Larval Diet Abundance Influences Size and Composition of the Midgut Microbiota of Aedes aegypti Mosquitoes

Abstract

The midgut microbiota of the yellow fever mosquito Aedes aegypti impacts pathogen susceptibility and transmission by this important vector species. However, factors influencing the composition and size of the microbiome in mosquitoes are poorly understood. We investigated the impact of larval diet abundance during development on the composition and size of the larval and adult microbiota by rearing Aedes aegypti under four larval food regimens, ranging from nutrient deprivation to nutrient excess. We assessed the persistent impacts of larval diet availability on the microbiota of the larval breeding water, larval mosquitoes, and adult mosquitoes under sugar and blood fed conditions using qPCR and high-throughput 16S amplicon sequencing to determine bacterial load and microbiota composition. Bacterial loads in breeding water increased with increasing larval diet. Larvae reared with the lowest diet abundance had significantly fewer bacteria than larvae from two higher diet treatments, but not from the highest diet abundance. Adults from the lowest diet abundance treatment had significantly fewer bacteria in their midguts compared to all higher diet abundance treatments. Larval diet amount also had a significant impact on microbiota composition, primarily within larval breeding water and larvae. Increasing diet correlated with increased relative levels of Enterobacteriaceae and Flavobacteriaceae and decreased relative levels of Sphingomonadaceae. Multiple individual OTUs were significantly impacted by diet including one mapping to the genus Cedecea, which increased with higher diet amounts. This was consistent across all sample types, including sugar fed and blood fed adults. Taken together, these data suggest that availability of diet during development can cause lasting shifts in the size and composition of the microbiota in the disease vector Aedes aegypti.

Variation in diet and microbial exposure shape the performance of the Asian tiger mosquito,Aedes albopictus

“…albopictus. Bacterial growth in rearing water depends on the strain and diet considered although total bacterial load increases with diet concentration (43, 46). Maintenance of a bacterial homeostasis in mosquitoes is under tight immunological control (65).…”

“…A previous study showed that diet concentration impacts microbiota composition in Ae. aegypti larvae and adults (46). Our results unravelled a more complex interaction involving both the diet concentration and the bacterial load inoculum in shaping bacterial communities in larval water.…”

Starvation at the larval stage increases the vector competence of Aedes aegypti females for Zika virus

“…aegypti mosquitoes in comparison to large mosquitoes while fecundity was decreased in the former suggesting that in small size mosquitoes, the blood-meal was predominantly processed for nutrient supply rather than diverted for egg development [ 33 ]. In addition, the midgut microbiome in adult mosquitoes has been shown to be altered by restricting the larval diet [ 34 ]. This, in turn, can impact midgut infection of arboviruses; for instance, a microbial metalloprotease secreted by Serratia marcescens increased the susceptibility of the Ae .…”

Bacterial communities of Aedes aegypti mosquitoes differ between crop and midgut tissues

“…qPCR: To assess the total amount of bacteria in each tissue sample, we conducted qPCR targeting the 16S rRNA gene as described in [35]. Briefly, each reaction contained 7.5 μL SYBR master mix (Applied Biosystems), 0.35 μL of each primer (primer starting concentrations were all 10 μM), 5 μL template (diluted 1:20), and MilliQ water to a final volume of 15 μL.…”

“…High-throughput 16S amplicon sequencing and data processing: High-throughput 16S amplicon sequencing was performed as described in [35] at the Microbial Analysis, Resources, and Services center at the University of Connecticut. Briefly, 5ng of DNA was used as template in a PCR with 515F and 806R primers with Illumina adapters and eight basepair dual indices [37,38].…”