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Invasive Alien Species: An emerging threat to agriculture and biodiversity in Nepal
Government of Nepal Ministry of Agriculture and Livestock Development
Plant Quarantine and Pesticide Management CenterHariharbhawan, Lalitpur
2019
Invasive Alien Species: An emerging threat to agriculture and biodiversity in Nepal
Government of Nepal Ministry of Agriculture and Livestock Development
Plant Quarantine and Pesticide Management CenterHariharbhawan, Lalitpur
2019
ForewordInvasive Alien Species (IAS) are one of the major causes of crop loss and adversely affect food security. With increasing globalization of trade and human movement, the number of IAS has been increasing in all continents and climatic regions without any sign of saturation, including in high mountains and Polar Regions. Under high threat of invasion by insect pests, pathogens and weeds with high economic cost in absolute term, the developing countries like Nepal are among the countries with high risk of biological invasion in agriculture sector.
Biological invasion in Nepal has also emerged as a challenging problem in biodiversity conservation, ecosystem services flow and agriculture production. Physiographic and climatic diversity of Nepal is not only supporting wide spectrum of organisms and ecosystems but also providing potential suitable habitats for the species native to everywhere in the world. Increasing human movement and the import trade along with the insufficient quarantine facilities and infrastructures are increasing the potential threat of entry, invasion and eventually the establishment of the IAS in Nepal.
Food security and agriculture sector is also increasingly more dependent on imported agriculture products, seeds and seedlings/plantlets. Due to these scenarios, Nepal’s agriculture sector has been ranked third among the most threatened countries out of the 124 countries assessed.
To address the emerging threat of IAS, Nepal’s National Biodiversity Strategy and Action Plan (2014-2020) has targeted a number of activities including impact assessments of selected invasive alien plant species (IAPS) and release of biological control agents against IAPS.
Biological invasion, a major component of human-induced global environmental changes, is a direct outcome of human movement and trade across continents. The negative impacts of biological invasion have been considered significant in countries from underdeveloped to developed economy.
Natural development of new strains of pathogens including fungi, bacteria, and viruses, as well as accidental introduction of new pests through trade, transport and immigration, requires an alert and aggressive response to
prevent economic disruption of our stable supply of food, fiber, and industrial raw products.
This booklet is a small initiative for the awareness on the importance of IAS to all the stakeholders and has been compiled from the available resources in the internet and other available references. I hope this book will be very useful to all the stakeholders concerned. I would like to thank Senior Plant Protection Officers Mr. Mahesh Chandra Acharya, Mr. Ram Krishna Subedi and Dr. Ratna Kumar Jha; Debraj Adhikari, Senior Agriculture Officer, PMAMP, Junar Superzone, Sindhuli; Plant Protection Officers Mr. Mahesh Timilsina and Surakshya Subedee and all officials of PQPMC who have contributed in preparing this book in this form.
Date: 2076/3/12
Dilli Ram Sharma, PhD Chief PQPMC
Contributors:
Mr. Mahesh Chandra Acharya1
Mr. Debraj Adhikari2
Ms. Surakshya Subedee3
Mr. Mahesh Timilsina3
Edited by:
Mr. Mahesh Chandra Acharya1
Mr. Ramkrishna Subedi1
Dr. Ratna Kumar Jha1
Dr. Dilli Ram Sharma4
1 Senior Plant Protection Officer, Plant Quarantine and Pesticide Management Center
2 Senior Agriculture Officer, PMAMP, Junar Superzone, Sindhuli 3 Plant Protection Officer, Plant Quarantine and Pesticide
Management Center4 Chief, Plant Quarantine and Pesticide Management Center
Citation: PQPMC (2019). Invasive Alien Species: An emerging threat to agriculture and biodiversity in Nepal. Plant Quarantine and Pesticide Management Centre, Hariharbhawan, Lalitpur.
Disclaimer: All the content in this book are brought from various published and unpublished sources including related research articles, books, and websites. It is not the original views of the authors. This is a free resource.
i
Contents
1 Background: ............................................................................................. 1
2 Scenario of Nepal .................................................................................... 4
3 Invasive alien plant species (IAPS) of Nepal. ........................................... 6
4 Impacts of invasive alien species ........................................................... 13
4.1 Negative Impacts: .......................................................................... 13
4.2 Positive Impacts ............................................................................ 14
4.2.1 IAS for food, nutrition and other purposes ............................ 14
4.2.2 IAS as Bio-control Agents ........................................................ 15
5 Management of IAS ............................................................................... 16
6 Legal instruments related to IAS ........................................................... 19
7 Some important Invasive Alien Species in Nepal .................................. 20
7.1 The African Giant Land Snail - Achatina fulica .............................. 20
7.1.1 Introduction ............................................................................ 20
7.1.2 History ..................................................................................... 20
7.1.3 Description .............................................................................. 21
7.1.4 Damage ................................................................................... 22
7.1.5 Biology and behaviour ............................................................ 22
7.1.6 Reproduction and Life cycle .................................................... 23
7.1.7 Management........................................................................... 23
7.2 Tomato Leaf Miner (Tuta absoluta) .............................................. 24
7.2.1 Introduction ............................................................................ 24
7.2.2 Biology .................................................................................... 24
7.2.3 Identification ........................................................................... 25
ii
7.2.4 Damage ................................................................................... 25
7.2.5 Geographical distribution & entry verification in Nepal ......... 26
7.2.6 Management........................................................................... 26
7.3 Potato tuber moth: Phthorimaea operculella (zeller) ................... 27
7.3.1 Introduction ............................................................................ 27
7.3.2 Distribution of PTM in Nepal .................................................. 27
7.3.3 Life Cycle ................................................................................. 28
7.3.4 Nature of injury ....................................................................... 29
7.3.5 Management........................................................................... 30
7.4 Fall armyworm (Spodoptera furgiperda) ....................................... 32
7.4.1 Introduction ............................................................................ 32
7.4.2 History ..................................................................................... 32
7.4.3 Life cycle.................................................................................. 33
7.4.4 Nature of damage ................................................................... 34
7.4.5 Potential damage in Nepal...................................................... 35
7.4.6 Management........................................................................... 35
7.5 Chinese citrus fly Bactrocera minax (Enderlein) ........................... 37
7.5.1 Introduction ............................................................................ 37
7.5.2 Field Identities of Bactrocera minax (Enderlein) .................... 37
7.5.3 Distribution ............................................................................. 38
7.5.4 Life cycle of Chinese citrus fly ................................................. 39
7.5.5 Nature of Damage ................................................................... 40
7.5.6 Means of movement and dispersal: ....................................... 40
7.5.7 Management........................................................................... 40
7.6 Eupatorium adenophorum (Ageratina adenophora): ................... 43
iii
7.6.1 Introduction ............................................................................ 43
7.6.2 Damage ................................................................................... 43
7.6.3 Biology .................................................................................... 44
7.6.4 Management Strategy ............................................................ 44
7.7 Parthenium hysterophorus ............................................................ 45
7.7.1 Introduction ............................................................................ 45
7.7.2 Biology .................................................................................... 45
7.7.3 Geographical distribution in Nepal ......................................... 46
7.7.4 Damage ................................................................................... 46
7.7.5 Management Approaches ...................................................... 47
7.8 Mikania micrantha ........................................................................ 50
7.8.1 Introduction ............................................................................ 50
7.8.2 Ecological characters .............................................................. 51
7.8.3 Invasion of Mikania................................................................. 51
7.8.4 Management........................................................................... 52
8 References ............................................................................................. 53
1
1
Invasive Alien Species: An emerging threat to agriculture and biodiversity in Nepal
1 Background:
In the distant past, the earth’s mountains and oceans represented tough natural barriers for the natural dispersal of species. Ecosystems evolved in relative isolation. Early human migration saw the first intentional introductions of alien species to satisfy physical and social needs, but the magnitude and frequency were minor compared to those associated with today’s extensive global trade and passenger movements. History is rich with tales of the disastrous outcomes of some intentional introductions. An example is that of a fish (Nile perch) to Lake Victoria, Africa in 1954 to counter act the drastic drop in native fish stocks caused by over-fishing. It has contributed to the extinction of more than 200 endemic fish species through predation and competition for food. Its flesh has higher fat content, demanding more firewood to fuel fires for drying. The subsequent erosion and run off contributed to increased nutrient levels, opening the lake up to invasions by algae and water hyacinth (Eichhornia crassipes) and to oxygen depletion in the lake and increased mortality of other fishes. Commercial exploitation of the Nile perch has displaced local men and women from their traditional fishing and processing work (Lowe S. 2000).
Nepal’s natural resources have been under excessive pressure due to growing population demand and over exploitation for livelihoods and subsistence farming. It is not only agricultural crops but also other unwanted pests and weeds that have been introduced affecting agro-ecosystems as well as forest, fallow land and wetland ecosystems. A number of species is known to prey on, out- compete, hybridize and infect native species thereby causing habitat deterioration, ecosystem disturbance and decline of native species. They are considered as second greatest threat to native species after habitat loss. However, knowledge base on Invasive Alien Species (IAS) in Nepal is rather meager and limited.
2
2
There is a great need of comprehensive study and research work revealing the status and impacts of invasive species of Nepal, on the face of some alarming impacts of IAS such as Eichhornia crassipes in wetlands of international significance and Mikania micrantha in the grasslands of national parks and protected areas (Tiwari, et al. 2005).
The genes, species and ecosystems that make up the earth’s biological diversity are important because their loss and degradation diminishes nature. No one can estimate which species are essential to ecosystem functioning, which are redundant, and which will be the next to flourish as the world changes. When a new species is introduced into an ecosystem, the full impact is often not immediately apparent. For example, invasion by species such as Mikania micrantha, a widespread weed in the tropics which grows very quickly (as fast as 80 to 90 millimeters a day and covers other plants, shrubs and even trees) and is a problem in Nepal covering more than 20 percent of the Chitwan National Park (Mikania mikarantha n.d.).
Not all introduced species are invasive, but are potential to be invasive through invasion process i.e. introduction, establishment and spread. For
Figure 1: Type of alien species introductions
3
3
a species to become invasive, it must successfully out-compete native organisms, spread through its new environment, increase in population density and harm ecosystems in its introduced range. To summarize, for an alien species to become invasive, it must arrive, survive and thrive. Thus IAS are plants or animals that are introduced by man, accidentally or intentionally, outside of their natural geographic range into an area where they are not naturally present (IUCN). In other words, an IAS is a species that is established outside of its natural past or present distribution, whose introduction and/or spread threaten biological diversity” (CBD n.d.).
While a small percentage of organisms transported to new environments become invasive, the negative impacts can be extensive and over time,
Figure 2: Process of invasion
4
4
these additions become substantial. A species introduction is usually vectored by human transportation and trade. IAS is the second biggest threat to biodiversity (after habitat destruction) and is the major cost to the economic wellbeing of the planet.
