Rearing, Ovipositional Biology, and Plant Host Range of the Rice Greenhorned Caterpillar Melanitis leda ismene Cramer

(Lepidoptera: Satyridae)

James A. Litsinger1, Vichien Bumroongsri2, Wendell L. Morrill3, and Ouab Sarnthoy4

1Current address: 1365 Jacobs Place, Dixon, California 95620 USA2Entomology and Zoology Division, Department of Agriculture, Bangkhen, Bangkok 10900, Thailand3Entomology Research Laboratory, Montana State University, Bozeman, Montana 597174Department of Entomology, Kasetsart University, Bangkhen, Bangkok 10900, Thailand

Abstract: Melanitis leda ismene Cramer is a widely distributed minor pest of rice in Asia. A rearing method employed three cages of the same design (3.0-3.4 m3) for mating/oviposition, larval development, and adult emergence. M. leda ismene readily mated and oviposited in a cage as small as 0.04 m3. A carbohydrate food source for the females did not significantly increase egg production. Fecundity linearly increased with decreasing temperature from 30 to 26oC and increasing relative humidity from 56 to 81%. Oviposition was more in the early morning then late afternoon but least during mid-day or night in this diurnal butterfly. Least oviposition occurred on early vegetative and ripening stage rice, but greatest oviposition and largest pupae developed on late vegetative and reproductive stages. M. leda ismene completed development on 20 plant species and is better adapted on Poaceae than Cyperaceae. The reported plant host range now lists 28 plants. The low population densities on rice can be attributed to its late colonization and low fecundity (mean 57 eggs/female). It is apparently more adapted to upland environments where rice is normally a minor crop. Its larvae readily fall off of rice plants during storms and thus survival in wetland rice is low. As rice is not highly preferred over other plants for oviposition, its wide host range would tend to dilute its numbers on rice during the favorable rainy season.

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Keywords: Rice, rearing, biology, plant age, plant host range

INTRODUCTIONThe rice green caterpillar Melanitis leda ismene Cramer is the most abundant of the five satyrids that defoliate rice in the Philippines. The other species are M. leda determinata (Butler), M. leda leda (Linnaeus), Mycalesis mineus (Linnaeus), and Mycalesis persoides persoides Moore. None of the more than one dozen satyrids known worldwide that feed on rice can be called an economic pest as damage is normally minimal (Grist and Lever, 1969). However, the larvae are large and patches of damage conspicuous, often causing farmers to react by applying insecticide even though plant injury is non-economic.

M. leda ismene is polyphenic where the adult coloration varies by season. It is more adapted to a rainfed environment with distinct wet and dry seasons. According to Talbot (1947), the subspecies M. leda determinata is the wet season form, while M. leda ismene is the dry season form.

The closely related subspecies M. leda leda, which occurs in Africa, also exhibits polyphenism (Brakefield, 1987). It was noted that wet season generations produce a smaller butterfly (wing area averaging 10.8 cm2) that is active, fecund, and has deflective eye spots on the wings to ward off predators such as birds. Dry season generations are larger (12.2 cm2 wing area) with reproductive diapause and cryptic wing coloration to pass the dry season in litter and vegetation. According to Brakefield (1987), the apparent strategy of the wet season form is to reproduce when growth of local plant hosts is most favorable. Dry season forms partially wait out the dry period, and with larger wings are able to fly longer distances to locate more favorable habitats.

The rice area of Los Baños, where this study took place, is located along a narrow wetland strip (2-3 km wide) bordering a large lake. The dryland form M. leda ismene is common and may emigrate from the surrounding rainfed uplands, its normal breeding grounds. The wet season form M. leda determinata has not been found in Los Baños, even with intensive

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collecting for over 15 years, suggesting that the breeding area is located outside of the lake periphery.

M. leda ismene has a wing expanse of 6.5-8.0 cm, is crepuscular, makes darting flight movements, and can be flushed from vegetation and litter under shades trees during the day. This butterfly is more abundant on a wet season crop (Rai, 1978). The yellow-green larvae camouflage well on young rice vegetation and bear a pair of tubercles, both on the head and tip of the abdomen. Larvae go through five stadia and feed at night to avoid birds. Mature larvae range from 4.0 to 5.5 cm in length and feed openly on leaf blades. The larvae are more prevalent from the late vegetative to pre-flowering stages (Amu Singh, 1979).

