Medfly May Have Gained Hold in 1988 : Agriculture: UC science panel finds state failed to eradicate West Los Angeles outbreak. Possibility of earlier origins still under study.

The current Medfly infestation in Southern California probably originated with a small West Los Angeles outbreak that agriculture officials failed to eradicate in 1988, a scientific panel reported Wednesday.

The group of eight scientists, convened by the University of California to investigate Southern California’s infestation, said the Medfly boom this year even may be linked to a single fly found in the same West Los Angeles neighborhood in 1987. Agriculture officials implemented no eradication efforts after that find.

The scientists said the apparent failure to destroy the last vestiges of the Medfly in 1987 or 1988 allowed the pest to spread and multiply over hundreds of square miles in Southern California.

UC Berkeley entomologist Robert A. Van Steenwyk, the panel’s chairman, said his group could not decide if the current infestation traces its origin even further back.

But he said the group expects to continue its work and, with the help of genetic analysis, may be able to resolve the controversial theory that the current infestation is actually an outgrowth of a Medfly infestation in 1975 or outbreaks in the early 1980s.

“This initial report is what we feel comfortable with,” Van Steenwyk said. “But this is not the end.”

The UC task force was formed in early March to resolve a furious dispute between state eradication officials and UC Davis entomologist James R. Carey, one of five scientists serving on the state’s Medfly Science Advisory Panel.

Carey proposed in March that the Medfly outbreaks in Southern California were not isolated introductions of the pest as the state maintained, but connected infestations that possibly stretched back to the 1975 outbreak.

Carey claimed that the repeated trapping of Medflies in the same neighborhoods over the last 15 years suggested that past eradication efforts have not worked and that small colonies of Medflies have been able to breed undetected because of the state’s porous fly trapping network.

State officials maintained that each infestation was an isolated outbreak caused by immigrants or travelers who illegally brought infested fruit into the state. They argued that the Medfly breeds so quickly that even a tiny population could not escape discovery for long.

Van Steenwyk said the UC report does not resolve the dispute, but does support parts of both views.

Carey said the report “affirms my theory that these Medflies are not being eradicated. They’ve linked two or three years. That’s a start.”

Roy Cunningham, a U.S. Department of Agriculture entomologist and chairman of the state’s Medfly Science Advisory Panel, said he was satisfied with much of the report’s conclusions, saying it backed up the state’s contention that the current infestation did not originate in 1975 or the early 1980s.

As part of the report, the UC panel also came up with a series of recommendations to improve the state’s eradication program, including increasing research on Medfly breeding habits, fly-trapping efficiency and genetic analysis, which could be used to determine the origin of individual Medflies.

The panel also recommended the creation of an independent committee to improve the use of sterile flies to eradicate the Medfly.