Evaluation of Adjuvants on Enhancing the Bioefficacy of Hear NPV Against Helicoverpa armigera (Hubner) in Pigeonpea and Field Bean

Helicoverpa armigera (Lepidoptera, Noctuidae) is polyphagous insect pest of pigeonpea and field bean crop causing yield losses of 10–90%. Chemical control has led to insecticide resistance and environmental concerns, making biological control with nucleopolyhedrovirus (NPV) a viable alternative. For effective infection, larvae must ingest sufficient virus before it is degraded by environmental factors. To improve NPV efficacy, adjuvants possessing phagostimulant properties were tested under field conditions. In both pigeonpea and field bean the treatments with adjuvants has shown significant differences in reducing the larval population which was on par with the chemical treatment and also enhancing the yield of the crops. The treatment T1 (HearNPV + Glycerol 0.1%) showed the highest larval reduction (1.17 and 1.43 larvae) and yield (13.25 and 12.95 q/ha), followed by Emamectin benzoate (1.32 and 1.23 larvae), (12.33 and 13.67q/ha). The untreated control had the highest larval count (2.40, 2.59 larvae) and lowest yield (6.67 and 7.33 q/ha) respectively in pigeonpea and field bean crop. Thus, adjuvants played a vital role in retaining the persistence of HearNPV and enhanced yield of crops.