Evaluation of toxicological responses of Helicoverpa armigera (Hübner) against some insecticides by using probit analysis in laboratory

The present study was designed to determine the LC50 of some insecticides commonly used against Helicoverpa armigera and their comparative efficacy against the insect pest. The second instar larvae of H. armigera reared in the laboratory were selected for leaf dip bioassay. Two types of insecticides viz. conventional (deltamethrin and bifenthrin) and new chemistry (spinosad and indoxacarb) were assessed in the present studies. The results revealed that bifenthrin was more toxic to the second instar larvae of H. armigera at all the doses with lower LC50 value of 120.007 ppm as compared to deltamethrin with the highest LC50 value of 292.404 ppm. Among the new chemistry insecticides, indoxacarb proved to be more toxic than spinosad with LC50 of 5.592 ppm. LC50 of spinosad was 8.201 ppm showing 1.46 times less toxicity than indoxacarb.