Response of Cotton Bollworm Helicoverpa armigera (Hubner) (Lepidoptera:noctuidae) to Different Insecticides in Maharashtra, India

This study deals with Insecticide Resistance Management of cotton bollworm Helicoverpa armigera to five commonly used insecticides on cotton were carried out during 2008. In August, LD value for 50 chlorpyriphos varies from 0.046μg/larva in Parbhani district to 0.172 mg/larva during October in Aurangabad district. Resistance to chlorpyriphos was highest in Aurangabad district (3.65-8.25 fold) followed by Parbhani district (2.15-7.55 fold). In Jalna district, a maximum LD value of 0.070μg/larva was observed for quinalphos 50 in October with a minimum of 0.025 mg/larva in August. Resistance to quinalphos was greatest in Jalna (2.50-7.00 fold) followed by Aurangabad (3.0-5.0 fold) and Parbhani (3.7-4.9 fold). The LD value for 50 cypermethrin was highest, during October (1.459 mg/larvae in Aurangabad) and lowest during August in Parbhani (0.157 μg/larva). Resistance to cypermethrin increased from the same throughout the three districts over the time. Resistance to endosulfan showed an increasing trend as the season progressed and was greatest in Jalna (3.10-9.15 fold) followed by Aurangabad (3.92-8.25 fold) and Parbhani (1.93-6.93 fold).