Debugging Vector-Borne Disease Transmission Through Multidisciplinary Studies of Two Vectors of Infectious Disease

Vector-borne diseases (VBDs) are pathogenic infections transmitted by hematophagous arthropods, accounting for a significant global burden of disease. Interrupting the transmission of VBDs is a complex problem requiring nuanced understanding of the host, vector, and parasite, as well as their interactions with one another and the environments they occupy. Here, I attempt to elucidate some biological and epidemiological aspects of two important vectors of disease using various molecular, genomic, and surveillance tools. First, I updated the reference genomes of two major vectors for leishmaniasis, Lutzomyia longipalpis and Phlebotomus papatasi, using newer sequencing technology improving both quality and contiguity, allowing higher resolution genomic inquiries in the future. Leveraging these new genomes, I completed population genetics analysis of Lu. longipalpis field specimens collected throughout Brazil, identifying divergent populations living in sympatry with one another, and providing greater clarity on species delineations and genomic regions contributing to species differentiation. Additionally, I performed microbiome analyses on these samples, and identified patterns of clustering that were congruent with genomic population clustering, as well as some that blurred geographic and species lines. I supplemented this with in-lab microbiome experiments of colony sand flies fed on sugar, blood, and parasite-infected blood, and found that microbiome species diversity suffered immediately after a bloodmeal, but rebounded to sugar-fed levels after 8 days post-feeding. I also identified stable taxa common to our field and lab experiments that can be leveraged for future paratransgenesis and vector competence studies. Finally, I identified a panel of differentially expressed genes that can be used to determine the age of sand flies. For mosquitoes, I conducted four years of surveillance in two county parks, creating models based on weather to reliably predict mosquito abundance. These various studies add to our growing understanding of the population genetics, microbiomes, and age of sand flies, as well as actions supporting mosquito control. My contributions will enable future work on reproductive isolation, paratrangenesis, vector competence, and novel vector control strategies for sand flies, as well as long-term abundance trends and their relationship to human disease in mosquitoes.