Insecticide Resistance Status of Aedes aegypti Adults and Larvae in Nouakchott, Mauritania

<i>Aedes aegypti</i> mosquitoes are established throughout Nouakchott, Mauritania, where its insecticide resistance status is unknown and dengue has become endemo-epidemic since 2014. Eggs were collected using ovitraps at 12 sites in five districts of Nouakchott, in August 2024. Adult females and larvae of the F1 generation were used for bioassays. Permethrin, deltamethrin, bendiocarb, and malathion were evaluated at discriminating concentrations. Larval assays were carried out at seven concentrations with <i>Bacillus thuriengensis</i> var <i>israelensis</i> (<i>Bti</i>) and temephos. The presence of knockdown resistance (<i>kdr</i>) mutations known to be associated with pyrethroid resistance was assessed by polymerase chain reaction and amplicons sequencing. Adults showed high levels of resistance to all insecticides tested. Larvae were susceptible to <i>Bti</i> (LD50 < 50 µg/L) and temephos (LD50% = 6.8 ± 0.7 µg/L). Only three <i>kdr</i> point mutations, S989P, V1016G, and F1534C, were found. The tri-locus genotypes SP/VG/FC were significantly associated with pyrethroid survival while only the tri-locus genotypes PP/GG/FF showed significant association with deltamethrin resistance. Given their level of insecticide resistance, there is an urgent need to control <i>Ae. aegypti</i> populations by several methods, including the use of biological larvicides, physical elimination of peridomestic breeding sites, water drainage, and public education to prevent arbovirus transmission.