Gypsy moth may have met its match Fungus produces deadly infection

April 14, 1997|By KNIGHT-RIDDER NEWS SERVICE

PHILADELPHIA -- They toiled in labs for nearly a century and spent inestimable millions. They tested an arsenal of pesticides, parasites, predators and viruses. But the best brains in bug science couldn't produce the silver bullet that would bring down the gypsy moth.

Through it all, the voracious insect chewed its way across the Northeast, stripping vast swaths of forest.

Now, faster than you can say "Mother Nature," researchers appear to have found the solution growing right under their noses.

Fungus. Specifically, Entomophaga maimaiga - a mysterious, microscopic cousin of bread mold that is spreading through forests from Maine to West Virginia. The spores stick to gypsy caterpillars on their spring travels, leading to a deadly infection.

Apart from its fatal attraction to gypsy moths, the fungus is a puzzle to forestry experts - and a bit of a worry. Although they had been gathering up mounds of it and spreading it in woodlands, they've since stopped. No one can say for sure whether the fungus is a threat to other insects, although preliminary tests indicate it targets only the gypsy moth.

A stunning toll

"People are keeping their fingers crossed," said Daniel B. Twardus, an entomologist with the U.S. Forest Service in Morgantown, W.Va. "We could be playing with fire if we don't know what we're playing with."

Since first identified a few years ago, the fungus has taken a stunning toll on its host. In 1990, gypsy moths defoliated more than 7 million acres in 11 states; last year, damage was reported on just 200,000 acres. In Pennsylvania, 4 million acres were eaten in 1990, compared with 9,000 acres last year. In the same period in New Jersey, the amount of land under siege dropped from 431,000 acres to 28,000.

Experts predict that decline will continue. While saying they might never eradicate the moth, they now talk confidently of suppressing it to near-extinction.

"We entomologists may get to the point where we're all sitting around saying: 'Remember the good old gypsy moth days?'" joked Twardus, who also edits the Gypsy Moth News, a quarterly journal published by the Forest Service.

Entomophaga maimaiga was introduced from Japan in 1910-1911 in an attempt to kill off gypsy moths, another Japanese import. The moths had been brought to Massachusetts in 1869 by a Frenchman who wanted to cross-breed them with silkworms. Not only did his experiment fail, but the insects escaped and began eating trees (oaks being their favorite).

The fungus didn't do its job, either, and it was forgotten.

Reappeared in 1989

It reappeared in 1989 near the Connecticut-New York border. Scientists speculate that it may have lain dormant all that time, or simply gone undetected. Some suspect it's a newer, stronger strain that accidentally was reintroduced in the Northeast, where it has taken hold.

News of the fungus' power spread like wildfire through forestry circles - and touched off a veritable stampede, Twardus said. The U.S. Forest Service, National Park Service, and state forest agencies began collecting fungus spores. "People were like Johnny Appleseed, running around with buckets of dirt [containing spores] and spreading it all around," Twardus recalled. "Then some people started asking: 'What are we spreading here?' "

That practice has ended for the time being, out of concern that the organism could prove even more harmful than the gypsy moth. Research on the fungus continues, although Twardus said the answers aren't coming fast enough. "We really ought to be devoting significant resources to it," he said.

Meanwhile, Mother Nature's moth-control program has thrown hundreds of government-run projects into limbo. Funding for federal, state, county and local efforts - including pesticide-spraying and use of a virus that attacks the moths - totals $9.7 million this year. Twardus said those programs are in "a wait-and-see mode" until more data on the fungus are collected.

Pub Date: 4/14/97

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