It has already colonized just under half of the Ile-de-France municipalities. The tiger mosquito, an invasive insect in full expansion, likes in Ile-de-France. Known to be a vector of tropical diseases, such as chikungunya, dengue and zika, the tiger mosquito, so called for its dress and its black legs striped with white, it has spread rapidly in France since the early 2000s.
Today, it is present in nearly sixty departments. Ile-de-France has not escaped this mosquito of just 2 millimeters, five times smaller than its common cousin.
Hauts-de-Seine and Val-de-Marne among the most affected last year
The Ile-de-France Regional Health Agency (ARS) indicates that "the tiger mosquito has been identified in all the departments of the region with the exception of Val d'Oise", where there were too few of reports last year to move the department into the red zone. Vigilant, the ARS observes “an expansion of the territory of the tiger mosquito with several communes newly colonized last year. The departments most affected were 92 and 94. "
What can we expect this year in the region? "At this stage, it is too early to establish a potential recrudescence targeted by department, specifies the ARS IdF. It is indeed difficult to project on the dynamics of expansion because it is influenced by the weather. An alternation of hot and sunny weather with showers being particularly favorable to the development of the mosquito. "
No case of chikungunya, dengue or zika in Ile-de-France
The ARS also examines its data tables and wants to be reassuring, figures in support. The region is not affected by an upsurge of tropical disease cases. "No indigenous case has been identified in Ile-de-France, we only have imported cases," said the agency.
The latter nonetheless notes that “around 200 cases of arboviruses (Editor's note: infectious disease caused by an arbovirus, such as chikungunya, dengue or zika) in Ile-de-France last year required intervention to find the presence tiger mosquito nearby to avoid the risk of mosquito transmission. Three of these interventions led to a mosquito control operation. "
Nearly 500 traps set in the region
If the proliferation of the tiger mosquito seems difficult to control without the application of reflex gestures (read box at the end of the article) , the fight is indeed carried out wherever the insect is detected, but also as a preventive measure. In total, "470 traps are installed in the region in the general environment and around more sensitive sites such as hospitals, airports and certain places with high tourist traffic," says ARS IDF. Among these, there are notably the Disneyland park, in Seine-et-Marne, as well as the castle of Vincennes, in Val-de-Marne.
The regional mosquito control agency (ARD) is responsible for placing the traps in the cities. "We are working with the ARS in several departments of Ile-de-France, including Essonne where we have installed our traps in fifty municipalities," said an operations manager. "
A "harmless" organic larvicide for birds
The trap consists of a three-liter tank containing water. On the surface floats a polystyrene plate on which the mosquito will lay its eggs. "The water contains a biological larvicide which will prevent the larvae of the eggs from developing", explains the specialist, who specifies that this product is "harmless". "A bird can perfectly drink in this nest without being affected and the trap is surmounted by a grid to prevent the polystyrene from flying away or that large animals sneak in and damage the device," he enlightens us. The traps are set right now and the campaign is expected to last until November.
"Every two weeks, our teams remove the polystyrenes," he adds. They are sent to our laboratories to determine whether the laid eggs belong to the family of tiger mosquitoes or whether they are common mosquitoes. These surveys allow you to see which areas are colonized and in what quantity. "
Fewer natural predators of mosquitoes
Julie Ozenne, elected official (SE) in Vigneux-sur-Seine (Essonne) and vice-president of the environmental protection association Renard (Rally for the Study of Nature and Development of Roissy and his District), welcomes this vigilance. "Last year, alerts to the tiger mosquito were recorded in Vigneux in the sector of Lake Montalbot," recalls this environmental activist. These surveys seem very useful to me in order to know precisely the zones colonized or not. "
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If she wants to avoid panic over this proliferation, she regrets "the decline in populations of natural predators of mosquitoes, such as bats, birds and amphibians. This phenomenon promotes the massive establishment of tiger mosquitoes and the commons, and chemical mosquito control campaigns which are necessarily harmful to the environment. "
Useful gestures to fight against their proliferation
Let us say it without delay: mosquito repellents (insecticides and repellents) do not make it possible to fight effectively and over time against these insects. To counter the proliferation of the tiger mosquito, it is necessary to eliminate its places of rest and its places of laying. To achieve this, a few simple reflexes must be adopted.
“The first is to eliminate standing water points around your home, we are told at the ARS Ile-de-France. The tiger mosquito needs very little water to grow. »Cups, flower boxes with tanks, outdoor gardening tools and other objects that sometimes hang around in the garden should be the subject of great vigilance. Used tires, sometimes carelessly stored in a corner, must be sheltered or filled with soil.
Another essential point is the rainwater and wastewater drainage system. Regular cleaning of gutters, manholes, gutters and drains is more than advisable. "We must also pay attention to shared gardens and rainwater tanks for watering that must be covered to prevent access," says ARS.
If the municipalities must act at their level in green spaces and on public roads, individuals are invited to maintain their garden, that is to say clearing, pruning trees, pruning tall grasses and hedges, but also collect fallen fruit and plant debris. Everyone can also report the presence of the tiger mosquito through the portal specially dedicated to this approach.