Acute toxicity of Different Insecticides against Helicoverpa armigera (Hubner) in Punjab

Five insecticides were tested for their relative toxicity against third instar larvae (30–50 mg) of Helicoverpa armigera (Hubner) on cotton using leaf disc dip bioassay technique. The LC₅₀ values for spinosad, chlorpyriphos, endosulfan, acephate and cypermethrin were 0.4, 6.6, 80.4, 629.0, and 2087.0 µg ml⁻¹, respectively, indicating that spinosad was highly effective followed by chlorpyriphos. Cypermethrin and acephate were ineffective in controlling H. armigera, whereas, endosulfan was intermediate in this respect.