Djogbénou Luc auteur aut IRD Labbe P. auteur aut IRD Chandre Fabrice auteur aut IRD Pasteur N. auteur aut IRD Weill M. auteur aut IRD text journalArticle eng text/pdf reformatted digital access Background: Insecticide resistance is a rapid and recent evolutionary phenomenon with serious economic and public health implications. In the mosquito Anopheles gambiae s.s., main vector of malaria, resistance to organophosphates and carbamates is mainly due to a single amino-acid substitution in acetylcholinesterase 1 (AChE1). This mutation entails a large fitness cost. However, a resistant duplicated allele of the gene encoding AChEI (ace-1), potentially associated to a lower fitness cost, recently appeared in An. gambiae. Methods: Using molecular phenotype data collected from natural populations from West Africa, the frequency of this duplicated allele was investigated by statistical inference. This method is based on the departure from Hardy-Weinberg phenotypic frequency equilibrium caused by the presence of this new allele. Results: The duplicated allele, Ag-ace-1(D), reaches a frequency up to 0.65 in Ivory Coast and Burkina Faso, and is potentially present in Benin. A previous study showed that Ag-ace-1(D), present in both M and S molecular forms in different West Africa countries, was generated by a single genetic event. This single origin and its present distribution suggest that this new allele is currently spreading. Conclusion: The spread of this less costly resistance allele could represent a major threat to public health, as it may impede An. gambiae control strategies, and thus increases the risk of malaria outbreaks. specialized 052 8 70 2009 1475-2875 https://www.documentation.ird.fr/hor/fdi:010046111 10.1186/1475-2875-8-70 1475-2875 [F B010046111] https://www.documentation.ird.fr/hor/fdi:010046111 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers17-09/010046111.pdf IRD - Base Horizon / Pleins textes 2009-07-08 2018-12-07 fdi:010046111 fre