IAS exacerbate poverty and threaten development through their impact on agriculture, forestry, fisheries and natural systems, which are an important basis of peoples’ livelihoods in developing countries. Invasive species can degrade the productivity of agricultural lands and compromise significant cultural landscapes. They cost billions of dollars every year, in lost production, control and mitigation efforts, loss of ecosystem services and many other ways. IAS can profoundly perturb environments, and communities or societies that value these in any way are negatively affected as a result. This damage is aggravated by climate change, pollution, habitat loss and human-induced disturbance.
Biological invasion worldwide threatens biodiversity, ecosystem dynamics, resource availability, national economy and human health. It is a pervasive and costly environmental problem. Over the past half century, it has become the focus of intense management and research activities worldwide. The Convention on Biological Diversity (CBD), to which Nepal and 177 other countries are party, calls on governments to prevent the introduction, control or eradication of those alien species that threaten ecosystems, habitats or species (Article 8). Many alien taxa are known to cause socio-economic impacts by affecting the different constituents of human wellbeing, including food security, material and non-material assets, health, social, spiritual, and cultural relations.
2 Scenario of Nepal
Situated in the lap of the Himalayas, Nepal is blessed with beauty and bounty of biological resources that underpin our economy, livelihoods and ecological functions. Nepal ranks the 31st richest country in the world and 10th in Asia in terms of biodiversity. The bounty in Nepal has become possible due to exceptional variation in geography, ecology, and climatic
5
5
conditions across the country. A total of 118 ecosystems, 12 of 867 global terrestrial eco-regions and eight climatic zones (ranging from tropical to nival) are found in Nepal. Occupying merely 0.1 percent of global area, Nepal has the privilege of harboring world’s 3.2 percent flora and 1.1 percent fauna, which include 5.2 percent of the world’s known mammals, 9.5 percent birds, 5.1 percent gymnosperms, and 8.2 percent bryophytes (MoAD 2017).
Traditional farming is predominant in the rural areas where crop, livestock, fisheries, agro-forestry, and other associated biological resources are integrated. Crop diversity is tremendous. A variety of crops are grown in different geographic regions, and in different agro-ecological niches and climatic zones even within a geographic region. A total of 790 plant species are useful for food and 577 of them (including forage) are cultivated – 484 indigenous (74 crops, 145 horticultural crops and 275 forages) and 93 introduced. Moreover, there are 224 crop wild relatives that are closely related to crops. About 21% (3.2 million hectares) of the total land area of Nepal is used for cultivation and the principal crops are rice (45%), maize (20%), wheat (18%), millet (5%) and potatoes (3%), followed by sugarcane, jute, cotton, tea, barley, legumes, vegetables and fruits. In the mountains, finger millet, foxtail millet, proso millet, buckwheat, barley, naked barley, and amaranth constitute important staple crops. Crops such as rice, rice bean, eggplant, buckwheat, soybean, foxtail millet, citrus, and mango have high genetic diversity relative to other food crops (MoAD 2017).
Despite their great ecological and economic significance, several species are rare and/or threatened, while several are endemic to some particular geographic locations, particularly in high altitude range lands. A total of 284 flowering plants, 160 species of animals, one species of bird, and 14 species of reptiles and amphibians are endemic to Nepal. A total of 54 species of wild mammals and 18 species of trees inhabited in the mountains are also threatened. Nine species of plants, 55 mammals, 149 birds, 64 reptiles and amphibians and 21 fish are included in the IUCN Red List. A total of 15 groups and species of plants, 52 mammals, 108 birds and 19 reptiles and three insects have been listed in the Convention on
6
6
International Trade in Endangered Species of Wild Fauna and Flora (CITES). Similarly, 27 mammals, 9 birds, 14 angiosperms, and 4 gymnosperms have been declared as protected species by the government (MoFSC 2014).
Nepal lies at the cross-road of six floristic provinces of Asia (Sino-Japanese, Southeastern Asiatic, Indian, Sudano-Zambian, Irano-Turranean and Central Asiatic) and the floral elements of all provinces are represented in Nepal. With the widest elevation gradient and heterogeneous geomorphology, organisms from anywhere of the world may find suitable habitat and climatic condition in Nepal (TISC 2002).
3 Invasive alien plant species (IAPS) of Nepal.
There are at least 219 alien species of flowering plants and 64 species of animals that are naturalized in Nepal. An assessment of invasive alien plant species (IAPS) was undertaken for the first time by IUCN Nepal during 2002 - 2003 and reported 21 naturalized flowering plant species to be invasive in Nepal. In addition to them, four naturalized species Ageratum conyzoides, Erigeron karvinskianus, Galinsoga quadriradiata and Spermacoce alata Aubl (Syn. Borreria alata) have been also found to be invasive in agro-ecosystems and range lands. Among 25 IAPS, four species (Chromolaena odorata, Eichhornia crassipes, Lantana camara and Mikania micrantha) are included in world’s 100 worst invasive species. Similarly, 69 species of alien species of fauna-20 species of insects including commercial insects, pests and bio-control agents (predator, parasitoid, defoliator, gall insect), one freshwater prawn, one species of Platyhelminthes, 16 species of fish, 2 species of wild mammals, 3 species of birds, and 25 species of livestock breeds have been reported in Nepal. Out of all reported alien species 8 species are the most dangerous species of the world listed in the top 100 invasive species of the world (Budha 2014).
Nepal’s biodiversity is threatened by multiple factors. Loss and degradation of natural habitats, such as forests, grasslands, and wetlands
7
7
due to the expansion of settlements, agriculture and infrastructure; over exploitation of resources; invasion by alien species; and pollution of water bodies remain the predominant threats. Poaching and illegal wildlife trade and human-wildlife conflict are other major direct threats to forest biodiversity, particularly in protected areas. Rapid expansion of hybrid varieties and improper use of insecticides and pesticides are major threats to agro-biodiversity. Climate change can have profound impacts in the future, particularly in mountain ecosystems (MoFSC 2014a).
Accidental and intentional introduction by gardeners, traders and foresters have contributed to the large number of exotic plants in Nepal. It has a long history of introduction of non-native species, especially species proven to be productive elsewhere and offering potential economic benefits to the country. Eupatorium odoratum, E. adenophorum, Lantana camara and Eichhornia crassipes were first introduced as ornamental plants and they are now well established and dominant in forest, farmland, wetland and wasteland. In the 20th century, the country’s economic development including growth in trade and transportation systems multiplied the avenues of introduction and spread of invasive species.
In comparison to alien plant species of Nepal, alien fauna are poorly investigated and seem to be relatively neglected. Exotic species of insects and non-insect invertebrates are the most neglected groups and the information on how many species of alien and invasive species occur in Nepal are not yet documented properly. Many species including Potato Tuber Moth (Phthorimaea operculella), San José Scale (Quadraspidiotus perniciosus = Diaspidiotus perniciosus), Leucaena Psyllid (Heteropsylla cubana), African Giant Land Snail (Lissachatina fulica), tomato leaf miner (Tuta absoluta), brown plant hopper (Nilaparvata lugens) have been established as pests causing serious problems in agriculture.
The major IAS in Nepal are listed in the foregoing tables.
8
8 T
able
1:
Inva
sive
alie
n pl
ant s
pecie
s of N
epal
Sn
Nam
e of
IAPS
Co
mm
on n
ame
Loca
l nam
e Fa
mily
Na
tive
rang
e$ Fi
rst
Repo
rt**
1.
Ager
atin
a ad
enop
hora
L.
(Eup
ator
ium
ade
noph
orum
) Cr
ofto
n w
eed
Kalo
Ban
mar
a As
tera
ceae
M
exico
1952
2.
Chro
mol
aena
odo
rata
(Spre
ng.)
King
and
Robi
nson
* Si
am w
eed
Seto
Ban
mar
a As
tera
ceae
M
exico
, C&
S
Amer
ica
1825
3.
Eich
horn
ia cr
assip
es (M
art.)
So
lms.*
W
ater
hya
cinth
Ja
lkum
bhi
Pont
eder
iace
ae
S Am
erica
1966
4.
Ipom
oea
carn
ea ss
p. fi
stul
osa
(Mar
t. ex
Cho
isy) D
.F. A
ustin
Bu
sh m
orni
ng-
Glor
y Be
sara
m
Conv
olvu
lace
ae
Mex
ico, C
& S
Am
erica
1966
5.
Lan
tana
cam
ara
L.*
Lant
ana
Kirn
ekan
da
Verb
enac
eae
C &
S A
mer
ica
1848
6.
Mik
ania
micr
anth
a Ku
nth*
M
ile-a
min
ute
wee
d La
hare
banm
ara
Aste
race
ae
C &
S A
mer
ica
1963
7.
Alte
rnan
ther
a ph
iloxe
roid
es
(Mar
t.)Gr
iseb.
Al
ligat
or w
eed
Jala
jam
bhu
Amar
anth
acea
e S
Amer
ica
1994
8.
Myr
ioph
yllu
m a
quat
icum
(V
ell.)
Ver
dc.
Parr
ot’s
feat
her
Ho
lara
gace
ae
S. A
mer
ica
9.
Par
then
ium
hys
tero
phor
us L.
Pa
rthe
nium
Pa
ti jh
ar
Aste
race
ae
Sout
hern
USA
to
S A
mer
ica
1967
10.
Age
ratu
m co
nyzo
ides
L.
Billy
goat
Ra
unne
/Gan
dhe
Aste
race
ae
C &
S A
mer
ica
1910
9
9 Sn
Na
me
of IA
PS
Com
mon
nam
e Lo
cal n
ame
Fam
ily
Nativ
e ra
nge$
Firs
t Re
port
**
11.
Am
aran
thus
spin
osus
L.
Spin
y pi
gwee
d Ka
nde
lude
Am
aran
thac
eae
Trop
ical
Amer
ica
1954
12.
Arg
emon
e m
exica
na L.
M
exica
n po
ppy
Thak
al
Papa
vera
ceae
Tr
opica
l Am
erica
1910
13.
Sen
na to
ra (L
.) Ro
xb.
Sick
le p
od se
nna
Tapr
e Ca
esal
pini
acea
e ??
1910
14.
Hyp
tis su
aveo
lens
(L.)
Poit.
Bu
shm
int
Tulsi
Jhar
La
mia
ceae
Tr
opica
l Am
erica
1956
15.
Lee
rsia
hex
andr
a Sw
artz
. So
uthe
rn C
ut
gras
s Ka
raut
e gh
ans
Poac
eae
??
1820
16.
Pist
ia st
ratio
tes L
. W
ater
lettu
ce
Kum
bhik
a Ar
acea
e S
Amer
ica
1952
17.
Bid
ens p
ilosa
L.
Blac
k ja
ck/ H
airy
Be
ggar
tick
Kalo
kur
o As
tera
ceae
Tr
opica
l Am
erica
1910
18.
Sen
na o
ccid
enta
lis (L
.) Lin
k.
Coffe
e Se
nna
Panw
ar
Caes
alpi
niac
eae
Trop
ical
Amer
ica
1910
19.
Mim
osa
pudi
ca L.
Se
nsiti
ve p
lant
La
jjaw
ati
Mim
osac
eae
Mex
ico to
S
Amer
ica
1910
20.
Oxa
lis la
tifol
ia K
unth
. Pu
rple
woo
d so
rel
Char
i am
ilo
Oxal
idac
eae
C an
d S
Amer
ica
1954
21.
