Hereditary Genetics: Current Research

Abstract

Evaluation of Chlorpyrifos Resistance and Biochemical Mechanisms of Culex pipiens in Five Localities of Grand Tunis Area, Northeast Tunisia

Jaber Daaboub, Ahmed Tabbabi, Ali Lamari, Raja Ben Cheikh, Ibtissem Ben Jha and Hassen Ben Cheikh

Five Culex pipiens samples were collected at preimaginal stages from breeding sites in 5 localities of Grand Tunis area, Northeast Tunisia, between March 2002 and November 2005. Larvae were used for bioassays using ethanol solutions of chlorpyrifos and propoxur insecticides. All samples were resistant to chlorpyrifos (RR>1, p<0.05). The highest resistance levels (>1,000-fold) were recorded in samples # 2, 4, and 5. Our synergist study showed that the increased detoxification by EST (and/or GST) had only a minor role in the chlorpyrifos resistance, although several overproduced esterases, known to be involved in the OPs resistance, were detected in all the resistant field samples. The mortality due to propoxur was significantly correlated with the LC50 of chlorpyrifos and indicated an insensitive AChE.