Production of cuticle degrading enzymes by Isaria fumosorosea and their evaluation as a biocontrol agent against diamondback moth

Production and biocontrol efficacy of culture filtrates containing cuticle degrading enzymes from three isolates of Isaria fumosorosea against diamondback moth (Plutella xylostella) was observed during this study. This fungus when cultured in liquid medium having different carbon sources showed maximum biomass production when 1% chitin was added as carbon source. These isolates when grown in liquid culture conditions having 1% chitin as source produced cuticular degrading enzymes (proteases (Pr1 and Pr2), chitinases, chitosanase, and lipase) in a sequential manner and the production of these enzymes differed from control. Biocontrol assays with P. xylostella showed that the culture filtrates of I. fumosorosea were potent antifeedants because reduction in the feeding rate and body weight of the larvae was observed. Similarly, reduction in rates of successful pupation, adult emergence was observed when the culture filtrates were applied topically. At the end of the test period, the lowest ST50 value (1.57 +/- 0.20 days) was recorded for insect groups treated with culture filtrates from isolate IF28.2 when compared to the control. In view of the need for safer and environmentally friendly pest management tools, the present study can help in the development of enzyme-based biopesticides against P. xylostella.