Victory Declared Against Medflies : Infestation: A quarantine on fruit will be lifted today. Some experts say the pest is still entrenched.

Agriculture officials declared Thursday that their controversial, 16-month battle with the Mediterranean fruit fly in Southern California finally has ended in victory--an assertion that some entomologists believe ignores evidence that the pest is entrenched in the region.

As they claimed victory, officials announced that the last vestige of the $52-million eradication campaign--a state and federal quarantine that has prevented the free movement of home-grown fruit through some areas--will be lifted today.

“We’re here to celebrate that we’ve eradicated the Medfly from California and unless there is another introduction, it will remain eradicated,” said Jack Parnell, deputy secretary of the U.S. Department of Agriculture, who flew to California to join local and state officials in a round of congratulatory speeches. “We are absolutely appreciative of the patience of the people of the Los Angeles Basin.”

The campaign began after discovery of a single fly near Dodger Stadium. At its height, the effort required pesticide spraying over several hundred square miles of residences; a debate over priorities raged between pesticide-wary urbanites and the state’s farmers, who feared that the crop-damaging pest would move into prime agricultural regions. In the end, the infestation largely spared farmland.

Officials told reporters that the campaign had left a positive legacy of greater understanding of how to battle the pest and keep it out of California. Some scientists were skeptical of such analyses, mindful of a new Medfly theory that has raised fundamental questions about any eradication tactics.

The theory, advanced by one of five scientists who advised the eradication campaign and based largely on statistical evidence, suggests that pockets of the state have been infested with Medflies for roughly 15 years and remain so today. Only a porous system of detecting flies makes it appear they have been eradicated from time to time, goes the theory of UC Davis entomologist James R. Carey.

“It’s a short-term victory, but in a biological sense, I’m skeptical,” Carey said in an earlier interview. “They’re going to come back.”

Carey was absent from the festivities Thursday, but even those who only partially embrace his theory--still being explored by researchers--were doubtful that Southern California has experienced its last major Medfly outbreak.

“We just won another battle, but the war is never going to be over” said Richard Rice, a UC Davis entomologist and another member of the state’s science advisory panel.

At the official ceremony, held at the county agriculture office in El Monte, skepticism was kept to a minimum.

“The scientific evidence says today that we have eradicated the fly,” said Henry J. Voss, director of the California Department of Food and Agriculture. “I’m happy and relieved and proud of the people who worked in this eradication.”

Nonetheless, Voss conceded that more Medflies will be found and agreed that exclusion and trapping programs are under-funded, but he added: “When my team wins, that’s a victory, even if they lost last week and will lose again next week.”

The declaration of victory was founded on the lack of discovery of anything but isolated flies in four breeding cycles, or four months. The last fly was trapped Oct. 1 in Riverside County, and it did not prompt pesticide spraying.

Parnell said the end of the battle heralds a shift in strategy to preventing the Medfly from entering the country in the first place, either in mailed packages, cargo or baggage.

“The eradication programs are going to have to be replaced with exclusion strategies that work,” he said. “Exclusion is the name of the game.”

Parnell said the USDA already has bolstered its overseas fruit inspection system with the use of a fruit-sniffing dog to check first-class mail from Hawaii.

“We’re doing everything we can and we will continue to do everything to avoid what we have just gone through,” Parnell said.

Nonetheless, some officials were disappointed that efforts to prevent the Medfly from entering the state and improve the state’s admittedly leaky fly trapping network have fallen short of earlier, more ambitious expectations.

The state’s five-member science advisory panel had recommended placing as many as 25 fly traps for every square mile to ensure quick warning of a potential outbreak. Voss, citing budget restraints, said that the trapping levels will drop next year to five for each square mile.

And one official challenged Parnell’s description of a beefed-up inspection system, saying it consisted of the addition of a single fruit-sniffing beagle.

“One beagle does not an exclusion program make,” said the official, who asked not to be identified. Parnell said he would push for more dogs or other systems.

Voss said he believes that the state has the ability now to prevent another large infestation because of experience gleaned from the Southern California battle and the completion of a $7-million sterile fruit fly breeding facility. This, he said, will allow the state to handle major infestations with only limited malathion spraying.

Southern California’s Medfly infestation began on July 20, 1989, when a county inspector found a single Medfly in a fruit fly trap in Elysian Park. The discovery came just a month after agriculture officials had declared victory over the Medfly in a 10-month-long infestation in West Los Angeles that was limited to 35 square miles.

The state launched its first assault against the pest with a single aerial spraying of the pesticide malathion, followed by the release of millions of sterile Medflies to breed with wild flies and thus prevent the growth of another generation.

But the infestation continued to spread, reaching San Bernardino and Riverside counties for the first time in history. The state exhausted its supply of sterile Medflies in December and was forced to begin repeated sprayings of malathion, as many as a dozen in one neighborhood.