ECOLOGICAL STUDY OF THE SUGARCANE MOTH BORER, Chilo ... · venosatus (Bojor). Lewanich (1975) reported that five species of sugarcane moth borers in Chon Buri, Nakhon Pathom, Ratchaburi,

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ECOLOGICAL STUDY OF THE SUGARCANE MOTH BORER,Chilo tumidicostalis (HAMPSON) (LEPIDOPTERA: PYRALIDAE)

AND ITS NATURAL ENEMIES

INTRODUCTION

Sugarcane, Saccharum officinarum L., is one of the most economicallyimportant crop of Thailand. It is the main source of sucrose, and is used in sugar andalcohol production. Insect pest complex is the most important limiting factor insugarcane production. Among the sugarcane insect pest complexes, the sugarcanemoth borers complex is considered most important. Chilo infuscatellus Snellen, Chilosacchariphagus (Bojer) and Sesamia inferens (Walker) are key pests of sugarcane andhave caused heavy damage in many areas of sugarcane plantation(Suasa-ard, 1982).

Sugarcane moth borer, Chilo tumidicostalis (Hampson) (Lepidoptera:Pyralidae) are minor pests, but in the last few years this species was the mostimportant pest and outbreak in some areas such as in the northern of Thailand and 100percent of infestation occurred in some areas in Sa Kaew and Buri Rum provinces(Suasa-ard and Allsopp, 2000). The sugarcane moth borer, C. tumidicostalis is animportant pest of sugarcane in many areas of countries such as India, Nepal andThailand.

The objective of this study is to conduct an investigation on the biologicalattributes, including the construction and analysis of the life table of C. tumidicostalis,a survey and evaluation of the parasite of this sugarcane moth borer including studieson the biology of the important parasites; studies on the population dynamics of thissugarcane moth borer, assessment and evaluation of the parasites of these sugarcanemoth borer as potential biological control agents. The result obtained from this studywill be further utilized as a basis for the development of an integrated pestmanagement program for this sugarcane moth borer in Thailand.

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LITERATURE REVIEWS

Cantelo and Pholboon (1965) reported that there were 66 species of insectsattacking sugarcane in Thailand and among these, the moth borers were most serious.Long and Hensley (1972) reported that there were about 50 species of lepidopterousborers recognized as pest of sugarcane in the world. None were cosmopolitan andmany attacked other cultivated hosts, especially the members of Gramineae.

Napompeth (1964, 1977) gave accounts on the biology of sugarcane mothborers and their parasites and reported that there were at least four important speciesof sugarcane moth borers which attacked sugarcane in Thailand, namely, Scirpophaganovella (F.), Chilo infuscatellus Snellen, Sesamia inferens (Walker) and Procerasvenosatus (Bojor). Lewanich (1975) reported that five species of sugarcane mothborers in Chon Buri, Nakhon Pathom, Ratchaburi, Suphan Buri and Kanchanaburiwere Chilo infuscatellus Snellen, Chilo sacchariphagus (Bojer), Sesamia inferens(Walker), Scirpophaga excerptalis (Walker) and Chilo tumidicostalis (Hanpson)

Prachuabmoh and Taleungwut (1980) and Prachuabmoh et al. (1984) reportedthat there were 77 species of insects attacking sugarcane and among these, 12 specieswere important, the moth borers were most serious. They stated that the Chilotumidicostalis (Hampson) attacked sugarcane mostly during July to August in therainy season.

Bleszynski (1970) reported that the sugarcane moth borer Chilo tumidicostalis(Hampson) was important pest sugarcane in the Southeast Asia and Eastern Africa. Itis distributed in India, Burma and Nepal and especially damaged only sugarcane plant(Williams et al., 1969) Bleszynski, (1970) reported that its distribution was in Indiaand Nepal.

Long and Hensley (1972) reported that there were about 50 species oflepidopterous borers recognized as pest of sugarcane in the world. None werecosmopolitan and many attacked other cultivated hosts, especially the members ofGramineae. All stages of sugarcane moth borers usually appeared in the field whenbuds of sugarcane sets began to germinate, through the vegetative developmentalstages and until the harvest time. An infestation by moth borers resulted in thecharacteristic “dead heart” with subsequent reduction in crop stands in the youngshoot stage, and reduction in stalk weight and juice quality after internode formation.

Metcalfe (1969) stated that the larvae of sugarcane moth borers destroyed thegrowing point of stalk preventing further development of internodes, and tunnelingwithin stalks caused the stalks to break and lodge and reduced juice quality. Mayeauxand Colmer (1960) mentioned that the larval tunnels served as entry points forinfestation by secondary pests such as other insects, bacteria, fungi and yeasts.Blesynski (1969) stated that many species of sugarcane moth borers in the old worldbelong to the genera Chilo and Sesamia, whereas those in the new world are mostlyDiatraea. He also added that Chilo and Diatraea forms were compact monophyleticgroups and were kept as distinct genera mainly for practical purpose. Ruinard (1971)

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stated that the relative importance of different sugarcane moth borer species changedfrom country to country and they were diversed in numbers and usually of limitedgeographical distribution.

Pitaksa and Prachuabmoh (1989) stated that Chilo tumidicostalis (Hampson)damage on sugarcane during elongation stage at Sam Chuk, Song Phi Nong andU Thong, Suphan Buri, were 0.68, 3.94 and 1.98 percent respectively. At Ban Bung,Chon Buri damage was 1.00 percent and at Tha Muang, Kanchanaburi damage was1.18 percent.

Pitaksa (1999) reported that Chilo tumidicostalis was the most serious pest ofsugarcane and reported that the adult female usually laid egg linearly along the leaves.The duration periods of egg, larval, pupa and adult stages were 9, 25-30, 7-10 and 3-5days, respectively, and the total life cycle was 46-49 days, and the average number ofeggs emerging in the field was 96.96 percent. Chilo infuscatellus,Chilo sacchariphagus and Sesamia inferens have been the key pest species and heavydamage occurs in many areas of sugarcane plantation (Suasa-ard, 1982).Chilo tumidicostalis is generally a minor pest, but in the last few years this species hasbeen the most important pest species and has risen to outbreak status in some areassuch as in the northeast of Thailand. In some areas of Sa Kaew and Buri Rumprovinces, 100 percent of stalks have been infested. The biological studies ofChilo tumidicostalis revealed that the adult is nocturnal in habit and mating occurs atdusk. The adults are slender body moths, measuring 16.28±4.32 mm from the head tothe tip of forewing. The general color of forewings is brown to pale brown with somedarker marking. Hindwings are white in female and dirty white to light brown inmale. The longevity of adult is about 5 to 7 days. Eggs are laid in batches on bothsides of leaf blades. Individual egg is oval-shaped, flat and overlaps each other. Theindividual egg measures 1.4±0.24 mm in diameter. The larva is creamy white withbig dark spots on the body and a dark brown head. Larvae prefer to feed on timebefore pupation. The larval period is 26.4±2.46 days. The pupa period is 7.5±1.15days. The total life cycle is 43.21 days (Suasa-ard and Allsopp, 2000).

The species complexes of moth borers vary in various sugarcane growingareas of the country and damage occurred in many areas of sugarcane plantation. Thesugarcane moth borers Chilo infuscatellus Snellen (Lepidoptera: Pyralidae), Chilosacchariphagus (Bojer) (Lepidoptera: Pyralidae), Chilo tumidicostalis (Hampson)(Lepidoptera: Pyralidea) and Sesamia inferens (Walker) (Lepidoptera: Noctuidae) arethe most important pests of cane in Afghanistan, Korea, India, Indonesia, Pakistan,Philippines, Sri Lanka, Taiwan and Vietnam. This cane-borer complex causeseconomic damage in every cane-growing area in Thailand. Infestations occur year-round but are heaviest on the young cane shoots and in the mature plants. There aremany parasites and predators of sugarcane moth borers in Thailand. Among theparasites, Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) is considered themost effective, playing an important role in the biological control of these cane borersin Thailand (Suasa-ard and Allsopp, 2000).

In Taiwan, Anonymous (1928) and Chen and Hung (1975) reported that therewere seven species of sugarcane moth borers. They stated that biological control was

4

a practical method for these borers, and egg, larval, and pupal parasites wereintroduced into Taiwan for the control of these borers.

