May 22, 2023 – Anyone who has ever been on a picnic knows that mosquitoes are more attractive to some people than others. An outdoor “smell test” conducted in Africa may partly explain why.
The researchers found that mosquitoes were drawn to human odor that contained high levels of carboxylic acids, secretions that protect the skin, in keeping with the study, which was published in Current Biology.
Some of those carboxylic acids are also present in “stinky” cheeses akin to Limburger, which have long been known to draw mosquitoes. Humans naturally produce these acids in various amounts, but cannot smell them on their skin.
The mosquitoes were significantly less drawn to the chemical eucalyptol, which is present in plants akin to sage and eucalyptus trees.
The researchers don't have any immediate advice for picnickers, but their findings could help develop higher methods to combat malaria, said Conor McMeniman, PhD, assistant professor of molecular microbiology and immunology on the Johns Hopkins Bloomberg School of Public Health and the Johns Hopkins Malaria Research Institute. CNN.
Malaria causes over 600,000 deaths annually, mostly amongst children under 5 and pregnant women. “Malaria causes a lot of suffering around the world, and part of the motivation for this study was to really understand how the mosquitoes that transmit malaria meet humans,” he told CNN.
Previous studies were mostly conducted within the laboratory, while this study was conducted outdoors in Zambia in a 66-square-foot tent. About 200 mosquitoes within the tent were observed between 10 p.m. and a couple of a.m., their most lively time.
Six small sleeping tents were arrange around the big tent for volunteers. The breath and body odor of every participant was pumped into the big tent via an extended tube. The tubes led into absorbent pads that were heated to a temperature near the typical human body temperature.
Infrared cameras observed the mosquitoes' behavior. “We found that mosquitoes showed an innate preference for certain people, even as they navigated a complex sensory environment with multiple host odor sources,” the study says.
The researchers then analyzed the themes' skin to create a chemical profile of every person. Mosquitoes preferred human odors that contained high levels of carboxylic acids, the study says.