M. leda ismene rarely becomes sufficiently abundant to cause extensive damage, but sporadic reports have been noted in the uplands (Nigan and Verma, 1985; Garg, 1986), rainfed lowlands (Lumaban and Litsinger, 1978; Amu Singh, 1983), as well as in the irrigated wetlands (Katiya et al., 1976; Alam and Alam, 1977; Singh and Sinha, 1978; Barwal, 1984; Sathiyanandam et al., 1986).

Despite a wide distribution, the life history of M. leda ismene, aside from the developmental time of its life stages, is not well known. Developmental periods were determined by Jandu (1943), Banerjee (1956), Alam (1961), Sajjan and Singh (1972), and IRRI (1988) who found the stadia for the egg to be 3-4 days, larva 21-23 days, pupa 9-10 days, and adult 12-14 days. Fecundity averages 50-60 eggs per female.

Kalshoven (1981), Jandu (1973), and van Vreden and Ahmad Zabidi (1986) list eight plants in its host range, including rice, but records are based only on field observations. In none of the studies was M. leda ismene reported to be reared in culture, which is a limitation in determining its biological host plants. A greater understanding of the life history and population ecology of M. leda ismene is warranted to explain what factors prevent economic populations from occurring. This paper focuses on rearing, ovipositional biology, and plant host range whereas a companion paper focuses on natural enemies (Litsinger et al. 1997).

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MATERIALS AND METHODSGeneralBiological studies were carried out in a greenhouse and non-airconditioned headhouse (28 ± 4oC and 81 ± 6% relative humidity) at the International Rice Research Institute (IRRI), Los Baños, Laguna, Philippines. A breeding colony was established in the greenhouse from adults field collected in Los Baños. Rearing consisted of employing a succession of three cages for mating/oviposition, larval development, and adult emergence. Except for the mating/oviposition cage design experiment, adults were caged in a 3.4 m3 nylon mesh (0.5 mm) cage set in a galvanized tray on a greenhouse bench filled to 12 cm water depth. IR64 rice, utilized in the studies, was planted in 12-cm-diameter clay pots from seed, and thinned to three seedlings. The adults were offered a 10% honey solution in a cotton dental wick. As adults prefer shady habitats in nature, we placed a cloth on top of the mating/oviposition cage. All experiments were randomized complete block design and each cage was a replicate. Except where noted, experiments on the adults utilized 10 newly emerged pairs placed on 10 potted rice plants per cage aged 8 to 10 weeks after transplanting (WT). For statistical tests, separation of means is at the 95% confidence limit. Means are expressed as ± standard errors.

Mating/oviposition cage designFive cage designs for mating and oviposition were tested representing different sizes and degrees of ventilation. Three cages were of a frame box design with sides and top of nylon mesh of decreasing dimensions of 1.5 x 1.5 x 1.5 m (3.4 m3), 1.0 x 1.0 x 1.0 m (1.0 m3), and 0.5 x 0.5 x 0.5 m (0.13 m3). Two other cages were cylindrical, made of Mylar sheeting: 1) 0.6 m diameter x 1.2 m high (0.34 m3) and 2) 0.3 m diameter x 0.6 m high (0.04 m3) -- with small side and top windows of nylon mesh. These Mylar tube cages were less aerated than the frame cages. The bottomless cages were set in a galvanized iron tray on a greenhouse bench, filled to 12 cm depth with water. The number of eggs laid was recorded over four days. The five cage designs were treatments, replicated five times.

Adult sustenance

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Pairs of cages were established with and without honey. A 10% solution of honey in a cotton wick was provided to the adults in one cage. There were two treatments replicated nine times. Oviposition and adult survivorship were observed over four days. Eggs were incubated in petri dishes on filter paper moistened with a 1% solution of M-Tegosept, a fungistatic agent.

Effect of temperature and relative humidity on ovipositionAdults were caged for a period of 10 consecutive months from October 1988 to July 1989. Each month was a treatment, and the experiment was replicated ten times. Egg production was recorded until all adults died. The temperature and relative humidity were measured daily with a hydro-thermograph. The daily mean was determined as the average of the maximum and minimum values. These values were then averaged each month over the ovipositional period and correlated with egg production.

