeper replicate)
StandardError
•
, Mean of 4 replicates; F-value of the interaction larval instar-timeof exposure being 34.94; df = 2, 18; and p < 0.0001 .
• 178
Table 29. Ouration of l ife-cycle parameters of Neotrichoporoidesnyemitawus in the l aboratory (26 (± 1) 0 C, 75% R.H. (± 2) and12:12 (llO).
Mean duration Standardlife-cycle stage in days (n z 30) error
Egg to adult emergence 20.33 4.77
• Egg to A. soccata parasitized 8.06 2.37larva dying
A. soccata parasitized larval 11.43 0.66mortality to adult emergence
Egg to adult mortality 41.50 12.42
Adult l ife span 21.56 10.41
•
•
•
. '
179
CONNECTING STATEMENT
In chapter 4, l concluded that sorghum shoot fly control measures
should be taken before dead heart formation. In Chapter 8, l found that
Trichogrammatoidea simmondsi Nagaraja (Hymenoptera: Trichogrammatidae),
an egg parasitoid, could reduce shoot fly eggs during the susceptible
stage of sorghum.
Seven to 12% of the sorghum shoot fly eggs were parasitized by
Tri chogrammatoidea simmondsi. It has been postul ated that thi s egg
parasitoid could be a potential biocontrol agent against the shoot fly.
When a potential biological control agent is identified, research on
its biology is essential to understand how. to establish a control
program. Chapter Il deals with the first study on the biology of T.
simmondsi. The objective is to determine the number of instars, adult
life span and host preference .
•
•
•
Il Biology of Trichogrammatoidea simmondsi Nagaraja
(Hymenoptera: Trichogrammatidae) on sorghum shoot fly,
Atherigona soccata Rondani (Diptera: Huscidae) eggs
Submitted to Entomophaga, July 1992.
Authors: ZONGO, J.O., STEWART, R.K., VINCENT, C.
180
•
•
•
181
11.1. Abstract
Experiments were conducted in a rearing room to study the biology
of Trichogrammatoidea simmondsi Nagaraja (Hymenoptera:
Tri chogrammatidae) on sorghum shoot fly, Atherigona soccata Rondan i
(Diptera: Muscidae) eggs. Shoot fly eggs were divided in two groups:
1) eggs < 24 h old and, 2) > 24 h old eggs. Thirty eggs of each group
were used in a randomized complete block design with four replicates.
Shoot fly eggs less than 24 h old were preferred (73% of parasitism)
over 24 h old eggs (7.25%). Three larval instars of T. simmondsi were
observed. Few eggs with two T. simmondsi exi t holes (1. 87%) were
recorded in > 24 h old eggs compared with < 24 h ones (3.74%). The sex
ratio male:female was 1:1.47. The development from oviposition to adult
emergence ranged from 7 to 12 days (average = 9.8 ± 1.31, n = 40), and
the average life span of male and female T. simmondsi was 25 ± 1.46 h,
(range 22 - 26 h, n = 12) and 35.17 ± 10.9 (range 25 - 50 h, n = 28)
respectively at 26' C, 60-65% R.H. and 12:12 (LlO) photoperiod. This
paper constitutes the first published information on the biology of T.
simmondsi on the sorghum shoot fly .
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182
Il.2. Introduction
The Trichogrammatidae, whose species attack eggs of various
insects, i s a large Family of economi c importance (Nagarkatt i and
Nagaraja, 1977). The genus Trichogrammatoidea contains about 18
species recorded from different countries (Nagarkatti and Nagaraja,
1977) . Pi ntureau and Babault (1988) li sted six Afri can speci es
including Trichogrammatoidea simmondsi Nagaraja which has been recorded
in Ghana and Malawi. Feijen and Schulten (1981) recorded T. simmondsi
on eggs of Diopsis macrophtha7ma Dalm. (= thoracica Westwood) (Diptera:
Diopsidae), an insect pest of rice in Malawi. They also found that
other rice insect pests such as Chi70 parte77us Swinhoe (Lepidoptera:
Pyralidae) and Sepedon angu7aris (Diptera: Sciomyzidae) were
alternative hosts of T. simmondsi. T. simmondsi was also recorded on
sorghum shoot fly, Atherigona soccata Rondani (Diptera: Muscidae) eggs
in Burkina Faso (Zongo et a7. unpublished data). Establishing a time
sequential sampling plan for the sorghum shoot fly, Zongo et a7. (1992)
concluded that control measures against A. socci!ta should be taken
before dead heart formation. Studying the effect of intercropping
sorghum-cowpea on natural enemies of A. soccata, (Zongo et aJ.
