War on Southland’s Biggest Medfly Infestation Expands : Agriculture: Malathion will be sprayed over Corona. Three-county quarantine widened to 1,461 square miles.

Agriculture officials on Thursday announced a massive eradication effort and a 1,461-square-mile quarantine area across three counties to battle the largest infestation of the crop-ravaging Mediterranean fruit fly in Southern California’s history.

In addition, they said aerial spraying of malathion--which generated a widespread public outcry four years ago--will begin Jan. 24 over Corona, where a mated female Medfly was discovered in December. The discovery of a Medfly in Riverside County--outside the already targeted eradication zone--could presage its spread to rich agricultural lands, state and county officials said.

The new offensive overshadows the efforts to eradicate the Medfly in 1989-90, when widespread aerial spraying of malathion was believed to have eliminated the pest from the region.

This outbreak once again threatens to devastate the $18-billion California agriculture industry. Officials in Japan--which annually buys about $300 million worth of California citrus and other fruit susceptible to the Medfly--are threatening an embargo on that fruit, citing fear of a Medfly infestation there, said Henry Voss, secretary of the state Department of Food and Agriculture. A statewide medfly infestation could cost the state economy $900 million annually, he said.

“We’re being pushed by our trading partners to put a lid on this problem before they have to put a quarantine on us,” Voss said at a news conference in Corona. The spread of the Medfly “has developed to a point where it is a threat to the economic well-being of the state,” he said.

To battle the Medfly in Los Angeles, Orange and San Bernardino counties, more than 400 million sterile Medflies will be released weekly for two years beginning in March. The strategy relies on female Medflies mating with the sterile flies, creating sterile offspring that will ultimately doom the population.

Officials said there were no plans to renew aerial spraying of malathion in the three-county quarantine zone.

Because laboratories in Hawaii cannot radioactively sterilize enough Medflies to blanket Corona all at once, aerial spraying will be done over that city, Voss said. The insecticide dose will be half the strength of that used in the 1989-90 sprayings.

Corona officials complained that they were given no notice of the spraying before Thursday’s public announcement, although Riverside County supervisors were given advance notice as a courtesy.

Corona City Councilman Jeffrey Bennett said the area targeted for aerial spraying has a population of about 90,000, and said it was clear to him state officials chose his community, rather than Los Angeles, for aerial spraying because Corona lacks the power of larger cities.

“Los Angeles has more political clout, and I resent that,” Bennett said.

At the conclusion of the news conference, Bennett said angrily: “Your project has failed . . . (to eradicate the Medfly). This happens every year. What the hell is going on?”

In May, 1990, agricultural officials said they hoped Southern California was rid of the Medfly, after they had quarantined a 1,300-square-mile area, done widespread aerial spraying of malathion and flooded the region with sterile Medflies.

But in 1991, a pregnant Medfly was discovered in a peach tree near the Koreatown section of Los Angeles, and through 1992 more than 200 other Medflies were discovered.

At most recent count, officials said Thursday, more than 400 Medflies have been discovered in the region. Among the more troublesome finds was the mated female Medfly in a Corona grapefruit tree two months ago.

J. R. Reynolds, a regional director for the U.S. Department of Agriculture, blamed the increase in Medflies on both the transporting of fly-infested fruit outside quarantine areas and continued illegal importation of infested fruit from Asia, Latin America and the Mediterranean.

Much of the banned Asian fruit arrives here by way of teh Canadian province of British Columbia, which does not have a Medfly quarantine because of its cold winter climate, Reynolds said. Some of the fruit is unwittingly taken to California by travelers, and other fruit is smuggled here for sale at grocery stores.

“A large percentage of stores are selling fruit that is illegal in the United States,” he said.

Voss characterized the current Medfly campaign as “proactive” in stopping the insect’s spread across the state. A statewide infestation, he said, would cost the state $900 million a year in lost trade, related jobs and the increased costs for pesticides by growers and backyard gardeners wanting to keep their plants free of Medfly maggots.

Voss said he was braced for opposition to the aerial spraying. “I’m sure people won’t be jumping up and down and be happy over this,” he said. Three helicopters will spray the malathion while flying about 500 feet above the ground. The helicopters will be “very intrusive,” he conceded.

But because the larger Los Angeles Basin quarantine area already is stocked with sterile Medflies, he said, it would be counterproductive to spray malathion there.

Corona will be blanketed by a mist composed of 10% malathion and 90% corn syrup-based bait.

The use of malathion has been challenged because of its unknown long-term effects and questions of whether, at high doses, it is carcinogenic. But the California Department of Health Services said that a health risk assessment after the 1989-90 sprayings showed no significant health effects on those exposed to it.

Some people experienced mild, short-term skin irritation but “it was concluded that it is very unlikely malathion causes major chronic health effects such as cancer and birth defects,” according to a statement issued by the state and the Malathion Public Health Effects Advisory Committee. “Concerns about eye disease were found to be unwarranted, and pesticide poisoning and other serious effects did not occur.”

The statement acknowledged that the anger and anxiety created by aerial spraying of malathion, a common garden insecticide, is “an important public health consideration” in itself.

Voss said malathion will be sprayed over Corona eight to 10 times, starting Jan. 24 and ending in late June. Each application will take three to four hours, he said. The effort will cost between $750,000 and $1 million, officials said.

At the completion of the sprayings, if no Medflies are found, the existing 2,400-acre quarantine area around Corona will be lifted.

A multiagency task force will hold a public meeting on aerial spraying at 6 p.m. Tuesday at the county library in Corona.

The release of sterile Medflies in the Los Angeles Basin quarantine area will continue weekly through December, 1995, and will cost about $70 million. If deemed successful, the quarantine would be lifted in early 1996, officials said.

The female Medfly lays its eggs in ripening or ripe fruit and the larvae feed on the fruit pulp, rotting it. The emerging flies can live up to four weeks in the summer and up to three months in the winter.