Medfly War Winds Down; Scientists Are Optimistic : Pests: Victory may be declared in November. But some skeptical experts fear further infestations.

Sensing victory at last in a yearlong battle that has cost taxpayers $44 million and stirred public debate about pesticide safety, state and federal officials have begun to wind down their eradication campaign against the Mediterranean fruit fly in Southern California.

A month has passed since a fertile Medfly has been trapped in the region, and scientists who advise the eradication effort now express cautious optimism that a 13-month quarantine on the movement of fruit and vegetables through the region can be lifted by mid-November.

More than 150 of the 500 people originally assigned to the eradication effort have been released to their home agencies, and the state agricultural official who spearheaded the Medfly campaign said he is devoting more of his time to less newsworthy pests such as boll weevils and harmful aquatic plants.

The squadron of helicopters that once was a pounding annoyance over Southern California’s skies has been gone for months. Sterile fly releases, which replaced pesticide spraying and have dispersed 5.5 billion flies over the region, are now restricted to just three pockets of infestation, encompassing a relatively small 48 square miles.

And in the latest sign of the growing confidence, a long-planned conference of entomologists scheduled for this week in Los Angeles has been canceled--in large part because there is little to talk about.

“We felt we wouldn’t lose too much by delaying the meeting,” said Roy Cunningham, chairman of the five-member Medfly Science Advisory Panel. “Instead, we want to combine our next meeting in November with a critique of the program, which could coincide with the lifting of the quarantine.”

Still, the Medfly campaigners remember too well the embarrassing events of last spring, when the state’s top agriculture official set a deadline for the end of spraying only to see the Medfly population explode, prompting another vigorous round of spraying.

“While there won’t be any dancing in the street until mid-November, maybe we ought to start practicing a few steps,” said Gera Curry, spokeswoman for the state Department of Food and Agriculture. “At the end of September, if there are no more flies, the 40 or 50 people involved in sterile fly releases will no longer be needed.”

Isi Siddiqui, department assistant director and the man in charge of the eradication program, said that although he is spending “more time now on the boll weevil, gypsy moth and hydrilla,” the discovery of a single Medfly could change everything.

The first Medfly infestation was discovered July 20, 1989, in Elysian Park. At the time, officials believed it was an isolated case that could be put down with one or two aerial sprayings followed by the release of sterile Medflies.

Instead, the Medfly population exploded across 200 square miles of Los Angeles and Orange counties in a crisis compounded by the fact that state officials quickly exhausted their supplies of sterile flies.

Their only alternative was repeated aerial doses of malathion on wide swaths of Southern California. The sprayings were met with intense opposition from city officials and more than 1,800 complaints to the county Department of Health of illnesses ranging from headaches to nausea.

In the escalating war over the potential health effects of malathion spraying, the Los Angeles City Council last week issued a subpoena to have the official in charge of the county Health Department’s toxics epidemiology program release to the city all documents and test results that would show whether the spraying has caused health problems.

Dr. Paul Papanek is expected to make his presentation before the council’s Arts, Health and Humanities Committee sometime today.

Nonetheless, the five scientists who advised the eradication effort already are turning their attention to a debate over how to do better next time.

Cunningham, for example, has proposed a review of the “triggers” used to determine whether to launch aerial malathion spraying or to release millions of sterile Medflies to make it virtually impossible for wild flies to find a fertile mate.

As it stands, Cunningham said aerial spraying typically is initiated with the discovery of a single mated female or two male flies.

Cunningham believes the state may have started spraying too soon in many instances without completely understanding the extent of the infestation. At the height of the aerial war, the spray zone encompassed 536 square miles.

“I am in favor of more intense scrutiny around these finds,” Cunningham said, “and not to respond to a find as if two flies or a mated female is an infestation.”

“Maybe we need to raise the trigger up to three or four mated flies,” Cunningham said. “It will cost more to respond with a more intense survey, but in the long run it will save money.”

Other Medfly experts believe the use of malathion in the eradication effort has been ineffective. They argue that statistics show that Medflies long have been established in California. What are seen as new infestations, they argue, actually are old, ongoing infestations finally being detected by a porous system of trapping.

“In my view, all we’ve done is dodge a bullet,” said James R. Carey, a UC Davis entomologist on the scientific advisory panel who compared the use of malathion to fight Medflies to “taking aspirin at the first signs of cancer.”

“I believe there is an established population down there,” Carey said. “Malathion does kill flies, but killing flies and eradicating a population are two different things.”

Others argue that the Medfly is repeatedly introduced in this country in infected produce that is mailed, shipped or carried on ships and planes.

Advisory panel member Carrol Calkins, a research scientist with the U. S. Department of Food and Agriculture in Florida, is pressing for stiffer fines and penalties for illegal transportation of fruits and vegetables into U.S. ports of entry including international airports.

“In the future, we might expect a Medfly reintroduction a year unless things are tightened up,” Calkins said. “Now, there is a $50 fine if you are caught (deliberately carrying quarantined fruit), but if there was a real tough fine, word would spread quickly.”

Times staff writer Ashley Dunn contributed to this report