Bioresidual effect of two insecticides on melon aphid Aphis gossypii Glover (Homoptera: Aphididae) and its parasitoid Aphidius colemani Verick (Hymenoptera: Brachonidae).

摘要

Bioresidual effects of two insecticides, cypermethrin and chlorpyrifos, were studied using Aphis gossypii and its parasitoid Aphidius colemani that grown on water melon plants under laboratory conditions. A total of 135 water melon plants were used in different treatments to study the direct and indirect effects of the two insecticides on both aphid adults and parasite as adult and as pupa inside aphid mummies. The application rate of the insecticides was 0.125 ml/0.25 L for cypermethrin and 0.25 ml/0.25 L for chlorpyrifos. 100% mortality of aphid was obtained using chlorpyrifos when aphid introduced to plants at same day of spray, while cypermethrin produced 81.6% aphid mortality. chlorpyrifos revealed longer period of plant protection against aphid infestation for about two weeks more than cypermethrin. For Integrated Pest Management program of A. gossypii by using the parasitoid A. colemani, cypermethrin showed a high survival percentage for parasitoid when introduced 72 hr after spraying; while chlorpyrifos was severely harmful to the parasitoid adults and parasitoid pupae in aphid mummies at all post-spraying introducing periods.