L.A.’s War on Medfly Heats Up : Pests: Infestation area will be inundated with sterile males. Aerial spraying of malathion ruled out for now.

Clouds of sterile Mediterranean fruit flies were released over 30 square miles of Los Angeles Friday as agriculture officials continued to mount a quiet battle against the latest infestation of the crop-destroying pest.

Every week for the next five months, about 50 million sterile flies will be set loose from buckets stacked on flat-bed trucks in a core area roughly centered around Koreatown and Country Club Park and dropped from two small planes in the surrounding neighborhoods.

Inundating the area with millions of sterile male Medflies greatly increases the likelihood that wild flies will mate with their sterile counterparts. Over time, scientists said, the population will be bred out of existence. The $5-million effort will continue until May, the equivalent of three Medfly life cycles.

Initiation of the sterile-fly release program effectively rules out for the time being the controversial use of aerial pesticide spraying to knock down the Medfly in the infested area, agriculture officials said. An aerial pesticide application would only serve to kill the sterile flies in the midst of their biological war.

“Aerial spraying is not being considered,” said Leon Spaugy, Los Angeles County agricultural commissioner. However, he said, if new flies are found in far-flung locations during the warm spring and summer breeding months, aerial spraying could be used “as a last resort.”

Since they were confronted with a new Medfly outbreak in October, state and local agriculture officials have taken a decidedly low-key approach to fighting the infestation, hoping to avoid the use of the malathion-spewing helicopters. An extensive air battle was waged during the last Medfly infestation in 1989-90, releasing a torrent of public criticism. Since Oct. 7, 22 Medflies have been found in a six-square-mile core that includes Country Club Park and Koreatown. A single fly also was found in San Gabriel several months ago, but no others have been detected and scientists view it as an isolated incident.

The results of new, intense trapping methods persuaded a majority of the state’s five scientific advisers that the current infestation is likely confined to the core area.

The novel Medfly weapon that has been deployed is called a “yellow sticky panel” and is considered to be a more effective trap than earlier traps. About 100 panels have been hung around each new fly find, about a tenfold increase from previous trapping practices. Officials said this has enabled them to more accurately measure the extent of the infestation.

“Never have we had so clear a picture of an infestation,” Spaugy said.

In addition to increased trapping, officials ordered malathion ground spraying within 400 meters of each fly find and fruit stripping in the core area. Federal agriculture inspectors also have seized about 2,500 pounds of illegally imported fruit from street vendors and produce truck operators in the area. Such contraband fruit, much of it from Mexico and Central America, can harbor Medfly larvae.

In assessing the current outbreak, Roy Cunningham, chairman of the Medfly Science Advisory Panel, said he “feels confident we are talking about a small infestation . . . We are committed to using steriles because we have a small population in a very confined area.”

Two of his panelists, however, have disagreed with that conclusion, a split in opinion that could grow if new infestations are found in the spring and summer.

Entomologist Richard Rice recently warned that the current eradication campaign has been far too cautious and unsuccessfully argued for aerial spraying to aggressively wipe out the infestation.

And panel member James Carey has long insisted that the Medfly is a permanent pest in Los Angeles. Although he agreed that the sterile releases will quell the latest outbreak, he said he will continue to push for long-range control measures, such as an ongoing sterile fly program.

Several representatives of farming interests said that they are satisfied with the current eradication program, but will loudly call for aerial spraying in the event of additional outbreaks.

“Springtime will be critical,” said Richard Matoian, spokesman for the California Grape and Tree Fruit League. “Our group will be the first to demand that the helicopters return to the skies.”

In the meantime, opponents of aerial spraying credit their vehement protests of two years ago with influencing the current battle plan. And they say they stand ready to renew their opposition if the helicopters take flight once again.

“There will be massive and larger protests if we return to aerial spraying,” said State Sen. Art. Torres, an outspoken opponent. “People have become more and more environmentally aware. We are tired of breathing dirty air in Los Angeles and aerial spraying won’t be taken anymore.”

Medfly Treatment

Here is the 30-square-mile area where about 50 million sterile Mediterranean fruit flies a week will be released. The flies will be set loose from roving trucks in the core area and will be dropped from small planes in the outlying sections.