Xan
thiu
m st
rum
ariu
m L.
Ro
ugh
cock
le-
Bur
Bhed
e ku
ro
Aste
race
ae
Amer
ica
1952
22.
Age
ratu
m h
aust
onia
num
Mill
. Bl
ue B
illyg
oat
Wee
d Ni
lo g
andh
e As
tera
ceae
M
exico
& C
Am
erica
10
10
Sn
Nam
e of
IAPS
Co
mm
on n
ame
Loca
l nam
e Fa
mily
Na
tive
rang
e$ Fi
rst
Repo
rt**
23.
Erig
eron
kar
vins
kian
us D
C Ka
rwin
sky’
s Fl
eaba
ne
Phul
e Jh
ar
Aste
race
ae
Mex
ico &
C
Amer
ica
24.
Galin
soga
qua
drira
diat
a Ru
iz &
Pav.
Sh
aggy
Sol
dier
Jh
use
Chitl
ange
As
tera
ceae
M
exico
25.
Spe
rmac
oce
alat
a Au
bl
Broa
d le
af
botto
n w
eed
Alu
Pate
Jhar
Ru
biac
eae
Wes
t Ind
ies
and
T.Am
erica
Note
: *Sp
ecie
s lis
ted
in w
orld
’s 10
0 w
orst
inva
sive
spec
ies
(Low
e et
al.
2000
). **
inclu
des
both
firs
t sc
ient
ific
repo
rt/c
olle
ctio
n of
firs
t he
rbar
ium
spe
cimen
s, $
Base
d on
dat
abas
e of
CAB
I’s I
nvas
ive
Spec
ies
Com
pend
ium
(ht
tp://
ww
w.ca
bi.o
rg/is
c)[e
xcep
t Ag
erat
um
haus
toni
anum
http
://ke
ys.lu
cidce
ntra
l.org
/key
s/v3
/eaf
rinet
/wee
ds/k
ey/w
eeds
/Med
ia/H
tml].
Tabl
e 2:
Inv
asiv
e al
ien
faun
al sp
ecie
s of N
epal
.
S.n.
Sc
ient
ific N
ame
Co
mm
on N
ame
Or
der
Fam
ily
Intr
oduc
tion
1.
Lir
iom
yza
huid
obre
nsis
S-Am
erica
n Le
af M
inor
**
Dipt
era
Agrim
yzid
ae
Unkn
own
2.
Da
cus (
Dida
cus)
cilia
tes
Ethi
opea
n M
elon
Fly
**
Dipt
era
Teph
ritid
ae
1978
3.
Carp
omya
ves
uvia
na
Frui
t Fly
**
Dipt
era
Teph
ritid
ae
Unkn
own
4.
Ca
rpom
ya p
arda
linia
Ba
luch
istan
Mel
on F
ly**
Di
pter
a Te
phrit
idae
Un
know
n 5.
Bact
roce
ra (P
arat
ridac
us)
dive
rsa
Guav
a Fr
uit F
ly *
*
Dipt
era
Teph
ritid
ae
Unkn
own
6.
Ba
ctro
cera
(Dac
ulus
) ole
ae
Oliv
e Fr
uit F
ly**
Di
pter
a Te
phrit
idae
Un
know
n 7.
Bact
roce
ra (Z
eugo
dacu
s)
Frui
t Fly
**
Dipt
era
Teph
ritid
ae
Rep
orte
d in
11
11
S.n.
Sc
ient
ific N
ame
Co
mm
on N
ame
Or
der
Fam
ily
Intr
oduc
tion
caud
ate
19
76
8.
Pr
ocec
idoc
hare
s util
is Ga
ll Fl
y*
Dipt
era
Teph
ritid
ae
1963
New
Ze
alan
d 9.
Cera
tova
cuna
lani
gera
Su
garc
ane
Aphi
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ly A
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.
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dia
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tero
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yllid
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opte
ra
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nium
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ante
les s
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s PT
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0 16
.
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lus L
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us
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asito
id*
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men
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ra
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honi
dae
2009
-10
17.
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pido
som
a ko
ehle
ri PT
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aras
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*
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cyrt
idae
20
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0 18
.
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mel
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rope
an b
ee≠
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enop
tera
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idae
19.
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mby
x m
ori
The
silw
orm
≠ Le
pido
pter
a Bo
mby
cidae
20.
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thor
imae
a op
ercu
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PT
M
Lepi
dopt
era
Gele
chid
ae
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from
In
dia
21.
Lis
sach
anin
a fu
lica
Afric
an G
iant
Land
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il St
ylom
mat
opho
ra
Acha
tinid
ae
1930
s-40
s 22
.
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lla b
icolo
r Tw
o-to
ned
gule
lla
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omm
atop
hora
St
rept
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ae
23
.
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cera
s lea
ve
The
Mar
sh S
lug
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omm
atop
hora
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ae
24
.
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te
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ra
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mac
ea ca
nalic
ulat
a Th
e Go
lden
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Note
: * B
ioco
ntro
l age
nts,
** p
ests
, ≠ C
omm
ercia
lly e
xplo
ited
spec
ies,
Sour
ce: K
apoo
r &M
alla
(197
8, 1
979)
, Jos
hi (2
004)
; Kap
oor (
2005
), Sh
arm
a an
d Su
bba
(200
5), C
ABI (
2009
), FA
O (2
009)
, Shr
esth
a (2
011)
, Bud
ha (2
013)
.
1213
4 Impacts of invasive alien species 4.1 Negative Impacts:
The devastating effects of IAS on agriculture are two-fold. Firstly, IAS destroy livelihoods by devastating crops and secondly, IAS affect international trade through interception and rejection of produce at the borders of potential export markets and have led to a collapse of trade of the affected crop altogether. The damage to ecosystem services has not been quantified at all.
On the other hand, biological invasion has become one of the major causes of environmental and socio-economic damages as well as major driver of biodiversity decline (CBD 1992). Many alien taxa are known to cause socio-economic impacts by affecting the different constituents of human wellbeing, including food security, material and non-material assets, health, social, spiritual, and cultural relations. Anthropogenic pressure, land use change, and climate change have accelerated invasion by invasive species in the Himalayas (Thapa et al. 2018). For a species to become invasive, it must successfully out-compete native organisms for food and habitat, spread through its new environment, increase its population and harm ecosystems in its introduced range.
Most countries are facing with complex and costly invasive species problems. For example, the annual environmental losses caused by introduced pests in the United States, United Kingdom, Australia, South Africa, India and Brazil have been calculated at over US$ 100 billion. Addressing the problem of IAS is urgent because the threat is growing daily, and the economic and environmental impacts are severe.
Because of the inherent linkage with human activities, the IAS is more common, and hence has more impacts in anthropogenic landscape than in intact natural landscape. This mainly includes the economic losses due to decline in agriculture production, increased labor to remove the weeds, suppression of useful species, and health hazard to human and livestock. From anthropogenic landscape, some of the IAS expands to natural landscape such as forest, grassland and wetland where they not only compete with native species for resources but also degrade the habitats
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thereby making the ecosystems hostile to native species and increasing the rate of human-induced biodiversity loss. Therefore, globally the biological invasion has been considered as the second major cause of biodiversity loss next to habitat degradation.
Their positive impacts also are taken into consideration; ornamental value, option and existence value are the examples. These sometimes have lightened the controversial statements, whether invasive species are friends or foe, pests or providence and weed or wonder. Introductions of non-native species can be both boon and bane to society. The relative magnitudes of costs and benefits vary both in space and over time. Although an introduction may meet a desired objective in one area, at one time, or for some sectors, unwanted and unplanned effects may also occur.
The insect pest species are major problems in agricultural productivity by reducing significant loss of yield for example the PTM is an introduced species which causes 30-85% losses of stored potato and the standing crop, often reached to 100% during heavy infestation if control measures are not applied. Liriomyza huidobrensis is a serious pest for the floriculture industry where leaf-miner damage directly affects the marketable portion or in vegetable crops where the leaves are sold as the edible part, i.e. spinach, beet greens, Asian greens, lettuce and leeks. Tuta absoluta is a devastating pest of tomato which was reported to have entered Nepal for the first time in 2016. If timely and proper management actions are not taken, this pest can cause tomato yield losses in Nepal of up to 80-100% and financial losses of in excess of $50 million USD.
4.2 Positive Impacts 4.2.1 IAS for food, nutrition and other purposes
Many introduced species of corn, wheat, rice, plantation forests, domestic chicken, cattle, and others are beneficial and now provide more than 98% of the world food supply with a value of more than US$ 5 trillion per year (USBC 1998). All crop and livestock species originated in various geographic regions of the earth, such as the chicken from south eastern Asia have been introduced worldwide for food and feed purpose. Other
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alien species are used for landscape restoration, biological pest control, sport, pets, and food processing. In the recent past, the rate and risk associated with alien species introductions have increased enormously because human population growth and human activities altering the environment have escalated rapidly (Pimentel, et al. 2000).
4.2.2 IAS as Bio-control Agents
Natural enemies, as well as a number of other factors, play an important role in regulating plant populations in their native environments. The absence of natural enemies may be an important contributing factor to the invasiveness of some non-native species.
Biological control (or bio-control) reunites invasive plants with their enemies to restore natural controls and reduce dominance of invasive plants within the plant community. Promoted as a self-sustaining, self-dispersing control method, bio-control is often used to gradually suppress widespread infestations in low-value or remote areas where other methods are not economically feasible.
Despite a reputation as an environmentally generous, cost-effective approach to invasive plant management, the long-term efficacy and environmental impacts of releasing one organism to control another are not fully understood. Classical bio-control is irreversible and therefore it is essential that all potential consequences are adequately considered beforehand. Importing biological control agents from aboard would seem to be easy but disadvantages might include problems of establishment in the new environment, problems arising from interspecies' competition with the native species, and the danger of introducing hyper parasites and organisms pathogenic to indigenous bio-control agents. Much more detailed studies will have to be conducted on these organisms and comparisons made with indigenous agents, if proper introductions are to be done (Pandey, n.d.).
Earliest initiation of classical biological control was started in 1978 with successfully importing parasitoids, Aphelinus mali (Halderman) from France against apple wooly aphids (Eriosoma lanigerum Hausmann) (Joshi
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et.al., 1991). This parasitoid has been established in Jumla and the inoculum has also been maintained at Entomology Division of NARC, Khumaltar.
Similarly, three exotic parisitoids viz. Apanteles subandinus, Orgilus lepidus and Copidosoma koehleri were introduced from International Potato Center (CIP) in 2009/10 where C. koehleri and O. Lepidus were successfully reared in laboratory and released in the field (Aryal and Jung, 2015)
There are only two biological control agents present for two invasive exotic plants: leaf feeding beetle Zygogramma bicolorata Pallister and winter rust Puccinia abrupta var. partheniicola (Jackson) Parmelee for Parthenium hysterophorus, and stem galling fly Procecidochares utilis Stone and leaf spot fungus Passalora ageratinae Crous and A.R. Wood for Ageratina adenophora. However, these biological control agents were not introduced officially but spread naturally into Nepal from India and other Asian countries. Recently, Nepal Agriculture Research Council (NARC) has imported two weevils Neochetina eichhorniae Warner and N. bruchi Hustache from USA (Florida) as an effort to biological control of Eichhornia crassipes and both these weevils are under laboratory trial.