unpublished data) found that egg natural enemies such as
Trichogrammatoidea simmondsi, T. bactrae, Trichogramma spp., Tapinoma
sp. (Hymenoptera: Formicidae), Abro7ophus sp. (Acari: Erythraeidae),
Fusarium sp., and Corynebacterium sp., could be appropriate candidates
as they prevent the eclosion of shoot fly larvae, which are responsible
for dead heart formation. They found 7 to 12.30% of eggs parasitism
caused by T. simmondsi in the field and postulate that T. simmondsi
could be a potential biological control agent against A. soccata.
No work has been published on the biology of this parasitoid on
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183
A. soccata. Therefore, the present study was carried out to provide
basic information for use in a biological control program against the
sorghum shoot fly.
Il.3. Materials and Methods
Experiments were conducted in an incubator set at 26° C, 60-65%
R.H. and 12:12 (L/D) photoperiod. Parasitoids were obtained at
Matourkou from shoot fly eggs collected from sorghum fields SONn at
weekly intervals. The eggs were placed on a piece (1.5 x 8 cm) of
filter paper wetted with 10 droplets of distilled wa'~r, inserted in
vials (5 x 10 cm) and kept in the incubator.
To feed emerging adults, a diet comprising 1/3 honey and 2/3
distilled water was streaked inside the vials using a fine camel brush.
Adult parasitoids emerging on the same day were transferred to a common
vial using a fine camel brush.
A. soccata adults were obtained by rearing third instar larvae
using Singh et a7.'s (1983) diet. Third instar larvae from the field
were identified using Deeming's (1971) and Raina's (1981) descriptions.
A. soccata adults were maintained using Soto's (1972) methods. Sorghum
plants were grown in 18 cm diameter plastic pots. To obtain shoot fly
eggs, a plastic pot containing five to ten 14-day old sorghum plants
was kept in 40 x 40 x 40 cm screened cage in an insectarium. Five to
ten A. soccata females were then released between 7:00 and 8:00 h in
each cage for egg laying. After laying, the eggs were divided in two
groups: 1) eggs < 24 h old and, 2) > 24 h old eggs. To obtain > 24 h
old eggs, the sorghum plants were removed from the cage after egg
laying and transferred in another cage without A. soccata females for
24 h. Thirty eggs of each group were used in a randomized complete
black design with four replicates. Each group of eggs was kept in 5 x
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184
la cm vials. The eggs were exposed to two couples of T. simmondsi
adults of the same age until the parasitoids died.
Shoot fly larvae and parasitoids emerging from eggs were
recorded. Two weeks after egg exposure to the parasitoids, all
remaining eggs were dissected in Ringer's solution using two fine pins
under a binocular microscope to detect unemerged parasitoids.
To study the development of the parasitoid, 40 parasitized shoot
fly eggs were kept each in a 2.5 x 9.5 cm vial. The number of days
from egg to adult emergence and from adult emergence to adult mortality
was recorded per hour from 7 to 12 h and from 15 to 17 h.
To distinguish instars, parasitized eggs of the same age were
dissected daily; larvae were removed and larval instars identified
using the length, col our and form. Pupae were removed and described.