Diel oviposition rhythmEgg production was determined over a 24 h day divided into five periods: 6 to 9 AM, 9 AM to noon, noon to 3 PM, 3 to 7 PM, and 7 PM to 6 AM. Fresh potted plants were replaced at the end of each segment. The five periods were treatments, each replicated 10 times. Egg production was measured over a five-day period for each replicate.

Effect of plant age on developmental biologyFour stages of rice were compared for preference and biological fitness: early vegetative (2-3 WT), late vegetative (5-6 WT), reproductive (8-9 WT), and ripening (12-13 WT). Oviposition preference was determined by placing 10 pairs of adults in the mating/oviposition cage with four potted plants of each stage randomly arranged in a free-choice test. Eggs were counted after three days. The four plant ages were treatments, each replicated six times. Egg hatch was recorded in petri dishes with a fungistatic agent solution added to the filter paper.

Larval development was determined on each of the four plant ages by placing 10 neonate larvae on a potted plant in a 30-cm diameter and 60-cm high Mylar tube cage. The experiment was also replicated six times. The cages were observed daily

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and plants changed as needed. Upon pupation, the pupal fresh weight was recorded, and the pupae were held in cages to determine percentage emergence to adulthood. The naked pupal chrysalis typically hangs suspended from vegetation.

Plant host rangePlant host preference was conducted in a series of three trials. The first tested 42 local plants and the number was then reduced to 20 where larval survival occurred and ended by comparing 7 of the most preferred hosts. The rice variety was IR64. Plants in their reproductive stage were uprooted and transplanted in 12 cm diameter clay pots, 1-3 plants per pot to equalize plant biomass between species. The selected plant species were compared to rice as a standard check in each trial, replicated four times. Ten neonate larvae were placed on each potted plant (replicate). The plants were then caged with a Mylar tube (12 cm diameter and 75 cm tall) with the top and side nylon mesh vents. Daily observations noted survival and duration to pupation. Upon pupation, each pupa was weighed fresh on an electronic balance (± 0.1 mg). Developmental parameters were larval survival to pupation, pupal weight, growth index (% larval survival/larval period measured in days). Plants with the highest survival rate, heaviest pupae, and shortest maturity would be the most fit hosts.

Ovipositional preference on alternate hostsSix species of rice-field plants were compared with rice in a free-choice test to determine egg-laying preference. Plants were prepared as in the plant host range experiment. Six pots, one pot per species, were randomly arranged in a circle in the 3.4 m3 oviposition cage. There were six replicates. Ten pairs of recently emerged moths were released into each cage. Egg production was recorded every 3 days until all adults died.

RESULTS

Life history parameters

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Table 1. Developmental periods of the life stages of M. leda ismene.

The eggs hatched after 3 days and the larval period developed 21.3 days from eclosion to the prepupal stage (Table 1). Pupal development took 8.7 days and that of the adult stage of each sex survived for 13.2 days. The developmental period from egg to adult took 32.8 days and average fecundity resulted in 57 eggs per female. The sex ratio was equal. Mating/oviposition cage design

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There was no effect of cage design on egg production (no. eggs/female) which ranged from 54.7 ± 4.7 for the 0.13 m3 cage to 47.1 ± 2.5 for the 0.04 m3 cage. Egg hatch also was not significantly different between treatments (84.9 ± 2.6 to 89.9 ± 2.3%), indicating normal mating behavior.

Adult sustenanceFemales laid more eggs when provided honey (29.5 ± 2.6 eggs/female) than without (21.0 ± 3.4), but the difference was not significant. Percentage egg hatch also was similarly higher with honey (73.3 ± 2.3%) and without (71.9 ± 2.6%). However, female longevity was significantly longer with honey (14.2 ± 0.3 days) than without (11.7 ± 0.2 days).

Effect of temperature and RH on ovipositionEgg production (Y) linearly increased as relative humidity increased from 56 to 81% (Fig. 1A). The regression equation (X = relative humidity) was Y = -222 + 8.5 X, r = 0.68 (P < 0.05). Egg production linearly decreased as temperatures warmed from 26 to 30oC (Fig. 1B). The regression equation was Y = 1874 - 52.2 X, r = 0.65 (P < 0.05), where X = temperature.

