Background: The mosquito species Culex pipiens is a known vector of several pathogens and occurs in two distinct bioforms, pipiens and molestus. The bioform molestus thrives in urban environments where there are below-ground habitats; it can mate in confined spaces and feed on mammals as well as birds. In contrast, the bioform pipiens is found above ground, is thought to require more space for mating, and mainly feeds on birds. The pipiens bioform is present in large parts of Sweden but the molestus bioform has previously only been found in major cities. Materials and Methods: People experiencing mosquito nuisance in southern Sweden submitted mosquito samples as part of a citizen science project, and these samples were analyzed to determine the geographical distribution of the molestus bioform of Cx. pipiens. Mosquito specimens were identified to the species level by DNA barcoding of the cytochrome C oxidase subunit I (COI) gene, and the bioforms were determined through the CQ11 microsatellite marker. Results:Culex pipiens f molestus was observed to be spread across large parts of Gothenburg as well as in the suburbs. This bioform was found both in urban and rural areas at several sites across southern Sweden. In one site, hybrids between the two bioforms were found. Conclusions: The detection of Cx. pipiens f molestus in several rural areas was surprising, indicating that it may be more widely spread than urban areas alone, where it has been previously reported.
Keywords: CQ11; Culex pipiens f molestus; Culex pipiens f pipiens; DNA barcoding.