As you close your eyes to fall asleep, the quiet of the room is disturbed by an annoying zoning. No need to say more to know what we’re talking about: with the humidity of spring and the warmer temperatures, the mosquito is back. But the specimen that we fear the most to discover does not make any noise. And its black and white streaked body comes out mainly during the day.
The tiger mosquito – or Aedes albopictus – colonized the Auvergne-Rhône-Alpes region in 2012, first at the margins. Since then, it has continued to proliferate, and the year 2023 has not slowed down its expansion, far from it. This is indicated by the annual report on regional surveillance published by the Regional Health Agency (ARS) at the end of April. No department is spared: according to measurements taken between 1er May and November 30, 2023, the insect established itself in 261 new municipalities in the region, bringing the total to 1,070. That is, one in four.
Strong progression in Ain, doubling in Haute-Savoie
This census was carried out by the Interdepartmental Agreement for Mosquito Control (EID). And he doesn’t just list the places where the tiger mosquito has been reported. For a municipality to be considered colonized, the tiger mosquito must be spotted at several observation decks more than 150 meters apart. “In their lives, they rarely move beyond this distance,” explains Gilles Besnard, entomologist (insect specialist) within the EID. Obviously, not all the municipalities listed are affected in the same way, because “there is a great variation between those who experience a daily nuisance between October and May and those who discover in an article that their municipality is affected. »
According to him, the proliferation of the tiger mosquito differs from previous years, in that it has spread to a large number of small communities on the outskirts of cities. “At the beginning, it spread in urban centers and along major roads because as it doesn’t move around much, it takes advantage of cars,” continues Gilles Besnard. This year, it has expanded, certainly taking advantage of people who live outside urban areas but go there to work or do their shopping. »
Our departments have been unequally affected by this phenomenon in 2023. In any case, if we refer to the number of new colonized municipalities.
With 56 municipalities conquered by the tiger mosquito, Ain is the department which has seen the insect colonize the most. More than 40% of contaminated municipalities were contaminated in 2023. In Haute-Savoie, this figure rises to 50%, although the volume is lower. Ardèche and Drôme were the least affected by the progression of the bird, whether in quantity or proportion.
Rapid colonization
If we must remember one thing from this report, it is that the tiger mosquito continues to establish itself, year after year, more and more widely. Just twelve years after its arrival, three out of four residents of the region are now exposed to its bites.
In Haute-Savoie, as in Ain, the population concerned is well below the regional average. On the other hand, it is in these departments that we note the most rapid progression of the tiger mosquito. On the contrary, in Isère and Drôme, more than four out of five inhabitants live in areas colonized by the striped insect. “We will not be able to return to an initial state without tiger mosquitoes, we have to get used to it,” says Gilles Besnard. On the other hand, we can reduce its proliferation. And for this the role of citizens is crucial,” underlines the entomologist.
How to stop its proliferation?
The tiger mosquito does not need a lot of water to reproduce. According to the ARS, the equivalent of a cork may be sufficient for the larvae to reproduce. The female lays eggs on containers likely to fill with water. When the good weather returns, they develop for about a week. Once it takes hold, it becomes extremely difficult to get rid of.
The challenge is therefore to prevent its influence from spreading, and the action of individuals can prove crucial. By tidying up, emptying and covering containers that are at risk of filling up, egg-laying sites can be greatly reduced. “You have to pay attention to all the bowls, vases, flower pots, plastic toys lying around outside,” says Gilles Besnard. “A rainwater collection container can bring in hundreds of mosquitoes per week.” However, there is no need to send everything in the trash: it is possible to put coarse sand on the cup of the plants, or to prevent access to birds using an anti-insect net. For more information, go to the website https://agirmoustique.fr/.
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