Relationships among activities of extracellular enzyme production and virulence against Helicoverpa armigera in Beauveria bassiana

Abstract

Extracellular enzymes produced by Beauveria bassiana, are believed to play a key role in cuticle hydrolysis. Enzyme production and pathogenicity has been found to be positively correlated. Twenty-eight isolates of B. bassiana, collected from different geographical regions and host ranges were characterized by in vitro extracellular enzyme production and SDS-PAGE techniques for discerning biochemical basis for virulence among the different isolates. In vitro analysis of extracellular enzymes like protease, amylase, caseinase, chitinase and lipase was undertaken in an attempt to understand their relevance to virulence of the isolates. The different isolates of B. bassiana were evaluated for virulence to the second instar larvae of Helicoverpa armigera in laboratory bioassays. SDS-PAGE of total intracellular soluble proteins was also studied in order to understand affinities among the different isolates of B. bassiana. The relationship between enzyme production and pathogenicity and vice versa was nearly 50%. There was a 50% relationship associated with original insect host, pathogenicity and enzyme production.