Publication Date

5-2019

Date of Final Oral Examination (Defense)

3-4-2019

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Biology

Department

Biology

Supervisory Committee Chair

Merlin M. White, Ph.D.

Supervisory Committee Member

Sven Buerki, Ph.D.

Supervisory Committee Member

Kevin Feris, Ph.D.

Abstract

Mosquitoes are vectors for a variety of human pathogens and have a significant impact on human health worldwide. There is growing evidence that host-associated microbiota influence mosquito vector competence for certain viruses. Transstadial transmission of bacteria from larvae through pupae to adults could affect these interactions, though further studies are needed to fully unravel the mechanisms involved. Current microbiome research primarily focuses on bacterial communities, whereas the potential role endosymbiotic gut fungi have in transstadial transmission dynamics remains largely unknown. Trichomycetes is an ecological group of endosymbiotic microfungi that colonize the digestive tracts of arthropod hosts, including the Yellow Fever Mosquito (Aedes aegypti). The trichomycete fungus Zancudomyces culisetae infects A. aegypti populations in the wild and was investigated using laboratory-based assays to identify fungal-bacterial-host interactions in mosquito larvae and adults.

Next generation sequencing of 16S rDNA gene amplicons and measures of microbiome diversity found that fungal infestation in the larval digestive tract influenced their microbiomes and reduced microbial transstadial transmission variability. Comparative analyses of beta diversity measures indicated that fungal infestation affected larval microbiome composition. Measures of alpha diversity revealed that newly emerged fungal adults contained microbiomes characterized by high bacterial diversity and even community distributions. In contrast, non-fungal adults harbored microbiomes with variable compositional structures, often with low bacterial diversity and high levels of dominance by few taxa. Additionally, transstadial transmission processes impacted certain bacterial families. Fungal infestation in larvae restricted the transmission and establishment of the bacterial taxon Burkholderiaceae and increased relative abundance of Corynebacteriaceae and Moraxellaceae in newly emerged adults. Identifying biotic factors that interact with host-associated microbiota and contribute to adult microbiome formation may reveal microbial interactions that affect human pathogen contraction and transmission in mosquitoes. These findings emphasize the importance of accounting for endosymbiotic gut fungi in host-associated microbiome studies.

DOI

10.18122/td/1522/boisestate

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