Several methods are employed for the control of sugarcane moth borers.Mechanical and cultural methods such as the removal of dead hearts along with theborers and their subsequent destruction, and the hand picking of the moth borers wereused in some regions, but it was not very effective (Charpentier and Mathes, 1969).Agarwal, et al. (1971) and Khanna, et al. (1947) reported that there were somevarieties of sugarcane resistant to sugarcane moth borers in India. Basheer, et al.(1954) and Long, et al. (1959) stated that infested by sugarcane moth borers, andapplication reported at monthly intervals gave good results. However, this methodwas not used intensively for the control of sugarcane moth borers in any other regionsof the world. It was also not practical to spray in the sugarcane field after theinternode formation stage (Long, 1969).

Attempts to control sugarcane moth borers by biological agents wereinvestigated in many countries. Nagarkatti and Nagaraja (1978) made a study onTrichogromma confusum Viggiani and reported that in was the most important eggparasite of sugarcane borers. The fecundity and longevity of Trichogramma differredgreatly when reared on eggs of different moths (Flanders, 1945).

Mohyuddin (1971) reported that the life cycle of A. flavipes was completed in16 days at 30 ºC and 21.4 days at 24.5 ºC. In Japan, Kajita and Drake (1969)observed that the life cycle of A. flavipes was about 15.5 days, the duration period ofegg, larval and pupal stages lasted 3 days, 6.6 days and 5.6 days respectively at 30 ºCand the total life cycle was 18.2 days. In India, Subba Rao, et al. (1969) reported thatthe average number of cocoons per host larva was 44.4 and the average number ofadults emerged per host larva was 31.8. Almost all of adults were female and the sex-ratio between female and male was 5%

In Thailand, Pongsamart (1979) studied the biology of A. flavipes andreported that its life cycle was completed in 21.01±0.80 days. The longevity of adultwas 2-5 days. The adults began to mate immediately after emergence and matinglasted for about one minute.

Varma and Bindra (1973a) stated that superparasitism of larvae of C. partellusby A. flavipes more than twice, some of the parasites failed to emerge from the hostfor pupation, furthermore those that emerged died in the pupal stage or became toosmall adult.

Verma and Bindra (1973c) studied the technique for rearing Apanteles spp.and concluded that host larvae of 10-12 days old was suitable for rearing Apantelesspp. The host was exposed to adult female parasites for 24-26 hours, after the femaleshad been kept with males in groups of three females and one male. Afterparasitization hosts were reared individually until parasites emerged and spun theircocoons. Gifford and Mana (1967), and Varma and Bindra (1973b) stated that matingof A. flavipes began immediately after the adults emerged, often before the parasitestook food or moisture and usually lasted about 30-50 seconds. Both sexes exhibited

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repeated mating habits, males mated as many as 23 times and females 8 times. Theyalso stated that more than 40,000 adult of A\ were reared on the sugarcane borers inthe laboratory and about 28,000 of these were released in commercial fields. A fewfield recoveries occurred four months after release, but none were recovered in 1964.

Cotesia flavipes is an effective parasite for augmentative biological control ofsugarcane moth borers in many countries such as India, Mauritius, Pakistan, Indonesiaand Brazil (Suasa-ard and Charernsom, 1992; Mohyuddin, 1992; Pan and Lim, 1979).

The study of natural enemies of Chilo tumidicostalis (Hampson) (Lepidoptera:Pyralidae), was studied in the laboratory and under field conditions. The studyshowed that Trichogramma chilotraeae Nagaraja and Nogarkatti and Cotesia flavipes(Cameron) were the most important egg and larval parasites of C. tumidicostalis,respectively. Other important natural enemies were Telenomus sp., Xanthopimplasp., an unidentified tachinid, some earwigs and some spiders (Suasa-ard and Allsopp,2000) Tetrastichus spp. and Xanthopimpla spp. were the most important pupalparasite of sugarcane moth borers in Mauritius (Moutia and Courtois, 1952).

Larval parasite, Cotesia flavipes is an important larval parasite of sugarcanemoth borers in Thailand. The egg of Cotesia flavipes is creamy white and becomespale-yellow before hatching. The larva is vermiform, white to pale-yellow in color.The full grown larva comes out from the host larva for pupation by cutting its host’scuticle. The mature larva of Cotesia flavipes begins to spin a cocoon immediately forpupation after coming out from the host larva. The pupa inside the cocoon is creamy-white and becomes light-brown before adult emerges. The cocoon is stoutlyconstructed, white in color and measures 2.23±0.13 mm in length and 0.83±0.07 mmin width. The cocoons of Cotesia flavipes are closely packed with white fluffy hairaround the host larva were 82.63±24.14, ranging from 47 to 133 pupae. The thoraxand abdomen of adult were black in color, while the legs, antennae and mouthparts arelight reddish-brown. The wings are mostly brown. The head is large, black andshining. Sex differentiation can be detected by using antennae and morphologicalcharacteristics of the abdomen. The female antennae are submoniliform, short, not aslong as the body, and the abdomen is stout in shape with a long ovipositor. Theantennae of male are filiform, longer than body, and the abdomen is slender. Theaverage lengths of male and female from head to the tip of abdomen are 1.23±0.11mm and 1.83±0.06 mm. The wing expanses of male and female are 3.14±0.12 mmand 4.03±0.16 mm respectively. The oviposition of adult female occurs on the firstday after emergence. The adult parasite lays egg inside the host larvae, and theincubation period is about 1 to 2 days. The duration of development from egg toprepupa is 12.76±0.79 days. The prepupal stage takes 1.75±0.62 days. The pupalstage took 5.70±0.45 days. The longevity of male and female adults are 3.75±0.88and 2.92±0.75 days respectively. The total life cycle from egg to adult emergence is20.10±1.17 days (Wilkinson, 1928 and Suasa-ard, 1982).

Egg parasite, Trichogramma chilotraeae is important egg parasite ofC. tumidicostalis. The adult T. chilotraeae is pale-yellow with a compound eye red incolor. The male is slightly smaller than the female from the same host. The averagelength from head to the tip of abdomen of the male is 0.42±0.44 mm, ranging from

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0.42 mm to 0.49 mm. The wing expanse of the male is 1.12±0.06 mm, ranging from1.08 mm to 1.25 mm, and that of the female is 1.31±0.05 mm, ranging from 1.23 mmto 1.37 mm. Sex differentiation can be detected by using the types of antennae andmorphological characteristics of the abdomen. The male has a slender shapedabdomen and the antenna is plumose while the female adult had a stout abdomen andlong ovipositor. The preoviposition period is less than 24 hours after adultemergence. The incubation period takes about 1 to 2 days, the larval period is about 4to 6 days and the pupal period emergence is about 9 to 13 days. The longevity ofadult is about 2 to 5 days and sex ratio averages about 1:3:5 male and female (Suasa-ard, 1982)

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MATERIALS AND METHODS

Laboratory study of the sugarcane moth borer, Chilo tumidicostalis (Hampson)was conducted at National Biological Control Research Center (NBCRC), CentralRegional Center (CRC), Kasetsart University, Kamphaeng Saen Campus, NakhonPathom, Thailand. The studies included mass rearing of sugarcane moth borerC. tumidicostalis as stock culture, biological study of C. tumidicostalis and its naturalenemies.

Stock culture of Chilo tumidicostalis (Hampson)

The stock culture of the sugarcane moth borer, C. tumidicostalis were obtainedby collecting larvae of sugarcane moth borer from the sugarcane fields. They werereared in the plastic boxes measuring 23 cm in diameter and 10.5 cm in height withpieces of sugarcane stalk, until pupation. The pupae were kept in a petri-dish withadequate moisture provided with water-soaked filter paper until the adult ofC. tumidicostalis emerged and then transfered them to the insect rearing cagemeasuring 60x60x90 cm in dimension, with young shoots of sugarcane planted in aclay pot.A cotton soaked with honey 5% was provided as food for adult moths. Afteroviposition occured on the leaf of the plant, the pot was taken out from the cage andnew pot of fresh sugarcane substituted. Four days after oviposition, eggs werecollected from the plant for hatching in the plastic boxes measuring 23 cm in diameterand 10.5 cm in height with cut pieces of young shoot of sugarcane. The second instarslarvae were transferred to new plastic box with cut pieces of sugarcane stem as food.It was changed every three day until pupation. Using this method, it was possible tomaintain a stock culture of sugarcane moth borer, C. tumidicostalis for study on thebiological attributes, construction of the life tables and other various experimentalpurposes on a continuous basis. The stock culture of C. tumidicostalis weremaintained at the room temperature of 20-30°C (Figure 1)

Biological studies of Chilo tumidicostalis (Hampson)

The newly laid eggs of C. tumidicostalis was collected from the stock cultureand transferred into circular-shaped plastic boxes measuring 23 cm in diameter and10.5 cm in height. The cover of plastic boxes were cut open with hole which wascovered with a organza screen for ventilation, some cut pieces of young shoot ofsugarcane were provided as food of larvae and adequate moisture provided withwater-soaked filter paper. The observation of the incubation period was done. Thenewly hatched larvae were reared singly in plastic boxes, measuring 11x11x7 cm indimensions with cut piece of young shoot of sugarcane. The cut piece of sugarcanewas changed everyday until pupation. After pupation, pupae were kept singly inplastic boxes, measuring 11x11x7 cm in dimension with young shoot of sugarcanewith adequate moist cotton. Daily observation was made and necessary data recordedthroughout the span of development period. The head-capsules of each stage waspreserved for necessary measurement to determine growth increment. The width of

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Figure 1 Stock culture of Chilo tumidicostalis (Hampson) reared in the insect rearing cage in the insectary

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the capsule of each larval instars was measured by an ocular micrometer to determinethe growth increment.

