1International Crops Research Institute for the Semi-Arid Tropics, Patancheru-502324, Andhra Pradesh.
2Acharya N.G. Ranga agricultural University, Agricultural College, Bapatla, Andhra Pradesh.
Comparative virulence of six isolates of HaNPV was assessed through concentration-mortality responses of second and third instar larvae of Helicoverpa armigera by diet surface contamination method. Concentration-mortality response against third instar on 9th day showed that the ICRISAT-HaNPV isolate was most promising with lower lethal concentration at 50% mortality (LC50) value of 1.5×103 POB/ml followed by GAU-HaNPV (1.9×103 POB/ml), PAU-HaNPV (2.26×103 POB/ml), TN-HaNPV (2.3×103 POB/ml), AK-HaNPV (3.1×103 POB/ml) and UASD-HaNPV (3.7×103 POB/ml). Observations with second instar also showed similar trend, whereas ICRISAT-HaNPV found superior with lower LC50 value of 3.25x102 POB/ml followed by GAU-HaNPV (3.43×102 POB/ml), PAU-HaNPV (5.28x102 POB/ml), TN-HaNPV (7.33×102 POB/ml), AK-HaNPV (8.18×102 POB/ml) and UASD-HaNPV (9.99×102 POB/ml). The six HaNPV isolates were purified and morpho-physical characters were compared in by electron microscopy and SDS-PAGE. Results of this study will be discussed.