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RENEE MONTAGNE, host:

This is MORNING EDITION from NPR News. Good morning. I'm Renee Montagne.

MARY LOUISE KELLY, host:

And I'm Mary Louise Kelly.

Today in Your Health, we'll go back to nature, foraging for nutritious wild food. But first, the search for a new, all-natural insect repellent. NPR's Richard Knox reports on the sweet smelling work being carried out by the Centers for Disease Control and Prevention.

RICHARD KNOX: Right now, the leading bug repellent is DEET. Lots of people don't like it because it has a greasy feel and a chemical smell. At the CDC's laboratories in Fort Collins, Colorado, bug expert Marc Dolan and his team have come up with a new repellent. Dolan rubs some of it on his right hand.

Mr. MARC DOLAN (Centers for Disease Control): It's non-greasy, dries very quickly. And it has a very pleasant, citrus-y grapefruit odor to it.

KNOX: It's an extract of the Alaska yellow cedar tree.

Mr. DOLAN: So I'm opening up the cage.

KNOX: To try it out, Dolan puts his hand into a cage that contains 50 hungry mosquitoes.

Mr. DOLAN: The ones on the wall I'm placing my hand next to and they try to get away in the opposite direction as quickly as they can.

KNOX: No mosquitoes are landing on his hand. And now he puts his other hand -unprotected by any repellent - into another mosquito cage.

Mr. DOLAN: Within a matter of seconds, I had mosquitoes feeding on my untreated hand. And I still do not have any mosquitoes on my treated hand.

KNOX: And five minutes later, they're still not biting.

The stuff on Dolan's treated hand is called nootkatone. In addition to cedars, it's also found in grapefruit and other citrus, and in some herbs and grasses. Nootkatone is so non-toxic you could drink it. In fact, it's already an approved food additive, and a natural ingredient in some foods.

DOLAN: If you've had a grapefruit, you've consumed some nootkatone, or drank a Squirt, for instance.

KNOX: He says nootkatone could be put into soaps and sunscreens. That way, people wouldn't have to apply a separate bug repellent. The reason the CDC is doing this research is that bug bites transmit dangerous infections, such as Lyme disease and West Nile virus. The government has licensed its nootkatone patent to a company that will make the repellent and sell it.

And here's a remarkable thing, nootkatone could be both a repellent and an environmentally friendly pesticide. That's because it doesn't just repel bugs. It kills them. Dolan's colleague, Nick Panella, demonstrates.

Mr. NICK PANELLA (Centers for Disease Control): It sounds like a mosquito, this thing.

(Soundbite of vacuum)

KNOX: Panella uses a vacuum pump to transfer mosquitoes into a jar. He's coated the inside of it with nootkatone.

Mr. PANELLA: OK. I think that's enough.

KNOX: As soon as they're in the jar, the mosquitoes begin to die. Here's Marc Dolan.

Mr. DOLAN: Already in that short duration, there's only two mosquitoes - is there three left alive? This stuff has incredible knock-down, so it kills things very, very quickly, usually within a matter, depending on the concentration, in about 15 seconds.

KNOX: It kills by blocking receptors on insects' nerve cells, receptors humans don't have. It makes them hyperactive. They basically shake themselves to death.

DOLAN: Yeah, they buzz around on their back. Usually they get completely disoriented. And then eventually they keel over.

KNOX: It works in a completely different way from other insecticides, so mosquitoes aren't resistant to it yet. And nootkatone works on other insects too: ticks, which transmit Lyme disease, and probably bedbugs and head lice.

But don't look for the new repellent this season. Human trials are just getting started. So it'll be a couple of years, at least, before you can scare away bugs with the scent of grapefruit.

Richard Knox, NPR News.

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