Insecticide resistance, mechanisms and gene flow in Culex quinquefasciatus from West Africa Proceedings of the 2nd international conference on insect pests in the urban environment /Chandre, Fabrice /Darriet, Frédéric Doannio, J.M.C. Pasteur, N. /Guillet, Pierre ENTOMOLOGIE MEDICALE INSECTICIDE CHIMIQUE RESISTANCE VARIABILITE GENETIQUE POLYMORPHISME ENZYMATIQUE Larval susceptibility to organophosphates (OP), carbamates (CARB) and pyrethroids (PYR) was investigated in Culex quinquefasciatus from Côte d'Ivoire and Burkina Faso. A total of 33 populations collected in 25 cities were tested. The resistance of these natural field populations was compared to a susceptible reference strain under the same conditions. In Côte d'Ivoire, populations showed a heterogeneous response to OP and CARB. A range of 40 %-98 % of larvae had a low resistance level to both chlorpyrifos (2-8x) and propoxur (1-4x). The remaining 2 % to 60 % of larvae displayed a high level of cross-resistance between chlorpyrifos (15-30x) and propoxur (>700x). Biochemical studies showed that low level resistance to OP was due to A2-B2 overproduced esterases and that cross-resistance to OP and CARB was conferred by an insensitive acetylcholinesterase (AChE). This AChE provided a lower resistance to temephos (10x). In Burkina Faso, populations were slightly resistant to OP (1-3x) and not to CARB. The esterases A2-B2 were only present at 50 % frequency. In contrast, PYR-resistance was similar between the two countries. All populations were resistant to either permethrin (20-80x) and deltamethrin (15-40x). Bioassays using piperonyl butoxide (PB) and biochemical studies showed that PYR-resistance involved increased metabolism by mixed function oxidases. Knowing that synergism of PB did not completely suppress resistance and that adults did not show a knockdown effect with high permethrin concentrations, it is likely that PYR-resistance was also due to a Kdr gene. (Résumé d'auteur) BPC Weatons Wildey, K.B. (ed.) 1996 text https://www.documentation.ird.fr/hor/fdi:010007010 fdi:010007010 Chandre Fabrice, Darriet Frédéric, Doannio J.M.C., Pasteur N., Guillet Pierre. Insecticide resistance, mechanisms and gene flow in Culex quinquefasciatus from West Africa. In : Wildey K.B. (ed.), . Proceedings of the 2nd international conference on insect pests in the urban environment BPC Weatons, 1996, 640 Insect Pests in the Urban Environment : International Conference, 2., Edinburgh (GBR), 1996/07/07-10 EN COTE D'IVOIRE BURKINA FASO