@phdthesis{Janssen2023,
  author    = {Janssen, Nele},
  title     = {Distribution and population genetics of the invasive Asian bush mosquito Aedes japonicus (Diptera, Culicidae) in Germany and eastern Europe},
  institution = {Abteilung f{\"u}r Mikrobiologie und Molekularbiologie},
  pages     = {98},
  year      = {2023},
  abstract  = {The present study deals with the spread and population genetics of the invasive Asian bush mosquito Ae. japonicus in Europe and Germany. Since the first detection of Ae. japonicus in Europe in 2000, the species spread rapidly through Europe, either actively by flying or passively by human activities. In 2017, four confirmed populations of Ae. japonicus existed in Europe. The largest population covered western Germany, parts of France, Switzerland, Liechtenstein, Austria and Italy. The most northern population around Hanover, Germany, did not spread since 2013. A very small population existed in Belgium and the second largest population covered parts of Austria, Italy, Slovenia, Croatia and Hungary. By 2019, Ae. japonicus had established in 15 European countries. Most of the monitoring programmes in Europe dealing with the distribution and spread of Ae. japoncus investigate cemeteries for juvenile stages. However, activities are not harmonised, e.g. regarding numbers of investigated collection sites and declaration of negative sites, making data comparison between different studies difficult. Therefore, suggestions for a standardised Ae. japonicus monitoring method have been developed and provided. In the present study, 445 individuals of Ae. japonicus originating from five different European countries were investigated for population genetic analyses by sequencing parts of the nad4 gene and genotyping seven polymorphic microsatellite loci. In total, 16 different nad4 haplotypes were identified with haplotype H1 being the most common and widespread one through all populations. Within Germany, Ae. japonicus has been spreading immensely over the last decade. Even though the present results (2017) demonstrate incipient genetic admixture of populations as compared to previous studies (2012-2015), no complete genetic mixture has taken place yet. The populations of Ae. japonicus still fall into two genetic clusters, but the genetic diversity on individual level had increased considerably (from three nad4 haplotypes in 2012 to 12 according to the present thesis). Both additional introductions and mutation are possible reasons, but determining the origin of the German populations is not possible anymore. In the years following the invasion of Germany, Ae. japonicus spread to southeastern Europe. In 2013, it established in Croatia, in 2017 in Bosnia and Herzegovina and in 2018 in Serbia. In the current study, immature stages of Ae. japonicus were found at 19 sites in Croatia, two sites in Bosnia and Herzegovina and one site in Serbia. The population genetic analyses indicate at least two independent introductions in that area. Aedes japonicus collected west of Orahovica (Croatia) seemed to be genetically similar to samples previously investigated from Southeast Germany/Austria and Austria/Slovenia. By contrast, samples from east of Orahovica, together with those from Serbia and Bosnia and Herzegovina, were characterised by another genetic make-up, but their origin could not be determined. In 2021, individuals of Ae. japonicus were detected at two collection sites in the Czech Republic for the first time: Prachatice close to the Czech-German border and Mikulov on the Czech-Austrian border. Population genetics and comparison of genetic data showed a close relationship of the Prachatice samples to a German population, while for Ae. japonicus from Mikulov close relatives could not be identified. In the future, the global spread and establishment of invasive mosquitoes through international trade and travel will increase. Potential vectors, like the Asian bush mosquito Ae. japonicus, can become a problem in Europe and Germany, especially in the course of global warming which supports pathogen transmission. Monitoring the known populations and identifying introduction and migration routes are therefore essential for vector managing.},
  subject      = {Populationsgenetik},
  language  = {en}
}