The intense and prolonged rains of early summer have only delayed the return of the tiger mosquito, which with the more stable weather in this second part of the season has found the conditions to breed again and return to bother those who want to enjoy some time outdoors. Without underestimating the resulting health hazards.
The Vector Ecology Sector of the Microbiology Institute of SUPSI (Department of Environment Construction and Design) has been carrying out for years initiatives to monitor and control the spread of the tiger mosquito; moreover, it constantly experiments with new techniques to counter its spread.
One example of this is the use of the sterile male technique, first tested last year in the municipality of Morcote with very encouraging results, as Diego Parrondo, a scientific collaborator at the Microbiology Institute, explains: we found that in 2023 with the release of about 3 million sterile males the population of female tiger mosquitoes in Morcote decreased by 60 percent compared to other areas, in accordance with similar, where we did not carry out any release. This year with nearly two million released, the decrease stands at 80%.
A promising technique, then, that can be combined with other control measures already applied on the ground to further reduce the presence of this pesky insect and the risk of transmission of typically tropical diseases it can carry. It is therefore important to be able to quickly acquire quality sterile males, and in order to produce them at low cost, SUPSI is working at the cantonal level to establish a biofactory where they can be bred.
The summer period also often coincides with intercontinental travel, which is potentially dangerous from the standpoint of transmissibility of tropical diseases for those returning from subtropical countries. In Ticino, the cases remain fortunately circumscribed, thanks to the low population of tiger mosquitoes and the effective monitoring and treatment of the Institute of Microbiology, which intervenes promptly in such cases on the recommendation of the cantonal medical office.
The expertise gained over the years by the Vector Ecology Sector, for which Eleonora Flacio is responsible, has made Ticino a model for other cantons to follow: our laboratory coordinates the Swiss mosquito network for the Federal Office for the Environment, we are a support for all cantons that want to start a mosquito surveillance and control system, and we collect reporting data from citizens throughout Switzerland. Once the presence of mosquitoes is ascertained, we help the cantons initiate the treatment activities adopted in Ticino.
The fight against the tiger mosquito is also a grassroots fight in which citizens and citizens play an important role. Eleonora Flacio gives clear directions: it is important to prevent mosquitoes from emerging at the source, such as by removing stagnant water points and treating those that cannot be removed with specific products. Skin repellents are effective, as is the treatment with Bacillus thuringiensis israelensis granules offered by many municipalities, which are to be distributed once a week from May to September. Other intervention measures are not recommended because they are not specific and may also cause secondary problems.
More information and guidance on tiger mosquito control is collected at the new website: www.supsi.ch/go/zanzare.