Why some people get bitten by mosquitos while others don’t, study finds
If you’ve ever been eaten alive by mosquitoes at a BBQ but the person next to you remains unbitten, your clothing color could be to blame.
New research shows that certain colors attract hungry mosquitos while others are disregarded, a discovery that could be exploited to develop new mosquito traps or repellents.
Mosquito bites can transmit diseases including malaria, yellow fever, dengue fever, and Zika, in addition to being a nuisance at outdoor events. Understanding how the bugs locate hosts may lead to the development of new preventive measures.
Earlier studies have demonstrated that mosquitos are attracted to the stench of carbon dioxide from human breath, and the latest study looked at how that aroma primes them to start seeking food.
The researchers tracked the behavior of female mosquitos of the common species Aedes aegypti to visual and olfactory cues in a test chamber. They looked at how the bugs reacted to dots of various colors on the bottom of the chamber, both with and without a CO2 spray.
The researchers discovered that mosquitoes would fly towards a dot whether it was red, orange, black, or cyan, and if it had previously sniffed CO2. Without the gas, the bugs would mostly disregard the dots, regardless of color. Even though they’d been primed to hunt with a spritz of CO2, they didn’t care for dots that were green, blue, white, or purple.
“Mosquitoes appear to use odors to help them distinguish what is nearby, like a host to bite,” says sr. author of the study, Jeffrey Riffell. “When they smell specific compounds, like CO2 from our breath, that scent stimulates the eyes to scan for specific colors and other visual patterns, which are associated with a potential host, and head to them.”
So, why are reds and oranges so appealing to mosquitoes? According to the researchers, human skin emits a strong red-orange signal to mosquito eyes, independent of its colour or color. In follow-up studies, the researchers utilized cards of various human skin tones or their own hands, and discovered that the bugs will only fly towards them if they first smelled CO2. Even with CO2, the insects went back to ignoring them if the long wavelengths were filtered out or the hand was wearing a green glove.
Finally, the researchers carried out the same tests with genetically engineered mosquitos. The bugs didn’t respond to the visual stimuli when genes responsible for smelling CO2 or seeing long wavelength colors were altered, demonstrating that both senses are required to ring the dinner bell.
According to the researchers, future research will look into other cues, such as skin secretions, that could assist mosquitoes to find their host. They also speculate that other creatures that hunt on certain animals may have distinct color preferences.
Meanwhile, the research could lead to new mosquito-control and bite-prevention strategies, such as wearing white or developing red CO2-emitting traps.
Source: 10.1038/s41467-022-28195-x
Image Credit: Getty
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