Insecticides Resistance Status of An. gambiae in Areas of Varying Agrochemical Use in Côte D’Ivoire

Background. Insecticide resistance monitoring of the malaria vectors to different classes of insecticides is necessary for resistance management. Malaria vector control management approaches are essentially based on IRS and LLINs. However, insecticide resistance is caused by several sources of selection and in case the selection pressure is from agricultural practices, then measures need to be taken to avoid a failure of the control methods put in place. The current study was undertaken to monitor the susceptibility of vectors to different classes of insecticides in areas of varying agrochemical use patterns. Methods. A survey to determine the agricultural chemical use pattern was undertaken in ten localities across Côte d’Ivoire. In addition, WHO susceptibility tests were carried out on adults Anopheles gambiae s.l. mosquitoes emerging from collected larvae from the sites surveyed. Four insecticides from each class of the four classes of insecticides were evaluated using the standard susceptibility test methods. Furthermore, the target site mutations involved in resistance mechanisms were identified following the Taqman assay protocols and mosquito species were identified using SINE-PCR. Results. The mortalities of all the An. gambiae s.l populations were similar regardless of the pesticide use pattern. The vectors were resistant to DDT, deltamethrin, and bendiocarb in all localities. In contrast, mosquitoes showed high susceptibility to malathion. High frequency of the Kdr-West gene allele was observed (70-100%). A single Kdr-East mutation was identified in a mosquito that harboured both Ace-1 and Kdr-West genes. Conclusion. Cultivated marshlands representing good habitats for mosquito development may deeply contribute to the selection of resistance genes given the intensive use of agrochemical for crop protection. In view of these, special attention must be given to them to mitigate mosquito resistance to insecticides

Alpha diversity measures of the internal body microbiomes of <i>Anopheles coluzzii</i> mosquitoes from seven homes.

(A) Observed OTUs, (B) Shannon diversity and (C) Faith’s phylogenetic diversity. (TIF)</p

Principal coordinate analysis (PCoA) of the bacterial composition of the external body of <i>Anopheles coluzzii</i> mosquitoes from seven homes.

Analysis was based on the Bray Curtis metric. (TIF)</p

Principal coordinate analysis (PCoA) of bacterial composition between internal and external body samples of <i>Anopheles coluzzii</i> mosquitoes.

Analysis was based on the Bray Curtis metric. (TIF)</p

Map of areas where mosquitoes sampling was conducted house-by-house in a five-block area of Tiassalé, Côte d’Ivoire, Africa (5°53’54" N, 4°49’42" W).

(TIF)</p

Bacterial mock community expected from ZymoBIOMICS™ Microbial Community DNA and actual taxonomic abundances in our samples.

(DOCX)</p

Principal coordinate analysis (PCoA) of the bacterial composition of the internal body of <i>Anopheles coluzzii</i> mosquitoes from seven homes.

Analysis was based on the Bray Curtis metric. (TIF)</p

Principal coordinate analysis (PCoA) of bacterial composition between internal and external body samples of <i>Anopheles coluzzii</i> mosquitoes.

Analysis was based on the weighted Unifrac metric.</p

Rarefaction curves of the mean number of observed ASVs in internal versus external body samples.

Rarefaction curves of the mean number of observed ASVs in internal versus external body samples.</p

Rarefaction curves of the mean number of observed ASVs from seven homes.

(TIF)</p