Response of Tobacco Caterpillar Spodoptera litura (Fab) to various Concentrations of Bacillus thuringiensis subsp. kurstaki

The effect of Bacillus thuringiensis subsp. kurstaki on different larlar instars of Spodoptera litura (Fabricius) was evaluated. The larval mortality in all the instars of S. litura was higher at higher concentrations of B.t. and vice versa. The early instars showed higher mortality percentages as compared to the later ones. The mortality rate decreased with the advance in age of the larvae. Longer incubation period was observed at lower concentrations of B.t. Higher concentrations of B.t. were associated with reduced pupation, higher pupal mortality, higher malformed adult emergence and lower emergence of normal adults in all the instars.