Nutritional sex-specificity during larval development in mosquitoes

Overview & Synopsis

Mosquitoes rely on their microbiota for B vitamin provision. We previously found that Aedes aegypti larvae cleared of their microbiota at the beginning of the third instar were impaired in their development and that folic acid supplementation increased the proportion of larvae reaching the adult stage. In this study, we investigated the effects of other B vitamins on the development of germ-free mosquito larvae. We found that diet supplementation using a cocktail of seven B vitamins did not improve mosquito developmental success, but rather had a significant impact on the sex-ratio of the resulting adults, with an enrichment of female mosquitoes emerging from B vitamin-treated larvae. A transcriptomic analysis of B vitamin treated male and female larvae identified few genes that may be involved in specific vitamin-induced mechanisms. The treatment of germ-free larvae with high doses of individual B vitamin solutions identified a specific toxic effect related to biotin exposure at high concentrations. The supplementation of germ-free larvae with varying biotin doses revealed divergent biotin requirements and toxic effects for male and female Ae. aegypti larvae. These findings shed new light on sex-specific nutritional requirements and toxicity thresholds during the development of insect larvae, and on their consequences on the sex ratio of adults.