Effect of life stage and pesticide exposure on the gut microbiota of Aedes albopictus and Culex pipiens L

Authors: JUMA, ELIJAH - University Of Illinois; ALLAN, BRIAN - University Of Illinois; KIM, CHANG-HYUN - University Of Illinois; STONE, CHRISTOPHER - University Of Illinois; Dunlap, Christopher; Muturi, Ephantus

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2020
Publication Date: 6/11/2020
Citation: Juma, E.0., Allan, B.F., Kim, C., Stone, C., Dunlap, C.A., Muturi, E.J. 2020. Effect of life stage and pesticide exposure on the gut microbiota of Aedes albopictus and Culex pipiens L. Scientific Reports. 10. Article 9489. https://doi.org/10.1038/s41598-020-66452-5.
DOI: https://doi.org/10.1038/s41598-020-66452-5

Interpretive Summary: Mosquitoes develop in a variety of aquatic habitats that are often exposed to pesticides via agricultural runoff or targeted vector control. The mosquito larvae thriving in these aquatic habitats feed on microbial communities associated with decaying organic matter. Some of these microbes colonize the mosquito gut and contribute important roles in mosquito biology. However, it remains unclear how these microbial communities respond to short term exposure to pesticides. This study used the Asian tiger mosquito and the northern house mosquito to investigate how exposure of mosquito larvae to sub-lethal concentrations of three common pesticides – atrazine, permethrin, and malathion affects the microbial communities that inhabit the mosquito gut. Pesticide exposure had significant effect on gut bacterial richness but not community composition, with the highest bacterial richness occurring in larval samples exposed to malathion and permethrin treatments. The bacterial community composition of larval and adult mosquito samples and water from their larval habitats was also significantly different. These findings suggest that the stage of development has a stronger impact on mosquito gut microbiota relative to larval exposure to sub-lethal pesticide concentrations.

Technical Abstract: Pesticides commonly contaminate the aquatic environments inhabited by mosquito juveniles. However, their role in shaping the mosquito microbiota is not well understood. We hypothesized that environmentally relevant concentrations of atrazine, permethrin and malathion will mediate a shift in the mosquito gut bacterial community structure due to their toxic effect on the aquatic bacterial communities, and reduce mosquito gut bacterial diversity by enriching pesticide-degrading bacterial communities over susceptible taxa. Illumina MiSeq sequencing of the V3-V4 hypervariable regions of the 16 S rRNA gene was used to characterize the microbial communities of larval and adult stages of the two mosquito species and the water samples from microcosms treated with each of the pesticides, separately. Bacterial community composition differed by sample type (larval stage vs. adult stage) and water sampling date (day 3 vs. day 7), but not by pesticide treatment. In larval stages, bacterial OTU richness was highest in samples exposed to malathion, intermediate in permethrin, and lowest in controls. Bacterial richness was significantly higher in larval stages compared to adult stages for all treatments. This study provides a primer for future studies evaluating mosquito microbial responses to exposures to chemical pesticides and the possible implications for mosquito ecology.