Procecidochares utilis entered Nepal naturally from India and established population by 1972 in eastern part of Nepal (Ilam, Terhathum and Dhankuta districts). In Nepal, the fly has reached to almost all areas where A. adenophora is present but its impact on the weed is insignificant.
5 Management of IAS
The biological invasion is likely to increase continuously in foreseeable future with increasing volume and diversity of merchandise being imported into Nepal. Due to porous border and less effectiveness of plant quarantine in Indo-Nepal border, any exotic species established in India can spread into Nepal sooner or later.
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Preventing the invasion by species as first task should exist as the most effective, economical, technologically adoptable, environmentally sound idea to manage the invasive species. If the infestation is already on site, focus needs to be given to prevent it from further spreading because eradication is very expensive and sometimes may not be possible. For the developing countries like Nepal, resource limitation is common so limited resource should be spent in an efficient way on proactive weed management which minimizes existing infestations and prevents the further spreading and new invasion.
Management of invasive species involves three basic strategies: prevention, eradication and control. Prevention involves restriction to the introduction of potentially IAS and requires strict quarantine and regular monitoring. It is the first and the best strategy for invasive species management but its implementation, even partial at best, cannot be effective in the context of globalization of trade and increasing human mobility. Because of the open border with India and high trade dependency, prevention of the entry of invasive species to Nepal is almost impossible. Eradication is the complete removal of invasive species from the habitat or region and this is possible only when the species occurs in a small area. However, in most of the cases, by the time when managers acknowledge the problem and prepare for action, it is often too late for eradication to be possible due to rapid spread of the invasive species covering large areas. Control involves reducing the abundance of invasive species in the invaded habitat or region and preventing further spread, thereby minimizing their impacts to ecosystem and economy. It does not necessarily result in elimination of species from any particular region. Due to a large number of IAS and their widespread occurrence, ‘control’ is the only strategy left to manage them across landscapes.
The control of the IAS requires the integration of cultural, physical, chemical and biological methods. In Nepal, the number of IAS, and their ecological and economic impacts – which are often irreversible – are increasing over the time. These facts are reflected in the recently prepared biodiversity related national documents such as the Nepal Fifth Report to Convention on Biological Diversity and Nepal National Biodiversity Strategy and Action Plan 2014-2020. Unfortunately,
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systematic and science-based management of the IAS has not been initiated yet in Nepal.
Effectiveness of the biological control agents in controlling target IAPS has not been evaluated systematically but field observations showed that the effect is only marginal. Distribution of fungal control agents (Puccinia abrupt var. partheniicola and Passalora ageratinae) of both species is much localized with apparently no effect to the target species. Zygogramma bicolorata seems to be the most effective biological control agent of IAPS present in Nepal but its population is still small and their effectiveness is erratic with year to year variation. For effective control of P. hysterophorus, it seems necessary that the control by Z. bicolorata need to be complemented by other biological control agents, displacement by competitive plant species, and other cultural, physical and chemical measure. Procecidochares utilis entered Nepal naturally from India and established population by 1972 in eastern part of Nepal (Ilam, Terhathum and Dhankuta districts). In Nepal, the fly has reached to almost all areas where A. adenophora is present but its impact on the weed is insignificant.
Therefore, though prevention is the first line of defense against IAS, it is less likely to be achieved. Practical approaches for management of invasive alien plant species, particularly in agriculture sector, may include :
1) Periodic assessment of naturalized plant species for their invasiveness and preparation of prioritized list of IAS for management;
2) Early detection and eradication of populations of new IAS;
3) Preparation of field guide and public education materials for identification;
4) Preparation of species-specific management guidelines for priority species; and
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5) Economic assessment of the impact and management of IAS. At the top of these activities, there is a need to prepare a National Strategy for the Management of IAS to effectively harmonize sectoral and cross-sectoral programs including release of biological control agents for high-risk species.
Management could be effective when community become aware to those species and take preventive measures.
6 Legal instruments related to IAS
Legal instruments related to IAS aim to prevent the entry of potential invasive species to a particular territory. Major international conventions and treaties related to biodiversity conservation and health have called upon to the Parties to develop mechanisms for preventing entry and spread of invasive species. For example, Article 8 (h) of the Convention on Biological Diversity (CBD) states that “Each contracting Party shall, as far as possible and as appropriate, prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species”. In addition to CBD, there are a number of international conventions and other legal instruments (e.g., Cartagana Protocol on Bio-safety to CBD, The Convention on International Trade in Endangered Species of Wild Fauna and Flora, Convention on Migratory Species of Wild Animals – Bonn Convention, Convention on Wetlands – Ramsar Convention, International Plant Protection Convention, Sanitary and Phytosanitary Measures (Quarantine) of World Trade Organization, International Health Regulation) which are related to IAS, and to which Nepal is a signatory. In line with international conventions and treaties, and acknowledging the increasing impacts of invasive species a few national policies of Nepal such as National Wetland Policy 2003 and Agro-Biodiversity Policy 2008 (First amendment 2014) call upon for controlling invasive species which threaten native biodiversity and ecosystems. The Plant Protection Act (2007) has included a number of provisions to regulate the import of plants, plant products and biological control agents, however, effective implementation of these provisions remain always a challenge due to porous border and weak regulatory mechanisms at entry points. Similarly, National Seed Vision 2013-2025
19 20
also identified uncontrolled flow of and increased dependency to seeds of exotic crop, fruits and vegetable species and varieties as a threat to seed sector development of Nepal (Seed Quality Control Center 2013). However, some other pertinent national acts (e.g., Forest Act 1993, Seed Act 1988 – First Amendment 2002) and policies (e.g., Rangeland Policy 2010) remain silent on the issues of invasive species. For example, the IAPS like Lantana camara, Chromolaena odorata, Ageratina adenophora, Mikania micrantha, Hyptis suaveolens have severely invaded rangelands of Tarai, Siwalik and Mid Hills of Nepal with obvious negative impacts to productivity and biodiversity of this important ecosystem. Nepal’s Rangeland Policy 2010, however, has not identified invasive species as a threat to the pastureland.
7 Some important Invasive Alien Species in Nepal 7.1 The African Giant Land Snail - Achatina fulica 7.1.1 Introduction
The giant African land snail A. fulica is a fast-growing polyphagous plant pest that has been introduced from its native range in East Africa to many parts of the world. It easily becomes attached to any means of transport or machinery at any developmental stage, is able to go into a state of aestivation in cooler conditions and so is readily transportable over distances. It has been classified as one of the world's top 100 IAS by The World Conservation Union, IUCN. It is supposed to enter into Nepal during 1930-1940 through eastern parts from India. Now, it has already been established in all districts of Terai region including hill districts such as Kaski, Parbat, Baglung, Gulmi, Syangjha, Palpa, Surkhet, Chitwan, Dhading, Myagdi and Dang. It is a serious pest of crops, vegetables and fruits in most of the established areas.
7.1.2 History
Having originated in east Africa, it has now spread through-out much of the tropics by human agency and, with such a wide distribution and often high densities, this large pest species is likely to have the greatest global biomass of any land snail. All A. fulica now occurring throughout South Asia, Southeast Asia and the Pacific Region are derived from a single pair
2021
of specimens released in a Calcutta garden in Chowringhee in 1847. By the mid-twentieth century its range in India was still supposedly confined to Bengal, but it seems likely that the spread was far more extensive by that time. Although the exact date of its arrival in Nepal is not known, it was likely entered to Nepal during 1930s-1940s in eastern Nepal.
It then spread to western limits of the Western Development Region of the Terai and extended north across the Siwalik Hills to Makwanpur, Chitwan and Tanahun. It has crossed the Mid Hill range and ascended the lower slopes of the Mahabharat Range at Baglung, Parbat, Arghakhanchi, Gulmi, DhadingKaski and Syangjha. However, the higher elevations are undoubtedly too cold in winter forit to survive.
7.1.3 Description
The Giant African Land Snail is one of the largest terrestrial gastropods. They have an average lifespan of about 5-7 years but can live up to 10 years under favorable conditions. The shell reaches up to 7.8 inches in length and 2.7-3.9 inches in height. An adult weigh about 32 grams. The body has two short tentacles and two long ones that have the eyes. The shell has an appearance conical and narrow, with 7 to 9 spirals visible on its surface. The color may vary depending on the environmental conditions but is usually slightly dark brown or reddish with yellowish vertical stripes. It has small teeth that allow snails to scrap the food before eating it. They have a “muscular foot” that helps them move releasing a mucus while they move to reduce friction and avoid damage to their tissues. The shell provides protection against enemies and outer environment if it is not suitable.
Photo 1: Achatina fulica adults
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7.1.4 Damage
This is an herbivore and feeds on both the living or dead plant matter. It feeds on more than 500 types of plants, including those farmed by humans. The snail eats leaves, flowers, fruits, stems, barks, wood, seeds, grains, nuts, seaweed and even lichens, fungi. When they aren’t able to get enough calcium in their diet from plants, they may feed on bones from carcasses, sand or small stones to get it.
The Giant African Snail is a serious pest of vegetables. They can completely wipe out vegetable crops such as cauliflower, potato, cabbage, pumpkin, cucumber, bottle gourd, white gourd, spinach, radish and tomato. Cereals such as hyacinth bean, cow pea, black gram, maize and millet, and fruits such as banana, guava, papaya, and jack fruit are all considered to be vulnerable.
7.1.5 Biology and behaviour
Achatina fulica is nocturnal in habit, and in the day time, often buried beneath the ground to stay safe from predators. It is a solitary species and not even after laying eggs, it establishes any bond with its offspring. They do not interact with each other except for when they are going to mate. They don’t produce any sounds, and they spend their time moving, eating, and resting. They are active between 9˚ and 29 ˚C, but they can survive above 2˚ C by hibernating inside of their shell during the colder months. They can remain inside of the shell for several months before they emerge again. Sometimes, these snails aestivate in the summer months to avoid the hot conditions. They can keep themselves moist by creating a barrier with a thin layer of mucus that their bodies create. In the case of severe drought, this process can take as long as three years.
Photo 2: Achatina fulica eggs on soil
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7.1.6 Reproduction and Life cycle
Though hermaphrodite, they usually mate in the “traditional way.” However, sometimes young or immature snails only produce spermatozoa, while adults can also produce eggs. About 8-20 days after intercourse, the snail puts between 100 and 500 eggs in a nest beneath the ground or between rocks and vegetation. Laying occurs every 2 or 3 months. Eggs hatch after 11-15 days, but the offspring do not receive any care from the parents. They don’t have a defined breeding period, and lay 5-6 clutches of eggs with about 200 eggs per clutch.
7.1.7 Management
Use of organized public campaigns, collect and destroys young and adult snails during their hibernation period in the winter when they hide under hedges and debris. Snails can be killed due to dehydration by dropping them into 5% salt solution.
