Susceptibility Status of Helicoverpa armigera Hub. to some Synthetic Insecticides and Neem Seed Kernel Extract as Influenced by Host Plant

Bioassay studies against Helicoverpa armigera for determining toxicity of endosulfan, monocrotophos, fenvalerate, dimethoate and neem seed kernel extract (NSKE) at different concentrations and exposure period (24 to 72 h) revealed that on pigeonpea fenvalerate registered lower value of LC₅₀ in comparison to other insecticides. Fenvalerate and monocrotophos proved 3.903 and 1.019 times more toxic than endosulfan, respectively, whereas, dimethoate was found less toxic. LT₅₀ value was lowest (42.92 d) and highest (136.83 d) for dimethoate and fenvalerate at 0.08 and 0.005% concentration, respectively, on chickpea. More or less similar trend was also observed on pigonpea.