Specimens were identified by Dr. B. Pintureau, INSA,
Vi 11 eurbanne, Lyon, France. Voucher specimens were deposited at the
Lyman Museum, Macdonald College of McGill University, Sainte-Anne de
Bell evue, Québec, and at the Bi osystematic Research Center, Ottawa,
Canada.
Data were analyzed using Scheffé's test of the software
SuperANOVA (version 1.1 for the Macintosh Computer) (Abacus Concepts
Inc. 1989).
11.4. Results
The T. simmondsi egg is white and fusiform. The larva is white
with the posterior end bulged and becomes more opaque with age. Three
instars were observed. The first instar is more slender than the
second. The second instar is shorter and thicker than the third instar.
The third instar can be distinguished from the second by the dark color
well developed in the posterior part and by the size. In first and
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185
second instars, the segmentation is not clear. The third instar has a
distinct head.
The pupa is exarate ar,d distinct. The eyes and ocell i are red.
Wh en there were two individuals per A. soccata egg, the pupal heads
were orientated to each pole of the egg or opposed to other.
Significant differences were observed with respect to egg age (F
= 344; df = 1,3; P < 0.0001). Eggs less than 24 h old were more
successfully parasitized (73%) than those > 24 h old (7.25%) (Table
30). Two days after parasitization, A. soccata eggs became more opaque.
Table 31 shows the size of T. simmondsi immature stages.
Fewer eggs with two exit holes were recorded in > 24 h old eggs
compared with < 24 h old eggs (Table 30). The averall sex ratio
male:female was 1:1.47 .
The duration of each stadium was not measured, but the
development time from egg to adult emergence ranged from 7 to 12 days
(avel'age = 9.8 ± 1.31, n = 40). The average life span of male and
female T. simmondsi was 25 ± 1.46 h, (range' 22 - 26 h, n = 12) and
35.17 ± 10.9 (range 25 - 50 h, n = 28) respectively.
Il.5. Discussion
Trichogrammatoidea simmondsi successfully parasitized shoot fly
eggs aged less than 24 h old. Specifie colors are included in
electromagnetic radiation and are used as physical eues by parasitoids
(Vinson, 1985). A. soccata eggs aged less than 24 h old were whiter
than older ones. This difference could be a physical cue used by the
parasitoid to distinguish its hosts. Takahashi and Pimentel (1967) also
reported that Nasonia vitripennis Walker preferred black housefly pupae
over brown ones •
We observed at most two exit holes of T. simmondsi per egg.
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•
186
However, longe et al. (unpublished data) recorded up to three holes
(1.63%, n = 305) from eggs collected in the field. This suggests that
superparasitism may be more prevalent in the field than in laboratory
conditions.
The sex ratio (40.5% males, 59.5% females) recorded in this study
is similar to that observed by longe et al. (unpublished data) from
eggs collected in the field at Matourkou (44 %males, 56% females in
1990, and 42% males, 58% females in 1991). Feijen and Schulten (1981)
found that laboratory eggs of D. macrophtha7ma contained 81.4% females
compared with field eggs (69.6%). Based on data obtained from one
single host egg, they pointed out that T. simmondsi was probably
arrhenotokous.
T. simmondsi took an average 9.8 days to develop from egg to
adult emergence. In D. macrophtha7ma eggs, T. simmondsi took Il days to
develop at 25° C (Feijen and Schulten, 1981). We found that the
average life span of an adult male and female was 25 h (range 22 - 26
h) and 35.17 h (range 25 - 50 h) respectively. Studying T. simmondsi
females at 25° C, Feijen and Schulter: (1981) reported a average l ife
span of 57.6 h.
T. simmondsi adults have a short life span. As a consequence,
shoot fly eggs shoul d be l ess than 24 h 01 d when exposed to adul t
parasitoids in a mass rearing programs. longe et al. (unpublished·
data) concluded that egg parasitoids and predators are the most
appropriate natural enemies of the sorghum shoot fly. Therefore, more
laboratory and field studies should be focused on L simmondsi to
determine its potential in controlling the sorghum shoot fly.
