Effects of Bacillus thuringiensis δ—Endotoxin on life history parameters of rice leaf folder Cnaphalocrocis medinalis (Lepidoptera)

Studies on the bioefficacy of native isolates of Bacillus thuringiensis Berliner against rice leaf folder Cnaphalocrocis medinalis (Guenee) were carried out in the Bt isolation and laboratory and Glass House Complex of Department of Plant Breeding, Genetics and Biotechnology, PAU, Ludhiana. Among 22 native isolates of Bt, three namely BtK₄, BtC₅ and BtJ showed more than 55 per cent larval mortality of C. medinalis. Sublethel effects of promising isolates of Bt revealed that larval and pupal duration were increased, whereas weights and survival of larvae and pupae were decreased with higher concentrations of Bt. but these concentrations did not show any lethal effects on the hatchability of eggs.