Toxicological and histological studies on the effect of spinosad or vinegar on Culex pipiens larvae (Diptera: Culicidae)

Abstract

Efficacy of Spintor® 24% SC (spinosad) and vinegar were studied to control Culex pipiens larvae by testing different concentrations of spinosad (10, 50, 100, 500 and 1000 µl/10 ml) or vinegar (125, 250, 500 and 750 µl/10 ml). The percentage mortality of larvae was increased by increasing concentrations and time. While 100 % mortality was obtained at the concentration 1000 µl/10 ml of spinosad after 48 h, in the case of vinegar treatment 100 % mortality was obtained at the concentration of 750 µl/10 ml after 72 h. Both spinosad and vinegar exhibited a histological effect on the midgut by degeneration of the epithelial cells, the disintegration of the plasma and basement membranes and extensive disruption of the cellular microvillar. Generally, spinosad manifested a higher level of activity against Cu. pipiens larvae than vinegar.