INTEGRATED APPROACHES FOR IMPROVING CERTAIN INSECTICIDES TOXICITY AGAINST Sitophilus oryzae and Tribolium castaneum

摘要

The effect of temperature and light on the insecticidal activity of the pyrethroid insecticide, permethrin and organophosphorus insecticides, pirimiphos-methyl and malathion was assessed against the rice weevil, Sitophilus oryzae (L.), and the red flour beetle, Tribolium castaneum (Herbst). Malathion is being used as a recommended insecticide against the stored product insects. Permethrin showed higher effect, to both insects, at 20°C than those of 30°C or 5°C. However. pirimiphos-methyl and malathion were more toxic at 30°C. The susceptibility of S. oryzae was greater than T, castaneum to the tested insecticides. The tested insecticides were more toxic to such insects after exposure to light at the optimum temperature for each of these insecticides, Mixing pipttronyl butoxide (PB) with the tested insecticides resulted in an increase in their toxicity against both insects at optimum temperature for each of the tested insecticides. Also, the combinations of permethrin, at its optimum temperature(20°C). with each of tri-o-cresyl phosphate (TOCP) for certain academic purposes only, malathion and pirimiphos-methyl resulted in potentation of the toxicity of permethrin against the tested insects.