Status of Resistant and Knockdown of West Nile Vector, Culex pipiens Com-plex to Different Pesticides in Iran

Abstract

Background: West Nile virus (WNV) can cause a fatal disease in humans and it is mainly transmitted to people through the bites of infected mosquitoes. Vector control using insecticides is a very important goal. Study of Culex pipiens re­sistance towards several insecticides in the city of Tehran, Iran was evaluated.

Methods: Adult females reared from field-caught larvae from southern part of Tehran and lab strain reared in the insec­tary of Tehran University of Medical Science were determined for resistant status by exposing to 4% DDT, 0.1% bendi­ocarb, 0.1% propoxur, 1% fenitrothion, 0.05% deltamethrin, 0.75% permethrin, 0.05% lambda-cyhalothrin, 0.5% etofenprox, 5% malathion and 0.15% cyfluthrin papers using the standard WHO susceptibility tests.  

Results: Results clearly showed resistance development of Cx. pipiens against tested insecticides. Mortalities of Cx. pipiens were less than 90% with high resistance, low knock down rate and knock down time (50%) observed against insec­ti­cides. DDT and Malathion showed the most and least lethal time (LT₅₀) values for the field strain. The results of the knock­down test showed that DDT and deltamethrin had the most and least knockdown times (50%) for the field strain, re­spec­tively, while DDT and lambda-cyhalothrin had the most and least knockdown times (50%) for the lab strain, respectively.

Conclusion: Resistance to mentioned insecticides in Cx. pipiens is widely distributed in southern part of Tehran. Regu­lar implementation of susceptibility test in Cx. pipiens mosquitoes will help local public health authorities to develop new and better control strategies.