Abstract
Chitinase-producing bacteria were isolated from diseased insect [Pieris brassicae Linnaeus (Lepidoptera: Pieridae) and Spodoptera litura Fabricius (Lepidoptera: Noctuidae)] cadavers. Serratia marcescens strain SEN showed highest enzyme production at temperature 27 A degrees C and pH 9.0 and was selected for further studies. It possessed exochitinase, endochitinase and chitobiosidase activities, of which endochitinase was found to be the predominant chitinase. Serratia marcescens strain SEN showed insecticidal activity against all the developmental stages of S. litura larvae. Ingestion of sublethal doses of S. marcescens strain SEN led to a decrease in the larval and pupal weight, percent normal pupation, adult emergence and a significant increase of the larval period. Effect on fecundity and egg hatchability were studied at LC20 and LC50 doses. Fecundity was significantly reduced at both doses tested, while egg hatchability was significantly affected only at the highest dose. To our knowledge, this is the first report of the potential of an entomopathogenic S. marcescens strain against different developmental stages of S. litura. The tested S. marcescens strain SEN showed promise as a biocontrol agent of S. litura.