Untersuchung zur Culicidenfauna in Deutschland mit besonderer Berücksichtigung des Culex pipiens-Komplexes und der Vektorkompetenz für Nematoden und Protozoen

Abstract

The present study was performed aiming to investigate a large number and a wide variety of mosquitoes from various regions of Germany for the presence of defined groups of parasites. Accordingly, during three successive years between 2010 and 2012, more than 140.000 mosquitoes, trapped at various sites in Germany, were characterized and analysed. The selected trapping sites, most of them located in southwest and northeast Germany, are known tor their abundant occurrence of mosquitoes, such as the foodplains of the river Isar. In addition, some of them represent important stepping stones for migrating birds, such as the Lake Chiemsee or the Lake Constance. The mosquitoes were characterized on the basis of morphological criteria. The results indicated, that the main autochthonous species generally present in Germany were trapped, in particular abundant species such as Aedes vexans and Culex pipiens s. l.. As morphological criteria do not allow the discrimination of members of the Culex pipiens complex or between females of Culex pipiens and Culex torrentium, a multiplex real-time PCR was developed for the rapid genetic differentiation of the various Culex species and biotypes. Using this method, hybrids of Cx. pipiens pipiens biotype pipiens and biotype molestus were detected in Germany for the first time. These hybrids are known as important bridge vectors for the transmission of West Nile virus from birds to humans. To fascilitate the detection of parasites in such a large number of mosquio samples within a reasoonable period of time, further multiplex real-time PCR assays were developed to allow analyses of respective microbial DNAs by high-throughput screening. The results indicated that a considerable number of German mosquitoes are carrying filariae. In this context, a new filarial species was detected, occuring primarily in southern Germany. The reservoir of this new filarial species is probably birds, as it was detected mainly in ornithophilic mosquitoes. Studies on Dirofilaria immitis, Dirofilaria repens as well as Onchocerca lupi, three zoonotic filarial species endemis in southern Europe and pathofenic for humans, revealed the detection of a focus of stable transmission of D. repens in the federal state of Brandenburg. This rilarial species was detected in several mosquito catches from 2011 and 2012, along the Oder Valley in the vincinity of the town of Eberswalde. As there were reports on cases of avian malaira in the zoo of Heidelberg in 2010 screening of mosquitoes was extended for the presence of Haemosporidia, such as Haemoproteus sp., Leukocytozoon sp. or Plasmodium sp.. A multiplex real-time PCR was developed able to detect nematodes as well as blood protozoans. Depending on the catchment area, more than 70 % of the mosquitoes were positive for at least one of the two groups of parasites.