Status of domestic anti-mosquito control tools against resistant Anopheles gambiae s.l. and Culex mosquitoes from the city of Kribi, South Cameroon

Communities living in the tropics use insecticide products to prevent or control mosquito nuisance in general. In Cameroon, these products are used at home without evidence of their efficacy against targeted mosquito populations. In this paper, we present a sample of anti-mosquito tools used by households in the city of Kribi, and their efficacy versus local Anopheles and Culex mosquitoes. The study protocol included: i) a survey in 500 randomly selected households using a questionnaire; ii) mosquito larvae and pupae collections in breeding sites and rearing; iii) WHO cone and susceptibility bioassays were conducted, respectively, using reared An. gambiae s.l. and Culex mosquitoes; and iv) molecular identification of members of the An. gambiae complex via PCR. The household survey revealed that long-lasting insecticidal nets (LLINs) (89%), insecticide aerosols (51.5%), or insecticide coils (35.3%) were the most used, as anti-mosquito tools. The aerosols provided optimal efficacy against An. gambiae s.l. and Culex mosquitoes with 98.6% and 100% mortality, respectively. Coils showed minimal efficacy (78.7%) to no efficacy (27.1%), respectively, against Anopheles and Culex mosquitoes, and LLINs showed no efficacy (25.6%) against Anopheles mosquitoes (P˂˂0,005). An. gambiae and Culex mosquitoes equally showed resistance to deltamethrin (81.7% and 78.5%, respectively) and permethrin (34.3% and 27.1 respectively). Bioassays conducted with the insecticide bendiocarb demonstrated that An. gambiae s.l. was fully susceptible, achieving a mortality rate of 100%. These findings highlight the challenges of individual anti-mosquito control measures in Kribi thus, there is a need for an integrated mosquito control approach involving effective household anti-mosquito tools to complement the use of LLINs, in the context of increasing insecticide resistance in natural mosquito populations.