Pesticide Research Journal

Malathion, dichlorvos and phosphine resistant Machilipatnam strain of C. ferrugineus hah dedeloped cross-resistance to fenitrothion, profenofos (47.0 and 3.7 folds at LC_99.9) and multiple resistance to carbaryl and deltamethrin (6.8 and 4.8 fold at LC_99.9) in comparison with susceptible or less resistant Charlapalli strain. Synergism due to PBO was found in malathion (SF 7.08), dichlorvos (SF 1.93), profenofos (SF 1.64) and deltamethrin (SF 5.04) at LC_99.9 level. Except in the case of deltamethrin, the synergistic factors were less than the corresponding resistance factors revealing the possibility of some other mechanisms of resistance in addition to the detoxification mechanism by MFO.