Figure 1 A. The effect of relative humidity on egg production.

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Figure 1 B. The effect of temperature on egg production.

Diel ovipositional rhythmTwo ovipositional periods were evident over a 24-hour period. Greatest egg laying per female (no. eggs/hour) occurred at early morning (6 to 9AM) (11.6) (Table 2). Egg production was significantly lower (4.5 eggs/hr) in the late afternoon (3 to 7PM). Lowest egg numbers (0.8 and 1.7 eggs/hr) were recorded for the rest of the 24 hour cycle (7 PM to 6 AM and 9 AM to 3 PM, respectively).

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Table 2. Diel ovipositional rhythm of M. leda ismene reared on rice, IRRI Greenhouse, 1988-89. 1

TimeEggs laid (no.

per hour) Range6:00-9:00 11.6 ± 1.7 a 6-25

9:00-noon 1.7 ± 0.3 c 0-3

Noon-15:00 1.0 ± 0.3 c 0-3

15:00-19:00 4.5 ± 0.8 b 0-10

19:00-6:00 0.8 ± 0.2 c 0-21 10 pairs of adult males and females/cageAvg. of 10 replications. In a column, meansfollowed by different letters are significantlydifferent (P < 0.05) by DMRT

Effect of plant age on developmental biologyThe greatest number of eggs per female (35.7) was recorded on late vegetative stage plants, with significantly fewer eggs on the early vegetative (13.9) and ripening (13.7) stages) (Table 3). Intermediate numbers of eggs were laid on reproductive stage rice (26.0). Egg hatch ranged from 60.0 ± 12.6% for ripening stage to 79.5 ± 8.2% for early vegetative stage, but differences were not significant for plant age.

Table 3. Comparison of four rice growth stages on the development of greenhorned caterpillar.

Larval development was most rapid on both early (20.6 days) and late (21.2 days) vegetative stage plants. Significantly longer development occurred on reproductive (22.9 days) and ripening (24.9 days) stages. Largest pupae (mg/pupa) developed on late vegetative (369.6) and reproductive (340.8) stage plants. These pupal weights were significantly greater than those reared on ripening stage rice (328.0). Lowest pupal weight (299.5 mg) occurred on early vegetative stage plants. Pupation ranged from 88.3 ± 4.3% on ripening stage rice to 91.6 ± 3.8% on reproductive stage rice, with no difference between growth stages. All pupae emerged to adulthood in the experiment.

Plant host range

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Forty-two species of rice field plants were first tested for M. leda ismene to survival from eclosion to pupation. Larval survival occurred on only 20 host plants ranging from 12.5 to 60.5% survival (Table 4). The twenty two species where M. leda ismene did not survive were: Amaranthaceae (Amaranthus spinosus L., A. viridis L.), Asteraceae (Ageratum conyzoides L., Eclipta alba (L.) Hassk.), Capparidaceae (Cleome rutidosperma DC), Cyperacerae (Cyperus compactus Retz., C. brevifolius (Rottb.) Hassk., C. iria (L.), C. imbricatus Retz., C. kyllingia Endl., Fimbristylis miliacea (L.) Vahl.), Euphorbiaceae (Phyllanthus amarus Schumm. & Thonn., Euphorbia hirta L.), Onagraceae (Ludwigia octovalvis (Jacq.) Raven), Pontederiaceae (Monochoria vaginalis (Burm. F.) Presl), Oxalidaceae (Oxalis corniculata L.), Poaceae (Panicum repens L., Echinochloa crusgalli (L.) Beauv., Imperata cylindrical (L.) Beauv., Leersia hexandra (L.)Sw.), Portulaceae (Portulaca oleracea L.), and Sphenocleaceae (Sphenoclea zeylanica Gaertn.).

The 20 species where survival occurred were 18 in the family Poaceae and 2 in Cyperaceae. It was remarkable that 20 of the 22 species of Poaceae tested were hosts with the notable exception of Echinochloa crusgalli and Panicum repens. Imperata cylindrica being a non-host, however, was not surprising as the tissue is very tough and it thrives on poor soils. The two Cyperaceae species (Cyperus rotundus and C. pilosus were among the least favorable five plants tested.

