New Mosquito Repellent Made, "Better Than Anything Else"

ORIGINAL: NatGeo
Christine Dell'Amore for National Geographic
September 17, 2013

Formula uses human compounds to block mosquitoes' sense of smell.

Mosquitoes avoid a hand treated with DEET (right).  Photograph by Greg Allen, USDA-ARS

Mosquitoes bugging you? There may be a new repellent on the horizon—and it's "so much better than anything else we've ever seen," its inventor says.

A few years ago, Ulrich Bernier was busy blending various chemicals together in the lab, hoping to figure out why the blood-sucking insects bite some people more than others. Mosquitoes home in on their targets by sniffing out various chemicals and bacteria on human skin.

When he created one blend with a group of chemicals that are very similar to ones found in low concentrations in our bodies, Bernier noticed that the bugs seemed to ignore it. (Read what happens inside you when a mosquito bites.)

These chemicals—which include the tongue twisters homopiperazine and 1-methylhomopiperazine, among others—seemed to have an incredibly robust ability to mask our scent from mosquitoes, said Bernier, a research chemist at the United States Department of Agriculture's Agricultural Research Service.

Next, Bernier and colleagues set up an experiment where people put their arms or hands inside a cage full of mosquitoes. The insects avoided the skin of the subjects when the chemical cocktail was released from a container inside the cage.

Bernier and colleagues created a formula of several chemicals for a repellent, which was approved by the U.S. Patent and Trademark Office in 2012.

"It's a pretty neat discovery because I don't think anyone else has shown chemicals this capable of blocking skin odors that are normally attractive to mosquitoes," said Bernier, who presented the research at the American Chemical Society meeting in Indianapolis last week.

Why do we need a new repellent?
Insect-borne diseases are prevalent and potentially dangerous. According to the U.S. Centers for Disease Control and Prevention, there are about 30,000 annual reported cases of Lyme disease, which is transmitted by ticks, and at least a thousand annual cases of mosquito-caused encephalitis—which includes West Nile virus—in the country. Bernier and colleagues' new repellent is also effective against other blood-sucking insects.

The most common insect repellent now in use is DEET, which is designed to be sprayed on the skin. However, there has been some concern about DEET and potential toxicity, and there's high demand for equally effective alternatives. (See "Mutant Mosquitoes Not Repelled by DEET.")

How does it work?
Bug repellents like DEET work by deterring mosquitoes that find the smell unappealing; the new formula actually makes you invisible to the insect.

Here's an analogy to explain the two: If you walk into a room and smell something bad and leave, that's how DEET works. But with the new repellent, it's as if you walk into a room and don't smell anything, Bernier said.

Bernier said it's unknown why insects can't smell the compounds.

How is the repellent applied?
Commercial availability is still far down the road—there needs to be more toxicology tests on the formula, as well as field tests, Bernier cautioned.

But he said that it could be used indoors or outdoors and would probably work best released into the air rather than applied to the skin. For example, the repellent could be emitted from a sealed canister that releases a vapor slowly into the air, creating a sort of protective bubble around your environment.

For instance, if you're sitting outside on a patio, you could install several canisters around the patio, he suggested.