Insect to Learn That Love Can Be Deadly : Cockroaches: Scientists will use pheromone to stimulate males’ sex drives and lure them to fatal fungus.

On this most fitting of days, love is literally in the air for cockroaches.

A researcher at Cornell University in Ithaca, N.Y., has identified the female pheromone of the brown-banded cockroach, an airborne chemical that drives male cockroaches . . . well, buggy.

But the researcher and his colleagues also are preparing a rude Valentine’s Day surprise for the ubiquitous household pests, a fungus that could render love’s labor lost.

Insect control specialists have long used pheromones to lure insects such as the pink bollworm and the Medfly to their destruction. But they have had less luck with cockroaches because the chemicals involved are present in such small quantities and are much more complicated than sex pheromones of other insect species, said biochemist Wendell Roelofs at a meeting of the American Assn. for the Advancement of Science.

It took researchers 30 years to identify the female sex attractant of the American cockroach, which along with the German cockroach is the most common form in the United States. But for the brown-banded cockroach--a subtropical pest that is found in all 50 states, but particularly in California--Roelofs was able to find the pheromone by taking advantage of a clever technique called the electroantennogram.

Entomologist Coby Schal of Rutgers University in New Brunswick, N.J., supplied Roelofs and Cornell post-doctoral fellow Ralph Charlton with the contents of 15,000 sex glands from female cockroaches. Roelofs and Charlton separated the thousands of chemicals present in the glands using a technique called gas chromatography. Each chemical was then given an electroantennogram.

To do that, Roelofs stripped an antenna from a male cockroach, hooked a miniature electrode to each end, and attached the entire assembly to an oscilloscope. Because the males detect the female pheromone with their antennae, the assemblage is highly sensitive to the pheromone. When the true pheromone was sprayed past the antenna, the antenna’s electrical response was clearly visible on the oscilloscope.

Roelofs and Charlton then had only to isolate enough of the chemical to identify its chemical structure. Larger quantities were synthesized by chemists Francis Webster and Aijun Zhang of the State University of New York at Syracuse.

The pheromone is extremely powerful, Roelofs said. “Just a few molecules set them off,” he added. The males follow the scent upwind until they find the source.

Roelofs believes the chemical can be used to lure cockroaches out of hiding in the buildings they frequent. Schal is now developing a fungus that will attack and kill the cockroaches slowly. The pheromone could be used to lure males to a trap, where they would be exposed to the fungus, which would then be passed through the cockroach colonies by mating or other behaviors.

“This is kind of a venereal approach to insect control,” Roelofs concluded.