2023-10-15 15:17:31
Par Anne-Laure Petit-Hénon
Published on Oct 15, 23 at 5:17 p.m. See my news Follow News The Culex-type mosquito might survive all year round if temperatures continue to rise. (©Illustration / Pixabay)
While the month of September 2023 is the hottest ever recorded in France and heat records were broken at the beginning of October, it is not only the seaside resorts and terraces that have benefited from these abnormally high temperatures. The mosquitonightmare of summer nights, continues to develop under ideal conditions.
A hot period more favorable for mosquitoes
Let’s get back to basics: when are you supposed to encounter mosquitoes? When it’s hot, of course.
Contacted by actu.fr, Fabrice Chandre, entomologist at the Institute of Research for Development (IRD) specifies for the tiger mosquito: “Normally, we come across it from the end of April-beginning of May until the end of October. But as high temperatures continue throughout the year, we now encounter it from the beginning of April until the end of November. »
In fact, it is not so much adult mosquitoes that like the heat as their larves. The warmer the water they are in, the more they will grow quickly.
Once the eggs are laid, it takes 24 to 48 hours for the larvae to hatch. In the water, if temperatures are optimal, they will take regarding eight days to become adult mosquitoes. If it’s cooler, they will need two to three weeks.
Fabrice ChandreEntomologist
The optimal temperature development of a mosquito larva is located between 25 and 28 degrees. If the water is around 15 degrees it will grow, but less quickly. If the water is really cold, below by 10 degreesthe larva will not develop.
Once adultmosquitoes have a lifetime from three weeks to a month.
But the mosquitoes know adapt to their environment and once the kiss comes: they put in place strategies to have offspring in the summer.
Videos: currently on Actu
Egg dormancy and mosquito hibernation
First the tiger mosquito. THE adults die in winter. But the eggs laid will survive.
When the days get shorter and temperatures drop, the eggs go dormant. Around April, when temperatures rise and the days lengthen, when the eggs are in the water, they will hatch and become larvae.
Fabrice ChandreEntomologist
The tiger mosquito certainly needs high temperatures to proliferate, but duration of sunshine is also a factor to take into account for its survival. “Eggs are sort of programmed to hatch when the length of the day lengthens. »
THE culex mosquitoesthe most common in mainland France, have another strategy to survive the winter.
“When temperatures cool, females do not lay eggs. They take shelter in cellars or caves to enter hibernation », explains Fabrice Chandre. They will therefore lay their eggs when milder temperatures return.
12 generations of mosquitoes in one year
The mosquito is a species that adapts quickly because it develops very quickly. Each week, the female mosquito lays between 400 and 500 eggs. “We can summarize by saying that in one year, there will be 12 generations of mosquitoes.”
Mosquitoes all year round?
Therefore, a question arises: with global warming, will we have mosquitoes all year round? For the entomologist, there is several scenarios possible.
For the culex mosquito, if the hot season continues, it will not go into hibernation. “So he might continue to lay eggs. »
For the tiger mosquito, it is different, since when the days shorten, the eggs do not hatch. But it adapts. And eggs only go dormant in areas with mild climate.
In tropical areas, females have lost the ability to lay eggs in diapause (temporary arrest of development in insects, Editor’s note). So they lay eggs all the time.
Fabrice ChandreEntomologist
Fabrice Chandre still wants to be reassuring, for the moment: “In mainland France, we are not there yet. »
Also read on
How to protect yourself from it?
If it seems impossible to get rid of mosquitoes, you can protect yourself. “The eggs hatch as soon as they are in water at the right temperature,” recalls the entomologist. Therefore, it is advisable to remove stagnant water points.
And if it’s already too late, there are repellent, but the best remain loose clothing and mosquito net. And the patience to endure for a while longer this unpleasant “bzzzz” to our ears in the middle of the night.
Follow all the news from your favorite cities and media by subscribing to Mon Actu.
1697394596
#Mosquitoes #month #October
