Asian tiger mosquito continues to spread in part of Switzerland

A tiger mosquito was detected on cantonal territory for the first time in autumn 2015. KEYSTONE/© KEYSTONE / ENNIO LEANZA

The Asian tiger mosquito spread further in the city of Basel in 2023 owing to the hot summer at all known sites. A widespread colonisation must be expected this year, according to the cantonal laboratory.

The areas where these insects were detected more than doubled last year. This means that around 70% of urban areas in canton Basel City are affected. The number of mosquitoes increased in various leisure gardens, for example. Towards the end of the season, 20 areas with 3,744 garden plots were affected, according to the laboratory’s report, published on Wednesday.

+ Asian tiger mosquito crosses Alps

The number of reports from the public in which the suspicion of a tiger mosquito was confirmed increased last year. A total of 543 suspected insects were reported. In 388 cases, these were actually tiger mosquitoes. In addition, 260 of 446 egg-laying traps were positive.

To monitor the mosquito population, the area-wide trap network already used in 2023 will therefore be continued. The aim is to identify areas that have not yet been colonised, such as the Bruderholz and Hirzbrunnen districts, Bettingen and parts of Riehen. In addition, the success of the control measures should also be able to be monitored based on the mosquito density detected, according to the report.

Monitored since 2016

A tiger mosquito was detected on cantonal territory for the first time in autumn 2015. The Swiss Tropical and Public Health Institute has been carrying out surveillance on behalf of the canton since 2016. The cantonal laboratory is responsible for coordinating the measures.

To control the tiger mosquito, the Civil Engineering Office treats the canals with a biological larvicide. The cantonal laboratory also makes this available to the municipality of Riehen.

The Asian tiger mosquito is an alien and invasive species. It is a potential vector of pathogens such as the dengue, chikungunya and zika viruses. However, no disease transmission by the tiger mosquito has yet been documented in Switzerland, the report said.

Translated from German by DeepL/ts

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