A pair of emerged adult was transferred into the oviposition cage, measuring60x60x90 cm in dimensions with young shoot of sugarcane planted in clay pot. Acotton soaked with honey was provided as food for adult moths. The number of eggslaid by the female adults on the leaves of sugarcane were counted everyday. Thenumber of eggs per batch and the oviposition site were noted, and they were kept forfurther observation on incubation period, and other biological studies.

Life Table Study of Chilo tumidicostalis (Hampson)

Biological life table study

Biological life table study of C. tumidicostalis were carried out by using 357newly laid egg of C. tumidicostalis respectively from the stock culture. The sugarcaneleaves with these eggs were kept in the test tubes measuring with 2.2 cm diameter and15 cm long with a moist filter paper. The newly hatched larvae was transferred to tenplastic boxes, measuring 11×11×7 cm in dimensions with some cut pieces ofsugarcane stalk as food of larvae. New cuts pieces of sugarcane stalk were changedevery three days or whenever necessary. Daily observation was made and data onnumber of individual larval and pupal survived recorded every three days until adultemerged. The adults were reared in oviposition cages measuring 60x60x90 cm indimensions. In each cage cotton soaked with 5% honey syrup and a young shoot ofsugarcane planted in clay pot were provided for adult survival and oviposition. Theyoung shoots of sugarcane were changed daily. Data on the number of adultssurvived and eggs laid were recorded daily until emerged adults died. These recordeddata were used for the construction of the biology life table using techniques given byAllee et al. (1949), Andrewartha and Birch (1954), Morris and Miller (1954),Laughlin (1965), Southwood (1968), Harcourt (1969), Napompeth (1973),Andrewartha (1970) and Varley and Gradwell (1970).

The net reproductive rate of increase (Ro) is calculated from equation:

Ro = Σ lx mx

where, 0 to α = life spanlx = proportion at birth of females being alive at age Xmx = number of female births during age Xlxmx = egg curve

The cohort generation time (Tc) is calculated from the equation:

Tc = Σ lx mx .X / Σ lx mx

α

x = 0

x = 0

α α

x = 0

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The capacity for increase (rc) of Laughlin (1965) is as approximation of theinnate capacity for increase (rm) the calculation of which was complicated. The rccould be calculated from the equation:

rc = loge Ro Tc

The finite rate of increase (λ) is calculated from the equation:λ = antiloge rc

The population doubling time (DT) is calculated from the equation:

DT = loge 2 rc

The egg curve was obtained by plotting lxmx against X. This curve representedthe egg schedule of births and deaths in terms of the age-schedule fecundity andprobability at birth of females being alive at each age group and the egg productivitywithin each age group through the life history.

Partial ecological life table study

The partial ecological life table study of C. tumidicostalis were carried out byusing newly laid eggs on leaves and leaf sheaths of sugarcane from stock culture.The leaves or leaf sheaths of sugarcane with eggs were kept in plastic boxes,measuring 23 cm in diameter and 10.5 cm in height with adequate moisture providedwith water-soaked filter paper. The newly hatched larvae were transferred to andother plastic boxes, measuring 23 cm diameter and 10.5 cm in height. Each plasticboxes contained twenty larvae provided with fresh cut pieces of young shoot ofsugarcane until they pupated. The pupae were kept under normal condition withsoaked filter paper in a petri-dish, with was kept in the oviposition cage, measuring60x60x90 cm in dimensions. Daily observation was made and the number ofindividuals survived in each development stage was recorded for construct the partialecological life table using techniques given by Napompeth (1973).

Survey of the Natural Enemies of Chilo tumidicostalis (Hampson)

Field survey and evaluation of parasites of C. tumidicostalis was done bycollecting and examining all stages of these sugarcane borers covering area andlocations where sugarcane was cultivated in Suphan Buri. The eggs, larvae and pupaeof these sugarcane borers were brought to the laboratory. Eggs were kept in the testtubes measuring with 2.2 cm diameter and 15 cm long; larvae and pupae were kept inplastic boxes, measuring 23 cm in diameter and 10.5 cm in height with some cutpieces of sugarcane stalk. Daily observation was done until the emergence of theparasites. The adult parasites were hold for proper identification. The more importantparasites species were reared, if possible and used for establishing stock cultures forfurther biological study and evaluation of their effectiveness.

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Biological Studies of The Important Parasite of Chilo tumidicostalis (Hampson)

Egg Parasites

Adult of egg parasites obtained from the survey were kept in the test tubes, 2.2cm diameter and 15 cm long, with small drops of honey on wax paper as food for theparasites and the tube plugged with cotton wool. The newly laid eggs of sugarcaneborer obtained from stock culture were exposed in the test tubes for parasitization.The eggs were changed after they had been parasitized and kept in the test tubesplugged with cotton wool. These test tubes with parasites were kept in the roomtemperature at 20-30 °C until the adult parasites emerged. By this method, it waspossible to maintain a stock culture of egg parasites for bionomic study and otherexperimental purposes.

Larval Parasites

Adults of larval parasites collected from field survey were kept in plastic boxes(11 cm high and 13 cm diameter) with few drops of honey in wax paper as food foradults. The cover of plastic boxes were cut open with hole which was covered withorganza screen for ventilation (A hole measuring 2 cm in diameter was made on thelateral side and plugged with a cork stopper for transferring the host and parasite intoit). The third to fourth instar larvae of sugarcane borers with small pieces ofsugarcane stalk were exposed to adult parasites in the plastic boxed. Afterparasitization had taken place the larvae were changed and reared in new plastic boxes(10.5 cm high and 23 diameter) until the parasites had spun their cocoons. Thecocoons were kept in new plastic boxes for emergence of the adults. The number ofparasites per host and biological data were recorded.

Pupal Parasites

Adults of pupal parasite collected from the field were reared in parasite-rearingplastic boxes, with few drops of honey on wax paper as food. The newly pupatedpupae of sugarcane moth borers were then exposed to the parasites in the plasticrearing boxes for parasitization. The pupae were changed everyday afterparasitization. The parasitized were kept in new plastic boxes for the emergence ofadult parasites. Daily observation was done and biological data of the parasites wererecorded.

Population Study Chilo tumidicostalis (Hampson)

The population study of sugarcane moth borer C. tumidicostalis was carriedout at Doembang Nangbuat, Suphan Buri province. The sugarcane on this plantationwas planted in rows with 25x100 cm spacing, and K 84-200 was used. The area usedfor the study was about 4.5 hectares at Doembang Nangbuat.

The sampling program was set by using one stool as a sample unit and 60samples were taken from the area 4.5 hectares in location. At location a border rowof 5 meters were makes off on all sides and samples were taken from every other 10

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rows within each plot. The number of tillers and infested tillers per stool; the numberof eggs, larvae, pupae and adults of C. tumidicostalis; and number of it naturalenemies were recorded from the emergence of sugarcane and followed through for 1year.

The data thus collected was utilized for the analysis of various populationparameters and assessment of the parasites of sugarcane moth borers as potentialbiological control agents. The method of analyzing the data in these field experimentswere done by using the techniques given by Napompeth (1973) and Southwood(1968). The population study was carried out from February 2001 to January 2002.

The climatological data at Kamphaeng Saen, Nakhon Pathom during theperiod of investigation was shown in Figure 2.

Assessment Potential of Natural Enemies of Cotesia flavipes

The adult of C. flavipes were used for field release, in a sugarcane plantationarea where sugarcane moth borer was considered as serious pest. Assessment of therelease in the form of augmentative biological control was carried out beginning inFebruary in 2001 to January 2002 at Suphan Buri.

