Persistent Toxicity of Malathion and Dichlorvos on Jute Surface Against Tribolium castaneum (Herbst)

Persistent toxicity of malathion 50 EC and dichlorvos 76 EC was studied on jute surface @ 100, 150, 250, 350 and 450 mg a.i./m² against susceptible and malathion resistant strains of Tribolium castaneum for six months. Malathion did not show any mortality after 2 days against malathion resistant strain at all the five doses and after 30 days, no mortality was observed at 100, 150 and 250 mg a.i./m² against susceptible strain whereas dichlorvos gave absolute mortality up to 60 days against S strain, and up to 30 days in MR strain at all the doses. This indicated that dichlorvos could be used as prophylactic treatment against malathion resistant strain insects.