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Table 4. The most suitable plant hosts for larval survival from trials in the IRRI Greenhouse, 1988-89.

The highest rate of survival from neonate larvae to pupation occurred on IR64 rice (60.5%) followed by Paspalum distichum (52.0%) with Echinochloa colona and Paspalum longifolium with 50%. Significantly lower survival occurred in the other 16 plant species ranged from 47.5 to 12.5%.

The mass screening was followed by more indepth studies.

Ovipositional preference on alternate hosts

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The first was ovipositional preference (Table 5). In a free-choice test, M. leda ismene laid significantly more eggs/10 females on L. chinensis (28.5), rice (27.2), and E. indica (27.0) than on P. flavidum (23.3) The other three plant species received intermediate numbers of eggs.

Table 5. Ovipositional preference of seven plant hosts.

There was no difference in leaf width although rice had wider leaves. Most eggs were deposited on Leptochloa chinensis (28.5), rice (27.2) followed by Eleusine indica (27.0) although the differences were not significant. Lowest egg deposition occurred on Paspalidium flavidum with only 3.3 eggs.

Most nutritionally favorable plant hostsThe final study compared the same seven host plants with four other life cycle parameters centered on nutrition (Table 6).

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Table 6. Comparison of four developmental parameters on seven plant hosts.

Although statistically there were differences between the seven plant hosts regarding the larval period but the differences between host plants ranged only from 22.5 days for rice and 24.2 days Leptochloa chinensis. A shorter larval development period signifies better host nutrition. Heavy pupal weight signifies a more nutritious plant host and the differences were again similar with 395.9 mg for rice to 298.1 for L. chinensis. Larval pupation occurred

The pupal weight of insects fed on rice averaged 374.2 mg per insect (Table 6). Pupal weights (mg/insect) similar to rice fed insects (395.9) were those fed P. flavidum (379.7), Eleusine indica (Linnaeus) Gaertner (366.9) followed by E. colona (353.3) E. glabrescens (350.7). Least weight was L. chinensis (298.1)

The growth index (Srivastava 1959) combines larval survivorship and larval period in one unit to enable a ranking of host suitability between the twenty host plants.

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Rice had the highest and most favorable growth index (average of 2.9) followed by P. flavidum (2.0), Echinochloa colona (L) Link (2.0), D. aegyptium (1.9), E. indica (1.9), and L. chinensis (1.8). Lowest weight was with E. glabrescens (1.5).

DISCUSSIONMass rearing of M. leda ismene was readily accomplished by utilizing knowledge of its biology and taking normal precautions outlined by Frederich (1986) in rearing butterflies. Plants removed from the field resulted in greater larval mortality during rearing due to Bacillus thuringiensis Berliner and other pathogens. Therefore rice plants used in rearing were sown in greenhouse pots, and regularly hosed with water to remove fungal spores. Cages were washed with 5.3% sodium hypochlorite (Clorox) bleach and disinfectant before re-using and plants were sprayed with fungistatic solution to prevent the pathogen infection. Potted plants were placed in galvanized trays filled to 12 cm water to provide humidity and relieve the necessity of watering regularly. Late vegetative stage rice was used in the mating/oviposition cages. Space was not a limitation, therefore plants were not crowded and ventilation was encouraged to create a less favorable microclimate to insect pathogens.

M. leda ismene oviposited year-round with no indication of reproductive dormancy. The large 3.0 or 3.4 m3 cages were used both as mating/oviposition cages and larval rearing cages. Providing a carbohydrate adult food source was adopted but not necessary.

After 3 days in the oviposition cage, the potted plants were placed in larval rearing cages where the eggs could undergo development to pupation on the same plants. Pupae, removed from the larval rearing cages, were placed in adult emergence cages suspended by thread from the sides of the cage. Suspending the pupae encouraged emerging adults to expand their wings upon emergence. A non-airconditioned headhouse was a better location for rearing than a greenhouse as it is cooler 27 ± 4o C and nearer ideal rearing temperature (26o C) and humidity (81%). High humidity was ensured as the cages were set in standing water.

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Rice was chosen as the plant to mass rear M. leda ismene, as it is a more fit host than other plant species studied and is readily grown under greenhouse conditions.

