Mosquitoes bite us to quench their thirst

American researchers have discovered that mosquitoes also use our blood to rehydrate when they are thirsty.

The tiger mosquito worries in France: 42 departments are currently under enhanced surveillance (red vigilance), 20 others are vigilant orange. In some parts of the world, this black insect with white stripes is vector of viruses such as dengue, zika or chikungunya. Indeed, it is infected by biting a sick traveler, carries the virus and secondarily transmits it to non-immune people during a next bite. Thus, a cycle of autochthonous transmission is generated and can be at the origin of one or more outbreaks. Why do mosquitoes bite?

It is known that mosquitoes bite to feed on proteins contained in our blood, but American researchers have just shed new light on the reasons that push these insects to bite us: they are thirsty! The study was conducted by researchers at the University of Cincinnati, Ohio, USA. Elise Didion, co-author of this research, explains that she "found the highest rates of West Nile virus transmission during periods of drought because mosquitoes seem to use blood to replace the water they are losing."

A quick reaction to dehydration

Biology students conducted research on a group of dehydrated mosquitoes when some tried to escape. The young researchers found that the insects were very aggressive and that all of them tried to bite, when they usually do, only when they need protein to lay their eggs.

In reality, mosquitoes dehydrate quickly enough. "We've seen effects on mosquito behavior after two or three hours, when the temperature is higher and the humidity is lower: it completely changes the way they behave," says Joshua Benoit, one of the researchers and researchers. authors of the research. The students tested the mosquitoes by providing them with a source of water and a replica of the skin with blood. All chose water. According to the researchers, dehydration would be responsible for 30% of cases where female mosquitoes seek to feed on blood.

Precautions to take

If you have to travel to areas affected by dengue, chikungunya or any other virus that can be transmitted by the tiger mosquito, some precautions should be taken.

"Everyone, by changing their behavior and adopting simple and uncomplicated gestures, can participate in the fight against the proliferation of tiger mosquitoes and help prevent the introduction of dengue, chikungunya or zika in mainland France. it is very important to remove stagnant water, which allows mosquito breeding, around his home, "the government recommends.

Indeed, used to being born in small cottages (plants retaining water), the tiger mosquito was easily able to colonize all kinds of larval lodgings that the urban and peri-urban environment offers as cups under the flowerpots, watering cans, old tires, clogged gutters, etc ... The best solution for better protection is to empty all these small "water reservoirs" or to renew them at least once a week.

To learn more about the Zika virus and the tiger mosquito, find our show with Anna-Bella Failloux, medical entomologist at the Institut Pasteur in Paris.

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