Response of Helicoverpa armigera (Hubner) to Different Insecticides in Akola Region (Maharashtra)

The failures in field control of Helicoverpa armigera (Hubner) in various localities of the country have been attributed to the changing response of this pest to different insecticides. Studies conducted during 1998–2000 at Akola (Maharashtra) revealed seasonal variations in response of H. armigera populations of this region to three different groups of insecticides viz. cypermethrin (pyrethroid), endosulfan (cyclodiene) and quinalphos (organophosphate). The comparative resistance levels in terms of LD₅₀ values revealed more resistance by Helicoverpa populations to cypermethrin (1.27 fold) and quinalphos (1 20 fold) during 1998–99 than 1999–2000 whereas for endosulfon, the resistance (0 97 fold) was higher during 1999–2000 than previous season.