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Scientists Say Fungus Killes Roaches

May 23, 1986

RIVERSIDE, Calif. (AP) _ University scientists stumbled across what they say could be one of the most potent cockroach killers yet when more than a million of their laboratory roaches died inexplicably.

Although the University of California at Riverside entomologists say they have no plans to market the killer soon, they see it having widespread commercial potential, as long as people don’t mind using fungus to kill roaches.

Entomologists Edwin Archbold, Michael Rust and Don Reierson, who have published their findings in the February issue of Environmental Entomology, say they accidentally discovered the fungus, which is thought to cause a deadly cockroach disease.

″They had broken and curled antennae and developed a rotten odor,″ Rust said in the article.

The scientists had been conducting research into the pesticide resistance of German cockroaches, the most common indoor pest in the world.

They collected specimens at Southern California restaurants and reared them in laboratory garbage cans when the first of several epidemics struck in 1980, said Rust, who has studied the insects for 15 years.

In an effort to save their cockroaches and research, Rust said, ″We cleaned, washed jars and rearing facilities, sterilized food and water. ... None of it was successful.″

In 1984, after losing $100,000 in time and research, Archbold isolated and identified the fungus that invades the insects’ circulatory system and robs them of nutrition.

Rust said the fungus seems to infect only the German cockroach colonies. Other less-common cockroach species have been unaffected in the laboratory.

Since their discovery, Rust and the others have been able to grow the fungus in laboratory equipment and believe they may have found a potentially powerful, biological means of controlling the almost universal pest.

Other roach experts, however, are cautious about the prospects.

″You need to have an awful lot of information on a microorganism before you reach the point where it can be of practical importance,″ said Gary Bennett, a professor of entomology at Purdue University in Indiana.

Rust said a commercial product for use in the home - likely a spray or a treated bait trap - may not be available for another five years or more. His team has yet to gauge the effects of the fungus on cockroaches in field conditions and its safety to humans and animals.

″You also have to deal with the public acceptance of it,″ said William Robinson, professor of entomology at Virginia Polytechnic Institute and State University. ″If you say we’ve got a fungus in this material, the public will wonder what it will do to their health.″

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