Insecticide resistance to Temephos and synthetic Pyrethroids in Culex quinquefasciatus say from sub-Himalayan West Bengal, India

Abstract

Culex quinquefasciatus Say is a vector for lymphatic filariasis in human populations throughout the world. Vector control, a major strategy for eradication of filariasis mainly involves the application of chemical insecticides giving rise to resistance against insecticides. In this context, a study was conducted to find out the resistance status of Cx. quinquefasciatus populations from seven densely populated sites in Siliguri sub division, West Bengal. Larval bioassay against temephos and adult bioassay against 5% malathion, 0.05% deltamethrin and 0.05% lambdacyhalothrin was performed following the standard WHO protocol. A total of 630 larvae and 360 adults were tested from one sampling site. The activity of major insecticide detoxifying enzymes i.e., carboxylesterases and monooxygenases was also assessed through biochemical assay. The seven tested populations were found to exhibit moderate to severe resistance (27.27% - 83.33% mortality) against deltamethrin, lambdacyhalothrin and temephos. However, all of the seven populations were found to be completely susceptible to malathion. This study provides new information on the current status of insecticide resistance in Cx. quinquefasciatus from this area, which may be helpful to the concerned authorities to design an effective mosquito control strategy for efficient management of vector-borne diseases.