Levels of Insecticide Resistance to Temephos, and Associated Mechanisms in Culex pipiens Mosquitoes from Central Tunisia

Abstract

Five populations of Culex pipiens collected in central Tunisia were evaluated for their susceptibility to temephos. The resistance level was high for samples # 5 (>50-fold), and low, not exceeding 4-fold in the other resistant samples. LC 50 showed the susceptibility of sample # 2. The CYP450 enzyme was found related to temephos resistance in three samples. In fact, the addition of Pb to temephos bioassays completely suppressed the resistance in samples # 1 (RR 50 =0.84, p>0.05, RSR=3.0) and 5 (RR 50 =1.5, p>0.05, RSR=37.1). The temephos resistance level of sample # 3 decreased slightly (RR=1.9, p 75%) were recorded in the most susceptible samples. There is an urgent need to replace the insecticide temephos for continued control of Culex pipiens in Tunisia.