A distinct group of north European Aedes vexans as determined by mitochondrial and nuclear markers.

The floodwater mosquito Aedes (Aedimorphus) vexans (Meigen, 1830) (Diptera: Culicidae) is common in several areas of Sweden and is predicted to become more abundant in the wake of expected changes in precipitation and temperature caused by climate change. As well as being a nuisance, Ae. vexans can act as a vector of over 30 viruses. In the event of an outbreak of disease caused by a vector-borne virus, knowledge of the distribution, population structure and intermixing of populations from different locations will help direct resources to target locations to prevent spread of the pathogen. The present study analysed individual Ae. vexans from eight locations throughout Sweden. Based on the mitochondrial cytochrome oxidase I (COI) marker, a subset of the analysed mosquitoes cluster apart from the other samples. Similarly, two nuclear loci were sequenced and the same phylogenetic structure observed. These results indicate that this group represents a reproductively isolated population among Ae. vexans. Comparisons with COI sequences held in the Barcode of Life Database (BoLD) for Ae. vexans from around the world show that specimens collected in Belgium and Estonia group together with the Swedish group, suggesting that this genotype is present throughout northern Europe. These results suggest there is a cryptic taxonomic unit related to Ae. vexans in northern Europe.