Tapping Exotic Fauna : Waging War With a Few ‘Good Bugs’

WASHINGTON —  A white-coated government scientist lifted up wide-eyed school children to peer through a microscope at a chilling drama: Tiny brown wasps imported from Colombia were savaging the shiny yellow eggs of Colorado potato beetles.

The delighted 7-year-olds were witnessing part of an Agriculture Department exhibit on drafting “good bugs” to fight “bad bugs.” As the ferocious little wasps made sure that none of the eggs would grow into potato-eating beetles, the scientist, Robert F. W. Schroder, remarked: “I’m going to write Meryl Streep a letter.”

The actress, in recent testimony to Congress, had blasted farmers for relying too heavily on dangerous pesticides to protect their crops. Schroder wanted her to know that the Department of Agriculture has other weapons--natural creatures, like the hungry Colombian wasps--to keep crop pests in check.

Offering an Alternative

“Amid all the hype about contamination of fruits and vegetables, we are really offering an alternative,” Schroder said.

For fully a century, the department has been waging war against pernicious pests by mobilizing their natural enemies against them. Schroder has been on the front lines for 23 of those years, scouting for good bugs all over Central and South America, once being abducted by shotgun-toting Mexican desperadoes.

Although Schroder’s bugs do battle on a miniature scale, the stakes are anything but. The discovery of one weevil-eating wasp, for instance, has saved U.S. farmers billions of dollars in pesticide costs and greatly boosted the growth of alfalfa, a prime food source for cattle.

And now the government is ranging ever wider in its search for good bugs. As part of an unprecedented exchange, American scientists soon will venture to the Soviet Union and China to seek enemies of pests that are devastating wheat fields and rangelands in the United States.

Soviets to Observe Work

In return, Soviet scientists will visit demonstration fields in New Jersey to watch the Agriculture Department’s Colombian wasps as they try to help save not only potatoes but also tomatoes and eggplants from the voracious potato beetle.

Nor are insects the Agriculture Department’s only allies. Disease is also part of its arsenal. As part of its new emphasis on natural enemies instead of pesticides, it is trying to develop a virus to help control tree-destroying gypsy moths.

Deputy Agriculture Secretary Peter C. Myers said that the department’s campaign reflects heightened interest in organic, or at least semi-organic, farming. A growing number of farmers are sharply reducing the use of chemical fertilizers and pesticides, which are expensive and threaten health and the environment.

“A lot of what we are doing is developing biological control agents aimed at reducing groundwater contamination and protecting endangered species,” said Richard S. Soper, a top official of the Agriculture Department’s research operations.

Even pesticide manufacturers--worried about growing criticism of agricultural chemicals--are thinking natural these days. They are, among other things, stepping up development of deadly disease organisms and synthetically produced sex lures for insect traps, as well as low-chemical repellents and genetically altered, pest-resistant plants.

In many cases, companies have agreements with the Agriculture Department that enable them to sell in the mass market what government biologists turn up in laboratories.

“There is a clear trend toward reduction of chemicals through what is called integrated pest management, integrating biologicals, chemicals and all the different pest-control practices” such as proper planting and harvesting, said Pam Marrone, a senior research official at Monsanto Co. in St. Louis.

Provided by Mother Nature

The oldest and most desirable weapons in the war against pests are provided by Mother Nature--predators, parasites and pathogens.

Predators and parasites include insects, mites and nematodes that naturally attack a target pest. Predators kill the pest outright. Parasites sap the target more slowly, gradually injuring or killing it. Pathogens include bacteria, viruses or fungi that cause diseases specifically harmful to a pest.

The government’s first big victory in biological control came a century ago with the rescue of California’s fledgling citrus industry. Orange, lemon, lime and grapefruit trees were covered by the large, white egg sacs of the cottony cushion scale, threatening massive ruin.

An alarmed Agriculture Department dispatched a scout, Albert Koebele, to Australia to look for a natural enemy of the pest. He found one. It was feeding on scale in a garden in North Adelaide--the black and orange vedalia beetle, nicknamed the Australian ladybug.

Just a year after 129 of the predatory beetles were released in California on Nov. 30, 1888, the problem was under control.

Since then, more than 600 species of what scientists jestingly call “good bugs” have been introduced in American agriculture, sparing the environment the sometimes damaging effects of tons of chemical pesticides and saving farmers millions of dollars.

There were many successes in the 1930s and 1940s, including complete control of the Comstock mealybug in the East and partial suppression of the San Jose scale, elm leaf beetle, fig scale and asparagus beetle in the West. Also developed was the first commercially marketed microbial pesticide: milky spore disease to control Japanese beetle larvae.

Later in the 1940s, however, chemical insecticides preempted bio-control, said Jack Coulson, an entomologist at the Agriculture Department’s Beneficial Insects Laboratory at Beltsville, Md. Starting with the discovery of DDT in 1939, chemists found that hydrocarbon toxins could be formulated to kill pests.

