Louisa Messenger (Environmental and Occupational Health) gave a presentation titled, "Bacterial Symbionts are Associated with Insecticide Resistance in the Major Malaria Vector Anopheles coluzzii," during the American Society for Microbiology Microbe conference held June 15-19 in Houston, Texas.
Abstract:
The mosquito microbiota consists of the bacterial, archaeal, viral, and fungal communities which inhabit the mosquito cuticle and internal structures. It is implicated in mosquito longevity, growth, oviposition, vector competence and, more recently, insecticide resistance. Evidence of links between the mosquito microbiota and insecticide resistance is increasing, with significant enrichment of insecticide degrading bacteria and enzymes in resistant populations. It has been proposed that upon exposure to insecticides, bacteria and the mosquito host experience a symbiotic relationship, with bacteria degrading insecticides to obtain access to novel compounds vital for growth and reproduction, with the mosquito host benefiting by surviving insecticide exposure. Using 16S rRNA amplicon sequencing, we characterized and compared the microbiota of Anopheles coluzzii, from Agboville, Cote d’Ivoire, in relation to their deltamethrin resistance and exposure profiles. Comparisons between 2- and 3-day-old deltamethrin-resistant and -susceptible mosquitoes demonstrated significant differences in microbiota diversity. Ochrobactrum, Lysinibacillus, and Stenotrophomonas genera, each of which comprise insecticide-degrading species, were significantly enriched in resistant mosquitoes. Susceptible mosquitoes had a significant reduction in alpha diversity compared to resistant individuals, with Asaia and Serratia dominating microbial profiles. Our results suggest these bacteria may contribute to, and/or that their enrichment is a consequence of, the observed resistance phenotypes. We also investigated the association between the microbiota and resistance in permethrin resistant An. coluzzii from Maferinyah, Guinea, who did and did not experience restoration of susceptibility upon exposure to the synergist piperonyl butoxide (PBO). Microbial profiles varied with PBO exposure and resistance status, with PBO-exposed mosquitoes having significantly lower microbial diversity and mosquitoes with restored susceptibility having an increased abundance of Staphylococcus spp. and Chromobacterium spp. Our findings revealed alterations of Anopheles coluzzii microbiota associated with pyrethroid resistance and PBO exposure, highlighting the potential for identification of novel microbial markers for insecticide resistance surveillance.
