hitchhiker's guide to becoming invasive: exotic mosquitoes spread across a US state by human transport not autonomous flight

• Published in: Molecular ecology Vol. 25; no. 13; pp. 3033 - 3047
• Main Authors: Egizi, Andrea, Jay Kiser, Charles Abadam, Dina M. Fonseca
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Ltd 01.07.2016; Blackwell Publishing Ltd
• Subjects: Aedes; Aedes - genetics; Aedes j. japonicus; ancestry; Animal Distribution; Animals; biological invasions; disease vectors; DNA, Mitochondrial - genetics; Ecology; flight; genetic distance; Genetics, Population; Genotype; genotyping; Human Activities; human-aided dispersal; humans; Introduced Species; landscape genetics; livestock; loci; Microsatellite Repeats; Mosquitoes; multiple introductions; Nonnative species; Ochlerotatus japonicus; Population genetics; public health; roads; spatiotemporal analyses; Transportation; Virginia; wildlife; Canada; Asia; Virginia; Europe; landscape genetics; Aedes j. japonicus; human-aided dispersal; spatiotemporal analyses; biological invasions; multiple introductions
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/mec.13653

Not all exotic species establish and expand aggressively (i.e. become invasive). As potential vectors of disease agents, invasive mosquitoes can have considerable impact on public health, livestock and wildlife; therefore, understanding the species characteristics and ecological circumstances promoting their invasiveness is important. The mosquito Aedes japonicus japonicus, originally from north‐east Asia, was introduced at least two separate times to the north‐eastern USA, as surmised from the initial existence of two populations with distinct nuclear and mitochondrial genetic signatures that later intermixed. Since these original introductions in the late 1990s, Ae. j. japonicus has expanded across 31 US states, two Canadian provinces and five European countries. Although some of the expanded range was due to other independent introductions, to understand what drove the postintroduction expansion of Ae. j. japonicus within the north‐eastern USA, we performed a high‐resolution landscape genetic analysis of 461 specimens collected across Virginia, a state south of the original introductions. All specimens were genotyped at seven pre‐optimized microsatellite loci, and a subsample was sequenced at one mitochondrial locus. We concluded that throughout Virginia this species has primarily expanded in association with humans: genetic distance and distance along roads remained correlated after controlling for geographic distance, and proximity to I‐95, a major interstate highway, strongly predicted nuclear ancestry. In contrast, there was very limited evidence of diffusion even at distances potentially suitable for autonomous mosquito flight. This implies that its association with humans (rather than innate species characteristics) is the single most important determinant of invasiveness in this mosquito.