Removal of all potential hiding places, habitats and shelters of snails from the fields, including plant debris, mulches, large wood chips, etc.
Encouragement of crows, lizards, the common mongoose, swans, pigs and poultry birds as they prey on juvenile snails
Dusting wood ash around plants to keep the snails away from them
Application of salt crystals in the paths or around the plots to avoid the snails' movement
Trapping snails in temporary hiding places by keeping plant debris in a pile during the night and their collection and destruction.
Use of 5% metaldehyde pellets @50 kg/ha along with wider sanitation and physical control measures.
Use of poison baits (1 kg wheat bran, 30 g metaldehyde or copper sulphate, 50 g of molasses).
Spraying of chemical pesticides such as chlorpyrifos (e.g. Dursban) 20% EC @ 2 ml per litre water in the field during night hours.
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7.2 Tomato Leaf Miner (Tuta absoluta) 7.2.1 Introduction
Tomato (Solanum lycopersicum L.) is one of the various potential vegetables cultivated in subsistent to commercial scale from Terai to Hills of Nepal. It is the fourth most important vegetable crop with total production of about 331,736 tons from 19,725 hectares (ha) of land with productivity 17 tons /ha (MOAD, 2016).
Tuta absoluta is a very harmful leaf mining moth with a strong preference for tomatoes. It occurs on eggplants, sweet peppers as well as potatoes and various other cultivated plants. It also occurs on weeds of the Solanaceae family (Solanum nigrum, Datura spp.). Tuta absoluta can cause 50-100% yield reduction on tomato crops and its presence may also limit the export of the product to several destinations.
7.2.2 Biology
Tuta absoluta reproduces rapidly, with a life cycle ranging from 24-38 days, depending on temperature. The minimum temperature for activity is 9°C. Its larval stage (caterpillars) does not enter diapause as long as food
Photo 3: Life stages of Tuta absoluta
2425
is available. One female may deposit up to 250-260 eggs during her life which are deposited on plant parts above ground. Eggs develop into a caterpillar, mining inside the leaf, stem or fruit but exit to pupate.
There are four larval instars. In between moulting, caterpillars can temporarily be found outside the leaf mines or fruit. Pupation may take place in the soil or on the surface of a leaf, in a curled leaf or in a mine. Overwintering can take place as egg, pupa or adult moth. Moths are active during night and hide between leaves during day.
7.2.3 Identification
Adult moths are grey-brown; approximately 6 mm in size and have a wing-span of 10 mm. Males are somewhat darker than females. Newly hatched caterpillars are small (0.5 mm) in size and yellowish. When maturing, caterpillars turn yellow-green and a black band develops behind the head. Fully-grown caterpillars measure approximately 9 mm with a pinkish color on their back. Pupae are light brown and approximately 6 mm.
7.2.4 Damage
Caterpillars prefer leaves and stems, but may also occur underneath the crown of the fruit and even inside the fruit itself. The caterpillars attack only green fruit.
Most distinctive symptoms are the blotch-shaped mines in the leaves. Inside these mines both the caterpillars and their dark frass can be found.
In case of serious infection, leaves die off completely. Mining damage to the plant causes its malformation. Damage to
fruit allows fungal diseases (for example) to enter, leading to rotting fruit before or after harvest.
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7.2.5 Geographical distribution & entry verification in Nepal
Tuta absoluta originates from South America where it has been a serious threat to tomato crops over a large area for several decades. It was first detected in Spain in 2007 and one year later it also appeared in Morocco and Algeria. At the end of 2008, Southern France, Italy and Tunisia reported the pest in tomato crops. The Dutch plant protection service has also detected the moth in some packing stations that process truss tomatoes imported from Spain. South American tomato leaf miner, Tuta absoluta (Meyrick), has been reported in a tomato farm for the first time in Nepal and the presence has been confirmed in five districts, Kathmandu, Lalitpur, Bhaktapur, Kavrepalanchowk and Dhading district. Studies carried out by the Nepal Agricultural Research Council (NARC) in May and June this year have identified and confirmed the presence of the pest in 14 locations in the five districts mentioned above. The highest infestation was identified in two districts, Ugrachandi Nala-2 and Panchakhal of Kavrepalanchowk district (CABI 2016).
7.2.6 Management
Grow healthy tomato seedlings inside a nylon net using plastic trays and coco-peat.
Destruction of the crop residue by burning or burying the residue one foot deep in a pit.
Use of bio-pesticide Metarhizium anisopliae @2g/lit in soil as drenching to kill the larvae and pupae residing in the soil. Alternatively, the entire planting field can be tilled to a depth of ten centimeters.
Use of plastic mulch to help identify and reduce pupation in the soil.
Start mass trapping of Tuta moths with pheromone and light traps seven days before transplanting tomato seedlings in the open green house or field. Mass trapping and other treatment activities listed below should be done using a community based approach where all the nearby farmers who are not following the approach and are growing tomatoes or other solanaceous vegetables are at least 50m away.
2627
Spray botanical pesticide neem oil (Azadirachtin 1%EC@3ml/lit) and bio-pesticide Bacillus thuringiensis1% @2gm/lit alternatively on standing crops as soon as there are >50 Tuta moths trapped per week in any of the pheromone traps. The Bacillus thuringiensis is UV light sensitive so it should be sprayed during the evening time. Remove and destroy the infested leaves, shoots and fruits immediately.
If the above management strategy fails to manage Tuta, Chlorantraniliprole 18.5% SC (Coragen, Alcora) @3ml/10 lit or Spinosad 45% SC (Tracer) @1ml/3 lit or Emamectin Benzoate @5%WG (Emamec, EMAR, King Star) @5gm/16lit may be used.
7.3 Potato tuber moth: Phthorimaea operculella (zeller) 7.3.1 Introduction
Potato tuber moth is exotic pest of potato of Nepal reported in 1966 from Kathmandu valley. At present, potato tuber moth is a major pest of potato in storage condition in Nepal. This pest is distributed in mid hills and plain areas. The abundance of the pest was found more in mid-hills where potatoes are grown twice a year. This pest is more problematic in stored potatoes harvested during May-June.
7.3.2 Distribution of PTM in Nepal
The PTM was found in Kailali, Dang, Jhapa, Makawanpur, Kavreplanchowk, Kathmandu, Argakhachi, Salyan, Parbat, Kaski, Ilam and lower altitude of Sindhupalchowk. This pest was not observed in high hills (above 2000 masl). Among the 15 districts Jumla (2550 masl), Solukhumbu (2840 masl) found PTM free and in higher altitude of Sindhupalchowk (2460 masl). This pest was reported from central Nepal (Kathmandu valley) in 1966 for the first time (Entomology Section 1967), Rolpa districts of mid-western resign in 2006 (Tiwaryet al., 2006), Dang and Salyan in
Photo 4: Damage by PTM Larvae
2728
2009 (Dangiel al., 2009). This data showed that this exotic pest is spreading rapidly except in high hills of Nepal.
7.3.3 Life Cycle
Moth and eggs
The adult potato tuber moth is 8 to 10 mm in length. The moth is nocturnal and usually active just after sunset. The male moth locates the female through pheromones excreted by the female. Mating occurs immediately, and the female lays all her eggs within two to three days.
Female moth lay about 100-150 eggs at dusk on the surface of the potato near the eye or in the cracks on the exposed skin of tuber. In field, the female laid eggs singly on the undersurface of the potato leaves. Within 3-6 days larvae hatches out from the eggs. The moth has a lifespan of one to two weeks and it does not need to feed, but it is able to live for a few days longer if it has access to liquids.
Larvae
The larva of potato tuber moth generally measure 12 to 15 mm length. They actively move around in search of a place where they can penetrate the plant.. The larva bores deep into the potato tuber and feed upon its content. They mine into the leaves between the upper and lower layers of the leaf. In the process, window-like tunnels are formed. Larvae also sometimes tunnel downward from the growth points. The larvae eat and live in this protective environment – so they are usually never observed on the plants. In hot weather the
Photo 6: Grown Up larva of PTM
Photo 5: Adult moth of PTM
2829
larvae will be fully grown within two weeks, but in colder conditions this process can take months.
On non-host plants, the larvae make fewer test bites and silk deposits. On average, the larvae walk faster on a non-host plant compared to a preferred host plant and if it reaches the edge of the leaf will leave the plant all together instead of turning around.
Pupae
The pupae of P. operculella are narrow in width and typically 0.5 inches in length. They are usually white in color and will take 10–30 days to develop, depending on environmental conditions .The fully grown larva comes out of the tuber and pupates inside a silken cocoon. In field the cocoons are formed among the dried leaves or thrash on the ground or in the soil.
7.3.4 Nature of injury
Larvae attack potato through two widely differentiated ways: (1) to the growing plant in fields, and (2) to the tubers in fields and stores. Mines in the leaf and petiole and tunnels in the stems are common nature of injuries. Eggs are deposited on the leaf and the larva after hatching starts to mine in the leaf. If there is not another leaf nearby to tie up, larva either rolls the leaf or enters the petiole. If the larva continues to feed on the leaves it injures one-third to one-half a leaf during its larval life, but where necessity drives it to mining the petiole it kills the entire leaf. Once the petiole is affected the larva rapidly works its way to the main stem. They do not bore into tubers via the stem. Under heavy infestation, potato haulms and stems occasionally desiccate and
Photo 7: Pupae of PTM
Photo 8: Damage symptoms on Potato tubers by PTM
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break. High PTM densities can affect yield (Lagnaoui and Bedewy, 1997). Leaf mining occurs more frequently on lower and larger leaves. Pest population on plants becomes apparent when the average daily temperature reaches 160 C (Lal and Prasad, 1989).
The larva generally moves downward in the stem, however it may also turn and work upward. When potato plants are young, considerable injury might result through the reduction of leaf surface and weakening of the plants. The tops of heavily infested potato plants die prematurely, consequently the potential yields are reduced (Lal, 1993).
PTM poses a serious threat particularly to the spring crop, both before harvest in the field and during storage. The losses are more pronounced on tubers. The tubers get infested in fields and stores rendering them unusable. The tuber feeding larvae injure the potatoes by tunneling through them, even if not severely injured, are very unsightly and of no market value. Some make sub epidermal channels while others tunnel directly through the tuber flesh. PTM infestation also predisposes tubers to secondary infection by organisms such as Fusarium and Erwinia which result in rots and ooze.
Later, the skin of the potato partially dries up and sinks with prominent scars due to sub-epidermal injury. Although potato is the most preferred host of PTM, it is able to perpetuate on alternate hosts when potato is not available.
7.3.5 Management
Potato tuber moth is capable of damaging potato both in field and storage condition. Thus the management must be done in both conditions.
7.3.5.1 Field Management
Reject seed lots from fields or storage that had been infested with PTM or tubers that are infested.
Avoid letting tubers be exposed outside of hill or be shallow, less than two inches covered by soil.
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Plant potato tubers below 20 centimeter. Keep potato plants well hilled with tubers adequately covered, deeper planting depth and broader hills.
Avoid late-season washed out areas as this will expose tubers above ground and PTMs can lay their eggs on the exposed tubers.
