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California and the West

Scientists Introduce New Soldiers in State Pest War

Agriculture: The wasps are meant to slow the spread of an insect that is the bane of vintners. Move is evidence of revival of 'biocontrol' approach to attacking pests.


RIVERSIDE — With a wing and a prayer, scientists are marching into orchards this summer and taking the caps off vials of tiny, hired killers.

The release of hundreds of wasps is an escalation in the war against pests that threaten California's citrus, its eucalyptus trees and now, even the state's wines. The latest struggle is to protect California's $33-billion wine industry, from Temecula's petite syrahs to the Central Valley's chardonnays.

A quick review of the plan suggests a plot line from a bottom-shelf alien movie, or maybe that somebody's been sipping too much zinfandel: The wasps, if the theory holds, will lay their eggs inside the eggs of the infamous and ravenous glassy-winged sharpshooter, a bug that has poisoned vineyards in 11 California counties. Wasp larvae will then have to eat their way through the sharpshooter eggs to start their life--wiping out the sharpshooter in the process.

The plan marks the latest development in what many see as a renaissance of biocontrol--the science of using natural predators, not chemicals, to fight pests. It turns out it's a bug-eat-bug world, and under the right circumstances, farmers can simply ride on the coattails of natural selection to protect their crops.

Although chemicals still dominate the business of fighting pests, there are now 35 commercial "insectories" in the United States--factories that produce bugs designed to eat or otherwise conquer pests. That's 15 more companies than there were 10 years ago.

Sales of bugs for biocontrol are growing by 10% each year and now top $100 million annually. Government agencies are starting to route more grant money toward biocontrol.

If the wasps do their thing and munch through the sharpshooter eggs, it will be another step in that evolution--a return to a science that began at California missions in the 1800s, but was largely forgotten as pesticides became all the rage.

Now that California faces an unprecedented number of imported pests that threaten farms, jobs and industries--a new critter surfaces every six months, according to Robert Luck, an entomology professor at UC Riverside--that could be a critical development.

The biocontrol industry is still dominated by its chemical cousin. Pesticides represent a $9-billion industry in the United States alone, according to the Western Crop Protection Assn., a trade group. And the new bandwagon in agriculture is less biocontrol than genetically engineered crops equipped with toxins that stave off insects.

Like pesticides, which raise a host of environmental concerns and safety issues, biocontrol has seen its share of troubles. In at least one case, so-called "good bugs" attacked the wrong targets, including several populations of rare and threatened thistles.

But the industry has celebrated a series of victories recently, giving it momentum it hasn't enjoyed in a century:

* By 1992, imported wasps from Israel ended the threat from the ash whitefly, which had begun decimating fruit and shade trees, stripping thousands of trees of their leaves, killing others and leaving sticky excrement on sidewalks and cars.

* Over the last five years, scientists have used wasps from Australia to fight off psyllids that have attacked a type of eucalyptus from San Diego to the Bay Area.

* On Friday, David Morgan, an entomology professor at UC Riverside, strolled into a Temecula citrus orchard to release 100 of the Mexican wasps imported to attack the sharpshooter.

Entomologists are monitoring the progress of the wasps across the state, and hope the insects will eventually spread their wings in all of the counties where the sharpshooters have introduced Pierce's disease, including Riverside, San Diego, San Bernardino, Ventura, Orange, Santa Barbara and Los Angeles.

The sharpshooter scenario is considered ideal for biological control. Farmers already use a complex system of "good bugs" on citrus farms, where the sharpshooters breed before moving to wineries. If farmers dumped pesticide on the sharpshooters, they would kill off those good bugs too--"so there's 14 years of work down the drain," Luck said.

"The nice thing about natural predators is that when they work, they are like programmed smart bombs," Luck said. "They know their target."

Many, however, remain unconvinced that biocontrol can be as effective as pesticides.

Don Luvisi, a farm advisor with the University of California Cooperative Extension in Kern County, points out that biocontrol is problematic even when it works. If a good bug is too successful in wiping out a bad bug, then the good bug won't survive because it won't have anything left to prey on, he said.

"There are a lot more notable failures than there are notable successes," he said. "I'm not in the camp that is going to run out and raise the flag and say: 'This is our salvation.' "

In recent years, however, biocontrol has had something of a comeback, especially among California's 89,000 farmers.

Rob Weppler, an entomologist at Gless Ranch's citrus and avocado farms in Orange, Riverside and Kern counties, said the majority of modern farmers believe biocontrol is now an important part of pest control.

At Gless Ranch, Weppler uses a parasitic wasp to control red scales, which are citrus pests. Whenever possible, he said--even if it's only to sidestep the environmental tangles and public relations problems that pesticides bring--Weppler tries to use biocontrol.

"There are people who think it's a waste of time," he said. "But the more we can control biologically, the better."

Even Steve Forsberg--whose job as the the chief executive and president of the Western Crop Protection Assn. is to promote chemical- and technology-driven pest control--says biocontrol can be an important weapon.

"The farmer needs every tool he can get his hands on," Forsberg said. "There are limitations, but it can work: Bugs can eat other bugs."

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