Novel Microbial Candidate Markers of Pyrethroid Resistance in Anopheles albimanus, a Major Latin American Malaria Vector


A deeper understanding of the biological mechanisms underlying insecticide resistance in malaria vectors is needed to mitigate its threat to vector control efforts. Our previous findings identified links between Anopheles albimanus microbiota and resistance to the organophosphate insecticide fenitrothion. We have now characterized the microbiota of An. albimanus with differing pyrethroid resistance profiles across four locations in Guatemala using 16S rRNA gene sequencing. We focused on identifying patterns of microbial composition across mosquitoes expressing susceptibility or resistance to alphacypermethrin, deltamethrin and permethrin, in both larvae and adults. F1 progeny of wild-caught mosquitoes from each location were reared separately under identical conditions, and characterized using the CDC bioassay as resistant (Res), susceptible (Sus) or unexposed to insecticide (Unexp). This resulted in 44 pools of late instar larvae and 45 pools of 2-5day old non-blood-fed virgin adult females - 3 mosquitoes/pool, 3 pools/category, with all insecticides tested in at least one location. Differential microbial compositions (p<0.05), mostly driven by type of insecticide (R2=0.51), were identified between Res, Sus and Unexp, for all three insecticides, in both larvae and adults, and across each location tested. With more than five-fold greater abundance in Res compared to any other category (p<0.05), Klebsiella (alphacypermethrin and deltamethrin), Asaia and Pantoea (permethrin) were identified as candidate markers associated with resistance in adults but not in larvae, suggesting the presence of transient microbiota in larvae. These results build upon our initial findings and identify candidate microbial markers of pyrethroid resistance in adult An. albimanus that are being functionally validated. The results also suggest a specificity of candidate microbial markers within the pyrethroid class of insecticides.

The American Journal of Tropical Medicine and Hygiene, Volume 99, Issue Suppl_4, p. 14
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