Mosquitoes hate coconut-scented soap

Humans have a unique body odor, and people have been using commercial products to alter their scent for generations.

The impact of soap smell on mosquito preference was largely ignored until Virginia Tech researchers in the College of Agriculture and Life Sciences asked this question: could certain soaps make people more or less attractive to mosquitoes? According to Clément Vinauger, an assistant professor of biochemistry and co-principal investigator on the study, “Just by changing soap scents, someone who already attracts mosquitoes at a higher-than-average rate could further amplify or decrease that attraction.”

The research, published in iScience, was funded in part by the United States Department of Agriculture and the National Institute of Food and Agriculture. The study was carried out on four volunteers, and the researchers first studied each person’s unique scent profile before and after washing with four different soaps. Vinauger explains, “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. So we think there is a lot of chemical interaction between our natural chemicals and soap chemicals.”

Mosquitoes were then released in a cage and given a choice between unwashed and washed scents gathered from the individuals. The tests were repeated for various combinations of scents to measure the effect of soap on attractiveness. Vinauger says, “That’s where we found that not all soaps have the same effect on all volunteers.”

The results showed that three of the four soaps increased mosquito attractiveness, while one decreased it. The soap that decreased attractiveness was coconut-scented, which was surprising since certain fatty acids found in coconut oil derivatives are known to be a repellent for mosquitoes and other insects. Vinauger says, “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.”

The researchers hope to expand the study with more people and soap varieties to better understand the implications of the results. They also want to study the duration of the effects and the impact of other scented products like deodorants and laundry detergents. The study suggests that using coconut-scented soap could be a simple and effective way to reduce mosquito attraction.

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