M. leda ismene is recorded year round in irrigated areas, where presumably it does not undergo dormancy. It is noteworthy that about half of its reported alternate hosts are perennial, evidence that its hosts are present during the dry season. Therefore in rainfed areas with distinct dry seasons, M. leda ismene could survive on these hosts, but not well, as plant growth would be poor except in restricted habitats where plant moisture is available. If the growth of its plant hosts were poor, surviving adults could undergo reproductive dormancy for several months.

M. leda ismene survived and completed development from egg to adult on 20 plant hosts, including rice. Plants from eleven families were evaluated, but M. leda ismene survived on only Poaceae and Cyperaceae. M. leda ismene is highly adapted to Poaceae as only 3 of the 22 species of Poaceae tested were non-hosts. Whereas only 2 of the 8 Cyperaceae supported development. Larval survival was also low on the two Cyperaceae hosts.

The plant host range of M. leda ismene is expanded to 28 species. We confirmed the host record of E. indica by Jandu (1943). Van Vreden and Ahmad Zabidi (1986) listed Saccharum sp. and Sorghum verticilliflorum (Steud) Stapf as hosts. Kalshoven (1981) reported four hosts: Panicum maximum Jacquin, Sorghum bicolor (Linnaeus) Moench, Anastrophous sp., and Imperata cylindrica (Linnaeus) Raeuschel. In our study, no survival occurred on I. cylindrica. These host records were from field observations of larvae feeding. Perhaps M. leda ismene had shifted to I. cylindrica as an older larva.

Nakasuji (1987) presented an argument for the evolution of polyphenism in skippers and satyrids that feed on perennial grasses during the dry season. Their critical period for survival is during the neonate larval stage. The larvae must have mandibles large enough to chew into the tough epidermis of perennial grasses. To do this, the species produce large eggs that become large neonate larvae with larger mandibles. However, they are only able to produce large eggs at the

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expense of greater fecundity. M. leda ismene has an intermediate egg volume compared to the skippers studied by Nakasuji (1987), thus providing evidence that it may follow this life strategy.

M. leda ismene is not well adapted to the wetlands as the larvae commonly fall off rice plants, particularly during windy weather, a common condition in monsoon Asia. An attempt to artificially infest plants in irrigated fields failed, as by the following day all the larvae had fallen from the foliage into the water and drowned. Examination of M. leda ismene larvae showed they possess a triordinal mesal pennellipse crochet with the hooks curved abaxially, a condition opposite the crochet orientation of pyralid rice defoliators. Apparently, M. leda ismene are not able to cling well to rice leaves.

Due to the late arrival on the rice crop, only two generations could develop on most modern varieties. Coupled with its low fecundity, a low biotic potential would explain its low populations in wetland rice. In the uplands, where rice is less prevalent and not highly preferred for oviposition, its broad host range would mean M. leda ismene populations would become diluted during the favorable wet season and thus rarely able to achieve economic numbers.

ACKNOWLEDGEMENTSWe gratefully acknowledge the assistance in the field and greenhouse provided by Monteflor Operio, Carlito Vecilos, and Ed Micosa. Keith Moody identified the species of host plants tested in this study and Alberto Barrion classified the larval crochets and provided the list of satyrids of the Philippines. We thank Miss Nonnie P. Bunyi for assistance in typing the manuscript.

REFERENCESAlam, M.Z. (1961) Insect Pests of Rice in East Pakistan and their Control. East Pakistan Government Press, Dacca, Bangladesh, 94 pp.

Alam, S. and A. Alam. (1977) Minor insect pests of rice. In Literature review of insect pests and diseases of rice in

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Bangladesh. pp. 72-78, Bangladesh Rice Research Institute, Dacca.

Amu Singh, A. (1979) Emergence of rice leaf butterfly as a rice pest in Manipur, India. International Rice Research Newsletter 4(4): 16-17.

Amu Singh, A. (1983) Changing trends of insect pests of rice in Manipur. International Rice Research Newsletter 8(1): 12.

Banerjee, S.N. (1956) On the incidence of paddy pests in West Bengal. Proceedings of the Zoological Society, Calcutta, India 9: 65-83.

