Mosquitoes and Your Soap

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Mosquitoes are more than a major nuisance, often causing significant skin reactions, and some people with skeeter syndrome are allergic to them. Commercial repellents abound, but what if there’s something we can do ourselves to reduce our attractiveness to the pests?

We know mosquitoes seem drawn to some people more than others. Sometimes it’s the color of a person’s clothing, their natural body odor, or an applied scent that can make a difference. Researchers at Virginia Tech explored different smells from soaps to see which were most likely to attract the pests. Three scents from soaps attracted the mosquitoes, and one repelled them.

Report from Virginia Tech: People have been using products to alter their scent for generations. From soaps to perfumes, people gravitate to floral and fruity smells.

Whether we think these smells are good or bad is of little consequence to mosquitoes, transmitters of diseases that kill hundreds of thousands of people each year. Additionally, mosquitoes rely on plant nectar to get some sugars needed to sustain their metabolism in addition to needing nutrients in the blood to produce eggs.

And humans with nutrients and a floral scent? That’s two strikes.

Despite these scents being right under humans’ noses, the impact of soap smell on mosquito preference was largely ignored until Virginia Tech researchers in the College of Agriculture and Life Sciences asked the question.

They found that certain soaps could make people more or less attractive to mosquitoes.

“Just by changing soap scents, someone who already attracts mosquitoes at a higher-than-average rate could further amplify or decrease that attraction,” said Clément Vinauger, co-principal investigator.

The research on mosquito soap interactions was published May 10 in iScience and was funded in part by the U.S. Department of Agriculture and the National Institute of Food and Agriculture.

Hidden under human noses

The connection between soap and mosquito attractiveness was studied through four volunteers. First, the research team, which included graduate student Morgen VanderGissen and postdoctoral associate Anaïs Tallon, studied the unique scent profile of each individual, unwashed and washed with each Dial, Dove, Native, and Simple Truth soaps. Reportedly, more than 60 percent of what is smelled after washing comes from soap rather than natural body odors.

“The other aspect is that it’s not simply adding stuff to our body odor, but it’s also replacing some chemicals while eliminating others that are washed away,” Vinauger said. “So we think there is a lot of chemical interaction between our natural chemicals and soap chemicals.”

To test the interactions between smell, the researchers released mosquitoes in a meshed cage that had two cups containing odor extracts and gave them a choice – unwashed scents gathered from the individuals or their washed scents. The scents were gathered from a nylon sleeve worn on the forearm with the body in both washed and unwashed states. Tests were repeated for the various combinations of scents.

“This way we can really measure and quantify the effect of the soap in terms of increasing or decreasing the attractiveness of the individual,” Vinauger said. “That’s where we found that not all soaps have the same effect on all volunteers.”

In terms of fragrance preferences, three of the four soaps increased mosquito attractiveness while one decreased. All of the soaps had a fruity or flowery scent. The one that decreased attractiveness was coconut scented.

“That was very interesting for us because there is other evidence in the literature that elevating certain fatty acids, such as those found in coconut oil derivatives, could serve as a repellant for mosquitoes and other insects,” Vinauger said.

Odors are everywhere!

With the results of the proof-of-concept study in hand, the researchers hope to expand the study with additional people and soap varieties to get a clearer understanding of the implications.