Avoid deep soil cracks (2 inches and greater) using cultural practices such as irrigation. This will inhibit female PTM from laying eggs on the tubers.
Irrigate slightly after vine desiccation to avoid soil cracking and harvest tubers as soon as skin sets.
Do not leave potato tubers in containers in the field overnight; likewise do not dig and leave tubers atop of ground to be picked up the next day and stored. At night the female PTM is most active laying eggs.
Eliminate volunteer potato plants. Intercrop potato with onion, garlic, cowpea, bean, soybean and
maize. Use PTM lure. Apply 0.05% Fenitrothion or 0.04% Dimethoate or 0.05%
Malathion or 0.01% Fenvelarate.
7.3.5.2 Storage Management
PTM damage is yearlong as the PTM will continue to breed in storage and lay eggs which will hatch into larva. The length of the life cycle will depend on the storage temperature.
Sanitize storage facility (walls, floors, ceiling). Treat facility with malathione, if PTM was detected the previous
year. Keep storage temperatures below 52 deg F. Screen storage area from the outside to keep out PTMs. If potato sacks, crates or other containers are used, they should
be new or thoroughly sanitized.
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7.4 Fall armyworm (Spodoptera furgiperda) 7.4.1 Introduction
The Fall Armyworm (Spodoptera frugiperda), FAW, is an insect native to tropical and subtropical regions of the Americas. FAW larvae can feed on more than 80 plant species, including maize, rice, sorghum, millet, sugarcane, vegetable crops and cotton. FAW can cause significant yield losses if not well managed. It can have several generations per year and the moth can fly up to 100 km per night. FAW is a damaging trans-boundary pest that will continue to spread due to its biological characteristics. Farmers will need substantial support to sustainably manage this new pest in their cropping systems using Integrated Pest Management (IPM).
7.4.2 History
FAW was first detected in Central and Western Africa in early 2016 (Benin, Nigeria, Sao Tome and Principe, and Togo) and further reported and confirmed in the whole of mainland Southern Africa (except Lesotho), in Madagascar and Seychelles (Island State). By 30 January 2018 FAW had been detected and reported in almost all Sub Saharan African countries, except Djibouti, Eritrea, and Lesotho. The pest having been detected in Sudan raises the alert for Egypt and Libya. Fall Armyworm keeps spreading to larger areas within countries in sub-Saharan Africa and becomes more destructive as it feeds on more crops and different parts of crops, increasingly growing an appetite for sorghum and millet, in addition to maize. United Nations' Food and Agriculture Organization (FAO) has warned that the pest could spread to Northern Africa, Southern Europe and the Near East. It was first detected in India in 2018, where it is causing significant loss to farmers in Karnataka and other Southern Indian states. The presence of FAW has recently been confirmed in Bangladesh and Sri Lanka, and Thailand. There is a high probability that the migratory pest will reach Nepal soon. There are climatic conditions in Nepal are suitable for the establishment of FAW populations, which can potentially cause a huge crop loss in maize if not managed properly.
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7.4.3 Life cycle
The fall armyworm lifecycle includes egg, six growth stages of caterpillar development (instars), pupa and moth.
7.4.3.1 Egg
In general, 100-200 eggs are laid on the underside of the leaves typically near the base of the plant, close to the junction of the leaf and the stem. These are covered in protective scales rubbed off from the moth's abdomen after laying. When populations are high, eggs may be laid higher up the plants or on nearby vegetation. FAW eggs are normally whitish/cream when fresh and become dark/grey when about to hatch.
7.4.3.2 Larvae
The larva goes through six different instars, each varying slightly in physical appearance and pattern. The larva process lasts from 14 to 30 days, depending on temperatures. The mature caterpillar is about 1.5–2.0 inches (38–51 mm) in length. This is the most destructive life stage as the larvae have biting mouth parts. Newly hatched larvae is green during the 1st-2nd instars which turn brown to black from 3rd to 6th and have a dark head with a pale, upside down Y-shaped mark on the front.
Photo 9: Life life stages of s. Frugiperda: a & b, eggs; c-f, larval instars; h, adult male in habitus; i, adult male (dorsal view); j, adult female in habitus; k, adult female (dorsal view)
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7.4.3.3 Pupa
The larvae then pupate underground for 7 to 37 days in a cocoon they form of soil and silk. The pupa is reddish brown in color and forms a cocoon of about 20-30mm in length and is oval in shape. They are mostly found in the soil 2-8cm deep. The pupa lives for 12-14days before the moth emerges.
7.4.3.4 Adult
Adults are capable of flying long distances, so even though they are unable to overwinter. The moth is grey-brown in color. Male moth has conspicuous white spots on the tip and center of the forewings. The forewings are grey and brown in color. They live up to 2-3 weeks, are migratory and can travel long distances.
7.4.3.5 Host range
FAW larvae can feed on more than 80 plant species, including maize, rice, sorghum, millet, sugarcane, vegetable crops and cotton. Although FAW larvae can feed on more than 80 species of plants, they prefer maize, as well as, rice, cotton, groundnut, sorghum and vegetables.
7.4.4 Nature of damage
Fall armyworm causes serious leaf feeding damage as well as direct injury to the ear. While fall armyworms can damage corn plants in nearly all stages of development, it will concentrate on later plantings that have not yet silked. Late planted fields and later maturing hybrids are more likely to become infested.
After hatching the young caterpillars feed superficially, usually on the undersides of leaves. Feeding results in semitransparent patches on the leaves called windows. Young caterpillars can spin silken threads which catch the wind and transport the caterpillars to a new plant. The leaf whorl is preferred in young plants, whereas the leaves around the cob silks are attractive in older plants. Feeding is more active during the night
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7.4.5 Potential damage in Nepal
The most preferable host of FAW is maize which is the second largest crop of Nepal in terms of area and production. This is mainly a summer crop. The favorable humidity and temperature for establishment of FAW is summer season. All season survival in Nepal is almost impossible due to cold temperature but the probability of seasonal establishment is very high. As it has reached to the neighboring countries including China, Bangladesh and India, there is high potential of entry into Nepal. All of the Pathways (wind, air-craft, vehicles as well as agriculture commodities especially maize) for introduction are equally probable. So, temperature during pre-monsoon, monsoon and post monsoon is highly favorable for FAW. It possesses very high risk of food insecurity in these mid hill districts in case of its entry and establishment.
7.4.6 Management
The best and most effective strategy for managing FAW is taking preventive measures and immediate action when the FAW is detected. This can cause more damage to maize at the early growth stage, that is why the threshold for the use of pesticides is higher than in older maize crops
7.4.6.1 Cultural control methods/mechanical control methods
Destroy the eggs, larvae and pupae in the crop residues after harvest by deep burying the plant residues in soil (at least 12cm deep).
Practice crop rotation. Alternate maize with crops that are not attacked by the FAW e.g. cassava
Intercropping with pigeon pea, beans, groundnuts can attract more beneficial insects, and can help repel FAW from your garden and control other weeds
If the number of eggs or caterpillars are few, handpick and crush them. This is only practical for small gardens or few affected plants.
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FAW is food for certain birds and insects. Growing trees, hedgerows and a variety of crops in your garden helps increase the number of these predators that can feed on the FAW and will help to reduce on infestation in the farm.
7.4.6.2 Chemical control methods 7.4.6.2.1 When to apply pesticides
If 10 out of 50 randomly selected maize plants are affected, then start spraying with the recommended dose of the right pesticides. For the pesticides to be effective spray early in the morning from 6:00-10:00 am or late afternoon 4:00-7:00 pm provided the conditions are favorable for spraying because FAW actively feeds at night.
7.4.6.2.2 How to apply pesticides
1. Put on protective wears when handling, mixing and applying the pesticides, these include overalls, goggles, gloves, boots and mask and follow the instructions on the product label.
2. Always use a clean pump and clean water for mixing the pesticides.
3. Spray using the cone-shaped nozzle as this will target the plant and the maize funnel.
4. Remember that FAW caterpillars and eggs can be found anywhere on the maize plant, spray the whole plant and target the funnel where the caterpillars are usually found.
5. Avoid spraying when it is windy or if rain is imminent.
7.4.6.2.3 How often to apply pesticides
1. Spray crops and check for presence of caterpillars 4 days after spraying. Thereafter, continuously monitor for the presence of caterpillars.
2. If after 7-14 days' live caterpillars are identified in 10 out of 50 randomly selected plants, re spray with the same pesticide.
3. Two to three (2-3) times of spraying may be adequate in a maize season.
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4. Remember to apply alternately the pesticides with different modes of action after every season to avoid development of pest resistance.
7.5 Chinese citrus fly Bactrocera minax (Enderlein) 7.5.1 Introduction
The Chinese citrus fly, Bactrocera minax (Enderlein), is one of the most destructive insect pests of citrus in the Asian region from Nepal through to southwestern China (Bhandari et al., 2017, Wang et al., 2016 and Drew et al., 2013). Chinese citrus fly feeds exclusively on the fruits of citrus and oligophagus pest (Xia et al., 2018). Bactrocera minax (Enderlein) (Diptera: Tephritidae) is a major pest of tight skinned citrus in Nepal, which is distributing from eastern hilly area to central hilly part of the country. A study in National Citrus Research Program (NCRP), Paripatle, Dhankuta in 2006 confirmed that Chinese citrus fly (B. minax) is the species affecting the citrus fruits of NCRP, Dhankuta and vicinity areas but not the oriental fruit fly. An extensive survey of the fruit flies infesting citrus orchards were undertaken especially in five districts i.e. Dhankuta, Tehrathum, Gorkha, Lamjung and Syangja and studied its biology to identify the species. The adult fruit flies emerged from the samples taken from Tehrathum were identified to be B. minax but no adults emerged from the samples taken from Gorkha, Lamjung and Syanja (NCRP, 2011). These results confirm previous studies that referred B. minax as the problematic fruit fly species in eastern part of Nepal. Thus, there is strong need to develop an appropriate method of monitoring and management. Fruit loss due to the infestation of Chinese Citrus Fly (Bactrocera minax) is becoming devastating since 2014 (Adhikari and Joshi, 2018). This pest could be the reason up to 100% fruit damage in harsh situations.
7.5.2 Field Identities of Bactrocera minax (Enderlein)
Diagnosis: An extremely large species; face fulvous with narrow elongate facial spots reaching oral margin; scutum red-brown without dark patterns, scutellum yellow with a narrow red-brown basal band; legs with all segments mostly fulvous; wings with cells bc and c fuscous, microtrichia in outer corner of cell bc and outer 1/2 of cell c, a broad
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Photo 10 Field identifiable morphological structures in Bactrocera minax a. Holistic view, b. Lateral view, c. Dorsal view, d. Wing, e. Dorsal abdomen (Source: Adhikari and Joshi, 2016)
fuscous costal band overlapping R4+5 and becoming darker towards the apex but not expanding into a spot, a narrow fuscous cubital streak but not reaching margin of wing, supernumerary lobe weak; Abdomen: abdomen elongate oval and petiolate (similar to many Dacus species), terga III-V orange-brown with a moderately broad transverse fuscous band across anterior margin of tergum III and a medium width medial longitudinal pale fuscous band over all three terga, anterolateral corners of tergum IV fuscous, anterolateral corners of tergum V pale fuscous (Adhikari and Joshi, 2016).
