The researchers confirmed that this individual characteristic of being attractive to these insects endures over time.
In a study led by researchers at Rockefeller University (USA), it was determined that people who are very attractive to mosquitoes produce significantly more types of organic acids, called ‘carboxylic’, in their skin fumes . Scientists believe that understanding why some humans are more attractive to female mosquitoes than others is evidence of which skin odors are more important. This could help in the development of more effective repellents, they communicated this Tuesday.
“There is a very, very strong association between having large amounts of these fatty acids in the skin and be a magnet for mosquitoes,” says lead researcher Leslie Vosshall, director of the Behavioral and Neurogenetic Laboratory at Rockefeller University. These substances are found in the sebum that we secrete from our glands and are used by the bacteria on our skin to produce our unique human body odor.
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The Specialist group asked eight volunteers to cover their forearms with nylon stockings for 6 hours a day and repeat this process several days a week for 3 years. The researchers constructed a ‘olfactometer‘ of two alternatives, which consisted of a main Plexiglas chamber connected with two tubes, each one of which ended in a box containing a nylon stocking.
Then they placed mosquitoes Aedes aegypti into the main chamber and tested the nylons against each other in all possible pairings through a round robin style “tournament” (a total of 64 pairing possibilities). The insects were free to fly through the tubes towards one nylon or another depending on how attracted they felt by the odors
. This behavior was noted by the researchers, who quantified the number of mosquitoes that made a choice of each alternative.
A nylon stocking was four times more attractive to mosquitoes than the average of the next participant ‘
more attractive‘ of the study, and up to 100 times more attractive than the less ‘popular’ . The specialists noted that the insects always threw themselves towards that particular sample in any of the combinations evaluated. This situation was obvious “within seconds of starting the trial,” said María Elena De Obaldía, a postdoc in Vosshall’s lab. “It’s the kind of thing that really excites me as a scientist. This is real stuff. This is a great effect,” he stressed.
Scientists performed chemical analyzes to identify 50 molecular compounds that were elevated in the sebum of the skin of the high attractiveness participants. They found that the ‘mosquito magnets’ produced carboxylic acids at much higher levels than the less attractive volunteers.
They found that this individual characteristic of being attractive to mosquitoes lasts over time.”Some subjects were in the study for several years and we saw that, if they were a magnet for mosquitoes, they remained a magnet for mosquitoes”, says De Obaldía. “Many things could have changed if about the subject or his behaviors during that time, but this was a very stable property of the person”.
Something extremely interesting
Scientists were baffled when, even by removing the mosquitoes’ olfactory receptors, they could not make them lose all attraction to people, or have a weakened attraction to everyone and could not discriminate the individual magnet from the least attractive of all. This would have been very important, as it could lead to the development of more effective mosquito repellents. “And yet that’s not what we saw. It was frustrating,” Vosshall commented.
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These results complement one of Vosshall’s recent studies on the exquisitely complex olfactory system of the female Aedes aegypti. That study indicated that the ‘A. aegypti’ has a double or triple redundancy system with which, if it fails to perceive an aroma, it detects another or a third. And if they detect all of them, the signal is amplified. “Mosquitoes have a plan b to their plan b to their plan b. To me, the system is unbreakable,” Vosshall said in that study.
Practical applications
Researchers are thinking of smearing the skin of a ‘magnet person’ with sebum and bacteria from the skin of a low-attractive person to provide a mosquito-masking effect. “We haven’t done that experiment,” says Vosshall. She and her colleagues hope their paper, published Tuesday in Cell, will inspire researchers to try other mosquito species, including the genus Anopheles, which spreads malaria. “I think it would be really cool to find out if this is a universal effect,” she added.
