The feeding behavior of vectors influences the likelihood ofpathogen invasion and the exposure of humans to vector-bornezoonotic pathogens. We used multilocus microsatellite genetictyping of an introduced mosquito vector and DNA sequencing ofmosquito blood meals to determine the impact of hybrid ancestryon feeding behavior and the emergence of West Nile virus (WNV).The probability of ancestry of Culex pipiens mosquitoes fromtwo bionomically divergent forms, form molestus and form pipiens,influenced the probability that they fed on humans but did notexplain a late summer feeding shift from birds to humans. Weused a simple model to show that the occurrence of pure formmolestus mosquitoes would have decreased the likelihood of WNVinvasion (R0 in bird populations) 3- to 8-fold, whereas theoccurrence of pure forms pipiens mosquitoes would have halvedhuman exposure compared with the hybrids that are present. Dataand modeling suggest that feeding preferences may be influencedby genetic ancestry and contribute to the emergence of vector-bornepathogens transmitted by introduced species, including malaria,and dengue, Chikungunya, yellow fever, and West Nile viruses.
