Medfly Spraying Urged in Upland : Pests: Discovery of a single fruit fly prompts recommendation by state’s science advisers. Find is near a previously infested area.

The state’s panel of scientific advisers in the battle against the Mediterranean fruit fly recommended Monday that a section of Upland in San Bernardino County be sprayed with malathion because of the discovery last week of a single Medfly.

Roy Cunningham, one of five entomologists on the panel, said the unanimous recommendation was forwarded to Henry Voss, director of the state Department of Food and Agriculture. No final decision was announced Monday.

The panel acted on the discovery of an immature Medfly in Upland last Tuesday. The pest was trapped about four miles from where another Medfly had been discovered last September.

The borders of the spraying area will be determined when and if the state decides to order the spraying.

Cunningham said the discovery of a single Medfly does not normally require aerial spraying. But because the pest was found near a previously infested area, a single application of malathion was recommended. It would be followed by the release of sterile fruit flies, which are intended to disrupt the breeding patterns of wild flies.

The proposed enlargement of the spray zone comes as state agriculture officials are preparing to phase out spraying in 350 square miles of Los Angeles and Orange counties that were already infested with the pest. It follows creation last week of a new spray zone around Diamond Bar.

The state plans to stop all spraying in previously infested areas by May 9 and treat the infestation with the release of millions of sterile Medflies. New infestations, such as those in Diamond Bar and Upland, would still be treated with spraying, but only two times at most.

Several members of the state’s Medfly Science Advisory Panel have argued against the May 9 deadline.

Richard Rice, a UC Davis entomologist and member of the science panel, said it is too early to determine if enough sterile flies can be produced to allow the phasing out of aerial spraying. He added that with the warm spring weather, more Medfly outbreaks are certain. Each new infestation will deplete the supplies of sterile flies.

“They (state agriculture officials) are presuming they are going to be getting lots and lots of steriles,” he said. “But we don’t know that until we get them in hand, and it’s going to be a long, hot summer.”

Rice said it takes about 20 million sterile flies a week to treat a small infestation. The state uses about 1 million sterile flies to treat every square mile of infestation.

Isi Siddiqui, assistant director of the state Department of Food and Agriculture in charge of the eradication program, said that, by May, sterile fly breeding facilities in Hawaii should be able to produce enough flies not only to phase out spraying, but also handle several new infestations.