11/07/2007

Scientist says moth can't be eradicated
Too widespread to be wiped out, says entomology professor
By JULIA REYNOLDS

A key scientist in the decades-old fight against the Mediterranean fruit fly says eradicating the light brown apple moth from California is impossible.

And, he says, the most devastating economic consequences are likely to come more from trade embargoes than crop damage.

"This thing is so widespread that there is no way that they're going to eradicate it," said James Carey, a professor of entomology at the University of California-Davis known for his research on the medfly, which in the 1980s threatened California's citrus industry.

Now he questions claims by the state Department of Food and Agriculture and the U.S. Department of Agriculture that the pest can be eradicated by disrupting its mating cycle with aerially-applied
Click to view a map of the Salinas treatment area (PDF)
pheromones.

"The CDFA and USDA really need to do a major stock-taking," Carey said. "You have to come to grips with reality."

An Agriculture Department technical advisory panel that convened in May in San Jose disagreed, concluding that the moth was "eradicable."

In a statement, state Agriculture Secretary A.G. Kawamura said Tuesday that "pheromone mating disruption is a proven insect control technique," which, he said, was recommended by the panel as the primary tool to eradicate the moth.

Carey said the moth has spread to too many counties for aerial spraying to work and, like cancer cells in the body, can continue to grow undetected.

Two aerial applications over the Monterey Peninsula are complete. State officials
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expects to begin application over parts of Salinas, Prunedale and Santa Cruz County this week.

Since the spring, the moth has been spotted in a number of California counties.

"Jim Carey is looking at the size of the area (the moth) currently inhabits," said Kevin Hoffman, a leading entomologist for the state.

"Certainly it's a large area. Mostly, the geographic area is usually much smaller — (but) I wouldn't say that precludes us from doing it."

Department of Food and
Click to view a map of the Prunedale treatment area (PDF)
Agriculture spokesman Steve Lyle said the state "annually" eradicates widespread pest infestations such as gypsy moths.

"Populations can be eradicated," he said.

"I'm happy to be convinced that it can be eradicated," Carey said. "But using the tool that they have of mating disruption, there are major questions. I don't know that a pheromone has ever been used to eradicate a pest."

The same month the San Jose panel convened, officials imposed quarantines on parts of nearly a dozen California counties, including Monterey and Santa Cruz. The state of Hawaii, where the moth has lived for years, is under quarantine. Quarantines mean additional inspections on exported nursery plants and fresh produce from the region.

Carey and
Click to view a map of the Santa Cruz treatment area (PDF)
some growers say the primary economic impact of the moth is likely to be the result of trade restrictions from imposed quarantines, and not crop damage caused by the moth.

It's a Catch-22 that Carey calls the "medfly double bind." He says it applies to the light brown apple moth infestation.

"The double bind is that ... to acknowledge that they're established is to unleash economic consequences that are even more devastating than the spread would cause," he said.

That, he said, is why the state has to show it is making efforts to eradicate the pest, even if the efforts aren't effective.

"To acknowledge the truth is to trigger these embargoes and quarantines that are absolutely devastating, so they're always playing this game that it's 'eradicable,'" he said.

State officials say international trade hurdles have been mostly overcome, though Canada and Mexico have imposed some restrictions on items from the Central Coast.

"What initially happens is when quarantine is imposed, everything stops. That's when you have the initial issues," said Rayne Thompson, director of international trade and plant health for the California Farm Bureau. "But we've been under quarantine for a couple of months now."

Recently, she said, a Brussels sprout grower had problems shipping to Canada.

"We were able to work out additional inspections and get the product there," she said.

With major holidays around the corner, growers rely on shipments of fresh fruit gift baskets that could be delayed or stopped, she said, if quarantine areas are expanded to more counties.

As far as the moth's potential damage to the Central Coast's agriculture industry, Thompson said, the bureau is only beginning to compile data.

Lyle said the $160 million to $640 million figure quoted by the Department of Food and Agriculture reflects potential damage to plants and fruit crops, and doesn't include costs imposed by new regulations, inspections or embargoes.

Thompson said farmers in the Central Coast quarantine areas are already using alternative techniques to keep the pest in check.

California farmers have been battling similar leaf-rolling moths for years by using "integrated pest management" techniques, said Thompson.

"It seems like the best alternatives for our growers are IPM — trapping, keeping an eye out for populations, treatment on the ground. Just being really aware of the environment," she said.

Hoffman said the moth is "primarily a leaf feeder. It constructs a silken tent that it hides in. It goes out and feeds on the surface, and as it gets older, it folds the leaf over. It affects fruits when the leaf touches the fruit."

In Hawaii, farmers have coexisted with the moth for a century — but that is because it mainly lives at higher altitudes where there are few farms, said Hoffman.

"It doesn't affect their agriculture," he said.

However, the government still imposed a quarantine on the state, Hoffman said.

Carey said officials need to think harder before declaring a multi-million-dollar war on the apple moth via pheromones that is likely to be futile in the end. The state has never permanently eradicated many pests, he said, but farmers have learned to manage them.

"It's sort of like you pick your battles in this life. The USDA needs somebody to say this is just too far gone," he said. "We have to really rethink this."

To the state's farmers, the whole issue of whether the moth is truly a threat is not their most immediate concern.

"A quarantine is there, whether you agree with it or not," Thompson said. "Sometimes it takes a while to get all the science together. In the meantime, you live under the conditions of the quarantine."

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