Abstract
A deeper understanding of the mechanisms underlying insecticide resistance is needed to mitigate its threat to malaria vector control. Following previously identified associations between mosquito microbiota and insecticide resistance, we demonstrate for the first time, the effects of pyrethroid exposure on the microbiota of F1 progeny of field-collected Anopheles albimanus. Larval and adult mosquitoes were exposed to the pyrethroids alphacypermethrin (only adults), permethrin, and deltamethrin. While there were no significant differences in bacterial composition between insecticide-resistant and insecticide-susceptible mosquitoes, bacterial composition between insecticide-exposed and non-exposed mosquitoes was significantly different for alphacypermethrin and permethrin exposure. Along with other bacterial taxa not identified to species, Pantoea agglomerans (a known insecticide-degrading bacterial species) and Pseudomonas fragi were more abundant in insecticide-exposed compared to non-exposed adults, demonstrating that insecticide exposure can alter mosquito bacterial communities. We also show for the first time that the cuticle surfaces of both larval and adult An. albimanus harbor more diverse bacterial communities than their internal microbial niches. Together, these findings demonstrate how insecticide pressure could be selecting for certain bacteria within mosquitoes, especially insecticide-metabolizing bacteria, thus potentially contributing to insecticide resistance.
Highlights
Supplementary information The online version of this article contains supplementary material, which is available to authorized users.Recent evidence suggests that progress in global malaria control has stalled, with an estimated 2 million more malaria cases in 2017 than in 2016, and an increase in malaria incidence in the region of the Americas [1]
These results provided a comprehensive baseline regarding the bacterial composition of An. albimanus in relation to insecticide resistance and suggested that the mosquito microbiota could be affected by insecticides and/or contribute to insecticide resistance
To determine which variables were associated with shifts in An. albimanus bacterial composition, we fit a multivariate response linear regression model based on shifts in balance between community members [31] using the entire dataset post quality control and dereplication
Summary
Recent evidence suggests that progress in global malaria control has stalled, with an estimated 2 million more malaria cases in 2017 than in 2016, and an increase in malaria incidence in the region of the Americas [1]. This stall in progress overlaps with increasing reports of insecticide resistance [1, 2], which poses a growing challenge to malaria vector control programs [3]. The mechanisms underlying insecticide resistance in malaria vectors are not fully understood. The increase in access to advanced genomic tools has made it easier to investigate other aspects of mosquito biology, such as their microbiota, that may be associated with insecticide resistance
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