North America Insect Invades the World: the Case of the Flood Mosquito, Aedes vexans (Diptera: Culicidae), from Mitochondrial DNA

The flood mosquito, Aedes vexans (Diptera: Culicidae), native of Canada, and currently present in all continents, has a vector competence for 30 arboviruses, being responsible for transmitting diseases, like West Nile fever, Rift Valley fever, Saint Louis Encephalitis and Eastern Equine Encephalitis. Hence, knowing the structure and gene flow of A. vexans is important to develop adequate vector control strategies for this species. For this, from partial sequences of the mitochondrial COI gene available in Bold and GenBank, it was possible to determine the Haplotypic (Hd) and nucleotide ({pi}) gene diversity, genetic structuring and gene flow at global, continental, and country levels. In total, 1184 sequences were recovered, distributed between America (88.60%), Europe (7.35%), Asia (3.89%), and Africa (0.17%). From these, 395 haplotypes (H) were detected without presence of pseudogenes (NUMTs), with H1 being the most frequent (24.58%) and between H12 - H395 the least frequent varying between 0.93% (H12) and 0.08% (H395). Phylogenetically, the haplotypes were grouped into six clades. Clade I grouped haplotypes from countries in America and Europe, while clades II and III presented haplotypes exclusively from Asia and Europe; clade IV grouped only one haplotype from Africa and the last ultimo clade V grouped haplotypes from America and Africa. The global Hd and {pi} was 0.92 and 0.01, respectively. In addition, evidence was obtained of genetic structuring among continents (7.07%), countries (1.62%), and within countries (91.30%; FST = 0.08, p < 0.05) and no isolation by distance was detected (r = 0.003, p > 0.05). These results suggest that the mosquito populations that invaded other continents originate directly from the American continent, where possibly transcontinental commercial routes favored their long-distance dispersion.