At each location 2 plots (4.5 hectares) were established as release and controlplot. The latter was located some 10 km, away from the release plot. About 500adults C. flavipes were released at Doembang Nangbuat, Suphan Buri, and monthlyintervals.

Assessment was done by population counts to determine larvae density ofsugarcane moth borer carried out monthly. Data were used to assess the potential ofC. flavipes as a biological control agent for the sugarcane moth borerC. tumidicoslalis in field.

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0

100

200

300

400

FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEM JAN

RAIN

FALL

(mm)

0

50

100

150

200

FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN

RELA

TIVE

HUMI

DITY

(%)

MINMAX

0

20

40

60

80


TEMP

ERAT

URE (

C)

MINMAX

Figure 2 Monthly average of Rainfall (mm), relative humidity (%) andTemperature (ºC) at Kamphaeng Saen, Nakhon Pathom

during February 2001 to January 2002

20022001

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RESULTS

Biological Study of Chilo tumidicostalis (Hampson)

Description of Stages of Development of Chilo tumidicostalis (Hampson)

Egg

C. tumidicostalis is usually laid eggs in batches on both sides of leaf blades in2 to 3 rows linearly along the leaves of sugarcane at night. The average number ofeggs per batch is 123.31±70.89 and ranging from 5 to 250 eggs per batch. Theindividual egg was oval-shaped, flat and overlapped each other (Figure3). The newlylaid eggs were white, and turned yellowish-white and dark before hatching. The sizeof individual egg was 0.91±0.11 mm in width and 1.59±0.07 mm in length.

Larva

The newly hatched larvae were creamy white with a big dark spots on the bodyand dark brown head. The dark spots on the body of larvae tunneled darker in thelater instars and each segment has four such spots on the dorsal side (Figure4). Thelarva of C. tumidicostalis prefered to feed on the stalk than the shoot of sugarcane andusually live gregariousness in the same stock. Sometimes found more than 100 larvaein one stalk. Number of instars were depended on food and environment.

The larva of C. tumidicostalis molted five to seven times before pupation. Theaverage size of the body of the first larval instar measured 0.23±0.05 mm in width and1.53±0.12 mm in length. The second larval instar measured 0.51±0.1 mm in widthand 3.08±0.46 mm in length. The third larval instar measured 1.00±0.05 mm in widthand 6.26±0.81 in length. The fourth larval instar measured 1.23±0.05 mm in widthand 8.71±0.10 mm in length. The fifth larval instar measured 2.29±0.10 mm in widthand 13.53±0.91 mm in length. The sixth larval instar measured 2.53±0.05 mm inwidth and 18.24±0.26 mm in length and the seventh larval instar measured 3.30±0.22in width and 23.06±1.05 mm in length. The mean width of head capsule of the first tothe fifth instars were 0.35±0.01, 0.38±0.01, 0.89±0.07,1.39±0.21 and 1.64±0.11 mmfor the larvae with five-instars development respectively, and the mean widths of headcapsule were 0.35±0.01, 0.38 ±0.01, 0.88±0.07, 1.32±0.05, 1.63±0.10 and 1.99±0.04mm for the larvae with six-instars development, respectively and the mean width ofhead capsule for the first to the seventh instars larva were 0.34±0.02, 0.38±0.01, 0.88±0.10, 1.31±0.05, 1.63±0.1, 1.98±0.05 and 2.07±0.05 mm, respectively for the larvaewith seven-instars development. Larva in each subsequent instars assumed thegrowth, as expressed by the increasing width of head capsule, a geometric progressionwith and average ratio of 1.5476, 1.4739 and 1.4042 for the five- , six- and seven-instars larval development respectively (Table 1, 2 and 3), and conformed to theDyar’s Law [pooled x2 = 0.1661, df = 2, P = 0.01, pooled x2 = 0.1708, df = 2, P =0.01 and pooled x2 = 0.4408, df = 2, P = 0.01).

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Figure 3 Eggs mass of Chilo tumidicostalis (Hampson)

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Figure 4 Larvae of Chilo tumidicostalis (Hampson.)

17

Table 1 Width of head capsule of Chilo tumidicostalis (Hampson) in successive five instars (n = 30)

Larval Width of head capsule (mm) Head capsule CalculatedMean±S.D. rangeinstar growth ratio width of head

capsule (mm)

2x

Instar I 0.3527±0.0123 0.34-0.36 0.3527 01.0814

Instar II 0.381±0.0078 0.36-0.38 0.5458 0.04902.3424

Instar III 0.8934±0.0659 0.79-1.02 0.8445 0.00281.5522

Instar IV 1.3867±0.2145 1.25-1.40 1.3069 0.00491.2144

Instar V 1.6384±0.1125 1.28-1.77 2.1187 0.1089

Mean geometric progression ratio = 1.5476 Pooled 2x = 0.1661

18

Table 2 Width of head capsule of Chilo tumidicostalis (Hampson) in successive six instars (n = 36)

Width of head capsule (mm) Head capsule CalculatedLarvalinstar Mean±S.D. rage growth ratio width of head

capsule (mm)

2x

Instar I 0.3483±0.0111 0.34-0.36 0.3483 01.0902

Instar II 0.3797±0.0097 0.36-0.38 0.5134 0.03492.3297

Instar III 0.8846±0.0696 0.79-1.02 0.7567 0.02171.4868

Instar IV 1.3152±0.0490 1.25-1.40 1.1153 0.03591.2425

Instar V 1.6341±0.0988 1.40-1.77 1.6438 0.00011.2188

Instar VI 1.9917±0.0368 1.90-2.10 2.4278 0.0783

Mean geometric progression ratio = 1.4739 Pooled2x = 0.1708

19

Table 3 Width of head capsule of Chilo tumidicostalis (Hampson) in successive seven instars (n = 40)

Larval Width of head capsule (mm) Head capsule Calculated

instar Mean±S.D. rage growth ratio width of headcapsule (mm)

2x

Instar I 0.3430±0.0160 0.34-0.36 0.3430 01.0971

Instar II 0.3763±0.0119 0.36-0.38 0.4816 0.02302.3455

Instar III 0.8826±0.0958 0.69-1.02 0.6763 0.06251.4814

Instar IV 1.3075±0.0488 1.25-1.40 0.9497 0.13481.2514

Instar V 1.6262±0.1048 1.28-1.77 1.3336 0.06421.2191

Instar VI 1.9825±0.0501 1.90-2.10 1.8726 0.00651.0429

Instar VII 2.0675±0.0474 2.00-2.10 2.6295 0.1498

Mean geometric progression ratio = 1.4042 Pooled2x = 0.4408

20

The straight line relationship was obtained during the growth increment as shown inFigure 5, 6 and 7 using the width of head capsule and successive larval instars.

The pupa

Larva of C. tumidicostalis pupated in the tunnel made by the larva in thesugarcane stem, sometimes pupation took place in the leaf sheath. Before pupationthe body of larva become shortened during 1 to 2 days of prepupal stage.

The newly-formed pupa were pale-yellow. After 1-2 days thay becomered-brown. Male pupa measured 13.39±0.77 mm in length 3.30±0.21 mm in widthand female pupa measured 17.17±1.87 mm in length 4.24±0.24 mm in width. Themale pupa period was 4.37±0.71 days, and the female pupa 6.07±0.91 days. Sexdifferentiation could be detected in the pupal stage using morphological differentiationat the tip of abdomen especially the space between the genital pores, as shown inFigure 8. The pore of the female pupa was wider than that of the male. The size offemale pupa was slightly larger than of the male pupa (Figure 9).

The adult

Adults of C.tumidicostalis were nocturnal in habit. They were active andmating normally occurred on the leaf of sugarcane at dusk. The female adults laideggs in batch on both sides of leaf blades at night. The general color of forewings wasbrown to pale brown with some darker marking. Hindwings were white in female anddirty white to light brown in male. The body size, measuring from head to the tip ofthe last abdominal segment, averaged 11.49±0.30 mm and 12.70±0.27 mm in maleand female respectively. The wing expanse was 24.58±0.59 mm and 28.84±0.50 mmin male and female respectively (Figure 10). The body measurement of various stagewas shown in Table 4.

Duration of developmental stages of Chilo tumidicostalis

The oviposition period of C. tumidicostalis was 1.91±0.69 days, ranging from1 to 3 days. The number of egg laid per female averaged 123.31±70.89 eggs, rangingfrom 5 to 250 eggs. The incubation period was 5.28±0.85 days, ranging from 4 to 7days.

