Bioefficacy of Chikkamagalur Native Bacillus thuringiensis Isolates against Lepidopteran Insects

Laboratory bioassays were carried out to assess the efficacy of Bacillus thuringiensis isolates against lepidopteran insects, viz., cabbage leaf webber ( Crocidolomia binotalis (Zeller)) and diamondback moth, [ Plutella xylostella (L.)] and for their safety to mulberry silkworm, Bombyx mori (L). The commercial products Dipel and HD1 gave significantly higher mortality, but both were on par with isolates 2422c and 2459c in their efficacy against C. binotalis and P. xylostella , respectively. Of the five tested isolates against lepidopteran insects, the efficacy of each isolate varied with the insect. The isolate 2422c recorded the maximum mortality (80%) against cabbage leaf webber, whereas the isolate 2459c reduced P. xylostella by 80.0%. Both commercial products gave 93.3-96.7% mortality, whereas the isolates 2422c and 2459c gave 83.33 and 80% mortality, respectively, against silkworm.