Grapefruit vs. bugs.

NPR’s reporting sounds almost too good to be true as it extols the virtues of an all-natural, edible grapefruit extract that repels mosquitoes, ticks and bedbugs:

Marc Dolan of the CDC’s vector-borne infectious diseases laboratory… says nootkatone “is nongreasy, dries very quickly, and it has a very pleasant, citrus-y grapefruit odor to it.”

He recently demonstrated its effectiveness as a mosquito repellent, rubbing some on his hand and then sticking it into a cage containing 50 hungry mosquitoes. When he holds the treated hand near mosquitoes, they try to get away in the opposite direction as fast as they can.

Even after five minutes, Dolan has no bites on his nootkatone-treated hand.

Nootkatone is also effective against ticks, and scientists think it will work against bed bugs, head lice and other insects, too.

Moreover, nootkatone is so nontoxic you could drink it. In fact, it’s already an approved food additive, officially classed as “Generally Considered Safe.” It’s also a natural ingredient in some foods.

“If you’ve had a grapefruit, you’ve consumed some nootkatone,” Dolan says, “or drank a Squirt, for instance.”

It kills by blocking receptors on insects’ nerve cells for a neurotransmitter called octopamine. That makes the insects hyperactive. “They basically vibrate themselves to death,” Dolan says.

Humans don’t have octopamine receptors, so that may make nootkatone safe for humans, though Dolan says scientists don’t yet know whether there’s any cross-reaction between nootkatone and adrenaline receptors. Adrenaline is the human analog of insects’ octopamine.

Dolan thinks nootkatone is likely to be so nontoxic that it could be an ingredient in “the world’s first insecticidal soap.”