Resistance of Culex pipiens (Diptera: Culicidae) to Chlorpyrifos Insecticide in Central Tunisia
Field populations collected as larvae in five localities of central Tunisia were used to study the resistance to chlorpyrifos insecticide. The resistance levels exceeded 10,000 folds in samples # 3 (Centre East), and 5 (West Centre) not exceeding 5-fold in samples # 4 (Centre East). Our result showed that detoxification by oxydases, EST and/or GST was responsible, at least in part, in resistance to chlorpyrifos in samples # 1, 3, and 5. Different esterases were detected in all studied samples. Except A2B2 who recorded high frequencies ranged from 22% to 28%, all other detected esterases showed low percentages. Mortality caused by propoxur was very low in samples showed the highest resistance (# 3, and 5) and high in samples showed lowest resistant (# 1, 2, and 4) indicated an insensitive AChE 1. Our results of the resistance of Culex pipiens to chlorpyrifos in central Tunisia are consistent with those found in the literature. These data will help to better plan and program the vector control in Tunisia.