Mosquito B.O.: Nature’s Li’l Vampires

Posted on July 15, 2013


Have you ever awoken in your tent covered in mosquito bites, then arrived at the morning campfire to find out no one else was bitten nearly as badly as you? Well, it’s no anomaly. Some people are a delicious all-you-can-eat smorgasbord for mosquitoes, while others are the Brussels sprouts of the human population.

But why? Researchers have finally uncovered why mosquitoes prefer some people over others. It’s not your gender, and it’s not necessarily your cologne. It’s your B.O.

In reviewing his professor’s research on a herd of cattle and the flies they attracted, research student James Logan noted that when certain cows were present, fewer flies landed on the herd. When those cows were removed from the herd, more flies freeloaded off the bovine buffet. And when the attractive cows were moved to another herd away from the unattractive cows, the flies migrated along with their preferred cattle.

Logan tried a new spin on the experiment with female mosquitoes (only females bite). First, he placed yellow fever mosquitoes in the bottom of a Y-shaped container. Then, given what he knew about the mosquitoes’ distaste for the odor of pesticides, he placed the hands of two separate individuals over the upper branches of the Y. One was the hand of an individual who was determined to be unattractive to mosquitoes, and one of an individual who was known to be attractive to them. The mosquitoes preferred the attractive individual’s hand. It was the smell of the individual’s chemical imprint that made the difference… good ol’ body odor.

Mosquitoes, it turns out, pick up scents with the olfactory receptor neurons at the end of their antennae. That is their secret weapon against us. The specific chemical’s scent that attracts mosquitoes is nonanal, and it is present in all human anatomy. Nonanal (we know what you’re thinking, and it’s not pronounced like that… try “NON-uh-nal”) has a fruity odor, and is an additive in foods, detergents, and perfumes. CO2 is known to amplify the mosquitoes’ attraction to nonanal, and humans exhale a lot of that.

While some of us may be layering on the nonanal pretty thick, there are still some people who are naturally resistant to mosquitoes. Logan determined that these people produce a chemical that masks the nonanal’s smell. Logan did not know what the masking chemical was, but was testing for it using foil sleeping bags to catch the chemical imprint of the body odor of unattractive individuals. After a masking chemical is isolated, a new and potentially odorless (to humans) pesticide may find its way into markets and livestock herds, saving a lot of people and animals from illness and discomfort. A little B.O. isn’t such a bad thing, after all.

Kiped from the archives of the SyFy channel’s IdeaLab Blog for the TV show Eureka. Well kinda kiped, since I wrote it to begin with. Edited by Tiffany Lee Brown, without whom I’d be stuck in the land of curly quotes.

Posted in: science, writing