Field efficacy of Helicoverpa armigera nucleopolyhedro-virus isolates against H. armigera (Hübner) (Lepidoptera: Noctuidae) on cotton and chickpea in Tamil Nadu

Field efficacy of seven geographical isolates of Helicoverpa armigera nucleopolyhedrovirus (HaNPV) along with an insecticide control was evaluated against H. armigera on cotton and chickpea in the Coimbatore district of Tamil Nadu, India. Among the HaNPV isolates, CBE I (Coimbatore) and NEG (Negamum) applied at 3.0 × 1012 POB/ha to cotton and 1.5 × 1012 POB/ha to chickpea with an adjuvant, crude sugar, significantly reduced the H. armigera larval population and increased the yield. CBE I and NEG recorded the highest yield of 2038 kg/ha and 2033 kg/ha, which was on a par with endosulfan (2026.7 kg/ha) with cost/benefit ratios of 1:2.32, 1:2.48, and 1:1.12, respectively, on cotton. In chickpea grain yields of 980, 983, and 973.3 kg/ha and cost/benefit ratios of 1:1.36, 1:1.48 and 1:0.87, respectively, in CBE I, NEG and endosulfan treated plots were obtained. The isolate RAJ (Rajasthan) recorded the lowest yield comparable to that of the untreated control in both crops.