D3024: Insect microbiomes and insecticide resistance: Lessons from agricultural entomology for vector biology

Insects form symbiotic relationships with microbes—their microbiome—that are known to affect the host insect’s physiology and behavior such as insecticide resistance, a primary threat to the control of insects of agricultural and public health importance. However, the underlying microbial mechanisms of insecticide resistance are not known. As part of our research to fill this knowledge gap, we synthesized, for the first time, outcomes of primary research on the role of insect microbiomes on hosts’ insecticide resistance. We found that research in this area has primarily focused on agricultural insect pests, with a majority reporting associations between the insect microbiome and insecticide resistance. The body of literature shows that insecticide pressure changes the insect microbiome, and insect microbiomes differ by insecticideresistance phenotypes. Additionally, insects that directly acquire insecticide metabolizing microbes from their environment show enhanced insecticide resistance and can pass these microbes and their effects on to subsequentgenerations. While we did not find studies that completely describe the underlying microbial mechanisms of insecticide resistance, we recognized two recurring microbial processes; insect microbiomes are able to metabolize insecticides directly and indirectly by enhancing the host’s metabolism—in particular, some host insecticide metabolizing genes are associated with the presence of certain microbes. These processes, which have been confirmed through the removal and/or transplant of the insect microbiome, lay the foundation for understanding microbial mechanisms of insecticide resistance. We highlight future research directions and areas that we, in the vector biology community, could draw from for research advancement.