Involvement of p-glycoprotein in insecticide toxicity to Culex pipiens mosquitoes and implications for control programmes

Pesticide resistance has parallels with multidrug resistance syndrome in clinical medicine, which has been linked to an ATP-dependent pump, p-glycoprotein (P-gp). P-gps pump drugs out of the cell, thereby reducing cellular concentrations of the chemical. P-gps have been found in several invertebrate species and have been shown to provide a defence against environmental xenobiotics, including pesticides. This study was to determine whether i) P-gps were found in Culex pipiens mosquitoes and ii) whether P-gps regulated pesticide toxicity. Western blotting revealed that a P-gp monoclonal antibody (C219) bound to an 85kDa protein in C. pipiens larvae. The P-gp modulator verapamil increased toxicity to endosulfan but not to chlorpyrifos. The implications of these results are discussed.