Metabolite profiling of beauveria bassiana under enriched growth conditions and efficacy against diamondback moth plutella xylostella

Abstract

newlineDiamondback moth, Plutella xylostella is a devastating pest of crucifers. The attempts made so far to manage P. xylostella through chemical control measures were not much effective and necessiated repeated application. Entomopathogenic fungi (EPF), Beauveria bassiana proved to be an effective biological control agent against this key pest which needs to be substantiated. In the present investigation, infection process of a native isolate of B. bassiana TM (MH590235) was studied through scanning electron microscopy (SEM). Dose mortality responses showed increase in mortality with increase in spore concentration and recorded LC50 value of 2.4 x 107 spores mL-1 and LT50 of 3.62 days. newline Growth, sporulation and enzymatic activity are the virulence determining factors of EPF. In the present study, the basic culture media, Potato Dextrose Broth was amended with chitin (0.05%), chitosan (0.05 %) and yeast (1 %) and the effect of these supplements on virulence was evaluated for three strains of B. bassiana, viz., TM (MH590235), BR (MK918495) and BbI8 (KX263275). Significant variation existed among the three isolates in terms of biomass, newlinesporulation, enzyme activity and pathogenicity with TM being the promising isolate. Among the amendments, yeast addition was found to enhance the performance of all the three strains. Among the isolates, TM recorded higher biomass (3.33 g), spore production (10.84 x 109 spores ml-1), protease activity (2.53 cm), lipase activity (2.15 cm) compared to unamended control (1.57 g, 0.89 x 109 spores ml-1, 1.87 cm and 2.13 cm respectively). TM recorded highest protease production (2.23 cm) in yeast followed by BR (1.73 cm) and Bb18 (1.47 cm). Maximum production of lipase by TM was noticed in chitin, chitosan and yeast amended media (2.18 cm, 2.08 cm, 2.15 cm respectively) followed by BR (1.00 cm, 0.83 cm, 0.60 cm respectively in chitin, chitosan and yeast amended media). Addition of yeast and chitosan to media was found to cause cent per cent mortality of P. xylostella larvae by