7.5.3 Distribution
Sikkim, India, Bhutan, China, Nepal (Drew et al., 2007).
Note: B. minax (misidentified as B. tsuneonis Miyaka) was collected for the first time from sweet orange at Helambu, Sindhupalchok district in December 1984 (Joshi and Manandhar, 2001). While validating the said fruit fly species, Dr. Gary J. Steck, Florida State Collection of Arthropods, Florida, USA determined it being B. minax. Similarly, he identified the fruit fly specimens collected from sweet orange in Dhankuta dated 27 April 2007 being B. minax. Sweet oranges in the eastern mid-hills of Nepal, particularly, Dhankuta and Tehrathum districts are reportedly seriously
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Photo 11 Bactrocera minax and B. tsuneonis
infested of B. minax fruit flies (NCRP, 2011). There exists no fruit fly species like B. tsuneosis in Nepal. But, while making Agreement with China, B. tsuneosis was listed as a Nepali species (Adhikari et. al., 2019). B. minax has erroneously been considered synonymous with B. tsuneonis (OEPP/EPPO, 1996). Recently conducted organized fruit fly surveillance of citrus orchards in Sindhuli distrist confirmed sweet orange being devastated by B. minax (Photo 2). B. minax is reported for the first time in sweet orange in Sindhuli district (Adhikari and Joshi, 2016).
7.5.4 Life cycle of Chinese citrus fly
Chinese citrus fly (Bactrocera minax) is a uni-voltine fruit fly species. The life cycle stages and behavior of this pest is important to develop strategies to manage the pest. As per its problem observed in the sweet orange (Citrus sinensis) at Sindhuli district from 2014 to till date following below presented chart represent the life cycle stages in the different months of the year.
Similar life cycle stages and time period was mentioned in China by Xia et al., 2018. Adults of Chinese fruit fly emerged from soil during April to May and become active for oviposition after feeding proteinous food on May to July. Female adults lay eggs in the rind of fruit. The eggs then developed into the larvae (maggots) which are the damaging stage of this insect by feeding the pulps inside fruit. Larvae development stages inside citrus fruits start from July to October. The infested fruits are lighter in weight. Matured maggots get out from fruit making noticeable hole in the
Photo 12: Life cycle of Chinese Citrus Fly in Sindhuli, Nepal
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Photo 13 : Damage on fruit
fruit rind. The matured maggots enter into the pupae stage inside soil for around 6 months (Oct., to April). Management strategy of this pest should link with the biology and behavior of the insect. Integrated management measures in community with stakeholder's coordination could achieve the reduction in yield loss.
7.5.5 Nature of Damage
Eggs are laid just beneath the skin of the fruits. The oviposition spots can be observed. The maggots feed on the juice and pulp develops inside the maturing fruits. As a result of their feeding activity, the fruits turn prematurely yellow around the feeding site and eventually drop. When the maggots are mature they leave the fruit by making an exit hole, and enter into the soil to pupate (Ecoman Biotech, 2014).
7.5.6 Means of movement and dispersal:
According to the Fletcher (1989) adult flight and the transport of infested fruits are the main means of movement and dispersal from one place to other places. Many Bactrocera spp. can fly 50-100 km.
7.5.7 Management 7.5.7.1 Prevention:
Follow recommended orchard management practices (regular pruning, optimum manuring and fertilization, etc.). Bag the fruit to prevent egg laying by wax paper or oiled newspaper when flower petals drop after fertilization. Do not throw the infested fruit anywhere to prevent regeneration of fruit fly. Follow quarantine measures strictly (do not take infected citrus fruit where there is no problem of this pest) to prevent entry and spread of pest.
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7.5.7.2 Monitoring:
This uni-voltine (one generation per year) species attacks a wide range of citrus fruits such as Sweet Orange, Lemon and Mandarin etc. Monitor the citrus orchard using trap of protein bait (1 trap per ha). Take action when 4-6 adult flies detected in the trap (~1 cm long body with 1 cm wings). Observe the brownish body with three yellow markings in thorax and dark band along the margin of front wing. Check egg site on the fruit-rind. Observe the puncture with some sticky gum. Observe the fallen fruits in orchard and maggots inside an opened fruit. Infected fruits are lighter and have holes in the outer rind of the fruit. Recognize the history of pest attacks in the orchard to apply prevention measures. If there is fruit infestation by maggots, apply prevention measures for next year.
7.5.7.3 Control:
Collect and bury infested and dropped fruit at least 30 cm deep every 7days/feed to livestock/use for biogas/kill in sealed plastic bag in the sun to break life cycle. The maggots of fruit fly pupate in the soil. Till the soil under the tree canopies to kill larvae and/or pupae. Soil treatment with crushed neem seed cake 50-60 Kg/ha after fruit harvest (Jan-Feb). Trap adult flies using protein hydrolysate bait/lure to prevent egg laying using Malathion 50 EC (20 traps per ha). Spray Azadirachtin based product (3 ml/lit) water in the orchard during May-July in 15 day intervals to deter egg lying. Apply fungal pathogen Metarhizium anisopliae 2-3 kg per hectare against larvae and/or pupae incorporate in soil after fruit harvest (Jan-Feb).
Spray bait of Protein Hydrolysate 5-10 ml in 1 litre water with insecticides during May-July in 15 days interval with any of the following insecticides: Malathion based insecticide for ex. 50 EC 2 ml per litre. Chlorpyrifos based insecticide for ex.20 EC 0.5 ml per litre. Fipronil based insecticide for example 5 SC 2 ml per liter. Direct spray Abamectin based insecticide for example 1.80 EC 1.12 gm per lit during May-July in 15 day. Treat the soil with Malathion 5DP@20kg/ha after fruit harvest (Jan.-Feb.). Avoid grazing of poultry or other animals inside the orchard for minimum 2 weeks after Malathion application (Adhikari, 2016).
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Fortnightly protein bait spray applications from early May to late July would reduce the fly population markedly and prevent oviposition in developing fruit. Because the oviposition period is well defined, from mid-June to late July, a systemic insecticide cover spray in early July followed up by a second treatment in late July would provide high mortality of eggs in fruit. The extended period between fruit fall and pupation, at least 18 days, would provide opportunity for cultural control practices. Collection of fallen fruits only once every ten days would prevent the development of puparia and thus reduce the fly population for the next year. Effective community mobilization in order to manage this pest with the use of environmentally friendly approaches like protein baiting and fruit drop collection is important.
7.5.7.4 Area Wide Control Program (AWCP)
Area Wide Control Program (AWCP) of Chinese Citrus Fly (Bactrocera minax) in Sweet Orange Orchards at Sindhuli, Nepal has been initiated to manage CCF in sweet orange orchard. The objective of this program was to suppress populations of the CCF to minimize the extent of fruit damage due to the maggots. This program is conducted by the joint efforts of PMAMP, Program Implementation Unit (Junar Super Zone, Sindhuli), Karma Chemical Company Pvt. Ltd., Kathmandu, Ecoman Bio-tech, China and the Sweet orange growers of Tinkanya, Sindhuli, Nepal from April, 2018 in 100 Acres (800 Ropanies) Junar orchards at Golanjor-4, Tinkanya. Technically, trapping of adult flies in net and in protein hydrolasate bait was performed. Bait spray of protein hydrolasate [Application of GREAT Fruit Fly Bait (Protein Hydrolysate 25 % and 0.1 % Abamectin): 1 part in 2 part water, 50 ml solution spray on 0.5 to 1 m2 area under side of the leaf in the citrus tree 7-8 spots/ropani/week for ten times. Managerially, Stakeholders' consultation, clustering of orchards for the spray plan, orientation to the spray persons, monitoring of spray and observation and feedback were accomplished. The result of AWCP of CCF was found effective to minimize the fruit infestation by maggots. The result revealed that the leaf underside spot treatment with the protein bait was highly efficient to minimize the sweet orange fruit losses from 56.7 to 10.9%.
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7.6 Eupatorium adenophorum (Ageratina adenophora): 7.6.1 Introduction
Eupatorium species have a remarkable range of altitudinal distribution (800 to 2000 m asl) in Nepal, which overlaps with human settlements. It has been sporadically spreading and now it is reported from 305 to 2500 m in abandoned slopes after slash and burn cultivation, fallow lands and disturbed forests with severe human interference. It is represented by six species in Nepal viz. E. acuminatum, E. adenophorum, E. cannabinum, E. capillifolium, E. chinense and E. odoratum out of which two (E. adenophorum and E. odoratum) are highly undesirable. E. odoratum and E. adenophorum are aggressively colonizing abandoned slopes in the tropical to lower temperate zones, respectively. E. adenophorum is believed to be introduced into Nepal from India through eastern border probably before 1950. It is now widespread in eastern and central part of Nepal aggressively naturalized in Siwaliks and mid-hills of entire Nepal.
7.6.2 Damage
Invasion of Eupatorium is an enormous problem. Transitional zones and swamp forest are being invaded by dense mono-specific stands of Eupatorium, which have little understorey except for Eupatorium seedlings. Although the species of Eupatorium have pesticidal properties which have been applied in a few areas of Nepal, no commercially viable application has been found. Neither cattle nor goats eat this plant, and areas traditionally used for grazing can no longer be used for this purpose, forcing villagers to walk farther in search of grazing pasture. The increased time spent on this activity translates into a substantial economic loss.
Photo 14: Invasive nature of Eupatorium plant
Photo 15 Eupatorium Plant
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7.6.3 Biology
The numerous light seeds are easily contaminated with agriculture, horticulture, forestry and pasture seeds, or stick to the body of human, livestock and vehicle, etc. or in some adjoining places, seeds are dispersed by air current Ecological impact. The dominance of Eupatorium species has occurred in transitional zones with adequate moisture and disturbance regimes, which can be easily seen in disturbed forest sites. This plant inhibits growth and may even kill local plants and domestic animals.
7.6.4 Management Strategy
Biological control of Eupatorium species using gall fly Procecidochares utilis has been carried out throughout world including Nepal. It was successful in Hawaii, USA, and elsewhere (Bess and Haramota 1971); however, this technique has not yet been successful in Nepal.
The alternative, trying to control the weed, also involves a burden of labour and financial investment. Eupatorium spp. growing in fallow land prevents soil erosion. They are used as green manure during spring, when the plant is heavily laden with leaves. Dried Eupatorium may be burnt to yield potash rich fertilizer. In some parts of the country, it has been used for cattle bedding material. Eupatorium leaves when boiled and taken, cure severe stomachache and the apical leaves when made into paste and slaked with lime and applied on the cuts, stops bleeding. Local people apply the fresh juice of Eupatorium leaves to stop bleeding from cuts and wounds
Photo 16: Eupatorium at flowering stage
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7.7 Parthenium hysterophorus 7.7.1 Introduction
Parthenium weed (Parthenium hysterophorus L.) is an annual herbaceous plant, invades disturbed land and degrades natural communities. It can cause serious allergic reactions in people, domesticated livestock and other wildlife, and is a significant problem in crop, grassland and forestry production. It is a major invasive weed in many parts of the world, and is rapidly becoming a major threat to Nepal with a growing potential to cause immeasurable ecological and agricultural losses each year in this country.
