By Shiyori Iwase

Yomiuri Shimbun Staff Writer

When mosquitoes detect carbon dioxide exhaled by humans, their senses of sight and smell are sharpened and their responses to odors and other stimuli are enhanced, according to a study team from Riken research institute and Kao Corp., a major Japanese household products manufacturer.

The research team believes that the discovery will provide clues that will help formulate more effective ways to protect people from being bitten by mosquitoes. Its research paper was carried in the journal "Scientific Reports."

Mosquitoes are believed to be able to recognize humans from about 10 meters away in outdoor environments by detecting the CO2 they exhale. The insects then rely on their visual and olfactory senses to guide them toward their targets.

To learn how mosquitoes recognize targets, the research team developed a "virtual reality" device that gives mosquitoes the false impression that they are flying freely. They tethered the mosquitoes to prevent them from flying away and placed an LED panel in front of them. The research team displayed moving images of stripes simulating human figures on the panel. Then they exposed the mosquitoes to CO2 and various kinds of smells and measured their wingbeats to assess the strength of their responses.

The results showed that mosquitoes exposed to CO2 at a concentration level about 10% of that found in exhaled human breath reacted more strongly than those that were unexposed. The exposed mosquitoes tried to track the images even when they were moved faster or made fainter.

The research team also conducted an experiment in which they diffused the smell of used socks, which mosquitoes like, and the scent of an herb which they dislike. Mosquitoes exposed to CO2 moved toward the sock smell faster than the unexposed ones and more strongly avoided the smell of the herb.

"It appears that CO2 makes it easier for mosquitoes to track humans even in dark environments," said Aya Namba, a researcher at the Kao Human Health Care Products Research Laboratory. "The study shows what formidable opponents they are."

Namba added that she hopes that new materials and products will be developed based on these findings.

"How mosquitoes are attracted (to humans) had already been known, but this study provided more clear proof," said Kozo Watanabe, a professor at Ehime University who specializes in ecology and health sciences. "This method of using a virtual reality device to determine what draws insects has the potential for a wide variety of uses, including in testing methods to ward off and exterminate agricultural pests."

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This article is from The Yomiuri Shimbun. Neither Dow Jones Newswires, MarketWatch, Barron's nor The Wall Street Journal were involved in the creation of this content.

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September 24, 2025 06:04 ET (10:04 GMT)

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