The number of larval instar of C. tumidicostalis could range from five toseven instars. The duration of each successive instar with five molting were 3.43±0.5,3.87±0.89, 4.67±1.15, 6.87±1.47 and 6.4±1.45 days respectively. The total larvalperiod was 24.67±4.07 days, ranging from 19 to 29 days. The duration of prepupalstage was 1.77 ±0.43 days, ranging from 1 to 2 days. The average pupal period was47.23±1.52 days, ranging from 5 to 9 days. The longevity of male and female were3.97 ±0.76 days, ranging from 3 to 5 days and 3.9± 0.84 days, ranging from 3 to 5days respectively. The total life cycle of C.tumidicostalis with five larval instars was45.87±3.58 days, ranging from 37 to 49 days.

21

0

0.5

1

1.5

2

2.5

I II III IV V

LARVAL INSTARS

WIDT

H OF H

EAD C

APSU

LES (

mm)

Figure 5 The relationship between the width of head capsule and the larval instars of Chilo tumidicostalis (Hampson) (5 instars)

22

0

0.5

1

1.5

2

2.5

3

I II III IV V VI

LARVAL INSTARS

WID

TH O

F HEA

D CA

PSUL

E (

Figure 6 The relationship between the width of head capsule and the larval instars of Chilo tumidicostalis (Hampson) (6 instars)

23

0

0.5

1

1.5

2

2.5

3

I II III IV V VI VII

LARVAL INSTARS

WIDT

H OF H

EAD C

APSU

LES (

mm)

Figure 7 The relationship between the width of head capsule and the larval instars (7 instars)

24

Figure 8 Abdominal shape of pupae of Chilo tumidicostalis (Hampson): female (A) and male (B)

A

B

25

Figure 9 Pupae of Chilo tumidicostalis (Hampson): male (A) and female (B).

A B

26

Figure 10 Adults of Chilo tumidicostalis (Hampson): female (A1, A2) and male (B1, B2)

A1 A2

B1 B2

27

Table 4 Body measurements of various stages of Chilo tumidicostalis (Hampson)

Stage of Width (mm) Length (mm)

development Mean±S.D. range Mean±S.D. range

Egg: 0.91±0.11 0.7-1.1 1.60±0.07 1.5-1.7

Larva: Inatar I 0.23±0.05 0.2-0.3 1.53±0.12 1.0-1.7

Instar II 0.51±0.10 0.4-0.7 3.08±0.46 2.4-3.9

Instar III 1.00±0.05 1.1-0.9 6.26±0.82 4.5-7.8

Instar IV 1.23±0.05 1.2-1.3 8.71±0.10 8.5-8.8

Instar V 2.29±0.10 2.1-2.5 13.53±0.91 12.9-14.6

Instar VI 2.53±0.05 2.5-2.6 18.24±0.26 17.7-18.7

Instar VII 3.30±0.22 3.0-3.8 23.06±1.05 21.0-25.0

Pupa: Male 3.30±0.21 2.9-3.5 13.97±0.77 12.1-14.8

Female 4.24±0.24 3.7-4.5 17.17±1.87 14.5-19.4

Adult: Male 24.58±0.59 23.4-25.0 11.49±0.30 11.0-11.8

Female 28.84±0.50 27.5-29.5 13.05±1.78 12.2-13.0

28

The duration of each successive larval instars with six molting were 3.83 ±0.71, 5.03±0.89, 4.90±0.96, 7.13±1.57, 7.33±1.47 and 7.93±2.02 days respectively.The duration from the first to sixth instars averaged 33.43±4.46 days, ranging from 28to 42 days. The prepupal stage took about 1.70±0.47 days, ranging from 1 to 2 days.The duration of pupal stage was 7.03±1.19 days, ranging from 6 to 9 days. Thelongevity of male and female adults were 3.90±0.88 days, ranging from 2 to 5 daysand 4.03±0.76 days, ranging from 3 to 5 days respectively. The total life cycle ofC. tumidicostalis with six larval instars was 54.47±4.55 days, ranging from 49 to 64days.

The duration of each successive larval instars with seven molting were 3.90±0.31, 5.07±0.64, 5.03±0.81, 7.23±1.36, 7.57±1.63, 8.40±1.04 and 7.77±1.72 daysrespectively. The duration from the first to seventh instars averaged 37.30±2.76 days,ranging from 36 to 42 days. The prepupal stage took about 1.8±0.41 days, rangingfrom 1 to 2 days. The duration of pupal stage was 7.27±1.34 days, ranging from 5 to9 days. The longevity of male and female adults were 3.67±0.84 days, ranging from 2to 4 days and 3.50±0.90 days, ranging from 2 to 5 days respectively. The total lifecycle of C. tumidicostalis with seven larval instars was 58.13±3.00 days, ranging from54 to 63 days. The data on the duration of development stage of C. tumidicostalis withfive-, six- and seven-instars larvae were presented in Table 5, 6 and 7.

29

Table 5 Duration of various developmental stages of Chilo tumidicostalis (Hampson)

with five instars larvae under laboratory condition

(28 ± 20C and 75 ± 2 % RH)

Stage of development N Mean±S.D.

(days)

Range

(days)

Egg: 267 4.33±0.48 4-5

Larva: Instar I 35 3.43±0.50 3-4

Instar II 35 3.87±0.89 3-5

Instar III 35 4.67±1.15 3-6

Instar IV 35 6.87±1.47 4-9

Instar V 35 6.40±1.45 3-8

Total: first to last instar 35 24.67±4.07 19-29

Prepupa: 35 1.77±0.43 1-2

Pupa: 35 7.23±1.52 5-9

Adult: Male 18 3.97±0.76 3-5

Female 15 3.90±0.84 3-5

30


with six instars larvae under laboratory condition

(28 ± 20C and 75 ± 2 % RH)


(days)

Range

(days)

Egg: 267 4.37±0.49 4-5

Larva: Instar I 30 3.83±0.71 3-5

Instar II 30 5.03±0.89 3-6

Instar III 30 4.90±0.96 3-6

Instar IV 30 7.13±1.57 4-9

Instar V 30 7.33±1.47 5-9

Instar VI 30 7.93±2.02 4-12


29 1.70±0.47 1-2Prepupa:

Pupa: 29 7.03±1.19 6-9

Adult: Male 15 3.90±0.88 2-5

Female 15 4.03±0.76 3-5

31


with seven instars larvae under laboratory condition

( 28 ± 2 0C and 75 ± 2 % RH)


(days)

Range

(days)

Egg: 267 4.60±0.49 4-5

Larva: Instar I 26 3.90±0.31 3-4

Instar II 26 5.07±0.64 4-6

Instar III 26 5.03±0.81 4-6

Instar IV 26 7.23±1.36 4-9

Instar V 26 7.57±1.63 4-9

Instar VI 26 8.40±1.04 5-11

Instar VII 26 7.77±1.72 5-10


Prepupa: 26 1.80±0.41 1-2

Pupa: 23 7.27±1.34 5-9

Adult: Male 12 3.67±0.84 2-4

Female 10 3.50±0.90 2-5

32

Life tables of Chilo tumidicostalis (Hampson)

Both biological and partial ecological life tables of C. tumidicostalis wasinvestigated.

Biological life table

By proper planning and regular observation on the life history of sugarcanemoth borers, it was possible to obtain data for construction of a biological life table.From the construction of biological life table of sugarcane moth borers, the biologicalattributes obtained from the investigation were the net reproductive rate of increase(Ro), the capacity for increase (rc ), the finite rate of increase (λ) and the cohortgeneration time (Tc). The net reproductive rate of increase (Ro) was the multiplicationper generation. It was expressed as the ratio of total female births in two successivegenerations. The capacity for increase (rc) was an approximated value of the innatecapacity for increase (rm), it was an instantaneous growth coefficient when thepopulation was increasing in an unlimited environment. The finite rate of increase (λ)was the multiplication per female in unit of time and could be calculated from theapproximated valve of the innate capacity for increase. The cohort generation time(Tc) was the mean time from birth of parents to birth of offspring biological life tabledealing primarily with the female portion of the population and male were notincluded.

The biological life table of C. tumidicostulis was illustrated in Table 8. Thebiological attributes calculated from the table were the net reproductive rate ofincrease (Ro) = 28.5128. The capacity for increase (rc ) = 0.0779, the finite rate ofincrease (λ) = 1.0821 and the cohort generation time (Tc) = 8.8897 days. It meanedthat a population of C. tumidicostalis could multiply = 28.5128 times in eachgeneration or it could multiply 1.0821 times in every three days. The biologicalattributes of C. tumidicostalis obtained from biological life table study was shown inTable 9.

