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Status of Anopheles gambiae Resistance to Carbamates and Organophosphates Insecticides and Implication on Malaria Vector Control in Cote D’ivoire

Toure Mahama, Djogbenou Luc, Yapi Gregoire and Toure Donatie Serge

The current survey was carried out from February to May 2012 in eight locations in Cote d Ivoire. It aims to investigate the levels of resistance of field Anopheles gambiae populations to carbamates and organophosphates for future potential combined using of these insecticides with pyrethroids ones in malaria vector control based up on insecticide treated nets.

Bioassays performed with two carbamates showed high mortality rates solely to 0.4% bendiocarb in Zouan-Hounien and to 0.1% propoxur in Tiassale; 99% and 91%, respectively. With organophosphates, only mosquitoes from Zouan-Hounien showed again a high mortality rate (100%) to 1% fenitrothion. In comparison, mosquitoes’ mortalities in study sites were high with 0.4% chlorpyrifos-methyl.

Investigations in the G119S mutation revealed that the frequencies of the resistant allele (ace-1R) in field A. gambiae populations were low, varying from 0 in Zouan-Hounien to 0.52 in Bouaké (Yaokoffikro). Hardy-Weinberg equilibrium or disequilibrium in all the populations analyzed showed Fis (W&C) <0, indicating systematic exceed of heterozygous individuals at the ace-1 locus.

The low frequencies of the ace-1R in field A. gambiae revealed that the G119S mutation is not the main mechanism involved in resistance to carbamates and organophosphates in Côte d’Ivoire.