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If you’ve always suspected you might just be a mosquito magnet, scientists now have some proof for you: Mosquitoes are indeed attracted to some humans more than others, according to a new study.
A research team led by Leslie Vosshall, a professor at Rockefeller University and head of its Neurogenetics and Behavior Laboratory, set out to identify why some people seem to attract more mosquitoes than others. The research results were published in the journal Cell on October 18.
For three years, researchers asked a group of 64 volunteers to wear nylon stockings over their arms for six hours a day for several days. Maria Elena De Obaldia, the study’s first author and former postdoctoral fellow at Rockefeller University, constructed a “two-choice olfactometric test” – an acrylic glass chamber in which researchers place two of the stockings. The study team then released yellow fever mosquitoes, scientifically called Aedes aegypti, into the chamber and observed which bottom attracted the most insects.
This test allowed researchers to separate study participants into “mosquito magnets,” whose stockings attracted a lot of mosquitoes, and “weak attractors,” who didn’t seem as attractive to insects. The scientists examined the skin of the mosquito magnets and found 50 higher molecular compounds in these participants than in the others.
“We had no preconceived idea of what we were going to find,” Vosshall, who is also scientific director of the Howard Hughes Medical Institute, told CNN. But one difference was particularly distinctive: the mosquito magnets had much higher levels of carboxylic acid on their skin than the weak 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’re “not that smelly on their own,” she said. But beneficial bacteria on the skin “chew up these acids, which produce the characteristic human odor” — which could be what attracts mosquitoes, according to Vosshall.
One participant, identified only as subject 33, was the belle of the mosquito ball: the subject’s stockings were 100 times more attractive to mosquitoes than the less attractive participants.
And the level of attraction to humans seemed to remain fairly constant over time for participants who were tracked over the three-year period, Vosshall said.
Subject 33, for example, “never took a day off to be the most attractive human,” which could be “bad news for mosquito magnets.”
When it comes to Aedes aegypti, female mosquitoes prefer to use human blood to fuel their egg production, making their quest to find humans to prey on urgent. And these mini-predators use a variety of mechanisms to identify and choose the humans they bite, Vosshall said.
Carboxylic acids are just one piece of the puzzle in how pesky insects might choose their targets. Body heat and the carbon dioxide we give off when we breathe also attract mosquitoes to humans.
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 can’t completely eliminate natural skin moisturizers, it would be bad for your skin health,” she said. However, Vosshall said dermatological products may be able to minimize carboxylic acid levels and reduce mosquito bites.
“Every bite from these mosquitoes puts people at risk to public health,” she said. “Aedes aegypti mosquitoes are vectors of dengue fever, yellow fever and Zika. Those people who are magnets will be much more susceptible to getting infected with viruses.
Matthew DeGennaro, an associate professor at Florida International University who specializes in mosquito neurogenetics, told CNN the study results help answer long-standing questions about the specific factors that make mosquitoes like certain humans. more than others. He did not participate 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 particular chemicals are very heavy, so they’re hard to smell from a distance.
“It could be that these chemicals are modified by, say, the skin microbiome, and that causes some type of odor plume. Or it could be that other factors in the environment break down these chemicals a bit, so that they are easier for mosquitoes to detect.
The results are also “a really good example of how insects can smell,” DeGennaro added. “This insect evolved to hunt us.”
For DeGennaro, the endurance of certain humans’ attractiveness is one of the most interesting aspects of the research.
“We didn’t realize there were very stable mosquito preferences for some people,” he said. “This might suggest that the skin microbiome is important, although they didn’t address that.”
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 for reducing mosquito bites and the spread of disease.
“I think if we understand why mosquitoes find a host, we can design new repellents that will prevent mosquitoes from detecting these chemicals,” DeGennaro said. “And that could be used to improve our current repellents.”
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