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187
11.6. ReferencesAbacus Concepts Inc.- 1989. SuperANOVA, accessible general linear
modeling.- Berkeley, CA., 316 p.Deeming, J. C. - 1971. Some species of Atherigona Rondani (Diptera:
Muscidae) from Northern Nigeria, with special reference to thoseinjurious to cereal crops. - Bull. Entomol. Res., 61, 133-190.
Feijen, H.R., &Schulten, G.G.M. - 1981. Egg parasitoids (Hymenoptera;Trichogrammatidae) of Oiopsis macrophthalma (Diptera; Diopsidae)in Malawi. - Netherlands J. Zool., 31, 381-417.
Nagarkatti, S. & Nagaraja, H. 1977. Biosystematics ofTrichogrammatidae.- Annu. Rev. Entomol., 22, 157-176.
Pintureau, B., & Babault, M. - 1988. Systématique des espècesafricaines des genres Trichogramma Westwood et TrichogrammatoideaGirault (Hym. Trichogrammatidae). - Les colloques de l'INRA, 43,97-120.
Raina, A.K. - 1981. Movement, feeding behaviour and growth of larvaeof the sorghum shoot fly, Atherigona soccata.- Insect Sci .Applic., 2, 77-81.
Singh, P., Unnithan, G.C. &Del obel , A.G.L. - 1983. An artificial dietfor sorghum shoot fly larvae. - Entomol. Exp. Appl. 33, 122-124.
Soto, P.E.- 1972. Mass rearing of the sorghum shoot fly and screeningfor host plant resistance under greenhouse conditions. In:Control of sorghum shoot fly (Jotwani, M.G. &Young W.R., eds.).- Oxford &IBH, New Delhi, 137-146.
Takahashi, F. &Pimentel, D.- 1967. Wasp preference for black-brownand hybrid-type pupae of the house fly.- Ann. Entomol. Soc. Am.,60, 623-625.
Vinson, S.B. - 1985. The behavior of parasitoids. In: ComprehensiveInsect Physiology Biochemistry and Pharmacology, Vol. 9,Behaviour (Kerkut, G.A. &Gilbert, L.I. eds.).- Pergamon Press,New York, 417-469
Zongo, J.O., Vincent, C. & Stewart, R.K. - 1992. Time-sequentialsampl ing of the sorghum shoot fly, Atherigona soccata Rondani(Diptera: Muscidae), in Burkina Faso. Insect Sci. Applic. (Inpress) .
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•
11.7. TABLES
188
••
•
Tab
le30
.Pe
rcen
tage
ofA.
socc
ata
eggs
para
siti
zed
byT.
sim
mon
dsi
and
num
ber
ofex
itho
les
per
egg.
Mea
npe
rcen
tage
ofex
itho
les
(n-I
07)
Egg
age
<24
h
>24
h
%Pa
rasi
tis
m
•73
.00
a
7.25
b
Stan
dard
erro
r
3.10
1.70
one
hole
96.2
6aU
98.1
3a
two
hole
s
3.74
·'·
1.87
•M
ean
perc
enta
ges
wit
hin
aco
lum
nw
ithdi
ffer
ent
lett
ers
wer
esi
gnif
ican
tly
diff
eren
t,P
=0.
05.
Sch
effé
'ste
st.
••2 Xte
st,
P=
0.05
,*A
*2 Xte
stco
uld
not
bepe
rfor
med
due
toC
ochr
an's
rest
rict
ion
(i.e
.ex
pect
edfr
eque
ncy
<5)
.
189
•
Table 31. Relative size of T. simmondsi immature stages(28' C, 60-65% R.H.).
