Austrian gnat monitoring programme by AGES

In Austria, little used to be known about the spread and prevalence of exotic mosquitoes associated with climate change. For this reason, AGES set up a gnat monitoring programme to control vectors (carriers) of human viral pathogens such as the West Nile (WVN), Dengue and Chikungunya viruses. Furthermore, the vectors found are, in cooperation with the University for Veterinary Medicine Vienna, also tested for bacterial infections spread by mosquitoes such as tularemia (“rabbit fever”) and for parasitic diseases such as leishmaniosis transmitted by sand flies. Through the programme, mosquitoes are collected and classified at predefined locations. Using biomolecular methods, the level of endemic infection of the gnat populations with the above-mentioned pathogens is then systematically determined. Due to the mosquitoes found and the potential detection of human viral pathogens, data is now available providing information on the risk of transmission, thus possibly enabling further systematic investigation measures.

In all nine federal states, gnats are being caught, by means of special traps, so far at 37 selected locations. The target quantity is about 5,000 mosquitoes per year. Special attention is paid to the search for the species Aedes japonicus (Asian bush mosquito) and Aedes albopictus (Asian tiger mosquito).

The above map shows, by federal state, the gnat types that have been caught as part of the monitoring programme.

In Austria, there are currently about 40 different types of gnats of six different genera – see types of life forms of mosquitoes.

In 2011 we identified the Asian bush mosquito, Aedes japonicus japonicus (Theobald, 1901) (Diptera: Culicidae) for the first time in northern Slovenia and in the bordering Austrian federal state of Styria. Between May and July 2012 the distribution area of Ae. j. japonicus was already found to be extended westwards into Carinthia and eastwards towards Burgenland and bordering Hungary. In August 2012 the species was first detected in a western province of Hungary. In subsequent years, follow-up field studies demonstrated an active spread westwards throughout Carinthia, reaching the border to northern Italy. The Asian tiger mosquito Aedes (Stegomyia) albopictus (Skuse, 1895) (syn. Stegomyia albopicta) was detected for the first time in Austria in May 2012 in the most southern district of south-eastern Burgenland, bordering Hungary and Slovenia. In September 2012, Ae. albopictus larvae were also identified in the village of Angath in a north-eastern district of Tyrol, located in the River Inn valley, only 10 km south of the Bavarian (German) border, but more than 400 km from the first detection site in Burgenland. In 2017, Aedes (Hulecoeteomyia) koreicus  was identifed for the first time in the Austrian province Carinthia.

The individual species of the mosquitoes caught is determined. Thereafter, the mosquitoes are tested for West Nile (WNV) and other strains of viruses by means of PCR analysis. Where required, the virus type can be established as well by means of nucleic acid sequencing. The number of gnat traps will, in cooperation with the federal state authorities and the Federal Ministry of Health, be further optimised in order to fine-tune the monitoring measures.
It must be emphasised that especially the West Nile Virus can be transmitted by an unusually large number of mosquitoes (43 species in North America alone). The genera Culex and Aedes (=Ochlerotatus) in particular are regarded as possible vectors. They were also found as part of the gnat monitoring programme of the AGES. See also: vectors.