Effects of Alphacypermethrin selection on fitness traits of Culex quinquefasciatus (Diptera: Culicidae)

Abstract

Culex quinquefasciatus Say 1823 (Diptera: Culicidae), a vector of lymphatic filariasis and various arboviruses, is the most abundant mosquito owing to its breeding capacity in polluted stagnant water. Alphacypermethrin (C₂₂H₁₉Cl₂NO₃) is a highly effective synthetic pyrethroid insecticide, used for the management of agricultural pests as well as vector control. In this study, two strains of Cx. quinquefasciatus were reared in the laboratory with the same genetic background, one strain was selected against alphacypermethrin (AS) and another strain was devoid of insecticide treatment and reared as susceptible (S) for 15 generations. It was observed that the sub-lethal exposure to insecticide led to a low fecundity rate, less hatchability, longer larval developmental time, low pupation rate, and less emergence rate but no significant differences in sex ratio. AS strain showed 37.4-fold, 2.85-fold, fivefold, and 8.6-fold higher activity in comparison to S strain in monooxygenases, alphaesterases, betaesterases, and glutathione-S-transferases activity respectively, implying the role of detoxifying enzyme in metabolic resistance development. This study was conducted to elucidate the sub-lethal effects of insecticide on the life history traits of the exposed strain and their association with metabolic resistance which would ultimately help to design vector control programs against insecticide resistance.