Isolation and Characterization of Entomopathogenic Symbiotic Bacterium, Photorhabdus luminescens of Heterorhabditis indica from Soils of Five Agro Climatic Zones of Karnataka

The present study was undertaken at the Department of Agricultural Microbiology, College of Agriculture, University of Agricultural Sciences, Raichur. We selected Five agro-climatic zones of (covering one hundred and fifty locations) Karnataka to isolate, characterize for morphological and biochemical properties, to screen against some important crop pests and plant pathogens. All the five zones were found to harbor EPNs but with varying degree of occurrence in each cropping system. Photorhabdus luminescens was isolated by streaking the haemolymph of the dead larva of Galleria on nutrient agar and NBTA plates. A total of eight isolates were obtained. The colonies of P. luminescens from all zones were found to be smooth, small, circular, and glistering, convex with entire margin and white with shiny in colour and primary form was turned into secondary form due to prolonged static incubation of the culture. Both the forms of P. luminescens from all five zones were long to medium rod shaped, gram negative, motile, bioluminescent bacterium. Primary form was more bioluminescent than the secondary form. The broth culture of P. luminescens isolate, Z-8-1 caused 100% nymphal mortality of Aphis gossypii after 24 hr. of exposure while the isolate Z-3-1 caused 100% mortality of T. macferlanei after 36 hr.s of exposure. However, these two isolates failed to infect DBM and leaf worms - S. litura (Fabr.).The present study indicates that plant sap feeders are susceptible to P. luminescens.