Medfly Outbreak Threatens to Become State’s Worst : Agriculture: More than 1,000 square miles are quarantined. Pressure to use aerial spraying builds.

Three years after declaring Southern California cleansed of the crop-destroying Mediterranean fruit fly, state agricultural officials are facing a new and quickly expanding infestation that is threatening to become the largest in the region’s history.

With little public fanfare, 1,010 square miles in Los Angeles, Orange and San Bernardino counties have been placed under a federal agricultural quarantine--just short of the 1,300 square miles of the massive infestation of 1989-90.

The area in which steps are being taken to destroy the pest already has reached 619 square miles--surpassing the size of the 1989-90 eradication zone.

But in contrast to previous outbreaks, state agricultural officials have refrained from aerial malathion spraying, relying instead on a campaign of ground pesticide spraying and the release of radioactively sterilized Medflies to disrupt the normal breeding pattern of the wild insects.

Despite their efforts, officials acknowledge that the infestation has continued to grow at an alarming pace. That has unnerved farmers in the Central Valley, who could face economic disaster if the pest is found beyond the Tehachapi Mountains.

A quarantine over the state’s prime growing areas could devastate its $18.1-billion agricultural industry by crippling farmers’ ability to export produce to overseas and domestic markets.

For the first time since the 1989-90 infestation, officials are being pressured to resume aerial malathion spraying, despite the enormous public opposition in Southern California.

Although the prospects of spraying over urban areas appears to be remote, state agricultural officials signaled a willingness last week to launch their squadron of helicopters again--as a last resort.

“We’re going to do what needs to be done,” A.J. Yates, deputy director of the state Department of Food and Agriculture, told a group of farmers in the Central Valley community of Visalia last week.

Beyond the immediate concerns about the infestation, some scientists say that the current outbreak bolsters the controversial theory that the Medfly has become firmly entrenched in Southern California.

Even some of the most optimistic experts are acknowledging that the old strategies have failed and that even more radical and costly efforts may have to be mounted to destroy the pest.

“This is a defining year,” said UC Davis entomologist James R. Carey, a member of the state’s Medfly Science Advisory Panel. “They’re coming back in big numbers. This leaves no doubt that the flies are widespread and spreading.”

The roots of the current infestation can be traced back to the discovery two years ago of a single pregnant Medfly in a peach tree near Los Angeles’ Koreatown. At the time, the find caused little concern, since it came after nearly a full year in which no Medflies were found in Los Angeles.

State and county agriculture officials believed that the discovery was a newly introduced fly--most likely brought into the area by fruit that had been illegally shipped into the country from overseas.

Eradication officials were so confident that the infestation was small and isolated that they ignored their standard protocol for eradication, which required immediate aerial spraying, choosing instead a low-key strategy of ground spraying, fruit removal and release of sterile flies.

For other experts, however, the discovery near Koreatown raised an unsettling possibility that it was not a new introduction, but rather a continuation of the infestation that had supposedly been suppressed with aerial spraying a year earlier.

The area near the discovery had been sprayed twice from the air with malathion and blanketed with sterile Medflies.

In the months after the Koreatown discovery, continuing finds brought the realization that the long and painful campaign of 1989-90 may have failed to eradicate the Medfly.

Through 1992, 202 Medflies were found in Southern California--many in areas that had been treated with aerial malathion spraying in 1990.

This year, despite a continuing eradication effort, the number of finds has increased dramatically. So far, 392 Medflies have been found and the quarantine zone has nearly doubled.

The size of the current infestation and the speed of its expansion has shaken the eradication campaign. Farmers have grown skeptical of those in charge.

“We’ve got flies basically all over this basin,” one farmer told state agriculture officials at the meeting in Visalia. “Today, I see concern in your face for the first time. We’re concerned as hell out here because we’ve got the product. The state of California should be shaking in its boots because we’re talking about grave economic danger.”

Farmers, most of whom favor aggressive spraying, are frustrated with the state’s response, which they believe has been shaped by fear of political and environmental backlash in urban Southern California.

Because of the uproar over aerial pesticide spraying, Department of Food and Agriculture Director Henry Voss said even before the end of the 1989-90 infestation that aerial campaigns were a thing of the past, except as a last resort.

As a result, the eradication effort has relied on ground spraying and the use of sterile Medflies--a technique whose effectiveness is still debated.

Radioactively sterilized Medflies have been used for more than a decade. The idea is to saturate an area with sterilized male Medflies that will mate with wild female Medflies. According to the theory, with no offspring, the breeding population of wild flies would eventually fade away.

The technique has been successfully used in combatting a variety of exotic pests.

But where Medflies are concerned, some scientists believe that the sterilized flies are too weak to compete for females in the wild.

In the past, the efficiency of the technique was enhanced by first spraying an area with malathion to reduce the wild population.

This time, however, the state has done away with the initial spraying and relied entirely on sterile releases.

Some experts suggest the apparent Medfly population explosion is actually the result of a better detection tool: a simple fly trap called “the sticky yellow panel.”

The trap, which is just old-fashioned fly paper soaked in a chemical bait, is simple enough to be be scattered by the thousands around the region to provide early detection of any breeding population.

But Carey of the Medfly Science Advisory Panel said that does not completely explain why the numbers have nearly doubled since last year, when the sticky panel also was in widespread use.

“By any measure, this is getting worse,” he said. “This place is coming unglued.”

The first Medfly in California was discovered in Marina del Rey in 1975. For five years, officials believed they had stamped out the pests. But in 1980, Southern California again experienced an infestation, and since then Medflies have been found almost every year.

Even officials who had once believed that the Medfly could be eradicated through traditional means have been shaken by the size of the new infestation.

Los Angeles County Agricultural Commissioner E. Leon Spaugy once saw infestations as separate and distinct events--spot fires that could be easily extinguished.

“I’ve gone through a metamorphosis because it’s become such a repetitive thing,” Spaugy said. “It seems we can’t have even a single year here in which we are free of infestation.”

Although Spaugy believes that the current infestation will eventually be controlled, he and others say it is time to abandon the spot-fire mentality and adopt a long-term strategy to eradicate the pest.

The distinctions between the two visions may seem small on the surface, but they carry significant economic ramifications for the state’s agricultural industry.

More than a quarter of California’s agricultural products are sold overseas. The major markets, including Japan, Taiwan and South Korea, have stringent rules on the treatment of fruit and vegetables to keep exotic pests from migrating to their shores.

So far, those countries have agreed with state officials that the Medfly infestations here are isolated events--aberrations that have no effect on their basic import regulations.

If the state were to openly declare that the infestations were caused by an established Medfly population, it could invite countries to respond with stricter--and far more costly--import requirements, such as fumigation or cold treatment.

Finding an eradication strategy that acknowledges the persistent nature of the Medfly infestation but does not open the door to harsher import requirements has not been easy.

Spaugy said that instead of constantly chasing outbreaks each year, the state should embark on a multiyear eradication program covering the entire Los Angeles Basin.

The cost would be enormous; simply fighting the Medfly with each outbreak has also proved expensive. The 1989-90 infestation cost $52 million to fight. Estimates for the current eradication effort through next June are up to $40 million in state and federal money.

Richard Rice, a UC Davis entomologist and another member of the state Medfly Science Advisory Panel, said that despite the cost, a protracted eradication campaign may be the only solution.

“We’re talking about a humongous piece of real estate and I have no idea how you would accomplish a basin-wide eradication,” he said, “but these things are not going to go away by themselves. These flies are survivors.”