HO
Immature stage Length (mm) n
Mean Range
Egg 0.15 0.10 - 0.20 23
• Larval '; nstarFirst 0.22 0.20 - 0.25 13Second 0.35 0.30 - 0.40 11Third 0.55 0.40 - 0.60 19
Pupa 0.45 0.40 - 0.50 21
•
•
•
••
12 GENERAL DISCUSSION AND CONCLUSION
191
•
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•
192
In February 1986, the National Sorghum-Millet-Maize Board
(SOMIMA) during a meeting held at Kamboinsé, (near Ouagadougou, Burkina
Faso) was concerned about the lack of research on the sorghum shoot
fly. At that time, only three papers (Brenière 1972, Bonzi 1981, Bonzi
and Gahukar 1983) were published on the sorghum shoot fly in Burkina
Faso. Bonzi's (1981), and Bonzi and Gahukar's (1983) studies a110wed
identification of 28 shoot fly species, knowledge of the proportion of
two species (Atherigona soccata (14%) and A. marginifolia (36%) in a
unknown sample size in 1980, and understanding of fluctuations of shoot
fly adults during dry and rainy seasons. Brenière (1972) evaluated
shoot fly damage in the west central region and found that sorghum
seedlings were less damaged with early sowing dates. Considering the
lack of research noted by SOMIMA, this work was consequently initiated
to contribute in filling this gap.
Specifie conclusions have been drawn in each chapter of this thesis.
In considering the whole study, the main approaches investigated may be
di vi ded into four components represent ing an overa11 1PM program to
control the sorghum shoot fly: 1) monitoring populations, 2) cultural
practices, 3) natural and chemical pesticides, and 4) biological
control (Fig. 5). They constitute available techniques that may be
practiced to reduce shoot fly incidence under Burkina Faso conditions.
Monitoring shoot fly populations is an important way to'
understand the emergence pattern during the rainy season. Knowing that
shoot fly populations built up rapidly after May (Bonzi 1981), that
adult peak captures occur in August and September (Bonzi ·1981, Zongo et
al. 1991), and that peak numbers of eggs and dead hearts occur in July
and August (chapter 4, 5), sowing dates prior to June may be practiced
to avoid and reduce great losses caused by the pest. Screening dates
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193
may also be practiced in August or September to select appropriate
cultivar resistant to the shoot fly. Monitoring programs could
preferably cover regional levels including many countries. For example,
in West Africa, monitoring shoot fly populations could cover Burkina
Faso, Mali, Niger, the North of Ghana, and Togo. This could allow
coordinated action to implement shoot fly control. For example, sorghum
could be sown within a period of 2-3 weeks. The monitoring here
investigated the relative proportion of 36 species of shoot flies over
two years. This also showed that the Multi-Pher trap is effective in
monitoring the shoot fly. Thirteen species were new reports in Burkina
Faso, including a new species Atherigona zongoi Deeming (appendix 2)
that increased the total number of shoot fly species to 41. A Time
sequential sampling program based on egg sampling, and first
establ ished for the sorghum shoot fly, is a valuable technique in
controlling this pest. This tactic allows decision to be made on
whether or not an outbreak popul ation exi sts. Consequently, control
action is made before dead heart formation. However, the field worker
must keep in mind the most susceptible stage of sorghum to shoot fly
attack, which ranged from 10 to 40 days after sowing in this study.
Cultural practices here examined demonstrated that among the 52
local sorghum cultivars, none was resistant to shoot fly compared with
the resistant cultivar IS 2123 from the USA. This indicated that work
should be done on breeding sorghum against the shoot fly using the
cultivar IS 2123 or other appropriate resistant cultivar as source of
resistance. Although intercropping sorghum-cowpea was not conclusive in
reducing shoot fly damage at all times, it gave an agronomic advantage
in obtaining good yields of both crops. (chapter 5). Intercropping
sorghum-cowpea increased the number of Neotrichoporoides nyemitawus, a
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194
shoot fly larval parasitoid, and five species of spider (Araneus sp.
Meioneta prosectes, Misumenops sp., Neoscona sp., and Steatcda badia).
Therefore, this practice could be done to augment or conserve these
natural enemies (chapters 8, 9).
The cultural practices are the least expensive tactics for
farmers based on their present knowledge and agricultural income.
