The stuff in catnip that intoxicates cats repels cockroaches 100 times better than a powerful insect repellent, scientists said yesterday.
The discovery could lead to new, nontoxic methods for curbing these tenacious insects, which are more than just a nuisance. Roach infestations have been linked to rising rates of asthma.
Chris Peterson and Joel Coats of Iowa State University told a meeting of the American Chemical Society in New Orleans yesterday that they had isolated a chemical that roaches find repulsive.
They began studying catnip after a summer intern told them the plant was resistant to insects.
They boiled catnip leaves and distilled the active ingredient, a chemical called nepetalactone. Then they teased the most abundant form of nepetalactone from another, more elusive form with a slightly different atomic structure.
When cockroaches were placed in a dish that contained a piece of paper soaked on one half with the rare form of the chemical, the roaches scuttled away from the treated half.
Scientists tested their discovery against a widely used repellent, called DEET. Their catnip-derived chemical worked at doses only 1 percent as high.
Iowa researchers have not tested the effectiveness of simply spreading natural catnip leaves around the house. It might require so much of the stuff as to be impractical, Peterson said. And, of course, it might attract a lot of cats.