Strasbourg (AFP)

Small, discreet and urban, it is also thirsty for blood and a potential vector of serious diseases: in Strasbourg, where the tiger mosquito proliferates, the hunt for stagnant water is in full swing in the gardens.

"My wife no longer comes because of that," says José Sampaio at the entrance to the large family garden that he rents.

This summer, stays in the green spaces often end with a concert of slaps in the air and scratching sessions.

The abundant rains caused the so-called "native" mosquito to swarm, but also the tiger mosquito, Aedes albopictus, recognizable by its fine white stripes.

"There are more than usual," confirms Jean-Pierre Danard, the treasurer of the association of workers' gardens in Schiltigheim, which grows lemongrass, reputed to be repellent, in his vegetable garden in this town bordering on Strasbourg.

Armed with a roll of mosquito nets, a long ladle to check for the presence of larvae and leaflets, Christelle Bender and Alexis Bergeron from the Bas-Rhin mosquito control union (SLM67), public operator of the department, surveyed the alleys of the thousands of allotment gardens in Strasbourg to make amateur gardeners aware of the risks posed by tiger mosquitoes.

A tiger mosquito on pants, photographed during a prevention operation against the proliferation of this type of mosquito, led by the Bas-Rhin Mosquito Control Union in Strasbourg, August 23, 2021. ABDESSLAM MIRDASS AFP

- Urban mosquito -

"100% urban", Aedes albopictus grows at 80% in individuals and is all the more harmful as it stings constantly during the day and can transmit viral diseases such as dengue, chikungunya or zika s' he previously stung a patient.

"Absolutely anything that can hold water and that is artificial can constitute a breeding ground", explains Christelle Bender, technical manager of SLM67, who advises to empty any object where rainwater could stagnate, not be- what a small ashtray.

The mosquito net on José Sampaio's rainwater collection barrel has been renewed and is found to be well adjusted.

But in the plot next door, an inflatable pool adjoins a pierced barrel, a stack of cups and a watering can on the ground.

In short, a mosquito-tiger paradise.

"With a blood meal, a tiger mosquito can lay up to 200 eggs", which, once submerged, will give larvae and about a week later mosquitoes, details Alexis Bergeron, technician from SLM67.

Smaller and more discreet than the common mosquito which bites in the evening and roars, the tiger mosquito was spotted for the first time in mainland France in 2004 in the Alpes-Maritimes before gradually spreading to around sixty departments.

A member of the Bas-Rhin Mosquito Control Union collects stagnant water in a barrel where tiger mosquito larvae proliferate, during a prevention operation in Strasbourg, August 23, 2021 ABDESSLAM MIRDASS AFP

In the Bas-Rhin, it first appeared in 2015. Since then, "the colonization zone has doubled from year to year", recounts Christelle Bender.

"Once it is installed somewhere, it remains, so the objective is to reduce the population. The citizen has a preponderant role in the fight against the tiger mosquito," she underlines.

Hence the importance of these preventive actions even at the end of summer, because the tiger mosquito experiences its peak of activity in August and September, later than the native mosquito.

- Diseases -

In the Var, two cases of "indigenous" dengue fever in people who have not traveled have been detected recently.

Nothing like this in the Grand Est, where only the Bas-Rhin and Haut-Rhin are colonized, specifies the Regional Health Agency (ARS).

But five "imported" cases of people who have traveled were reported this year in Alsace, which required two emergency mosquito control operations.

The aim was to avoid any risk of transmission to other people "when the patient is in an area infested by the tiger mosquito".

A member of the Bas-Rhin Mosquito Control Union holds a mosquito net in his hands during an operation to prevent the proliferation of tiger mosquitoes, in Strasbourg, August 23, 2021. ABDESSLAM MIRDASS AFP

In both cases, an insecticide, deltamethrin, was sprayed at night in the municipalities concerned after informing the residents.

(The presence of the tiger mosquito can be reported on the site www.signalement-moustique.fr)

© 2021 AFP