The eggs curve, designated by Laughlin (1965), was obtained by plotting lxmxagainst X. This curve represented the egg schedule of births and deaths in terms ofthe age-schedule fecundity and probability at birth of females being alive at each agegroup and the egg productivity within each age group through the life history.

The egg curve of C. tumidicostalis as calculated from the biological life tablewas shown in Figure 11. It was obvious that the maximum productivity occurredduring the first four days of an oviposition period. The productivity rapidly declinedthere after.

33

Table 8 Biological life table, age-specific fecundity rate and net reproductive rate

(Ro) of Chilo tumidicostalis (Hampson) under laboratory condition

(28 ± 2 0C and 75 ± 2 % RH)

Pivotal agein days

(X)

Proportion at birth1/

of female beingalive at age X

(lxmx)

Age-specific2/

Fecundity(♀egg/♀ /X)

(mx)

Egg curve3/

(lxmx)lxmx.X

0 1.0000 - -3 1.0000 - -6 0.9076 - -9 0.7339 - -12 0.6947 - -15 0.5966 - -18 0.5490 - -21 0.4802 - -24 0.4286 - -27 0.3838 - -30 0.3613 - -33 0.3389 - -36 0.3249 Preoviposition period39 0.2941 5.6729 1.6703 65.141742 0.2717 67.3608 18.3019 768.679045 0.1905 32.5526 6.2013 279.058548 0.1765 13.2539 2.3393 112.2865

51 0.0812 - - -

R0 = 28.5128

1/ lx = The probability of individual being alive at the beginning of the age-interval.2/mx = The number of female eggs of offsprings for each age-interval.3/lxmx = After Laughlin (1965)

Immature stages

34

Table 9 Parameters calculated for biological attributes of Chilo tumidicostalis (Hampson) under laboratory condition (28±2 ºC and 75±2 %RH)

Biological attribute Notation Calculated value

Net reproductive rate of increase R0 28.5128

Capacity for increase rc 0.0779

Finite rate of increase λ 1.0821

Cohort generation time Tc 8.8897

35

0

5

10

15

20

33 36 39 42 45 48 51

X (DAYS)

l xmx

Figure 11 Eggs curve of Chilo tumidicostalis (Hampson) under laboratory condition (28±2ºC and 75±2%RH)

36

Partial ecological life table

It was not feasible to construct complete ecological life tables ofC. tumidicostalis, therefore, a partial ecological life table was constructed usinglaboratory life history data. It was an indicator of the innate mortality and not to othermortality factors. The mortality could differ if compared with the investigation in thefield and it was anticipated that the mortality should be much higher because under thefield condition they were limited by various biological factures such as parasites,predators, insect pathogens and other physical factors. The survivorship curves ofC. tumidicostalis was constructed by using the number of individuals survived in eachdevelopmental stages (lx) against stages of development (X)

The partial ecological life table of C. tumidicostalis was illustrated in Table 10.It was obvious that high mortality during first larval instars and also the second larvalinstars. The survivorship curve, as shown in Figure 12, indicated that the mortalitywas high during the first and second larval instars. This mortality was not high duringthe subsequent stages of development. This was probably due to certain physiologicalfactors. Mortality obtained under laboratory was apparently less than mortalityobserved under field condition. Under field condition high mortality occurred in lastlarval instars (instars 5, 6, 7) and caused mainly by the natural enemies, particularlydue to the parasitization of larval parasites, C. flavipes.

37

Table 10 Partial ecological life table of Chilo tumidicostalis (Hampson) under laboratory condition (28 ± 2 o C and 75 ± 2% RH)

Stage of development(X)

No. survivingin X(lx)

No. dyingin X(dx)

Percentmortality(100 qx)

Generationmortality(100dx/n)

Egg: 487 12 2.4640 2.4640Larva: Instar I 475 119 25.0526 24.4353 Instar II 356 129 36.2359 26.4887 Instar III 227 34 14.9779 6.9815 Instar IV 193 29 15.0259 5.9548 Instar V, VI, VII 164 24 14.6341 4.9281Prepupa: 140 18 12.8571 3.6960Pupa: 122 9 7.3770 1.8480Adult: 113 - - - Male 44 - - - Female 69 - - -

38

0

100

200

300

400

500

600

E I II III IV V,VI,VII PP P AX

l x

Figure 12 Survivorship curve of Chilo tumidicostalis (Hampson), under laboratory condition (28 ± 2 o C and 75 ± 2% RH)

39

Survey Natural Enemies of Chilo tumidicostalis (Hampson)

Field survey and evaluation of natural enemies of sugarcane moth borer,C. tumidicostalis were carried out at Doembang Nangbuat, Suphan Buri. The surveyand evaluation of parasites and predators were conducted every two weeks fromFebruary 2001 to January 2002.

In the field survey of the natural enemies of sugarcane moth borers,C. tumidicostalis, four species of hymenopterous parasites, few species of earwings,which feed on egg of sugarcane borers, and some species of spiders were found.Among the hymenopterous parasite, Cotesia flavipes (Cameron) (Hymenoptera:Broconidae) was important larval parasite; Tetrastichus sp (Hymenoptera:Eulophidae) was important pupal parasite; Telenomus sp. (Hymenoptera: Scelionidae)and Trichogramma chilotraeae Nagaraja & Nagarkatti (Hymenoptera:Trichogrammatidae) were important egg parasites. C. flavipes seem to play the mostimportant role in the natural control of C. tumidicostalis in area was conducted.

Biological studies of important parasite of Chilo tumidicostalis (Hampson)

Biological studies of Cotesia flavipes

Description of Stages of Development of Costesia flavipes (Cameron)(Hymenoptera: Braconidae)

Egg

The adult of C. flavipes laid eggs in the larva of C. tumidicostalis. Theindividual egg was hymenopteriform, rounded at the cephalic end, enlarged mediallyand tapered at the posterior end. There was a small button-like peduncle at theposterior end. The average size of egg was 0.123±0.009 mm, ranging from 0.113 to0.150 mm in length and 0.034±0.001 mm, ranging from 0.032 to 0.041 mm inmaximum width. The egg of C. flavipes was creamy white and became pale-yellowbefore hatching. Dissection of gravid adult female revealed that the number of uterineeggs per female was 81.5±16.68 eggs, ranging from 38 to125 eggs.

Larva

The larva of C. flavipes was vermiform, white to pale-yellow in color (Figure13). They fed in the host body until the last stage of development. The full grownlarvae emerged from their hosts before pupation. They were pupated outside the bodyof the host. The mature larvae were creamy-white and grub-like shaped and theaverage size of these larvae was 2.97±0.34 mm, ranging from 2.53 to 3.8o mm inlength and 0.82±0.05 mm, ranging from 0.56 to 0.84 mm in maximum width. Thelarva body was slightly slender at the anterior and posterior end, and the segmentationwas distinct. The full grown larvae came out from the host larva for pupation bycutting their host’s cuticle, as shown on Figure 14.

40

Figure 13 The larvae of Cotesia flavipes (Cameron)

41

Figure 14 The full grown larvae of Cotesia flavipes (Cameron) emerged

from larva of Chilo tumidicostalis

42

Pupa

The mature larva of C. flavipes began to spin cocoon immediately for pupationafter coming out from the host larva and took about 6 to 12 hours to complete thecocoon. The pupa inside the cocoon was creamy-white (Figure 15) and become light-brown before adult emerged. Sex differentiation could be detected in pupa stage byusing the length of the antennae. The average size of female pupa was 1.52±0.02 mm,ranging from 1.20 to 1.34 mm in length and 0.64±0.07 mm, ranging from 0.54±0.48mm in width. The average size of male pupa was 1.32 ± 0.32 mm, Ranging from 1.10to 1.30 mm in length, and 0.58±0.09 mm, ranging from 0.40 to 0.70 mm in width.The number of pupa obtained per parasitized larva were 82.63±24.14, ranging from 47to 133 pupae.

Cocoon

The cocoon was stoutly constructed, white in color and measured 2.03±0.17mm, ranging from 1.97 to 2.50 mm in length and 0.58±0.04 mm, ranging from 0.49 to0.96 mm in maximum width. The cocoons of C. flavipes were closely packed withwhite fluffy hair around the host larva (Figure 16).

