EVALUATION OF TWO REARING METHODS OF COTESIA FLAVIPES CAMERON (HYMENOPTERA: BRACONIDAE), A PARASITOID OF SUGARCANE BORERS

摘要

The comparative advantages of rearing an Indian and an Indonesian population of Cotesia flavipes Cameron (Hymenotpera: Braconidae) on sugarcane internode borer Chilo sacchariphagus indicus (Kapur) (Lepidoptera: Crambidae) and sorghum stemborer Chilo partettus Swinhoe (Lepidoptera: Crambidae) by group-exposure in glass chimneys (Chimney Method) and individual-exposure on Table-top (Table-top Method) were evaluated. In addition, mating rates, host acceptance time and oviposition rates of the parasitoid were examined to understand their importance in rearing the parasitoid. In a preliminary experiment, parasitisation rates were significantly higher in the Table-top method than in the chimney method for Indian and Indonesian populations. Parasitisation rates were significantly related to per cent males in the parent batch. In another comparative experiment, parasitisation rates and progeny cocoon or adult output per host larva invested were significantly highest in tine Table-top method. However, cocoon mass size was significantly lowest in the Table-top method. When freshly emerged adults of C. flavipes were grouped for mating in different batches with variable proportions of males, maximum mating occurred at the end of 15 min in all groups. The proportion of males in the group did not influence mating rates. It, however, influenced oviposition rates in the Table-top method. Oviposition rates showed considerable variation which, however, did not influence parasitisation rates. Host acceptance time for oviposition did not differ between Indian and Indonesian populations in the Table-top method.