Effect of Microbial Agents on Different Developmental Stages of Tobacco Caterpillar Spodoptera litura (Fabricius)

The effect of nuclear polyhedrosis virus (NP V) Bacillus thuringiensis Berliner (B.t.) and Beauveria bassiana (Balsamo) vuille on different developmental stages of Spodoptera litura (Fabricius) was evaluated. Results showed that the larval mortality in all the instars of S. litura were higher at higher concentrations of NPV, B.t. and B. bassiana. The per cent larval mortality decreased with decrease in microbial concentrations, higher mortality percentages were observed in the early instars compared to later instars. The mortality rate decreased with the advance in age of the larvae. Longer incubation period was observed at lower concentrations of NPV, B.t. and bassiana. Higher concentrations of pathogens were associated with reduced pupation, higher pupal mortality, higher malformed adult emergence and lower emergence of normal adults in all the instars.