Entomology
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Item Differential Gene Expression in the Heads of Behaviorally Divergent Culex pipiens Mosquitoes(MDPI, 2021-03-23) Noreuil, Anna; Fritz, Megan L.Host preferences of Cx. pipiens, a bridge vector for West Nile virus to humans, have the potential to drive pathogen transmission dynamics. Yet much remains unknown about the extent of variation in these preferences and their molecular basis. We conducted host choice assays in a laboratory setting to quantify multi-day human and avian landing rates for Cx. pipiens females. Assayed populations originated from five above-ground and three below-ground breeding and overwintering habitats. All three below-ground populations were biased toward human landings, with rates of human landing ranging from 69–85%. Of the five above-ground populations, four had avian landing rates of >80%, while one landed on the avian host only 44% of the time. Overall response rates and willingness to alternate landing on the human and avian hosts across multiple days of testing also varied by population. For one human- and one avian-preferring population, we examined patterns of differential expression and splice site variation at genes expressed in female heads. We also compared gene expression and splice site variation within human-seeking females in either gravid or host-seeking physiological states to identify genes that may regulate blood feeding behaviors. Overall, we identified genes with metabolic and regulatory function that were differentially expressed in our comparison of gravid and host-seeking females. Differentially expressed genes in our comparison of avian- and human-seeking females were enriched for those involved in sensory perception. We conclude with a discussion of specific sensory genes and their potential influence on the divergent behaviors of avian- and human-seeking Cx. pipiens.Item Studies on Host-Seeking Behavior and Differential Chemosensory Gene Expression in Above- and Below-ground Culex Pipiens(2020) Noreuil, Anna Nicole; Fritz, Megan; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Culex pipiens is the primary vector of WNV. It exists as two bioforms which can hybridize in nature. I characterized the behavioral and genetic variation across eight populations collected from above- and below-ground habitats. Three of the five above-ground populations had hybrid ancestry in our single locus assay, whereas the below-ground populations did not. In choice tests, four above-ground populations were avian-seeking, while the fifth showed no clear preference. All three belowground populations predominately sought the human host. Genetic ancestry was not correlated with host preference. Chemosensation drives host-seeking behaviors in female mosquitoes, which led me to quantify the expression of two chemosensory genes: odorant binding proteins (OBPs) 2 and 12. Both OBPs were more highly expressed in the heads of human-preferring females. While the patterns of OBP2 expression indicate that it may contribute to human host detection, OBP12 expression patterns are more consistent with odor-guided oviposition.