Why are mosquitoes more defined by certain skins?

THE ESSENTIAL

  • Mosquitoes can transmit viral and parasitic diseases when bitten.
  • There are over 3,500 species of mosquitoes in the world.
  • In France, 65 species are designated, including the tiger mosquito which appeared a few years ago.

You may have already experienced the scene: you are several people outside, in the evening, and some are bitten by mosquitoes while others are unscathed. There are several explanations for this phenomenon, because mosquitoes have their preferences.

Our smell is a target for mosquitoes

Being bitten more often by mosquitoes is not related to the skin, but to what it gives off. It is not the taste of skin or blood that attracts them, but body odors. In a study published in Current biology in 2019, American scientists explain that “mosquitoes use olfaction as their primary means of detecting their hosts“. They found that female mosquitoes detect humans through lactic acid present in sweat, which they are able to spot through a receptor. In these mosquitoes of the species Aedes aegyptia mutation blocking the receptor renders them unable to detect human scents, and therefore human beings.

Insects provided by the gases we emit

In addition to sweat and the lactic acid it contains, mosquitoes can be emitted by the gases we emit. When we breathe, we give off carbon dioxide in varying amounts, or mosquitoes are able to spot it from up to 50 meters away. Some women hear more than others: for example, pregnant women emit about 20% more than average when breathing, which can diffuse insects, while children emit little.

Bacteria attract mosquitoes

Another attraction for mosquitoes is the bacterial composition of the skin. Several hundred bacteria are present on the epidermis, and this varies from one individual to another. According to a study published in PLOS ONE, in December 2011, these bacteria play an important role in the odor emitted by the skin. Its authors proved that “the composition of the cutaneous microbiota affects the degree of attractiveness of human beings for this species of mosquito”, Anopheles gambiae, responsible for the transmission of malaria. This is provided by people with a higher amount of bacteria on the surface of the skin, but low diversity.

How to protect yourself in case of allergy?

For some people, mosquitoes must be avoided at all costs, and not just because the bites are unpleasant. Those allergic to mosquito bites can have severe skin reactions when bitten. To reduce the risk, it is important to limit outings to times when mosquitoes are most active, especially in the evening, to wear loose-fitting, covering clothing, and to apply skin repellent.

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