In the battle against bloodsucking mosquitoes, there always seems to be those unfortunate individuals who bear the brunt of the incessant bites while others remain relatively unscathed.
If you are one of the unlucky mosquito magnets, constantly swatting away the pesky insects, you are not alone. From genetics to body chemistry, experts say many elements come into play that determine who these bloodsuckers find most irresistible.
“They’re flying around looking for a dark object that’s releasing C02 and has heat,” Winnipeg entomologist Taz Stuart, said. “If you’ve been running around a soccer field for an hour, she may think you’re tasty because you’re throwing off lots of C02 and you’re warm.
“That person may be more attractive than a person sitting in the stands, who’s having a beverage and watching the game.”
It is only the female mosquitoes that hunt, and they are picky eaters. If a person’s scent fails to meet their standards, these selective females may find another host to feed on, he said.
When it comes to hunting, female mosquitoes rely heavily on scent in order to detect carbon dioxide emitted by humans, explained David Beresford, an entomology professor at Trent University in Oshawa, Ont.
“They will come to a gas lawn mower or a car exhaust for the same reason,” he said.
“They are following the smell, but it works more like soap bubbles in the air. So they get a big burst of these chemicals and then they track where the smell might be coming from until they get another burst of chemicals.”
And then they try and find more of the odor until they see or land on a target, he added.
What makes someone a mosquito magnet?
There are many theories that try to explain why mosquitoes find some people more attractive than others. It could be the heat you give off, your body odour and even the clothing colour you are wearing, Beresford said.
“Some people certainly are more mosquito magnets, and there are times when each of us will be more magnetic than at other times,” he said.
“If you have a couple of beers, we’re not sure why but you become more attractive to mosquitoes. Pregnant women are more attractive to mosquitoes, we think it’s because their body temperatures are a little higher, and they’re breathing more C02.”
There is also the theory that your blood type may attract mosquitoes, but Beresford said this has mixed evidence.
“It doesn’t make sense to me that that would be the case. Because they’re not actually after a specific chemical that’s unique to one or the other blood type,” he said.
Stuart agreed, saying there was not a lot of evidence to back up this claim.
But Stuart did cite a recent study showing the chemicals on someone’s skin may be more attractive to a female mosquito than someone else.
The 2022 study, published in Cell, found that people who are most attractive to mosquitoes produce a lot of certain chemicals on their skin tied to smell.
The researchers had 64 volunteers wear nylon stockings around their forearms to pick up their skin smells. The stockings were put in separate traps at the end of a long tube, and then dozens of mosquitos were released.
After pitting the different stockings against each other, the researchers found a winner that was about 100 times more attractive than the last-place nylon sample, meaning mosquitoes did indeed have a favourite person.
People who were more attractive to mosquitoes consistently emitted higher levels of carboxylic acids, which are fatty acids produced by skin microbes, the study said. The researchers discovered that those who acted as mosquito magnets exhibited elevated levels of this specific molecule on their skin surface.
“We determined that highly attractive humans have higher levels of several carboxylic acids on their skin than less attractive humans,” the researchers stated in their study.
The study was done over a period of three years, and the researchers also found that the people who were mosquito magnets remained one over the years.
How to keep mosquitoes away
If you live in Canada, it may be impossible to avoid mosquito bites in the summer, Beresford said.
But there are ways to minimize exposure, such as wearing light-coloured clothing.
Mosquitoes seem to be attracted to dark colours, such as black and blue, he said. This is because mosquitoes are drawn to high-contrast objects and dark colours may provide a contrasting visual against the surrounding environment.
“Black and blue will draw them in because it acts like a contrast. Blue has a certain wavelength that it’s reflecting, and for whatever reason their eyes are cued to that, and it translates in their minds to a blood meal,” he explained.
He also recommended wearing DEET to create a protective barrier on exposed skin. DEET is a chemical spray that can confuse mosquitoes’ olfactory receptors and throw them off. They may be near you, but they won’t necessarily bite.
Mosquitoes seem to love dawn and dusk, so avoid heading out during those times.
“But if it’s not windy out, and I happen to be sitting on my back deck in a cool corner, that mosquito still can feed during the day, too,” Stuart said.
According to Stuart, it’s also crucial to take measures to prevent standing water in your backyard, as this can act as a breeding ground for mosquitoes.
“It’s important to make sure that those water bodies in your backyard are either being covered, drained or treated,” he said.
— with files from the Associated Press
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