More Spraying Set as Sterile Medflies Are Labeled Unreliable : Infestation: Agriculture officials question the quality of insects from Guatemala. Short supplies of treated flies mean more malathion.

As two more fertile Mediterranean fruit flies were discovered in previously unaffected neighborhoods, agricultural officials balked Friday at obtaining from Guatemala a supply of sterile flies for Los Angeles County’s battle against the crop-destroying pest.

The decision, agricultural officials conceded, means that more double doses of pesticide spraying will be likely if additional fertile Medflies are found.

Glen Lee, regional director of the U.S. Department of Agriculture, said federal officials are concerned that tapping the Guatemalan supply of sterile flies could hurt efforts to stop the Medfly from advancing across the southern border of Mexico.

Expressing concerns about the quality of Guatemalan flies, Lee added, “We don’t want to relive Peruvian flies all over,” a reference to supposedly sterile flies from Peru released during California’s 1981 Medfly outbreak. Officials suspected that some of the flies were fertile and may have contributed to the infestation.

Earlier this week, officials said they were forced to abandon a policy of doing only one aerial pesticide spraying over infested neighborhoods because they have nearly run out of sterile Medflies, which are released by the millions in an attempt to breed out of existence any fertile flies that survive the pesticide spraying.

Officials at a sterile Medfly breeding facility in Mexico--one of only three in the world--have stepped up production to supply 50 million flies weekly to Los Angeles County. In addition, a California-run breeding facility in Hawaii, the state’s usual source of sterile flies, has increased production to 130 million a week.

But county Agricultural Commissioner Leon Spaugy said the flies will not arrive in time to prevent a second aerial spraying of malathion later this month over largely residential portions of East Los Angeles and the San Gabriel Valley.

An aide to Los Angeles City Councilman Richard Alatorre was on the phone all day Friday trying unsuccessfully to speed up the delivery of flies so that a second spraying over East Los Angeles, which Alatorre represents, will not be necessary.

Spaugy said the additional flies from Hawaii and Mexico are “going to satisfy our needs at the present time.”

It might at some point be necessary to expand the Guatemalan breeding facility if there are more infestations, Spaugy said. “If we’re faced with a shortage, then quality maybe becomes secondary,” he said, defining quality as the sterile fly’s ability to compete and mate with wild flies.

“We don’t want to ever put ourselves in a situation where we have inferior flies,” he said. “If they’re inferior, they’re not going to do the job. . . . The damage is that you may have the numbers out there, but they’re giving you a false sense of security.”

The Mexican facility, operated by the Mexican and U.S governments, produces 500 million sterile flies a week, according to assistant director Pablo Liedo.

If an effort is made to provide more than 50 million flies to Los Angeles County, Liedo said, “then we will have nothing to stop Medflies from coming into Mexico.”

Since the introduction of the Peruvian flies in 1981, officials have stepped up their “quality control” procedures to prevent the inadvertent introduction of sterile flies.

Fly eggs are gathered in the laboratory, grown to pupae stage and irradiated with cobalt 60 to make them sterile.

The sterile flies are then shipped to California in their pupae stage in two-foot-long plastic cylinders.

During the current infestations, the sterile pupae are being stored in trailers at Van Nuys Airport for four days while they incubate and reach maturity. Then they are released from airplanes and trucks over infested neighborhoods. They are dyed red so that agricultural workers checking traps can distinguish the sterile flies from their fertile counterparts.

The latest flies discovered were in Bellflower and Hacienda Heights, prompting officials to increase trapping in the neighborhoods. But no aerial pesticide spraying is planned unless additional flies are found, Spaugy said.

“The one in Bellflower is a little more disturbing because it is a little further south” of a current infestation in Whittier, Spaugy said.

So far, 168 fertile Medflies have been found in Los Angeles County since August. About 110 square miles have been sprayed with malathion, and another 12 square miles in the San Fernando Valley are due to be sprayed Monday night.