Polyphenol-Rich Diets Exacerbate AMPK-Mediated Autophagy, Decreasing Proliferation of Mosquito Midgut Microbiota, and Extending Vector Lifespan

Background

Mosquitoes feed on plant-derived fluids such as nectar and sap and are exposed to bioactive molecules found in this dietary source. However, the role of such molecules on mosquito vectorial capacity is unknown. Weather has been recognized as a major determinant of the spread of dengue, and plants under abiotic stress increase their production of polyphenols.

Results

Here, we show that including polyphenols in mosquito meals promoted the activation of AMP-dependent protein kinase (AMPK). AMPK positively regulated midgut autophagy leading to a decrease in bacterial proliferation and an increase in vector lifespan. Suppression of AMPK activity resulted in a 6-fold increase in midgut microbiota. Similarly, inhibition of polyphenol-induced autophagy induced an 8-fold increase in bacterial proliferation. Mosquitoes maintained on the polyphenol diet were readily infected by dengue virus.

Conclusion

The present findings uncover a new direct route by which exacerbation of autophagy through activation of the AMPK pathway leads to a more efficient control of mosquito midgut microbiota and increases the average mosquito lifespan. Our results suggest for the first time that the polyphenol content and availability of the surrounding vegetation may increase the population of mosquitoes prone to infection with arboviruses.

The dramatic climate changes currently occurring on our planet may likely influence the biology and the distribution of mosquitoes. Aedes aegypti is a major vector of arboviruses. However, females feed on plants for a few days before feeding on blood for the first time. Plants are sessile and cannot move to search for better environmental conditions. In times of extreme temperatures, drought, or UV radiation plants produce polyphenols that allow plants to survive under such extreme conditions. Polyphenol ingestion by mosquitoes enhances the activity of an enzyme named AMP-activated protein kinase (AMPK). Mosquitoes emerging from pupae leave the aquatic environment and are readily colonized by many bacterial strains. Polyphenol-fed mosquitoes display a huge activation of AMPK which enhances autophagy in the midgut cells that increases the capture and killing of midgut bacteria, thus enhancing vector lifespan. Therefore, early meals on polyphenol sources allow for the regulation of vector microbiota. These data may provide the basis of a novel strategy that promotes bacterial proliferation and a shortening of vector lifespan.