Adult

The thorax and abdomen of C. flavipes were black in color, white the legs, atantennae and mouthparts were light reddish-brown. The wings were mostly brown.The head was large, black and shining. Sex differentiation could be detected by usingantennae and morphological characteristics of the abdomen. The female antennasubmoniliform, short, not as long as body and the abdomen was stout in shape with along ovipositor. The antenna of male filiform, longer than body and the abdomenwas slender, the average length of male and female from head to the tip of abdomenwere 1.32±0.12 mm, (ranging from 1.09 to 1.46 mm) and1.9±0.14 mm, (ranging from1.58 to 1.97 mm), respectively. The wing expansion of male and female were 3.02±0.15 mm, (ranging from 2.89 to 3.2 mm) and 3.96±0.18 mm, (ranging from 3.78±4.27mm), respectively (Figure17 and 18).

43

Figure 15 Pupa of Cotesia flavipes (Cameron)

44

Figure 16 The mass of cocoons of Cotesia flavipes (Comeron) around the

parasitized larva of Chilo tumidicostalis (Hampson)

45

Figure 17 Female adult of Cotesia flavipes (Cameron)

46

Figure 18 Male adult of Cotesia flavipes (Cameron)

47

Duration of developmental periods

The adult parasite laid egg inside the host larva, and the incubation period isabout 1 to 2 days. The duration of development from egg to larva was 13.5±0.21days. The prepupal stage took 1.75±0.62 days. The pupal stage took 5.70±0.45 days.The longevity of male and female adult were 3.75±0.88 and 2.92±0.75 daysrespectively. The total life cycle from egg to adult emergence was 20.14±1.17 daysunder laboratory condition (28±2 oC and 75±2% RH), as shown in Table 11.

Behavior of adult

The adult of C. flavipes started to feed immediately after emergence. Thecopulation occurred in a few minutes after emergence and lasted for about 1 to 2minutes. Both sex exhibited polygamous mating habits. The adults of C. flavipesshowed positive phototaxis, and their activity increased in bright light. The adultfemale attacked its host by using its legs to grasp the host larva and folded itsabdomen downward and simutaneously inserted the ovipositor into the host larva.The oviposition was completed in about 15 to 32 seconds. Occasionally the adultparasite would die in attempt for oviposition. The female adult could oviposit manytimes. Parasitized larva continued their normal activity until 1 to 2 days beforeparasite larvae came out. They stopped to feed and became inactive, the body turnedto pale-yellow in color by they remained alive for 1 to 2 days after all of perasitelarvae came out.

The investigation revealed that female adult of C. flavipes could be parasitizedlarvae of sugarcane borers in each stage of development especially in the third tofourth instars of C. tumidicostalis (Figure 19).

48

Table 11 Duration period of various developmental stages of Cotesia flavipes

(Cameron) under laboratory condition (28±2ºC and 75±2%RH).


(days)

Range

(days)

Egg:

30 13.50±0.21 11-14

Larval:

Prepupa: 24 1.75±0.62 1-2

Pupa: 24 5.70±0.45 5-6

Adult: Male 10 3.75±0.88 2-5

Female 14 2.92±0.75 2-4

Total: Life cycle 20.14±1.17 17-22

49

Figure 19 The female adult of Cotesia flavipes (Cameron) parasitized on

larva of Chilo tumidicostalis (Hampson)

50

Description of Stages of Development of Tetrastichus sp. (Hymenoptera :Eulophidae)

Egg

The adult female of Tetrastichus sp. laid eggs in the pupae of C.tumidicostalis. The average number of eggs were 87.52±65.09 and ranging from 22-340 eggs.

Larva

The body of larva was white or pale yellow (Figure 20). They fed in the hostpupa until the pupation. The larva body was slightly slender at the anterior andposterior end and the segmentation was distinct. The last stage before pupation waspale brown and the average size was 0.17±0.22 mm, ranging from 0.69-1.84 mm inlength and 0.05±0.07 mm, ranging from 0.27-0.51 mm.

Pupa

The mature larva of Tetrastichus sp. was a short and rather stout shape andpupation in the host pupa (Figure 21). The pupae were white became pale yellow andbecame black before adult (Figure 22). Sex differentiation could be detected in thepupal stage using morphological differentiation at the antenna. The average size offemale was 0.038±0.052 mm while that of the male was 0.03±0.04 mm.

Adult

The head and thorax of the adult of Tetrastichus sp. was shining black, theabdomen and leg were red-brown to black, and the wings were clear. The femaleadult was stout in shape especially the abdomen, while the male was slender (Figure23, 24). Sex differentiation could be detected in the adult stage using morphologicaldifferentiation at the antenna was geniculate, the antenna of female was dark-brown.The antenna of male was longest than female and pedicel was biggest than femaleand club was dark brown (Figure 25). The size of male was smaller than female. Thelength from the head to abdomen of male and female adults were 1.62±1.89 mm,ranging from 1.20-1.78 and 1.70±0.14 mm, ranging from 1.40-1.80 mm respectively.The wings expansion were 2.51±0.02 mm, ranging from 2.00-2.75 mm and 2.81±0.25 mm, ranging from 2.10-3.55 mm in male and female respectively.

51

Figure 20 Larvae of Tetrastichus sp.

52

Figure 21 Pupae of Tetrastichus sp. in pupa of Chilo tumidicostalis

53

Figure 22 The pupae of Tetrastichus sp. were white became pale-yellow and became black before adult

54

Figure 23 Female adult of Tetrastichus sp.

55

Figure 24 Male adult of Tetrastichus sp.

56

Figure 25 The antennae of Tetrastichus sp.:

male (A) and female (B)

B

A

57

Duration of developmental periods

The color of parasitized pupae was darker and become black. The longevity ofincubation period was 1-2 days. The longevity of egg stage to larval stage was 8.25±0.64 days, ranging from 8-11 days. The prepupal stage was 1.75±0.44 days, rangingfrom 1-2 days and pupal stage was 4.88±0.52 days, ranging from 5-6 days. Thelongevity of male was 4.15±1.41 days, ranging from 2 to 6 days and that of the femalewas 6.96±3.12 days, ranging from 2 to 12 days. The total life cycle from egg to adultemergence was 20.50±3.74 days, ranging from 16 to 26 days. The number of adultparasites emerged from one host pupa were 79.37±58.50, ranging from 25 to 337, asshown in Table 12. The sex ratio of male to female was 1:2 under laboratorycondition.

Behevior of adult

Immediately after emergence the adult of Tetrastichus sp. started to feed andmate, and a few hours later that it began to parasitize the host pupa. The female adultwalked around the host pupa before attacking by grasping a host pupa by their legsand folded her abdomen downward, and then inserted the ovipositor into the host pupa(Figure 26). The parasitization was completed in 20-30 minutes. The female adult ofTetrastichus sp. laid egg into the host pupa. The larvae fed inside the host pupa untilpupation. The adult came out from the host pupa by making an emergence hole(Figure 27). The parasites normally attacked newly pupated pupae and it could alsoparasitize the pupae that was 4 days old. Tetrastichus sp. attacked pupae ofC. tumidicostalis.

58

Table 12 Duration period of various developmental stages of Tetrastichus sp. under

laboratory condition (28±2ºC and 75±2 % RH)


(days)

Range

(days)

Egg:

300 8.25±0.64 8-11

Larval:

Prepupa: 10 1.75±0.44 1-2

Pupa: 10 4.88±0.52 5-6

Total: Egg to adult 10 14.95±0.59 14-16

Adult: Male 10 4.15±1.41 2-6

Female 10 6.96±3.12 2-12

Total: Life cycle 20.50±3.74 16-26

59

Figure 26 The female of Tetrastichus sp. inserted the ovipositer in to the

pupa for parasitization

60

Figure 27 The adult came out from the host pupa by making an

emergence hole

61

Population Study of Chilo tumidicostalis (Hampson)

The population study of sugar moth borer C. tumidicostalis was carried out atDoembang Nangbuat, Suphan Buri Province from February 2001 to January 2002.Graphical population models of larvae of C. tumidicostalis during 2001-2002 wasshown in Figure 28.

The graphical population models of C. tumidicostalis revealed the changes inthe population density of larvae of C. tumidicostalis. The population of sugarcanemoth borer C. tumidicostalis was lower during the first four moths of sugarcane andthe population increased there after. The population of C. tumidicostalis increasedduring the last six months of sugarcane, its population was low during the yang shootstage of sugarcane.

The changes of population structure in terms of age structure were determinedat Doembang Nangbuat in 2001-2002. The age distribution of C. tumidicostalis wasshown in Figure 29. It was obvious that the adults of C. tumidicostalis moved into thesugarcane field during the elongation stage. The egg population was high in July andAugust 2001 and lowest in February to April and December to January. In June toAugust the population consisted of larger instars larvae and pupae, and every stage ofC. tumidicostalis was found during July and August in 2001.

