Insecticide Resistance Patterns and Mechanisms in Aedes aegypti (Diptera: Culicidae) Populations Across Abidjan, Côte d’Ivoire Reveal Emergent Pyrethroid Resistance

Abstract

From 2008 to 2017, the city of Abidjan, Côte d’Ivoire experienced several Aedes-borne disease epidemics which required control of the vector mosquito population based on the reduction of larval habitats and insecticidal sprays for adult mosquitoes. This study was undertaken to assess the insecticide susceptibility status of Aedes aegypti (Linnaeus) in the city of Abidjan. Immature Ae. aegypti were sampled from several larval habitats within seven communes of Abidjan and reared to adults. Three to five days old F1 emerged adults were tested for susceptibility using insecticide-impregnated papers and the synergist piperonyl butoxide (PBO) following WHO bioassay guidelines. The results showed that Ae. aegypti populations from Abidjan were resistant to 0.1% propoxur, and 1% fenitrothion, with mortality rates ranging from 0% to 54.2%. Reduced susceptibility (93.4–97.5% mortality) was observed to 0.05% deltamethrin, 0.75% permethrin, 0.05% lambda-cyhalothrin, 5% malathion, and 0.8% chlorpyrifos-methyl. This reduced susceptibility varied depending on the insecticide and the collection site. The restoration of mortality when the mosquitoes were pre-exposed to the synergist PBO suggests that increased activity of oxidases could be contributing to resistance. Three kdr mutations (V410L, V1016I, and F1534C) were present in populations tested, with low frequencies for the Leu410 (0.28) and Ile1016 (0.32) alleles and high frequencies for the Cys1534 allele (0.96). These findings will be used to inform future arbovirus vector control activities in Abidjan.

Multiple insecticide resistance and first evidence of V410L kdr mutation in Aedes (Stegomyia) aegypti (Linnaeus) from Burkina Faso

“…This mutation has previously been reported in the same locality at a frequency around 0.94 (Badolo et al, 2019). Elsewhere in Sub‐Saharan Africa, it has been reported since 2016 in Ghana (Kawada et al, 2016) and recently in Cote d'Ivoire (Konan et al, 2021), Cameroon (Yougang et al, 2020), Angola and Cape Verde (Ayres et al, 2020). This mutation is the most widespread and associated with both pyrethroid type I and II resistance (Moyes et al, 2017).…”

Semi-field evaluation of the space spray efficacy of Fludora Co-Max EW against wild insecticide-resistant Aedes aegypti and Culex quinquefasciatus mosquito populations from Abidjan, Côte d’Ivoire

“…Additionally, knocking down effects in both strains were faster with Fludora Co-Max EW than with K-Othrine EC. The reduction in Aedes and Culex Abidjan strain susceptibility and mortality to K-Othrine EC (deltamethrin being the only active ingredient) may be due to their resistance to pyrethroids [16][17][18], as reported on the island of Martinique in Marcombe et al [27]. However, the high effectiveness of Fludora Co-Max EW against the same insecticide-resistant mosquito strains may be explained by the mixture of two active ingredients, namely transfluthrin and flupyradifurone.…”

“…Recent studies detected three knockdown resistance ( kdr ) mutations (V410L, V1016I and F1534C) in the wild Ae. aegypti Abidjan populations, with low frequencies for Leu 410 (0.28) and Ile1016 (0.32) alleles and high frequency for Cys1534 allele (0.96) [18]. Aedes and Culex mosquito immatures (i.e.…”

“…Both mosquito Abidjan strains have shown varied resistance to insecticides; ranging from probable resistance and confirmed resistant to the insecticides (e.g. K-Othrine) usually used for their control in Côte d'Ivoire [16][17][18]. Recent studies detected three knockdown resistance (kdr) mutations (V410L, V1016I and F1534C) in the wild Ae.…”

“…quinquefasciatus populations are highly abundant [14,15], and resistant to many insecticides (e.g. deltamethrin, permethrin, lamdacyhalothrin, propoxur and fenitrothion) used for their control [16][17][18].…”