Bioefficacy of New Isolates of Bacillus thuringiensis Berliner Against Lepidopteran Pests of Economic Importance

Two new Bacillus thuringiensis Berliner isolates viz.. 01-TAD-01 belonging to B. thuringiensis var sotto and 01-CHI-01 of B. thuringiensis var kurstaki were isolated from cadavers of silkworm, Bombyx mori L. Cross infectivity studies conducted against insect pests of mulberry revealed that both the strains were pathogenic to mulberry leaf webber, Diaphania pulverulentalis (Hampson) causing a mortality of 95.0 and 78.8 per cent, respectively. The isolate, 01-CHI-01 caused 71.3 per cent mortality of Spodoptera litura (Fab.). The isolates, 01-CHI-01 and 01-TAD-01 caused a mortality of 99.0 and 61.0 per cent, respectively for Crocidolomia binotalis (Zeli), 91.0 and 48.0 per cent aginst Plutella xylostella (L.) and 64.0 per cent each against Adisura atkinsonii (M.). The isolate, 01-CHI-01 caused 85 per cent mortality of Helicoverpa armigera (Hub.). These isolates may have wider use for management in agricultural and horticultural ecosystems wherin the pests have developed resistance to certain strains of B. thuringiensis.