Graz is fighting the tiger mosquito: 600,000 sterilized males on the way!

Graz is fighting the tiger mosquito: 600,000 sterilized males on the way!

An innovative pilot project to combat the Asian tiger mosquito was launched in Graz. On Tuesday, August 12, 2025, around 126,000 sterile male tiger mosquitoes were released in the city. This measure is part of a comprehensive plan that will involve more than 600,000 of these special males over the next six weeks to significantly reduce the mosquito population. The procedure is coordinated by the International Atomic Energy Agency (IAEA) in Seibersdorf, where the males were sterilized using radiation and a cold room.

The aim of the project is to contain the tiger mosquito population, which has been considered a vector of over 20 pathogens, including dengue, Zika and chikungunya viruses, since it was first detected in Graz in 2021. The method that is now being used for the first time in Graz is called the sterile insect technique (SIT). This technique has already proven successful in countries such as Italy and Florida, where similar measures have been implemented.

A promising approach

The ready males are separated from females in the pupal stage and then sterilized. The plan calls for the sterile males to nest in the existing mosquito population to displace fertile males from reproducing. The pilot project takes place in a 15 hectare observation area in the Schönau garden. In addition, around 50 insect and egg traps will be set up to monitor the spread and success of the project.

With this initiative, the city of Graz is pursuing the ambitious goal of reducing the mosquito population by 70 percent. Previous projects in Spain and Portugal had shown that such a reduction is possible. Nevertheless, project leader Eva Winter emphasizes that the tiger mosquito will not disappear completely and the population is urged to avoid open water sources, as females can lay eggs there that can survive for up to two and a half years.

Residents and experts express concerns

Many residents are already reporting problems caused by the mosquito plague, especially in urban areas where the local population is severely affected. Global warming is also encouraging tiger mosquitoes to settle in more northern regions, which increases the risk of further tropical diseases spreading.

The entire project will run until the end of October 2025 and the data collected will be used to evaluate the project. The city of Graz plans to expand the measures next year if the results are positive. Still, experts warn that the tiger mosquito will remain an ongoing problem and that preventive measures remain essential to protect the population.

For more information about the background and progress of the project, please visit the following links: crown, courier, O3.