Cross-Resistance to Pyrethroid and Organophosphorus Insecticides Induced by Selection with Temephos in the Potential Mosquito Vector of West Nile Virus (Culex Pipiens) from Tunisia

A sample of Culex pipiens from Northwestern Tunisia, North Africa, with a high level of temephos resistance, was subjected to temephos selection to evaluate the utility of this organophosphate insecticide for mosquito control. High resistance developed after three generations of selection (52x). High cross-resistance was observed for the pyrethroid permethrin (32x). Synergism tests showed the implication of cytochrome P450 monooxygenases but not of esterase in temephos and permethrin resistance. Pyrethroid resistance could be associated with a cytochrome P450 monooxygenases and/or glutathione-S-transferase mechanism but not the esterases. The cross-resistance to permethrin from temephos selection could limit the use of both insecticides for Culex pipiens control.