By 1955, the trend began to swing back. But unlike the late 1880s, when scientists sought good bugs because there was no alternative, bio-controls regained popularity largely because of awakening concern about the impact of pesticides on water, soil, air and food.

Moreover, pesticides were losing their effectiveness as each generation of insect was able to tolerate a larger dose of chemicals than the last. Beneficial insects, on the other hand, offered long-lasting control to which organisms did not become resistant.

Used Also With Weeds

In recent years, bio-control has brought to heel not only numerous additional pests but also weeds. Scientists from an Agriculture Department laboratory in Albany, Calif., scored a major triumph over the alligator weed, a South American native that was clogging U.S. waterways. They went to Argentina and found a moth, a beetle and a thrips hungry for nothing but the weed, and it is now under widespread control.

Even home gardeners are reaping the benefits of good bugs. Garden shops sell Seven-spot lady beetles, praying mantises, lacewings and other general predators that devour pests ranging from aphids to caterpillars. The ravenous lady beetle consumes as many as 5,000 aphids in a lifetime.

The problems that plague farms and back yards alike often arose because crops brought into this country were frequently accompanied by pests--but not by the pests’ natural enemies. When scientists go looking for those enemies, they must often roam far beyond the nation’s borders. And they must carefully screen good prospects to make sure they are not importing monsters in disguise.

One of the pre-eminent explorers for beneficial bugs is Schroder, 49, a genial man with wire-rimmed glasses and mustache who conceived his life’s mission while with the Peace Corps in India, witnessing swarms of locusts decimate crops.

After obtaining his doctorate and joining the Agriculture Department, he made his first expedition in 1976, discovering in El Salvador a parasitic mite on the Mexican bean beetle. The find inspired other scientists to take a new look at mites as an effective weapon against pests.

Needle in Haystack

On his searches, Schroder likes to take along a taxonomist who can identify exotic species as well as a native familiar with local vegetation and insects. “Otherwise, it’s like looking for a needle in a haystack,” he said.

Traveling alone--armed with little more than a sweep net--can be dangerous, especially in countries with unstable governments, unchecked diseases and crime-infested rural areas. Schroder, for his part, has had unsettling adventures despite taking such precautions as dressing like the natives and secreting his U.S. passport.

He describes a 1983 trip to collect specimens in the desert near Durango, Mexico: “All of a sudden, we were run off the road by what I thought was a bunch of bandits in a pickup truck. Five guys put automatic weapons and shotguns in our bellies. Apparently, we were in a drug trafficking area. The State Department should have told us not to go there.”

Schroder escaped without harm. But another scientist was not so lucky. He was killed by a bullet in the back of the head when he stopped along the same road not long afterward.

On two other expeditions, political turmoil forced Schroder to hop from El Salvador to Nicaragua to Guatemala before he finally found the bean beetle parasite he was seeking in Honduras.

In addition to the hazards he faces, Schroder cannot always count on success. High in the Peruvian Andes, near the “lost colony” of the Incas, Schroder found a parasitic fly of the Mexican bean beetle and a parasitic nematode of the corn rootworm. “The fly turned out to be pretty tough to rear in captivity,” he lamented. Then, on a subsequent trip to Brazil, he found that the nematode attacked good creatures as well as bad, so “we had to scrub it.”

To make sure discoveries are beneficial, scientists subject all imported insects--as well as weed-fighting plants and fish--to close scrutiny under quarantine before they are released. Officials report few mistakes. “If something is brought here and causes a problem, they’d name it after me. That we can’t stand,” quipped R. Dean Plowman, head of the Agriculture Department’s Agricultural Research Service.

But he might welcome having his name on a parasitic wasp imported from Europe. It has dealt a major blow to the alfalfa weevil, in the largest biological control effort in U.S. history.

Farmers once spent up to $1 billion a year on pesticides to fight the weevil. It was so persistent that many farmers felt forced to abandon the cultivation of alfalfa, an important forage crop. Now, after a 30-year, $10-million campaign to distribute the European wasp, farmers need spray only one year in six.

Similarly, the imported Colombian wasp gives promise of cutting the spraying of eggplant, potato and tomato fields from 15 times per season to less than five, according to Schroder.

“Farm workers are safer; they don’t brush against insecticides,” he said. “And produce markets are looking for these vegetables because they are safer. That’s the big thing.”

BIOLOGICAL WAR ON THE FARM

For a century, the federal government has been seeking out “good bugs” to fight “bad bugs” that damage the crops of America farmers. With public concern mounting over the dangers of pesticides, that quiet war now is being intensified. Stakes are high. The discovery of one weevil-eating wasp for instance, has saved farmers billions of dollars in pesticide costs and greatly boosted crop growth.

The pest-control method also has meant sharp reductions in use of expensive chemical fertilizers and pesticides that can threaten health and the environment.

SOURCE: Department of Agriculture