Mosquitoes Have Individual Tastes: Each Species Favors Different People

Of the 119 people who volunteered for a mosquito study at Florida International University, not one turned out to be a favorite of all three species the researchers tested. That result, published in iScience, undercuts the familiar notion of a universal mosquito magnet, the person everyone at the picnic assumes will take the bites.

The team, led by neurogeneticist Matthew DeGennaro, who directs FIU's Biomolecular Sciences Institute in Miami, studied three of the world's most dangerous mosquitoes: Aedes aegypti, the Asian tiger mosquito (Aedes albopictus), and the southern house mosquito (Culex quinquefasciatus). Between them they spread yellow fever, dengue, Zika, West Nile and other illnesses. Ph.D. student Kaylee Marrero led the work, which the source describes as the first to directly compare how several mosquito species respond to the same group of human participants.

Each species, it turned out, favored its own subset of volunteers, and did so consistently. Aedes aegypti, which bites during the day, went for people who wore no added fragrances and whose skin carried lower levels of certain volatile chemical compounds. It also showed a slight preference for men over women. Aedes albopictus, another daytime feeder, was drawn to people whose skin gave off more ketones and naturally occurring plant-like volatile compounds.

Culex quinquefasciatus, which feeds after dark, behaved differently again. It appeared especially sensitive to the skin microbiome, the community of bacteria, fungi and other microorganisms living on human skin. Some bacterial families made a person more attractive to it, while others seemed to discourage biting.

To find out why, the researchers collected samples of each participant's body odor and skin microbiome alongside the preference tests, then identified the chemical compounds and microorganisms present and measured their relative abundance. Human skin releases a mixture of more than 1,000 volatile organic compounds, many of which scientists have not fully identified or understood. Even so, the team found strong links between what the mosquitoes preferred and differences in people's chemical and microbial makeup.

Marrero said the team did not expect the species to prefer different people at the outset. She found it surprising that each species appeared to rely on a distinct microbial signature as a cue. DeGennaro said the match with skin bacteria and odors was striking, and that it is clear to him now that skin microbiomes define a person's odor signature, with each species finding its own way to decode it.

The practical hope is more targeted protection. If researchers can isolate the specific odor components and skin bacteria that attract or repel each species, they may be able to build species-specific repellents. DeGennaro said that isolating those components could lead to novel strategies against vector-borne diseases. The findings could also help communities focus on the mosquito species actually spreading disease in their own region, rather than assuming all mosquitoes are drawn to the same people for the same reasons.

That work still lies ahead. The specific compounds and bacteria behind each species' preferences remain to be pinned down, and that identification is the step on which any new repellents would depend.