Toxicity of 25 synthetic insecticides to the field population of Culex quinquefasciatus Say

The Culex quinquefaciatus Say, commonly known as the southern house mosquito, is well known for biting nuisance and vectoring of some fatal diseases. Synthetic chemicals have been relied upon as the major control measure to control mosquitoes. Therefore, we have evaluated 21 insecticides belonging to different chemical classes for their toxicity to C. quinquefaciatus females. Chlorfenapyr was the most toxic adulticide among all the tested insecticides. Among pyrethroids, deltamethrin was the least toxic adulticide, and all other have same toxicity. In case of organophosphates, the chlorpyrifos was the most toxic insecticide. Neonicotinoids such as acetamiprid, nitenpyram, and clothianidin have similar toxicity based on overlapping of 95 % confidence intervals (CI) and were more toxic when compared with the imidacloprid. The spinetoram was more toxic as compared with the spinosad (based on non-overlapping 95 % Cl). In case of ketoenoles, spirotetrament was more toxic as compared with the spiromesifen. Emamectin benzoate was the most toxic insecticide when compared with fipronil and indoxacarb. We also have tested four insect growth regulators (IGRS) including lufenuron, methoxyfenozide, pyriproxyfen, and cyromazine as larvicides. The lufenuron and pyriproxyfen have similar toxicity based upon their overlapping 95 % CI and were more toxic as compared with the methoxyfenozide and cyromazine. The methoxyfenozide was the moderately toxic among all the tested IGRS, and cyromazine was the least toxic among all the tested IGRS. These results will prove helpful in effectuating an effective integrated vector management program for C. quinquefaciatus.