Resistance Levels in Pulse Beetle Callosobruchus Maculatus (F.) to Malathion and Deltamethrin

An experiment was conducted to estimate the degree of resistance to malathion and deltamethrin acquired by three populations of Callosobruchus maculatus from Ghantasala, Darsi and Lam. These were compared with the susceptible strain at the Post Harvest and Technology Centre, Bapatla, Andhra Pradesh during 2016–17. All the three populations were observed to show reduced susceptibility to both malathion and deltamethrin. However, the Ghantasala population showed moderate to high degree of resistance to malathion (136.83 folds) and deltamethrin (32.04 folds) at LC₅₀. These results indicate that the populations are subjected to constant selection pressure to these insecticides which are being routinely used on scheduled basis in the seed storage.