Barwal, R.N. (1984) Changing insect pest status in the Imphal Valley. International Rice Research Newsletter 9(4): 12-13.

Brakefield, P.M. (1987) Tropical dry and wet season polyphenism in the butterfly Melanitis leda (Satyrinae): phenotypic plasticity and climatic correlates. Biological Journal of the Linnean Society 31: 175-191.

Friedrich, E. (1986) Breeding Butterflies and Moths. A Practical Handbook for British and European Species (translated by S. Whitebread). Harley Books, Essex, UK, 176 pp.

Garg, D.K. (1986) Some new insect pests of rice in Uttar Pradesh, India. International Rice Research Newsletter 11(5): 30.

Grist, D. H. and Lever, R.J.A.W. (1969) Pests of Rice. Longmans, London, UK, 520 pp.

Kalshoven, L.G.E. (1981) The pests of Crops in Indonesia. (translated by P.A. van der Laan). P.T. Ichtiar Baru -Van Hoeve, Jakarta, Indonesia, 701 pp.

Katiya, R.R., Misra, B.P., Upadhayay, K.D., and Prasad, N. (1976) Outbreak of horned caterpillar of rice at Kanpur. Entomology Newsletter 6(8-9):48-49.

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International Rice Research Institute. (1988) Insect pests. pp. 238-239. In IRRI Annual Report for 1987. IRRI, Los Baños, Philippines.

Jandu, A.S. (1943) Biological notes on the butterflies of Delhi. Part II. Danaidae, Satyridae, Nymphalidae, Lycaenidae and Hesperiidae. Indian Journal of Entomology 5:223-241.

Litsinger, J.A., A. T. Barrion, V. Bumroongsri, W.L. Morrill, and O. Sarnthoy. (1997). Natural enemies of the rice greenhorned caterpillar Melanitis leda ismene Cramer (Lepidoptera: Satyridae) and rice skipper Pelopidas mathias Fabricius (Lepidoptera: Hesperiidae) in the Philippines. Philippine Entomologist 11:151-181.

Lumaban, M.D. and Litsinger, J.A. (1978) Insects in an introduced double-cropping pattern of rainfed lowland rice. International Rice Research Newsletter 3(2):17.

Nakasuji, F. (1987) Egg size of skippers (Lepidoptera: Hesperiidae) in relation to their host specificity and to leaf toughness of host plants. Ecological Research 2:175-183.

Nigan P.M. and Verma, R.A. (1985) Insect pests of upland rice in Uttar Pradesh. International Rice Research Newsletter 10(6): 22.

Rai, P.S. 1978. Cantheconidea furcellata (Wolff.) (Pentatomidae-Hemiptera): a predator of leaf-feeding caterpillars of rice. Current Science 47:556-557.

Sajjan, S.S. and Singh, J. (1972) Occurrence of horned caterpillar of rice, Melanitis leda ismene (Cramer) (Satyridae: Lepidoptera) on paddy in Punjab. Science and Culture 38:215-216.

Sathiyanandam, V.K.R., Venugopal, M.S., Gopalan, M., and Janarthanan, R. (1986) Laboratory evaluation of insecticides for controlling greenhorned caterpillar. International Rice Research Newsletter 11(3):20.

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Singh, J. and Singha, M.M. (197). Studies on the occurrence of different paddy pests under North Bihar conditions. Science and Culture 44:508-509.

Srivastava, B.K. (1959) Growth potential of Laphygma exigua Hb. in relation to certain food plants. Madras Agricultural Journal 46:255-259.

Steel, R.G. and Torrie, J.H. (1980) Principles and Procedures of Statistics. 2nd ed. McGraw Hill, New York, 633 pp.

Talbot, G. (1947) The fauna of British India including Ceylon and Burma. Butterflies. Vol 2. Taylor and Francis Ltd., London, UK), 506 pp.

van Vreden, G. and Ahmad Zabidi, A.L. (1986) Pests of Rice and their Natural Enemies in Peninsular Malaysia. Pudoc, Wageningen, Netherlands, 231 pp.Disclaimer: this article is not the published version of the paper as the authors never received any reprint nor could they access the journal in a library. This is the original text but the tables were taken from the MS thesis of Vichien Bumroongsri as the original ones have been lost.

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