Species composition and insecticide resistance in malaria vectors in Ellibou, southern Côte d’Ivoire and first finding of Anopheles arabiensis in Côte d’Ivoire

• Published in: Malaria Journal
• Main Authors: Bédjou P. N’Dri, Nadja C. Wipf, Jasmina Saric, Behi K. Fodjo, Giovanna Raso, Jürg Utzinger, Pie Müller, Chouaïbou S. Mouhamadou
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2023
• Subjects: Anopheles arabiensis; Anopheles gambiae; Côte d’Ivoire; Insecticide resistance; Metabolic resistance; Malaria; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-023-04456-y; https://doaj.org/article/7cbc9dd645424800ba8c435ece520ab6

Abstract Background Knowing the species composition and insecticide resistance status of the target vector population is important to guide malaria vector control. The aim of this study was to characterize the malaria vector population in terms of species composition, insecticide susceptibility status and potential underlying resistance mechanisms in Ellibou, southern Côte d’Ivoire. Methods A 1-year longitudinal entomological survey was conducted using light traps and pyrethroid spray catches to sample adult mosquitoes in combination with larval sampling. The susceptibility status of Anopheles gambiae sensu lato (s.l.) to bendiocarb, deltamethrin, DDT and malathion was assessed using the World Health Organization insecticide susceptibility test. Additionally, An. gambiae specimens were screened for knockdown (kdr) and acetylcholineesterase (ace1) target site resistance alleles, and the expression levels of eight metabolic resistance genes, including seven cytochrome P450 monooxygenases (P450s) and one glutathione S-transferase (GST), measured with reverse transcription quantitative real-time polymerase chain reaction (qPCR). Results Overall, 2383 adult mosquitoes from 12 different taxa were collected with Culex quinquefasciatus and An. gambiae being the predominant taxa. Molecular identification of An. gambiae s.l. revealed the presence of Anopheles arabiensis, Anopheles coluzzii, An. gambiae sensu stricto (s.s.) and Anopheles coluzzii/An. gambiae s.s. hybrids. Anopheles gambiae mosquitoes were resistant to all insecticides except malathion. PCR diagnostics revealed the presence of ace1-G280S and the kdr L995F, L995S and N1570Y target-site mutations. Additionally, several genes were upregulated, including five P450s (i.e., CYP6P3, CYP6M2, CYP9K1, CYP6Z1, CYP6P1) and GSTE2. Conclusion This is the first documented presence of An. arabiensis in Côte d’Ivoire. Its detection – together with a recent finding further north of the country – confirms its existence in the country, which is an early warning sign, as An. ...