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Working Out the Bugs

THE CUTTING EDGE

Scientists experiment with natural strategies in seeking benign ways to protect crops.

May 04, 1998|MARTHA GROVES | TIMES STAFF WRITER

Using simple technology borrowed from restroom deodorant dispensers, Harry Shorey, a UC Riverside entomology professor, is pumping new life into a 30-year-old concept: mating disruption.

Male and female moths do not congregate together. When a female is ready to mate, she emits a scent. A male catches the scent and follows the trail upwind.

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Shorey's experiment aims to confuse that natural pattern. He and his crews are installing aerosol cans in cabinets at 10,000 sites in orchards and fields in the west Central Valley and near Oxnard. Much like a deodorant dispenser, the cans puff a scent into the air that is designed to overwhelm male moths and make them unable to track the females.

Scientists have identified hundreds of these sexual scents, or pheromones. Because they are expensive to mimic, companies have synthesized only half a dozen.

Shorey plans to get the most bang for the puff by placing specially designed puffer cabinets at the perimeters of 40-acre blocks in neighboring fields. The idea is to put large amounts of pheromones into the air--with the amount of scent in each puff equaling that of as many as 10 million moths.

In test runs, Shorey said, he was able to cut the egg-laying of beet armyworm moths by 75%.

Shorey expects his technique, designed to protect peach, walnut and other trees from codling moths and other pests, to be available for commercial use within a year.

For several years in the Sacramento Valley, Les Ehler, an entomologist at UC Davis, has been experimenting with ways to lure beneficial insects into sugar beet fields by providing food. Ladybugs, green lacewings and other insects that devour crop-munching pests need sustenance whenever those pests aren't around.

Ehler has concocted food sprays of mixed sugar, molasses and yeast that mimic the nutritious nectar, pollen and "honeydew" (a sticky substance produced by aphids) that adult insects need for egg-laying.

The optimal formulation eludes Ehler, but he has hopes for solid versions of the goodies, which he has dubbed "power bars." Ehler expects insects will be drawn to them.

"I can't report spectacular success just yet," he said, adding that, at its best, such a strategy would be only one tool used along with synthetic chemicals.

In his fields of citrus, avocados, pistachios, pears, tomatoes and other crops, grower George E. Myers has tried pheromone disruption and other methods with some success. But, facing the loss of several key synthetic chemicals in coming years, he decided that his agribusiness concern, Esperanza Ranches near Sacramento, needed more weapons.

Myers invested in AgraQuest and sits on its board. He said he is excited by the prospects for two promising natural-product fungicides in AgraQuest's pipeline, both due on the market within two years. They are designed to control gray mold, brown rot, mildew and root rot--common afflictions in California's fruit, nut and vegetable crops. Marrone, AgraQuest's president and chief executive, projects that each product could eventually achieve sales of $50 million.

Three-year-old AgraQuest's only commercial product to date is Laginex, used to kill mosquito larvae. The company's scientists experiment continuously on promising fungi and bacteria contained in soil, lichen and other samples scoured from lake beds, forests, dunes and ocean caves.

Big chemical companies also are exploring the biocontrol trend--while making it clear that they believe synthetic chemicals are here to stay.

Dow AgroSciences, an Indianapolis-based unit of Dow Chemical Co., is eager to capitalize on its insecticide Success. It is expected to attract a following in California. Last year, it was used under an EPA exemption to control diamond-back moths in Salinas and other areas after growers were unable to solve the problem with the usual treatments.

"The new chemistries are fantastic," said Bryan Stuart, government relations manager for Dow AgroSciences in Sacramento, "but that doesn't diminish the importance of existing tools."

Among those tools are advancements in genetic engineering. About half of the many USDA-approved biotechnology applications involve the development of plants that can tolerate herbicides, such as the Roundup Ready varieties from Monsanto Co. Pesticide makers have invested heavily in such technologies to ensure expanded sales of their proprietary chemicals.

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Also approved for commercial use in the United States are corn, cotton and potato crops that have been supplemented through gene manipulation with a soil bacterium called Bacillus thuringiensis, or Bt. The bacterium helps the plants naturally resist certain harmful pests.

But other solutions are needed, farmers and scientists agree. The research has lagged in large part because of a lack of public funding. Fewer than 10% of the 1,800 research scientists at the USDA's Agricultural Research Service--and less than 10% of the service's $745-million research budget--are focused on developing natural crop-protection methods.

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