Persistent toxicity of selected insecticides on cowpea aphid, Aphis craccivora (Koch)

The persistent toxicity of commercial formulations of seven selected insecticides was conducted against cowpea aphid A. craccivora, using pot culture in the green house of Department of Entomology, College of Agriculture, Rajendranagar, and PJTSAU. Of different treatments, highest persistence was shown by the imidacloprid (19 and 20 days) followed by acetamiprid (15 and 16 days) > dimethoate (13 and 14 days) > thiamethoxam (11 and 19 days) > diafenthiuron, spiromesifen and chlorfenapyr (9 days each and 10 days each) at 24 and 48 hours of exposure, respectively. The PT (product of toxicity) of test insecticides were in the order: Imidacloprid, acetamiprid, dimethoate, thiamethoxam, diafenthiuron, spiromesifen and chlorfenapyr at 24 and 48 hours, respectively, which indicated that imidacloprid was more persistent followed by acetamiprid and dimethoate than the remaining insecticides.