First detection of N1575Y mutation in pyrethroid resistant Anopheles gambiae in Southern Côte d’Ivoire

Abstract

<b>Background.</b> The intensification of insecticide use for both public health and agriculture in Africa has contributed to growing insecticide resistance. Today, resistance to World Health Organization (WHO)-approved insecticide classes is widespread. In an agricultural area of Southern Côte d'Ivoire, the main malaria vector <i>Anopheles coluzzii</i> shows multiple resistance across insecticides mediated by both target site mutation and metabolic mechanisms. To plan new vector control strategies and avert future resistance liabilities caused by cross-resistance mechanisms extant within populations, it is crucial to monitor the development and spread of both resistance and mechanisms. <b>Methods.</b> Larvae of <i>Anopheles gambiae</i> were collected from natural breeding sites in Tiassalé and Elibou, between April and November 2016 and raised to adults <b>.</b> Adult female non-blood fed mosquitoes, three to five days old, were exposed to deltamethrin in WHO bioassays. Extracted DNA samples from exposed mosquitoes were used for species characterisation and genotyping. <b>Results.</b> Most adult <i>An. gambiae</i> tested were resistant to deltamethrin, with mortality rates of only 25% in Tiassalé and 4.4% in Elibou. Molecular analysis of DNA from samples tested showed the presence of both <i>An. coluzzii</i> and <i>An. gambiae s.s</i> in Elibou and only <i>An. coluzzii</i> for Tiassalé. As previously, the L1014F <i>kdr</i> mutation was present at high frequency (79%) in Tiassalé and the L1014S mutation was absent. The N1575Y mutation, which amplifies resistance conferred by L1014F was detected in a single unique individual from a Tiassalé <i>An. coluzzii</i> female whereas in Elibou 1575Y was present in 10 <i>An. gambiae</i> s.s, but not in <i>An. coluzzii</i>. <b>Conclusion.</b> This is the first report of the N1575Y mutation in Côte d'Ivoire, and as in other populations, it is found in both dominant West African malaria vector species. Continued monitoring of N1575Y is underway, as are studies to elucidate its contribution to the resistance of local vector populations.