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Right now, mosquitoes seem to be everywhere. A very widespread insect throughout the world, France is obviously not immune to the presence of this pest. In our region, the most widespread species is the common mosquito (Culex pipiens) but the tiger mosquito (Aedes albopictus ), originally from Asia, has arrived in our countries since 2004. This one is more problematic, because it can be vector of serious illnesses: dengue, chikungunya and Zika. In 2023, only 24 departments escaped its presence.
If we were more accustomed to seeing mosquitoes arrive in the summer season, it would seem that global warming favors mosquito invasions by extending their period of activity. A study published in 2018 in the journal Environmental Health Perspectivesis quite clear on the subject. Looking at data on mosquito populations in the northeastern United States over a 50-year period, researchers found that the mosquito season lengthened by 33 days during this period. The fault is the rising temperatures.
Even if it is currently difficult to say with certainty whether mosquitoes are more numerous than # Previously, it appears that several factors contribute to the increase in mosquito populations in certain regions of the world. Why are we suddenly faced with such a proliferation of these harmful insects?
An environment conducive to reproduction and remarkable adaptive diversity
The proliferation of mosquitoes is primarily due to the combination of favorable weather conditions and a habitat suitable for their reproduction. The abundant rains and mild temperatures of recent months have created an ideal environment for egg laying and larvae to hatch. For the mosquito, the concordance of these factors is a godsend.
Another very important factor to consider: the presence of&# 8217;water. Indeed, all species of mosquitoes need stagnant fresh water to lay eggs and ensure their offspring. In the middle of nature, it's not what's missing and neither in an urban area! Blocked gutters, sewers, uncovered water containers, public works, so many areas which constitute temporary water points and veritable breeding grounds for mosquitoes.
< p>Far from being simple pests, mosquitoes represent a true feat of animal evolution. Their exceptional adaptability allows them to thrive in a wide variety of environments, making them remarkable survivors in the face of to the changes and developments of the modern world. How to explain this extraordinary resilience ?
First, the diversity of mosquito species is quite astonishing. Today there are more than 3 500, spread across the four corners of the globe. This wealth is the fruit of a long evolutionary history, beginning more than 220 million years ago, on Pangea, the original continent.
Over generations, geographically isolated mosquito populations have accumulated genetic differences and evolved into distinct species, each with their own biological and morphological characteristics. On each continent, specific evolutionary forces have shaped these species, adapting them to the unique environments they occupy.
This genetic diversity is further reinforced by an extremely flexible genome. Mosquitoes possess one of the greatest genetic variability in the animal kingdom, allowing them to select more efficient variants and adapt to varied environments, even those that change rapidly. This study published in the National Library of Medicine looked into this specificity.
In addition to their remarkable adaptability, mosquitoes benefit from a demographic advantage which again makes all the difference: their exceptional prolificacy. A female mosquito can lay several hundred eggs during her life, an impressive number which is accompanied by a short generation time, around ten days in average. In ten days, a mosquito can be born, reach adulthood and reproduce. In the insect kingdom, this capacity remains quite remarkable.
Pestual insects, but an important role in the ecosystem
The mosquito is a pest, that's indisputable. According to the Geo.fr website, each year, this insect kills 800,000 people per year. “ For comparison, this insect kills more humans in 24 hours than the shark in 100 years ”. Think about it the next time a shark approaches you during your next swim and put things into perspective!
However, they occupy a special place in the balance of natural ecosystems and contribute to maintaining the food chain and biodiversity. Essential prey for many predators, mosquitoes constitute a vital food source for a wide variety of animal species. Dragonflies, adept at aerial hunting, watch for these flying insects with formidable precision. Bats, for their part, detect them using their sophisticated sonar and capture them in mid-flight, devouring hundreds of mosquitoes per night.
But they are not not just prey! Mosquitoes also contribute to the good health of aquatic ecosystems. Their larvae play a vital role in the degradation of organic matter present in the water. By feeding on micro-organisms and plant debris, they contribute to the purification of water and the maintenance of its ecological balance.
If we often (rightly) vilify the female mosquito for its bites, we must not forget that this insect can also play a positive role in the pollination of certain plants.In search of nectar to fuel their flight, they involuntarily transport pollen from one flower to another, thus promoting the reproduction of these plants. Indeed, males and females feed on nectar (sweet liquid produced by the flowers) before the laying period.
The invasion of mosquitoes is therefore a complex phenomenon which can be explained by a combination of environmental and human factors. Fighting these pests remains necessary for public health, but it must be done in a reasoned manner. Making them disappear entirely could cause unexpected cascading negative effects, some of which directly affect us. However, don't deprive yourself of breaking them out in your hands if you have the chance, it won't change much and you'll sleep peacefully.
- The proliferation of mosquitoes can be explained by environmental and human factors.
- These insects are little jewels of evolution, spoiled by a genome allowing them to adapt very easily.
- Far from being simple pests, they also play a positive role in the maintenance of natural ecosystems.
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