Haute-Garonne: where are the hot spots where the tiger mosquito proliferates?

the essential
For several years, the inhabitants of Haute-Garonne have had difficulty cohabiting with the tiger mosquito. But where does this pest like to settle? Where does he live ?

“We were bitten from morning to night,” said a tourist on vacation in Grau-du-Roi a few weeks ago. An unprecedented episode of mosquito infestation ruined the holidays of many Julyists before an emergency mosquito control was triggered. This year again, this insect is very present in the gardens and on the terraces. But where does the tiger mosquito grow the most? To fully understand the movements of the tiger mosquito, we must look at how it works. “There are two stages in the life of the mosquito, the first is the larval stage where it lives in an aquatic environment. The second is when the mosquito hatches and is in the adult stage. Very quickly then, the males and females mate and for the eggs to develop they need blood,” explains Fabrice Chandre, director of research at the Institute of Research for Development (IRD).

1,500 descendants in one month

Note that the female can store sperm and therefore theoretically only needs one mating for her entire life, which lasts on average one month. Over this period of time, the female is able to lay between 80 to 100 eggs every two days, which represents 1,500 offspring. “The mosquito only needs a bottom of water present in small containers that can be lying around in the garden, cups of flowerpots… In summary, the breeding sites where the female lays eggs are the work of man, we are responsible for its proliferation”, adds the specialist. The result is that today more than 65 departments are placed on red alert against the tiger mosquito.

A traveling insect?

How do mosquitoes move? “He’s not a great traveler, he’s more of a homebody, as soon as there’s a bit of stagnant water and especially food, that is to say our blood, it stays where it is. has board and lodging. On average, it is estimated that it moves about a hundred meters,” notes the researcher. This means that if mosquitoes are present in an individual it is undoubtedly because he was born here. The tiger mosquito is not a good flying insect either, but it is not uncommon to come across it on the 2nd or 3rd floor of a building. “In town where the habitat is very dense, it has blood and roosts in shambles and since it does not fly very well, it simply means that from the start, it settled there. Mosquitoes are where humans live,” says Fabrice Chandre of the IRD. As Didier Fontenilles, medical entomologist and director of research at the IRD, points out, the tiger mosquito tends to prefer the city to the countryside. “He has been in France since 2004, over the years this mosquito with extraordinary DNA has adapted to humans. It settles in the city because it has the optimal conditions to develop, lots of blood and small stagnant water spots”.

Among the places appreciated by this pest are water collectors, rainwater drainage manholes, watering cans with a bottom of water… “Even in a child’s toy abandoned on a terrace on the 4th floor, there is a bottom of water and humans, it settles down”, specifies Didier Fontenilles. The only conditions that the tiger mosquito does not tolerate: wind and high heat. “Beyond 40 degrees, it will seek shade and therefore necessarily be less aggressive. He doesn’t like to fly either, so he avoids these types of conditions”, slips the specialist. Beyond its power of nuisance with these stinging bites, the tiger mosquito is a public health issue. Indeed, this species can be the vector of a hundred viruses or diseases including dengue fever, Zyka or even chikungunya. Hence the need to tackle the problem at the root. “Everyone must play their role and do their best to eliminate the breeding sites where the female lays,” conclude the two researchers. The hunt is on.

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