First report of the East African kdr mutation in an Anopheles gambiae mosquito in Côte d’Ivoire

Abstract

<b>Background</b>. The intensive use of insecticides in public health and agriculture has led to the development of insecticide resistances in malaria vectors across sub-Saharan Africa countries in the last two decades. The <i>kdr</i> target site point mutation which is among the best characterised resistance mechanisms seems to be changing its distribution patterns on the African continent. The 1014F <i>kdr</i> mutation originally described only in West Africa is spreading to East Africa while the 1014S <i>kdr</i> mutation originally described in East Africa, is spreading to West and Central Africa. However, the East-<i>kdr</i> mutation has not been reported in Côte d'Ivoire so far. <b>Methods</b>. Immature stages of <i>Anopheles gambiae s.l.</i> were collected from breeding sites at the outskirts of Yamoussoukro, Côte d'Ivoire. Emerging 3-5 day old adult female mosquitoes were tested for susceptibility to deltamethrin 0.05%, malathion 5%, bendiocarb 1% and dichlorodiphenyltrichloroethane (DDT) 4% according to WHO standard procedures. A total of 50 <i>An. gambiae s.l.</i> specimens were drawn at random for DNA extraction and identification down to the species level. A subsample of 30 mosquitoes was tested for the East-African <i>kdr</i> mutation using a Taqman assay. <b>Results</b>. The tested mosquito population appeared to be strongly resistant to deltamethrin (1.03% mortality), bendiocarb (38.46% mortality) and DDT (0% mortality) with probable resistance observed for malathion (92.47%). Among the 41 mosquitoes that were successfully characterized, <i>An. coluzzii</i> was predominant (68.3%) followed by <i>An. gambiae</i> <i>s.s.</i> (19.5%) and a few hybrids (7.3%). Out of 30 specimens genotyped for East-<i>kdr</i>, a single hybrid mosquito appeared to be heterozygous for the mutation. <b>Conclusion</b>. The present study revealed the presence of the East-<i>kdr</i> mutation in Côte d'Ivoire for the first time in <i>An. gambiae</i> and highlights the urgent need to start monitoring the allele and genotype frequencies.