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Visitors or natives, Medflies raise fears

Discoveries at three spots in the state have experts fighting back. And wondering where the pests came from.

October 30, 2007|Eric Bailey | Times Staff Writer

DIXON, Calif. -- They discovered the corpse in the tidy backyard of a home near the corner of Washington and C streets.

The dreaded threat. A farm community's worst nightmare. A Medfly.

On an otherwise peaceful weekday in early September, a county agriculture inspector found the tiny carcass in an insect trap hanging from a peach tree. Then the inspector found another. And another.

In all, 13 of the dreaded crop-devouring pests were discovered, along with a couple dozen larvae, the first time in a quarter century that the Mediterranean fruit fly has been found in the Central Valley, California's farm heartland.

State and federal agriculture officials reacted immediately, launching eradication efforts and expressing confidence -- even with subsequent discoveries in San Jose and the Palos Verdes Peninsula this past week -- that the feared fly could be stopped once again.

For The Record
Los Angeles Times Thursday, November 01, 2007 Home Edition Main News Part A Page 2 National Desk 1 inches; 38 words Type of Material: Correction
Medfly discovery: An article in Tuesday's California section on the Medfly infestation in September in Dixon, Calif., incorrectly reported that the initial discovery was of a fly corpse. The first four Medflies caught in a trap were alive.

But concern is high in breadbasket communities such as Dixon.

This is a place where a farm tractor still can be seen lumbering past the Wal-Mart that sprouted up between alfalfa fields. The road into town is lined with a bumper crop of agribusinesses. The grain silo near main street remains the town's tallest structure.

Folks here worry that the federal government might be focusing so much on bombs during inspections that they're letting bugs slip through at borders and ports. They worry that today's Californians have grown too cavalier about carting back exotic and potentially pest-laden fruits from foreign lands.

They also worry about the hit on the agriculture-dependent economy of Solano County -- not to mention California's $34-billion agricultural industry -- if the Medfly proves to be a long-term resident. "We were lucky this time," said Joe Martinez, whose walnut crop fell under a 114-square-mile quarantine laid like a blanket on the farm fields around Dixon. "We caught it while it was a camp fire, before it could become a forest fire."

But what about next time?

State agriculture officials say they've grown more proficient at tackling infestations since the bad old days of the early 1980s, when then-Gov. Jerry Brown drew public anger for ordering aerial spraying of the pesticide Malathion to control a Bay Area outbreak.

Over the last decade, the state's approach has gone organic. Crews strip trees within 100 meters of infested fruit. They spray insect-killing Sinosad, an organic formula derived from a naturally occurring bacterium, within 200 meters of a find.

And they spread millions upon millions of sterile male Medflies -- their bodies dyed pink so they can be identified -- over the infestation zone. The flies, raised in a Los Alamitos lab, are chilled to 38 degrees to immobilize them for a ride aboard a twin-engine plane, and then dropped in weekly runs. They thaw as they fall, and reach ground level ready for romance.

Female Medflies typically mate just once, so a union with a sterile male can throw a wet blanket on an infestation.

"In every case where it has been employed, this approach has worked," said Steve Lyle of the California Department of Food and Agriculture. "But the fact that we've had three [infestations] this year really is of interest to us. It makes us wonder why."

Just up the road from Dixon, in the entomology labs at UC Davis, James Carey believes he has the answer.

Carey, a Medfly expert, says the recent discoveries are part of a larger pattern. Though state agriculture officials argue that each infestation likely is a fresh breakout caused by some wayward traveler carting in wormy fruit, Carey has reached a more ominous conclusion: "The Medfly never went away."

Just look at the numbers: There are 478 cities in California, and one in three has at some point had a Medfly infestation, Carey said.

"This is not the tourist model, but part of a larger population that has remained here," he said.

The discovery in Dixon is particularly disturbing, he said, because it means that, for the first time since a 1982 Medfly find in Stockton, the pest has appeared in farmland.

If it is unchecked, the devastation could be catastrophic. The fly feasts on 260 types of fruits, nuts and vegetables. It's a climatic survivor with a natural inclination to spread.

Infected crops wither and fall from tree or vine. Larvae-riddled fruit is inedible.

In the past, several Asian nations and Mexico have imposed restrictions on California-grown crops due to Medfly infestations. If the fly establishes itself, the hit to the agricultural economy could be as high as $1.8 billion a year, state officials estimate.

For farmers "they're public enemy No. 1," said Jerry Howard, Solano County Agricultural Commissioner.

Howard and most other agricultural officials around California don't buy Carey's theory of an expanding Medfly empire.

Genetic testing on the flies in Dixon show they're a genome that originated in Hawaii or Venezuela, while those in San Jose are likely from the Mediterranean branch, Howard said. Tests are still to come on the Southern California infestation.

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