May 28, 2023

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Why mosquitoes prefer to bite certain people. What scientists have discovered

If you’ve ever wondered why you attract mosquitoes like a magnet, scientists have the answer, according to a new study. Here’s why.

A team of researchers led by Leslie Vosshall, a Rockefeller University professor and head of the Neurogenetics and Behavior Laboratory, tried to identify why certain people seem to attract more mosquitoes than others, according to CNN.

Over the course of three years, the researchers asked a group of 64 volunteers to wear nylon stockings on their arms for six hours a day for several days. Maria Elena De Obaldia, first author of the study and a former postdoctoral fellow at Rockefeller University, built a “olfactometer test with two variants” – an acrylic glass chamber in which the researchers placed two of the stockings. The research team then released yellow fever mosquitoes, scientifically called Aedes aegypti, into the room and observed which of the socks attracted the most insects.

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This test allowed the researchers to separate study participants into “mosquito magnets“, whose stockings attracted a lot of mosquitoes, and “low attractors”, which did not seem to attract as many mosquitoes. The scientists examined the skin “mosquito magnets” and found 50 molecular compounds that were higher in these participants than in the others.

We had no preconceived ideas about what we would find,” Vosshall, who is also the chief scientific officer of the Howard Hughes Medical Institute, told CNN. But one difference was especially distinct: “mosquito magnets” had much higher skin carboxylic acid rates than “low attractors“.

Carboxylic acids are found in sebum, the oily substance that creates a barrier and helps keep our skin hydrated.

Carboxylic acids are large molecules, Vosshall explained. “They are not that smellyshe said. But the beneficial bacteria on the skin “they chew these acids, which produce the smell characteristic of humans” – which may be what attracts mosquitoes”according to Vosshall.

Odor from skin secretions plays an important role

One participant, identified as Subject 33, was the #1 mosquito attraction: The subject’s socks were 100 times more attractive to mosquitoes.

When it comes to Aedes aegypti, female mosquitoes prefer to use human blood to fuel their egg production. These mini predators use a variety of mechanisms to identify and choose the people they bite, Vosshall said.

Carboxylic acids are only one piece of the puzzle in explaining how insects might choose their target. Body heat and the carbon dioxide we release when we breathe also attract mosquitoes.

Scientists still don’t know why carboxylic acids seem to attract mosquitoes so strongly, Vosshall said. But the next step could be to explore the effects of reducing carboxylic acids on the skin.

You cannot completely remove natural moisturizers from your skin, it would be bad for your skin healthshe said. However, Vosshall said that dermatological products may be able to minimize carboxylic acid levels and reduce mosquito bites.

Every bite of these mosquitoes puts people’s health at riskshe said. “TAedes aegypti mosquitoes are vectors for dengue fever, yellow fever and Zika. Those people who are magnets will be much more likely to be infected with viruses“.

Mosquitoes evolved to hunt by smell

Matthew DeGennaro, an associate professor at Florida International University who specializes in mosquito neurogenetics, told CNN that the study results help answer long-standing questions about what specific factors make mosquitoes love some people more than others. He was not involved in the study.

This study clearly shows that these acids are important“, he said. “Now, the way mosquitoes perceive these carboxylic acids is interesting because these chemicals are very heavy, so they’re hard to smell from a distance.

It could be that these chemicals are altered by, say, the skin’s microbiome and cause a certain type of odor. Or it could be that other factors in the environment break down these chemicals a bit, making them easier for mosquitoes to detect. This insect evolved to hunt us“.

For DeGennaro, the staying power of certain people’s attractiveness is one of the most interesting aspects of the research.

I didn’t know there were very stable preferences for mosquitoes over certain people“, he said. “It could suggest that the skin microbiome is important, although they did not address this.

Further research should explore the microbiome that lives on human skin to understand why mosquitoes are attracted to certain compounds over others, he said. And that could lead to better products to reduce mosquito bites and the spread of disease.

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