However, they require careful timing and unified action by farmers. In
chapter 5, l found that shoot fly damage was lower (6.47% and 10.20%
~espectively in 1988 and 1989) when sorghum was sown on June 20 than
sowing dates after June 20. Therefore, l recommended that sorghum be
sown prior to June 20 in an unified action to avoid great losses caused
by the shoot fly. My recommendation could be more effective if farmers
from the same locality in cooperation with extension service applied
it. It is well known that staggering sowing dates of sorghum during the
cropping season favors shoot fly population outbreaks (Nwange 1988,
ICRISAT 1983). This supports the previous recommendation that sorghum
be sown at the same time for the same locality or when possible on a
regional basis. Hill (1989) pointed out that cultural practices are
valuable"control tactics but need implementation by governmental poliçy
and legislation, more research, training and publ ic education. In
Burkina Faso, the government could take measures favoring the
application of the classic system Research-Demonstration-Training.
This system would provide a secure knowledge base and access to
appropriate technologies. For example, broadcasting the results here
found on a large scale through the extension service could improve the
transfer of shoot fly technology to the farmer level.
The cultural practices discussed in this thesis could be
particularly useful when integrated with monitoring shoot fly
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195
popul at ions, sequenti al sampli ng, and the use of natural insect ici de
such as neem seed kernel extracts found to be effective in reducing egg
numbers and dead heart incidence (chapter 7). As stated in chapter 7,
neem tree grows well in all parts of Burkina Faso and thus could be an
appropriate component of an IPM program for farmers who have generally
low sorghum income and capital. For instance, 1 kg of neem would cost
50 F CFA comparing with 1 kg of carbofuran, which currently costs 1600
F CFA. Cultural practices may also be integrated with the use of
carbofuran, an effective chemical pesticide against the shoot fly.
However, this integration should be done when delayed planting entails
outbreak populations of eggs on a large scale during the cropping
season. The carbofuran treatment could be applied particularly in
larger scale farming where intensification of agriculture is better
than in smallholder farming.
Biological control, the fourth component investigated in this
study, offers a potential for implementing a sorghum shoot fly control
program. Important biocontrol agents such as egg natural enemies
(Fusarium sp. , Corynebacterium sp. , Tapinona sp. , and
Trichogrammatoidea simmondsi), larval parasitoids (Bracon sp., and
Hockeria sp.) were first recorded (chapter B). Other natural enemies
namely Neotrichoporoides nyemitawus, a larval parasitoid, and various
spider groups were also recorded (chapters 8, 9). These natural
enemies add to the existing wide range of shoot fly natural enemies.
Although these findings could not be directly applied to the farmer
level at the present time, they constitute an important step forward in
the implementation of biological control of the shoot fly. Potential
biocontrol agents such as T. simmondsi (7 to 12% of parasistism) and N.
nyemitawus (6 to 17% of parasistism) were identified with subsequent
•
•
•
196
studies on their biology. The studies revealed for the first time that
these parasitoids could be easily reared with low inputs (chapters 10,
11). Important quest ions such as wh i ch instar of the shoot fl y i s
susceptible, and how long are the parasitic stages have been answered
(chapters 10, Il). More research should be pursued in the laboratory
as well as in field conditions to improve possible timing of releasing
parasitoids, and to determine the potential of microbiocontrol agents.
In summary, the sorghum shoot fly control program shoul d be
focused on eggs before dead heart formation. Several tactics could be
transferred to the farmer level with an emphasis on cultural practices,
the use of neem seed extracts, and time-sequenti al sampl i ng. Thi s
transfer needs multidiscipl inary intervention in which researchers,
extension service personnel and politicians should play an important
role.
197
Figure 5. Approaches to sorghum shoot fly IPM investigated in this
thesis.
•
•
•
1.M
on
itori
ng
popu
latio
ns
-Tl8
ppln
gad
ult.
(ch
.pl.
r3)
-""'
Iu.n
llal
aem
plln
gDI
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.2.
