Persistence of Insecticides Against Sitophilus oryzae (L.) on Wheat

The present investigation was undertaken to study the persistence of different insecticides as seed treatment against rice weevil. The insecticide treated wheat seeds were exposed at monthly interval to the infestation by rice weevil Sitophilus oryzae to test the persistence of insecticides. The mortality of insect due to the toxicity of insecticides and adult emergence were the main criteria for testing the persistence of different insecticides. Persistence of insecticides on rice weevil, S. oryzae in storage condition revealed that among different insecticides Spinosad and Deltamethrin were found to be most effective and provided protection up to 6 months of storage period based on probit analysis, malathion and fenvelerate were found to be least effective which did not give protection for longer duration. Among all insecticides deltamethrin @ 3 ppm and 2.5 ppm recorded lowest adult emergence of Sitophilus oryzae. Malathion @ 20 ppm recorded highest population build up.