Associated Press

SOCORRO, N.M. — A new pest repellent taps the heat of one of the hottest chili peppers in the world, a pepper so hot that only humans would be crazy enough to eat it.

The repellent developed by the New Mexico Tech Research Foundation in Socorro exploits the heat of the ripe, red habanero pepper, which is 60 times hotter than its fiery cousin, the jalapeno, and 10 times hotter than cayenne.

Researchers are taking the nontoxic chili additive and mixing it into caulks, paints, glues and rubber–coating materials. Any animal unfortunate enough to take a nibble gets a spicy surprise.

Tests found roadrunners avoided pecking treated fence posts and rats shunned cables coated in the substance. A corral post treated with the repellent kept pests at bay for five years, said Darwin Van De Graaff, president of MEDD4, a Santa Fe company that will market the stuff.

Zebra mussels, the meddlesome mollusks that have invaded water intake pipes and displaced native species in the Great Lakes and Mississippi and Ohio rivers, may be next on the hit list.

The Aquatic Research Institute at East Chicago, Ind., is field testing the repellent 20 feet underwater in a mussel–infested Lake Michigan harbor.

"The implication here is that if, they've developed an effective material, it will have an application," director Tim Early said.

"It worked in the lab, will it work in the environment?" he asked.

The lake tests could be completed by the end of August or early September. The U.S. Coast Guard is among those interested in the results. Since boats are the most common method of transferring Zebra mussels from one body of water to another, perhaps a treated hull could cut down on the European invader.

"That would be really great if it works," said Lt. Chris Boes at the Coast Guard headquarters in Washington, D.C.

Mussel repellents currently use chlorine, ultraviolet light, sound vibrations and electric currents. Or people can simply scrape them off by hand. If the chili repellent passes EPA and other testing, "it's going to be a real hot item," Boes said.

Inland Steel Co., an East Chicago, Ind., steelmaker that draws huge amounts of Lake Michigan for its operation, sees potential in a chili–based repellent that could block fish and other aquatic life from entering pipes to the mill.

Pesticide marketers are keeping an eye on the chili–based product's development, too.

"It's an interesting concept," said Harold Harlan, a pesticide and repellent expert at the National Pest Control Association in Dunn Loring, Va. "It's arguable how successful they are."

Even though the product is organic, the developers may have to test for toxicity, cancer risk and reproductive harm before it is ready for market, said Harlan, an entomologist. It will also have to be tested for unintended side effects on other species.