Cu
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-Inl
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••
•
•
•
•
13 REFERENCES
198
•
•
•
199
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Barry, D. 1972. Notes on life history of a sorghum shoot fly,
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and related species in Burkina Faso. Trop. Pest Manag. 37: 231
235.
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press) .
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Appendix 1-
Manuscripts and Presentations Based on this Thesis.
Scientific publications
1) Zongo, J.O., C. Vincent, R.K. Stewart 1991. Monitoring Sorghum Shoot
Fly Atherigona soccata Rondani (Diptera: Muscidae) and Related
Species in Burkina Faso. Tropical Pest Management 37 (3),
231-235.
2) Zongo, J.O., C. Vincent, R.K. Stewart 1992. Time-sequential
Sampling of Sorghum Shoot Fly Atherigona soccata Rondani
(Diptera: Muscidae), in Burkina Faso. Insect Science and its
Application (In press).
3) Zongo, J.O., C. Vincent, R.K. Stewart 1992. Effects of Neem Seed
Kernel Extracts on Egg and Larval Survival of the Sorghum Shoot
Fly, Atherigona soccata Rondani (Diptera: Muscidae). Journal of
Applied Entomology (In press).
4) Zongo, J.O., C. Vincent, R.K. Stewart 1992. Effects of Intercropping
Sorghum-Cowpea on Natural Enemies of the Sorghum Shoot Fly,
Atherigona soccata Rondani (Diptera: Muscidae) in Burkina Faso.
Biological Agriculture &Horticulture (In press).
Papers submitted
1) Zongo, J.O., R.K. Stewart, C. Vincent. Biology of Trichogrammatoidea
simmondsi Nagaraja (Hymenoptera: Trichogrammatidae) on Sorghum
Shoot Fly, Atherigona soccata Rondani (Diptera: Muscidae) eggs.
Entomophaga, July 1992.
2) Zongo, J.O., R.K. Stewart, C. Vincent. Parasitism of Sorghum Shoot
Fly Larvae, Atherigona soccata Rondani (Diptera: Muscidae) by
Neotrichoporoides nyemitawus Rohwer (Hymenoptera: Eulophidae).
Insect Science and its Application, July 1992.
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228
Papers to be submitted
1) Zongo, J.O., R.K. Stewart, C. Vincent. Spider Fauna in Pure Sorghum
and Intercropped Sorghum-Cowpea in Burkina Faso. Journal of
Applied Entomology.
2) Zongo, J.O., R.K. Stewart, C. Vincent. Influence of Cultural
Practices on Sorghum Yields and Incidence of Sorghum Shoot Fly,
Atherigona soccata Rondani (Diptera: Muscidae), in Burkina Faso.
Sahel Phytoprotection.
3) Zongo, J.O., C. Vincent, R.K. Stewart. Screening of Local Cultivars
for Resistance to Sorghum Shoot Fly, Atherigona soccata Rondani
(Diptera: Muscidae), in Burkina Faso. Sahel Phytoprotection.
Miscellaneous papers
1) Zongo, J.O., C. Vincent et R.K. Stewart 1989. Etudes sur la mouche
des pousses du sorgho grain Atherigona soccata Rondani (Diptera:
Muscidae) dans l'Ouest Burkina, pp. 48-62. In Rapport de synthèse
de la campagne 1988-1989. Min. Agric. El.evage., Dir. Agric.,
Service Protection des Végétaux, Laboratoire de Recherches
Bobo-Dioulasso, Burkina Faso.
2) Zongo, J.O., C. Vincent et R.K. Stewart 1990. Etudes sur la mouche
des pousses du sorgho grain Atherigona soccata Rondani (Diptera:
Muscidae) dans l'Ouest Burkina: résultats sommaires de 1989.
In Rapport de synthèse de la campagne 1988-1989. Min. Agric.
Elevage., Dir. Agric., Service Protection des Végétaux,
Laboratoire de Recherches Bobo-Dioulasso, Burkina Faso.
