The Combined Efficacy of Malathion and Spinetoram against Three Stored Product Insects

Abstract

The effectiveness of malathion and spinetoram alone and in binary combinations was investigated against the adults of Sitophilus oryzae (L.), Rhizopertha dominica F. and Tribolium castaneum (Herbst.). The obtained results showed that, the toxicity of each insecticide to the adults of the three insect species was concentration and exposure period-dependent. Adults of S. oryzae were highly susceptible to malathion alone but, R. dominica and T. castaneum adults were the least susceptible to the insecticide .While R. dominica adults were higher susceptible to spinetoram alone than the two other species. Co-toxicity values resulted from adding LC 10 of spinetoram to various malathion concentrations showed a potentiation effects on the adults of T. castaneum at all concentrations of malathion, on R. dominica at the three lowest concentrations and at the lowest concentration(0.25ppm) only on the adults of S. oryzae. Meanwhile an additive effect was achieved with other concentrations of malathion and LC 10 of spinetoram against the three tested insect species.A complete protection for stored wheat seeds was achieved with the Six tested mixtures(Mix 1-Mix 6) against adults of S. oryzae and R. dominica up to 6 months. Also, the same effect extended against T. castaneum adults to 5, 4 and 2 months with Mix 1 , each of (Mix 2 and Mix 3) and Mix 4 ,resp. Contrarily, Mix 5 , Mix 6 failed to give a complete mortality for T. castaneum adults at all various intervals(months). Data concluded that, stored wheat seeds treated with Mix 3 (4ppmM+5ppmSm) or Mix 4 (4ppm M+4ppm Sm) were protected against the three insects infestation for 3months.

Impact of Malathion and Lufenuron Alone and Their Mixtures against Trogoderma granarium Larvae

“…Synergism was shown between (OP) and Pyrothriods and combinations of insecticides with other substances were evaluated against stored product insects (Bengston et. al, 1987;Nasr, 2017 andYasir 2019).…”