Evaluation of selected insecticides as seed protectants against the maize weevil (Sitophilus zeamais M.).

An investigation was carried out to evaluate the relative toxicity of selected newer insecticides viz., deltamethrin, spinosad, abamectin and emamectin benzoate in comparision with the organophosporus insecticide malathion to the maize weevil, Sitophilus zeamais Motschulsky, in an attempt to find out a safer and effective seed protectant. The LC50 values based on bioassay studies indicated that among the test insecticides, deltamethrin exhibited greater toxicity both at 24 and 48 hours of exposure. The relative toxicity of deltamethrin, abamectin, spinosad, and emamectin benzoate were 1.06, 1.005, 0.07 and 0.01 at 24 hours and 1.18, 1.08, 0.11 and 0.02 at 48 hours of exposure compared to check malathion.