Around 150,000 euros will be spent to control the population in the city, which is considered a hot spot in Austria. There are also other, some new, measures such as a pilot project with a new type of rainwater drain cover from Copenhagen. But the key is the help of the population, according to city councilor Robert Krotzer (KPÖ).
“Our package of measures cannot be thick enough: the help of the population is crucial,” said the politician responsible for health at a press conference on Tuesday. Eva Winter, head of the Graz health department, emphasized: “The Asian tiger mosquito feels very comfortable here.” Therefore, measures must be taken to prevent it from spreading unchecked.
Pilot project with Danish ZikaSeal
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Since the first reports in 2021, the experts in the Styrian capital have acquired a lot of knowledge, tried out a lot and are now sharing their knowledge with others. Inquiries come from Germany and Slovakia, says Winter. Erwin Wieser, the city’s infection protection expert, can now be loaned out as a speaker several times to give lectures on measures against the tiger mosquito elsewhere.
The University of Copenhagen also became aware of Graz and approached the Styrians for a pilot project. The Danes have developed a new type of closure system for rainwater drains. The so-called ZikaSeal closes the drain and only opens when enough water pressure presses on the magnetic silicone closures. The water then disappears under the lid and the tiger mosquitoes cannot lay their eggs in it. The city wants to test around 50 of them on one or two streets in the coming months.
Mosquito traps in kindergartens
In addition, professional mosquito traps are to be set up on a trial basis in several kindergartens to protect the offspring from the pests. The accompanying data collection takes place in cooperation with the Department for Education and Integration. If the purpose of the traps can be established, the city would also like to recommend their use to schools that could purchase such devices independently, said Wieser.
After the success of the previous year, sterile and non-biting male tiger mosquitoes are again being released so that they can mate with the females and produce unfertilized eggs from which no viable larvae grow. The city plans to release six to eight million of these sterile mosquitoes in selected regions in 2026. As last year, the research facility in Seibersdorf, Lower Austria, which is part of the International Atomic Energy Agency (IAEA), will recommend exactly where and when this will happen. The city wants to buy the mosquitoes on the open market because Seibersdorf cannot irradiate enough of them. According to Winter, for example, there is a company near Bologna that could deliver the mosquitoes to Graz at relatively short notice.
With the help of the Mosquito Alert app
The zones where the sterile mosquitoes will be released in 2026 are likely to be in the west of Graz in the Wetzelsdorf district as well as in Liebenau and possibly around the ORF Park. The exact locations are also determined based on the reports in the so-called Mosquito Alert app. Those responsible are also asking the public for help in this regard: Sightings can be reported in the app and show where the hot spots are in Graz.
As in the previous year, lectures on protective measures in home gardens and schools will continue to be held. Children have turned out to be true tiger mosquito detectives and serve as multipliers in combating the annoying insects on balconies and in gardens. Biological larvicide is also used to destroy larvae in drainage shafts after rainfall. Krotzer emphasized that no chemicals or pesticides are used in Graz. Further measures, tips and advice can also be found in the newly published brochure on tiger mosquito management.
First detection of the dengue virus in tiger mosquitoes north of the Alps
The Asian tiger mosquito, which originally comes from the tropics, is considered a possible carrier of over 20 different pathogens – including dengue, Zika and chikungunya viruses. The spread of insects is primarily determined by the temperatures in winter. In Europe, global warming has made it possible for populations to establish themselves in ever more northern areas – especially in cities, where it is usually significantly warmer than in the surrounding areas. In cities such as Trieste, poison against mosquitoes has been spread widely after cases of dengue fever.
Incidentally, the Cantonal Laboratory of Basel-Stadt announced on Tuesday that the dengue virus was detected for the first time during an examination of captured tiger mosquitoes. This represents the first published evidence of this virus in mosquitoes north of the Alps, as the Swiss cantonal laboratory announced.