3) Zongo, J.O., C. Vincent et R.K. Stewart 1991. Dépistage et
abondance relative des Muscidés (Atherigona spp. Rondani)
associées au sorgho grain cultivé au Burkina Faso. SAHEL PV
. INFO Bulletin d'Information en Protection des Végétaux de
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229
l'UCTR/PV (Bamako, Mali), 37: 11-16.
Oral presentations
1) longo, J.O., C. Vincent et R.K. Stewart 1990. Efficacité de quatre
types de pièges pour la capture d'Atherigona soccata Rondani
(Diptère: Muscidae) et effets de quelques pratiques culturales
sur ses dégâts au Burkina Faso. Deuxième Séminaire sur la lutte
intégrée contre les ennemis des cultures vivrières dans le Sahel
tenue à Bamako (Mali) du 4 au 9 Janvier 1990.
2) longo, J.O., C. Vincent, R.K. Stewart 1991. Sequential Samplin9 of
Sorghum Shoot Fly Atherigona soccata Rondani (Diptera:
Muscidae), in Burkina Faso. Major Symposium on Exotic Pests In
Africa; their Prevention and Control. 9th Meeting and Scientific
Conference of the African Association of Insect Scientists 23rd
27th September 1991, Legon, Accra, Ghana.
Poster presentations
1) longo, J.O., C. Vincent et R.K. Stewart 1990. Dépistage de la mouche
des pousses du sorgho, Atherigona soccata Rondani (Diptera:
Muscidae) au Burkina Faso. Annual meeting, Entomological
Society of Canada, Banff, Alberta, 7-10 octobre 1990.
2) longo, J.O., C. Vincent, R.K. Stewart 1992. Effects of Neem Seed
Kernel Extracts on Egg and Larval Survival of the Sorghum Shoot
Fly, Atherigona soccata Rondani (Diptera: Muscidae). XIX
International Congress of Entomology, June 28 - July 4, 1992,
Beijing, China.
• 230
Appendix z.Atherigona zongoi: trifoliate process and hypopygial prominence;
morphological characters used for identification' •
l
• a)
2
Aih09ona. ~n.3.0i sp.n.
•
A): trifoliate process; l ~entral Vi2W, Z profile.
B): hypopygial prominence; l apical view, Z profile.
1 Drawing by J.C. Deeming, National Museum of Wales, Cardiff, U.K .
231
Appendix 3.
Sorghum shoot fly, Atherigona soccata: adult, immature stages and
damage.
•
•
•
\.~ ">.'
.. '. ~
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,',
"\'" '::'~.~;''',: .,'
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"
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i'.
.: '
•Adult fly
Egg on a piece of sorghum leaf
•
Larva: third instar
Damaged pl~nt~and tillers
232
Appendix 4.
233 •
Copyright waiver given by Tropical Pest Management rel ated to the
publ ication of "Monitoring Adult Sorghum Shoot Fly, Atherigona soccata •
Rondani (Diptera: Muscidae), and Related Species In Burkina Faso" by
Zongo et al. (1991).
•
•
•
Taylor & Francis LtdInlt"I"J'UZlional SciOflific and Educalional Publishm. London and W'oshmglon, De
E"ablish<d in lh. Cisy ofLandon in 1798
4 John Street, London WCIN 2ET, UK. Tel: +44 (0)71405 2237 Telex: 858540 Fax: 071 8312035
19 June 1992
Joanny 0 ZongoMacdonald College of McGil! UniversityDepartment of Entomology21 111 LakeshoreSt-Anne-de-BellevueQuebecCanada H9X 1CO
DearJoanny
Tropical Pest Management
Peter Haskell has passed your letter of 13 May to us, in which you ask us to waivecopyright on your manuscript which appeared in our journal. so !hat yeu may includeit in your thesls.
This is to confirm !hat we are happy to do so on this occasion.
Yours sincerely
(j M(};D~Geraldine CrowePermissions
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