The plant produces allelopathic chemicals that suppress crop and pasture plants, and allergens that affect humans and livestock. It also frequently causes pollen allergies.
7.7.2 Biology
Parthenium weed normally germinates in the spring, produces flowers and seed throughout its life cycle and dies in late autumn. It can start flowering when plants are only 1 month old and will continue to flower for a further 6 to 8 months. It is able to germinate, grow and flower over a wide range of temperature and photoperiod conditions; hence in Nepal it can be seen growing in the field at any time of the year. However, the principal season of growth is in the monsoon when it is warm and rainfall is plentiful.
Parthenium weed reproduces by large numbers of seed. Under field condition more than 70% of seed buried 5 cm below the soil surface
Photo 17: Parthenium hysterophorus
Photo 18: Fully grown Parthenium plant at bloom
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would live for at least 2 years, with a half-life of 7 years. These seeds are dispersed by wind, water, animals, vehicles and machinery (particularly on harvesters and bulldozers) and in clothing. They are sometimes also spread in mud and contaminated agricultural produce (e.g. fodder and grain).
7.7.3 Geographical distribution in Nepal
In Nepal, the Parthenium was first reported in 1967 but the major population outburst has occurred since 1990s. This weed has already invaded Tarai, Siwalik (particularly the dun valleys) and mid hill regions of Nepal. From southern part of the country, the weed is spreading to northward along road networks. Since the first report of the weed by Mishra (1990) from Kathmandu valley, it has been rapidly spreading and currently it can be found in most parts of the valley with potential negative impact on ecosystem and public health.
7.7.4 Damage
Absence of natural enemies, wide adaptability to varying soil and micro-environment, high fecundity, efficient seed dispersal mechanisms, and allelopathic impact on most other plants have enabled Parthenium to invade a variety of habitats in its invasive range particularly under the situation of human activities. It causes health hazards to man and animals leading to socio-psycho-economic problem, modifies soil and species composition of native vegetation, and reduces agriculture productivity. Main categories of damage include:
Allelopathic interference and phytotoxicity: Allelopatiic chemicals released by the plant can inhibit the germination and growth of a wide range of plant species including native plants, as well as various crops and pasture species (Adkins et al., 1997). Parthenium weed residues are reported to have a phytotoxic effect upon a number of important field, horticultural, vegetable and agroforestry crops.
Direct and indirect effects on crop and livestock production: It can invade a wide range of crops and of particular concern is the invasion of cereal crops such as wheat and maize In such crops,
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Parthenium weed has been shown to reduce yields by as much as 40% and is also a serious weed of pastures and rangelands. It and can reduce the carrying capacity of pastures by as much as 90%. Parthenium weed can also cause indirect losses to crop production by acting as a secondary host to a number of important crop pests and diseases.
Effects on native plant communities: This weed disrupts the structure of natural ecosystems and displaces numerous native plant species from those ecosystems. The weed has become a major threat to many protected areas including Chitwan National Park in Nepal.
Effects on health: Parthenium weed is a notorious allogeneic plant, with health effects being reported from almost all the countries where this weed has invaded. People can become affected in two ways, either by direct contact, or by indirect contact through airborne particles. There is no treatment for sensitivity to the plant or its airborne parts, and no desensitizing therapies are available. Dermatitis, hay fever, asthma, bronchitis and non-contact, allergic respiratory disorders are caused. The weed is poisonous to livestock and may cause death after 30 days if significant quantities are ingested.
7.7.5 Management Approaches
A number of different approaches have been used for managing Parthenium weed, but to date no single method alone has been shown to be effective. Thus, an integrated weed management approach is more commonly used for Parthenium weed and this involves a number of the management approaches described below.
7.7.5.1 Physical management:
Parthenium weed populations readily regenerate after manual removal and will regrow from cut or partly pulled plants that still have a root system. The hand pulling strategy is commonly used in Nepal where labor is cheap and people are not aware of the associated health risks of pulling up the plant.
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7.7.5.2 Chemical management:
Chemical control is only financially feasible within some high value crops and in other circumstances such as along roadsides, in public parks or on small areas. It is not cost effective to chemically control this weed over the vast areas where the weed is commonly found. Plants should be chemically treated when they are small and at the pre-flowering stage. Various selective herbicides (e.g. glyphosate, paraquat, metsulfuron) have been reported to be effective in the chemical management of Parthenium weed in a number of different situations.
7.7.5.3 Biological management with suppressive plants:
One leaf of senna (Cassia uniflora Mill.) was found to be the most suitable with this plant suppressing the growth of Parthenium weed seedlings. Biological control agents and the suppressive plants to act synergistically to significantly reduce the biomass and seed production of Parthenium weed.
7.7.5.4 Biological management with insects and pathogens:
Classical biological control is one of the most important approaches used for the management of invasive weeds. Only five countries (Australia, South Africa, India, Ethiopia and Sri Lanka) so far have released biological control agents against Parthenium weed. Three agents, Epiblema strenuana Walker (a stem galling moth), Zygogramma bicolorata Pallister (a leaf feeding beetle) and Listronotus setosipennis Hustache (a stem boring weevil) appear to be having a significant impact upon the weed in the field.
There is no official record of deliberate introduction of Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) to Nepal. However, in August 2009 this beetle was observed defoliation of Parthenium in Hetaunda, which has possibly introduced from India. Zygogramma bicolorata has already been established in southern part of Nepal, it has not reached to all areas where Parthenium weed has infested. The beetle may expand its area by natural dispersal, but the time duration for
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natural dispersal will take longer period. It would be better to prepare distribution map of this beetle in Nepal as soon as possible and introduce it as bio-control agent of Parthenium weed in new areas after ecological assessment. The biological control agents that have been released to help manage Parthenium weed, their movement to other countries and the status of their establishment in those locations is given in Table 3.
Table 3 Biological control agents, their movement and the status of establishment
Insect/pathogen species
Order Origin Released country or
country where found
Establishment
Epiblema strenuana Walker
Lepidoptera Mexico Australia, Chinaa
Yes
Zygogramma bicolorata Pallister
Coleoptera Mexico Australia, Ethiopia, India,South Africa, PakistanbNepalb
Yes
Listronotus setosipennis Hustache
Coleoptera Argentina Australia Yes
Smicronyx lutulentus Dietz
Coleoptera Mexico Australia Yes
Contrachelusal bocinereus Fiedler
Coleoptera Argentina Australia Yes
Carmentanrithacae Lepidoptera Mexico Australia Yes Bucculatrix pathenica Bradley
Lepidoptera Mexico Australia Yes
Platphalonidia mystica Razowski & Becker
Lepidoptera Argentina Australia No
Stobaera concinna Stal
Homoptera Mexico Australia No
Puccinia abrupt var partheniicola (Jackson) Parmelee
Uredinales Mexico Australia, Indiac, South Africac, Kenyac, Nepalc,
Yes
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Insect/pathogen species
Order Origin Released country or
country where found
Establishment
Ethiopiac, Chinac
Puccinia xanthiif.sp. Parthenium hysterophorae
Uredinales Mexico Australia, South Africa, Sri Lanka
Yes
a First released as bio-control agent against rag weed, Ambrosia artimissifoliab Come through neighbouring country, India. c Source unknown
7.7.5.5 Integrated weed management:
In many locations Parthenium weed is able to survive the individually applied management measures. Integrated weed management, on the other hand, involves the combination of all available methods for the weeds management and is considered to be the most effective approach to the long-term control of Parthenium weed.
7.8 Mikania micrantha 7.8.1 Introduction
Mikania micrantha is a perennial sprawling vine with a wide distribution in Neotropics which extends from Mexico to Argentina. In its natural territory, it has no invasive behavior but in Paleotropical range it is a serious weed with a remarkable growth rate (8-9 cm) in a day, that’s why; also called as mile-a-minute weed. It was first reported in Nepal by Kitamura in 1966. It can invade and grow well in fallow lands, croplands, forests, scrubs or shrub lands and wetlands and basically, it blocks the light to plant by covering it and retards the growth and competes with plants for nutrients and water and sometimes produces the growth inhibitors.
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7.8.2 Ecological characters
The Mikania micrantha is a fast growing plant capable of climbing over other plants to gain more sunshine. It is also known as plant killer as it spreads appallingly fast, blocking sun lights for other plants, and strangles many plants, which wither as a result. Although intolerant of heavy shade and water logging condition, it readily colonizes gaps. Its shoot has been reported to grow 27mm a day. It is also reported that a single plant may cover over 25 sq. m. within a few months. It releases the substances that inhibit the growth of other plants.
7.8.3 Invasion of Mikania
Mikania micrantha got introduced in Nepal through north-east India. Further dispersal is possible due to numerous small seeds blown by air or due to humans, livestock and vehicles. Small seeds or stem fragments may easily be contaminated with agriculture, horticulture, forestry and pasture seeds.
Mikania micrantha is well established in the tropical part of eastern and central Nepal. It has been causing serious problems in the KoshiTappu Wildlife Reserve. The plant has seriously invaded the forest in the eastern embankment. The forest trees are totally engulfed by the Mikania micrantha.
About twenty percent habitat of National park in southern belt is covered with this species, which accounts for 50 % of the rhinoceros's habitat. It has severely decreased the food of rhinoceros and other herbivores Sapkota (2009) have reported that they have started to feed little bit on Mikania
Photo 19: Mikania micrantha
Photo 20: Mikania micrantha at flowering stage
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however the species has been used just as an emergency food. Bird’s nesting place is covered and they have started to migrate in other suitable habitats. Literature shows that; the species has very low invasion in area having very low forest cover and high forest cover. It was found with higher invasion in the area with crown coverage 20-85% (Sapkota 2009).
7.8.4 Management 7.8.4.1 Physical
Farmers dig out the plants, which are tending to invade in their agricultural land. Manual removal of Mikania micrantha is the most feasible method but possible only in early stage. Burning is not viable as it is fairly deep rooted and is almost impossible to burn out the roots to exterminate the plant and prevent it from regenerating. Well established areas pose serious problems because new plants can grow even from the tiniest stem fragments. Chemical Herbicides like glyphosphate and 2, 4-D are used before flowering while contact herbicides such as paraquat is used in seedling stage. Despite, established plants can grow from the base (Swarbrick, 1997).
7.8.4.2 Biological
An insect Liothrips mikaniae appears to be a specific biological control organism though it failed to establish in Solomon Island in 1988 (Swarbrick, 1997). Various researches on classical biological control methods are ongoing; Puccinia spegazzinii has been considered as a potential control agent. This rust is under final assessment in quarantine China while the Indian government has approved releasing it to the field. According to CABI Bioscience, the preparation for release is under progress.
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Government of Nepal Ministry of Agriculture and Livestock Development
Plant Quarantine and Pesticide Management CenterHariharbhawan, Lalitpur
Phone : 5010111, 5521597, 5524252, 5553798, 5535844Email : [email protected] : www.npponepal.gov.np
2019
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