Mosquitoes, like humans, seem to have special preferences for soaps. In a new study, scientists discovered that female blood-sucking mosquitoes are attracted to certain types of soap commonly used by humans, while being repelled, sometimes in unexpected ways, by others. The findings may eventually help us develop better mosquito repellents.
Mosquitoes are among the deadliest animals for humans due to the large number of different germs and bacteria they carry, and it is stated that more than one million people die each year due to mosquito-borne diseases such as malaria. However, it has been known for many years that not all of these mosquitoes are the same. Roughly 20% of potential human hosts are thought to be responsible for about 80% of mosquito-borne disease transmission in an area, according to study author Clément Vinauger, a biochemist and geneticist at Virginia Tech. Therefore, it is very important to learn the preferences of mosquitoes.
Some previous research has already identified chemicals in our body odor that are attractive to mosquitoes that feed on us. However, there aren’t many studies examining how the scents we add can affect mosquito attraction. Female mosquitoes are known to feed on animal blood, but they also feed on nectar, just like male mosquitoes. Therefore, it is possible that some of the fragrances common in soap may change the eating habits of people.
“We especially like to sniff our soaps with chemicals typically associated with the pleasant scent of flowers and herbs,” Vinauger said in a statement. But mosquitoes also use plant-derived volatiles to find them and extract sugar from their nectar,” he says. “So we suspected that adding these chemicals to our body odor would somehow affect their attractiveness. But this had to be tested experimentally.”
The team selected four human volunteers for their experiment. First, they identified each person’s unique olfactory signature. Then they had them washed with four soap brands Dial, Dove, Native, and Simple Truth. Finally, the scientists compared female Aedes aegypti mosquitoes, which are prolific disease carriers, with the clothes the volunteers wore when they were not bathing or were bathing. Overall, the team found marked differences in the behavior of mosquito preferences before and after bathing, though to varying degrees between brands and volunteers.
Soaps attract mosquitoes
“Our main results were that using soap on our skin drastically changed the way we smell, especially by adding lots of plant-derived chemicals to the composition of our body odor,” says Vinauger. It revealed the importance of the interaction between specific soap chemicals and each individual’s body odor in determining whether it would be appealing.”
For example, in only some volunteers, mosquitoes were more attracted to their scent after washing with Dove and Simple Truth brand soap, while Native brand soap was more consistently repellent for them.
The team also identified potential chemicals in these soaps that appear to be most responsible for attracting or repelling insects. Among these candidates, a coconut-smelling chemical was the most effective at keeping mosquitoes away. Their findings were published Wednesday in the journal iScience.
Since this study was a single study based on a relatively small sample size, the results cannot be definitively valid in general, and some of the other factors that may be important, such as the carbon dioxide ratio of individuals, were also excluded from the scope of the study. Still, the team hopes to raise funds for larger studies that can test a wider range of soap and volunteers while addressing other important questions, such as the typical length of any soap-related effect.
If this research continues to yield results, it could enable the development of mosquito repellent soaps or other important applications in the future.
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