Larviposition by the Tachinid fly, Sturmiopsis inferens Tns. on sugarcane shoot borer larvae was studied. One adult female laid on an average 285 maggots (range 126-521). More than 90% of the maggots extruded were free of the enveloping chorion. Less than 4% were found to be unfertilized and undeveloped. The mean number of maggots laid per host was 1.21 and more than 70% were laid at the bore hole, the remaining being larviposited near the bore hole. Larviposition began on the sixth day after emergence of the female and mating, reached its peak during seventh to eleventh days and declined thereafter. Over 90% of the total number of maggots were deposited by the thirteenth day. Some maggots (9.52%) were not extruded but remained in the fly's uterus. The number of maggots laid at a bore hole varied from one to nine, but in more than 50% of the shoots only a single maggot was deposited. The flies preferred third, fourth and fifth instar larvae and shoots having only wet frass for larviposition, although larviposition did occur in shoots having second instar larvae and freshly formed pupae.

An improved bioassay method was developed for evaluating entomopathogenic fungi (EPF) using pests and fungi from sugarcane crop system. Third instar larvae of white grub Holotrichia serrata F. (Coleoptera: Scarabaeidae) and shoot borer Chilo infuscatellus Snellen (Lepidoptera: Crambidae) surface-contaminated with suspensions (10 8 spores/ml) of Beauveria brongniartii (Sacc.) Petch and Beauveria bassiana (Balsamo-Criv.) Vuill., respectively were subjected to starvation and feeding regimes. Holotrichia serrata grubs maintained in starvation regime showed lower overall mortality and higher LT 50 values than those kept in feeding regime in one test; the trend was, however, opposite in the second test. On the other hand, C. infuscatellus larvae in starvation regime produced higher mortality and lower LT 50 values than those in feeding regime in both tests. Further, spore output per C. infuscatellus larval cadaver was equal in both regimes. In degeneration studies, spore output of Metarhizium anisopliae Metch. maintained on nutrient broth for 15 continuous subcultures showed overlapping differences and a decreasing trend after the first six subcultures. In virulence studies with M. anisopliae from eight subcultures against diet-reared C. infuscatellus, third instar larvae treated with the fungus and maintained under starvation regime showed two peaks of LC 50 and LT 50 values. In comparative studies with field-collected C. infuscatellus, third instar larvae treated with 10 8 spores/ml of the fungus from 15 subcultures and fed with sugarcane shoots showed indistinct peaks in per cent mortality which reached significantly lowest value in the 15th subculture. The advantages of the modified bioassay method in virulence tests and the importance of degeneration studies for candidate EPF such as B. brongniartii are discussed.

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In Petri plate tests, neonate or third to fourth instar larvae of the predator Dipha aphidivora Meyrick (Lepidoptera: Pyralidae) were offered its host Ceratovacuna lanigera Zehntner (Homoptera: Aphididae), the woolly aphid of sugarcane, frozen and stored at -4 0 C, and thawed at room temperature before releasing the predator. In preliminary tests, neonate and grown-up larvae built webs, fed on aphids, pupated and emerged as adults. In two tests with neonate larvae, adult emergence was 45.5 and 80.0% in 17-21 days. The predator moths laid eggs on white coarse filter paper strips but not on hard paper strips of different colors placed in oviposition cages. Egg-laden filter paper or leaf bits placed in Petri plates with frozen aphids showed hatching but larvae did not survive long. Poor survival of neonate larvae in several additional tests with fresh or one-year old frozen aphid indicated that the method may not be useful for long-term rearing of the predator. Short-term survival of grown-up larvae on frozen aphid may enable the use of the latter as food for predator larvae in transit.

The influence of constant temperatures of 27, 29, 31 and 33oC and alternating temperature of 31/33oC (18/6 h) on Sturrniopsis inferens TOWNSEND was studied during 12 successive generations. The larval and pupal periods for male parasites were 13.5 + 0.5 and 11.0 _+ 0.3 days respectively and for female 12.8 _+ 0.5 and 11.1 + 0.3 days respectively in the 1 st generation at 27 ~ C. It decreased progressively with increase in temperature. Survival of females, fertility and fecundity were adversely affected at higher temperatures. A temperature range of 27-29 ~ C appeared to be optimum for mass rearing of the parasite in the laboratory. The high~ premature mortality observed at a constant 33oC was not observed at temperatures fluctuating between 31/33oC, Presumably under field conditions, where temperature is constantly fluctuating, the flies will be able to withstand a comparatively higher temperature. TOWNSEND (Dip. : Tachinidae) is an important larval parasite of sugarcane shoot borers, Child infuscatellus SNELLEN (anon., 1971 ; KALRA & DUTTA, 1971) and C. auricilius DUDGEON (SINGH & YADAV, 1 979) in certain parts of India in recent years. The attempts made to breed it in the laboratory (DAVID et ai., 1980) and to colonize it in a new area (our unpubl, data) have given encouraging results. The success of a natural enemy in biological pest suppression depends mainly on its ability to survive in the environment. Environmental factors that influence the success of a natural enemy are weather, food, resource other than food (i. e. a particular place to live) and other organisms of the same and different species (SoLoMON, 1949). Among these factors, temperature plays a key role and affects the survival and activity of the parasite. In this laboratory study, an attempt was made to study the influence of temperature on S. inferens and to establish the optimum temperature for mass-rearing the parasite in the laboratory for field colonization. Sturmiopsis inferens MATERIALS AND METHODSA culture of S. inferens was started with puparia collected from cane fields around Coimbatore on larvae of the shoot borer, C. infuscatellus. One hundred freshly formed