Mosquito Surveillance in the Seaport of Cotonou, Benin: Monitoring of Species Diversity and Assessment of Susceptibility of Mosquitoes to Insecticides

Abstract

Background: Seaports are one of the most important gateways for coastal countries and deserve permanent surveillance of invasive species. Objectives: This study aims to monitor the species diversity of mosquitoes in the seaport of Cotonou and determine the phenotypic resistance profile to multiple insecticides. Methods: The study was conducted at the Port Autonome de Cotonou (PAC) from May to August 2022. BG sentinel traps were used to capture adults which were then identified morphologically. Additionally, larvae of Aedes and Culex mosquitoes were collected and reared until adult emergence. Four batches of 25 adult female mosquitoes, aged 3 to 5 days, were exposed to four insecticides (bendiocarb 0.1%, pirimiphosmethyl 0.25%, permethrin 0.75% and deltamethrin 0.05%) for 60 minutes using the WHO tube test protocol. Mosquito susceptibility was determined after 24 hours. Results: The captured adults yielded 455 adult mosquitoes, divided into six species: Anopheles gambiae, Anopheles pharoensis, Culex quinquefasciatus, Mansonia africana, Mansonia uniformism and Aedes aegypti, with Culex quinquefasciatus predominating (54.15%) and Aedes aegypti (30.66%) being the second most abundant. The females of Culex quinquefasciatus and Aedes aegypti were exposed to insecticides. Aedes aegypti showed resistance to pyrethroids but were susceptible to bendiocarb and pirimiphosmethyl, whereas Culex quinquefasciatus was resistant to pyrethroids and bendiocarb but susceptible to pirimiphos-methyl. Conclusion: Mosquito surveillance in the seaport of Cotonou is essential for detection and vector control in the event of invasion by new vectors carried by boats and cargo ships.