Mosquitoes are of major importance to human and animal health due to their ability to transmit various pathogens. In Europe the role of mosquitoes in public health has increased with the introduction of alien Aedes mosquitoes such as the Asian tiger mosquito, Aedes albopictus; the Asian bush mosquito, Ae. japonicus; and Ae. koreicus. In Austria, Ae. japonicus has established populations in various regions of the country. Aedes albopictus is not known to overwinter in Austria, although isolated findings of eggs and adult female mosquitoes have been previously reported, especially in Tyrol. Aedes koreicus had not so far been found in Austria. Within the framework of an alien mosquito surveillance program in the Austrian province of Tyrol, ovitraps were set up weekly from May to October, 2018, at 67 sites-17 in East Tyrol and 50 in North Tyrol. Sampling was performed at highways and at urban and rural areas. DNA obtained from mosquito eggs was barcoded using molecular techniques and sequences were analysed to species level. Eggs of alien Aedes species were found at 18 out of 67 sites (27%). Both Ae. albopictus and Ae. japonicus were documented at highways and urban areas in both East and North Tyrol. Aedes koreicus was found in East Tyrol. During this mosquito surveillance program, eggs of Ae. albopictus, Ae. japonicus, and Ae. koreicus were documented in the Austrian province of Tyrol. These findings not only show highways to be points of entry, but also point to possible establishment processes of Ae. japonicus in Tyrol. Moreover, Ae. koreicus was documented in Austria for the first time.

Systematic, continuous mosquito surveillance is considered the most reliable tool to predict the spread and establishment of alien mosquito species such as the Asian tiger mosquito ( Aedes albopictus ), Japanese bush mosquito ( Aedes japonicus ), and the transmission risk of mosquito-borne arboviruses to humans. Only single individuals of Ae. albopictus have been found in Austria so far. However, it is likely that the species will be able to establish populations in the future due to global trade and traffic as well as increasing temperatures in the course of global climate change. In summer 2017, a project surveilling the oviposition of newly introduced Aedes mosquitoes, using ovitraps, was set up by means of citizen scientists and researchers and was performed in six federal provinces of Austria—Tyrol, Carinthia, Vienna, Lower Austria, Styria, and Burgenland. Eggs of Ae. albopictus were identified in Tyrol during the months August and September, while Ae. japonicus was found in Lower Austria, Styria, and Burgenland. In Vienna and Carinthia, all ovitraps were negative for Aedes eggs; however, Ae. japonicus was found for the first time in Vienna in July 2017 during routine sampling of adult mosquitoes. With this project, we demonstrated the benefits of citizen scientists for ovitrap-based mosquito surveillance. The finding of Ae. albopictus eggs in Northern Tyrol is not yet a proof of the establishment of a self-sustaining population, although it indicates the ongoing introduction of this species along main traffic routes from Italy, where this mosquito is well established. The risk of establishment of the tiger mosquito in the Lower Inn Valley is therefore a given and informing the public about preventive measures to hinder and delay this development is highly recommended.