Have you ever felt personally targeted by a mosquito while sitting by the fire trying to roast the perfect marshmallow? Well, a recent study has found that you likely weren’t imagining things. Turns out, some mosquitos like the taste of certain people more than others.
The study, which was published in iScience in late August, tested the attraction level of three different mosquito species—Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus—to 119 different human participants.
Lead researcher on the study, Matthew DeGennaro, says these species were selected because they pose the highest health risks to humans in Florida, where the study was conducted. These species are known to spread harmful diseases like Zika virus, dengue fever, and West Nile virus, which are expected to become more common as climate change worsens and mosquito habitats expand. While the latter species has not been detected in Canada, the first two are known to inhabit parts of southern Ontario.
According to the study’s findings, mosquitos are surprisingly picky eaters, or rather, suckers. “There isn’t one type of person who is more attractive to all mosquitoes,” says DeGennaro. “There was a group of people who were very attractive to Aedes aegypti, for example, but there was also a group that was less attractive.” The same went for Aedes albopictus and Culex quinquefasciatus.
For one species, Aedes aegypti, male participants were favoured over female ones. But the overall attraction factor, says DeGennaro, wasn’t gender, but skin scent and microbiomes, which are unique to each person and change depending on diet and health.
On top of being slightly more attracted to males participants, Aedes aegypti favoured people with higher levels of Staphylococcus bacteria but lower levels of cyclic alcohols, which can be found in fragrances and cosmetics. Aedes albopictus liked people with abundant bacterias, odours, and ketones, which are natural chemicals your liver makes when it breaks down fat for energy. Meanwhile, Culex quinquefasciatus avoided odours and was not particularly drawn to bacteria, but it liked chemicals found in essential oils.
“Putting it all together, you could be a mosquito magnet, but not for all species,” says DeGennaro. For that reason, there aren’t specific things you can do to reduce your attraction to mosquitos, generally. “Even if you wash more, for example, you may actually get lower levels of certain odors that are coming from the microbial community on your skin, and that could be more attractive to certain species even if it makes you less attractive to others,” he says.
To obtain these results, DeGennaro and his team asked participants not to wash for 12 to 16 hours before arriving at the lab where they donned nylon sleeves to capture their skin odour and microbes for later study. Then, they inserted their arm into a uniport olfactometer—a device consisting of a container with a mesh screen between the participants arm and a tube where the mosquitos were released. Between the two is a smaller tube the mosquitoes travelled down if they were attracted to the arm. The more mosquitos that travelled down the tube, the higher the attraction level recorded.
While the study’s findings don’t provide clarity on how to become less attractive to mosquitos, especially since it would be hard for everyday people to identify the species in the first place, DeGennaro says we could one day use the findings to produce targeted repellents.
“The idea is that we would try to find universal microbes that could be modified so that they act as a living probiotic cream repellent that you put on your skin,” he says. “Since it’s living, the repellant would be constantly produced and then it would be potentially more effective than our current repellents.” Until then, you might have to get used to roasting marshmallows for two…or twenty.
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