Saldana, M. | bioRxiv Science

bioRxiv2025

Vertical transmission of mosquito microbiota and its effects on offspring development

BackgroundThe mosquitos gut microbiota plays a crucial role in determining its capacity to transmit harmful viruses and parasites. Accordingly, manipulating mosquito gut microbiota is a promising avenue towards reducing mosquito-borne human pathogen transmission. A successful microbial control campaign will require a thorough understanding of how bacteria are transmitted through mosquito populations. Through two parallel but complementary studies using the yellow fever mosquito Aedes aegypti as a focal host species, we surveyed vertical transmission of bacteria from individual mothers to cohorts of offspring maintained in a closed system. ResultsLaboratory- and field-derived mothers deposited bacteria that support offspring development, and the relative abundance of commonly transmitted taxa correlated with offspring fitness. Maternally transmitted bacteria were detected in both larval and adult offspring, and the relative abundances of specific taxa differed between life stages. Microbiota composition in adult offspring closely resembled microbiota composition in mothers, despite dramatic shifts in the relative abundance of specific microbial community members during the larval stage. Variability in microbiota composition in offspring was also greater than variability across the population of egg-laying mothers. Eggs that underwent a period of desiccation before hatching produced larval communities dominated by endospore-forming bacteria that were rare in maternal samples. ConclusionsOverall, our results demonstrate the vertical transmission of mosquito-associated microbiota across generations, including bacterial taxa that could potentially be leveraged for mosquito and mosquito-borne disease control.

microbiology↗

bioRxiv2019

Gut-associated bacteria invade the midgut epithelium of Aedes aegypti and stimulate innate immunity and suppress Zika virus infection in cells.

Microbiota within mosquitoes influence nutrition, immunity, fecundity, and the capacity to transmit pathogens. Despite their importance, we have a limited understanding of host-microbiota interactions, especially at the cellular level. It is evident bacterial symbionts that are localized within the midgut also infect other organs within the mosquito; however, the route these symbionts take to colonize other tissues is unknown. Here, utilizing the gentamicin protection assay, we showed that the bacterial symbionts Cedecea and Serratia have the capacity to invade and reside intracellularly within mosquito cells. Symbiotic bacteria were found within a vacuole and bacterial replication was observed in mosquito cell by transmission electron microscopy, indicating bacteria were adapted to the intracellular milieu. Using gene silencing, we determined that bacteria exploited host factors, including actin and integrin receptors, to actively invade mosquito cells. As microbiota can affect pathogens within mosquitoes, we examined the influence of intracellular symbionts on Zika virus (ZIKV) infection. Mosquito cells harbouring intracellular bacteria had significantly less ZIKV compared to uninfected cells or cells exposed to non-invasive bacteria. Intracellular bacteria were observed to substantially upregulate the Toll and IMD innate immune pathways, providing a possible mechanism mediating these anti-viral effects. Examining mono-axenically infected mosquitoes using transmission electron and fluorescent microscopy revealed that bacteria occupied an intracellular niche in vivo. Our results provided evidence that bacteria that associate with the midgut of mosquitoes have intracellular lifestyles which likely have implications for mosquito biology and pathogen infection. This study expands our understanding of host-microbiota interactions in mosquitoes, which is important as symbiont microbes are being exploited for vector control strategies.

microbiology↗