62

0

1

2

3

4


POPU

LATIO

N DEN

SITY O

F Ch

ilo tum

idicost

alis (L

OG N)

Figure 28 Population density of Chilo tumidicostalis (Hampson) at Doembang Nangbuat, Suphan Buri during February 2001 to January 2002

2001 2002

63

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

00.5

11.5

22.5

33.5

44.5


POPU

LATI

ON

DENS

ITY

(LO

G N

+1)

�� Egg�� larval�� pupal

Figure 29 Age distribution of Chilo tumidicostalis (Hampson) at

Doembang Nangbuat, Suphan Buri during February 2001

to January 2002

2001 2002

64

Assessment Potential of Natural Enemies of Chilo tumidicostalia (Hampson)

The assessment potential of C. flavipes as a biological control agent wasevaluated by percent parasitization. The total number of larvae of C. tumidicostalisand the number of parasitized larvae by C. flavipes were calculated in term of percentparasitization both in control and release plots. The percent parasitization in controland release plots at Doembang Nongbuat and Dan Chang, Suphan Buri wereillustrated in Figure 30.

It was evident that parasitization in release plot was higher than in controlplots at Suphan Buri. Parasitization in plots showed in the period of growth ofsugarcane during February 2001 to January 2002, four month after release,parasitization increased sharply in released plot. The highest peak of parasitizationwas occurring in July and the highest parasitization level of C. tumidicostalisincreased as the total number of larvae increased, though the population of parasiteswas low from February to April in 2001 and October 2001 to January 2002 ofinvestigation. The percent parasitization by C. flavipes during February 2001 toJanuary 2002 were 0, 0, 13.67, 15.36, 16.53, 47.21, 29.34, 31.48, 19.07, 13.42, 5.90and 2.3 percent respectively in released plot and in control plot were 0, 0, 5.25, 10.17,7.89, 29.95, 21.74, 12.69, 3.10, 9.09, 1.20 and 0 percent, respectively.

65

05

101520253035404550


PERC

ENT P

ARAS

ITIZA

TION

ReleaseControl

Figure 30 Percent parasitization of Chilo tumidicostalis (Hampson)

larvae by Cotesia flavipes in release and control plots at

Suphan Buri in February 2001 to January 2002

2001 2002

66

DISCUSSION

Sugarcane moth borers complex were the most important insect pest ofsugarcane. Amomg of these C. infuscatellus, C. sacchariphagus and S. inferens playas economic important pests of sugarcane and heavy damage occurred in many area ofsugarcane plantation (Suasa-ard, 1982).

The sugarcane moth borers, C. tumidicostalis was became serious pest ofsugarcane in few years ago this species was outbreak in many areas of sugarcaneplantation and outbreak in Sa Kaew and Buri Rum provinces, during 2000-2001.The biological study of C. tumidicostalis revealed that the number of larval instars ofC. tumidicostalis varied from 5-7 instars. Most of them under gone 7 instars,depending most probably on the moisture content and nutritional quality of thesugarcane stem. When larvae were provided with new and fresh food they wouldundergo 6-7 moults to reach stage of pupation. Larvae of C. tumidicostalis weregregarious habit a lot of larvae feed on the same plant. The competition for food wasapparently a great influence to determine the number of larval instars and as well asthe duration of each larval instar. The variation thus observed on the larvaldevelopment of C. tumidicostalis was probably due to moisture, competition forquality of food.

The study on biological life table and partial ecological life table were far fromadequacy and needed additional input. The method and rearing technique used in thisstudy must be refined because the larvae were internal feeders. Observation by meansof opening the stalk of sugarcane in physical disturbance and interfered with normalactivity of the larvae. The new and fresh food provided to them in the confinedcontainer could also give undesirable effect. However, the mortality obtained wasrelatively much lower than that observed under the field condition. Such a differencecould be contributed to the existence of other regulatory factors in the environmentunder the field condition such as activity of the hymenopterous parasite, otherpredators and other physical environmental factors.

The existence of strains of C. flavipes has been reported (Mohyuddin et al.,1981) and investigation of the possibility of introducing such strains to increase therate of parasitism is envisaged. The survey and assessment of natural enemies ofC. tumidicostalis was shown C. flavipes was important larval parasites and percentparasitization in released plot was higher than in control plots at Suphan Buri inFebruary 2001 to January 2002. Tetrastichus sp. was important pupal parasites. Thehymenopterous parasites were highly influential and considered important mortalityfactors regulating on the population of C. tumidicostalis. However, the populationstatistics obtained from this study could be of a great application in relation toplanning a pest management strategy for the satisfactory control of this pest.

Suasa-ard (1982), reported that the Doryctinae (Hymenoptera: Braconidae)and Temelucha philippinesis (Ashmead) (Hymenoptera: Ichnumonidae) were larvalparasites, Xanthopimpla sp. (Hymenoptera: Ichneumonidae) was pupal parasite ofChilo spp. but in this study was not found these parasites in the field but eggs

67

parasites; Telenomus sp. (Hymenoptera: Scelionidae) and Trichogramma chilotreaeNagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae) were found.

68

CONCLUSION

The investigation on biology of C. tumidicostalis, revealed that theoviposition period of C. tumidicostalis was 1.91±0.69 days, ranging from 1 to 3 days.The number of egg laid per female averaged 123.31±70.89 eggs, ranging from 5 to250 eggs. The incubation period was 5.28±0.85 days, ranging from 4 to 7 days. Thelarvae of C. tumidicostalis molted five to seven times before pupation, the total larvalperiods of C. tumidicostalis with five, six and seven larval instars were 24.67±4.07,33.43±4.46 and 37.3±2.76 days respectively. The full-grown larvae ofC. tumidicostalis pupated in the larval tunnels or in the leaf sheath of sugarcane. Thepupal staged took about 5 to 9 days. The longevity of male and female was 2 to 5 and2 to 5 days respectively. The total life cycle from egg to adult of C. tumidicostaliswith the five-, six- and seven-instars larvae periods were 45.87±3.58, 54.57±4.55 and58.13±3 .00days respectively.

The biological attributes calculated from the table were the net reproductiverate of increase (Ro) = 28.5128. The capacity for increase (rc ) = 0.0779, the finite rateof increase (λ) = 1.0821 and the cohort generation time (Tc) = 8.8897 days. It meansthat a population of C. tumidicostalis could multiply = 28.5128 times in eachgeneration, or it could multiply 1.0821 times in every three days.

In the field survey of the natural enemies of sugarcane moth borers,C. tumidicostalis, four species of hymenopterous parasites, few species of earwing,which feed on egg of sugarcane borers, and some species of spiders were found.Among the hymenopterous parasites, Cotesia flavipes (Cameron) (Hymenoptera:Braconidae) was larval parasite; Tetrastichus sp. (Hymenoptera: Eulophidae) waspupal parasite; Telenomus sp. (Hymenoptera: Scelionidae) and Trichogrammachilotraeae Nagaraja & Nagarkatti (Hymenoptera: Trichogrammatidae) were eggparasites. C. flavipes seem to play the most important role in the natural control of C.tumidicostalis.

The changes of population structure in terms of age structure were determinedat Doembang Nangbuat in 2001-2002. The age distribution of C. tumidicostalis wasinvestigated. It was obvious that the adults of C. tumidicostalis moved into thesugarcane field during the elongation stage of sugarcane. The egg population washigh in July and August 2001. During June to August the most of larvae populationconsisted the medium and last instars larvae and pupae, and every stage ofC. tumidicostalis was found during July and August in 2001.

It was evident that parasitization in release plot was higher than in controlplots at Suphan Buri province. Four month after release, parasitization in release plotincreased sharply to in locations. The highest peak of parasitization was occurring inJuly and the highest parasitization of C. tumidicostalis increased as the total number oflarvae increased, though the population of parasites was The percent parasitization byC. flavipes during February 2001 to January 2002 were 0, 0, 13.67, 15.36, 16.53,47.21, 29.34, 31.48, 19.07, 13.42, 5.90 and 2.30 percent, respectively in released plot

69

and in control plot were 0, 0, 5.25, 10.17, 7.89, 29.95, 21.74, 12.69, 3.10, 9.09, 1.20and 0 percent, respectively.

It is indicated that the larval parasite C. flavipes as the promising biologicalcontrol agent for augmentative biological control of sugarcane moth borer especiallyC. tumidicostalis in Thailand.

70

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Documents

ECOLOGICAL STUDY OF THE SUGARCANE MOTH BORER, Chilo ... · venosatus (Bojor). Lewanich (1975) reported that five species of sugarcane moth borers in Chon Buri, Nakhon Pathom, Ratchaburi,