Mexfly Eradication Appears a Success

Although less costly and time-consuming than the battle against the Mediterranean fruit fly, the eradication campaign against the Mexican fruit fly in Southern California is quietly achieving the same apparent success, agriculture officials said Thursday.

With the final batch of sterile Mexflies being released in El Cajon today and in Compton soon after, and the quarantine of citrus set to expire next month, officials are optimistic that the Mexfly has been driven from the San Diego and Los Angeles areas.

The odds are extremely slim that the tenacious citrus pest survived three doses of aerial malathion sprayings and the reproductive obstacle course of finding a fertile mate among the 360 million sterile flies released this summer, said Bill Routhier, San Diego area manager for the California Department of Food and Agriculture.

“Everything is running perfectly, right on track,” Routhier said. “We are very optimistic.”

The long-term forecast on the chances of reinfestation, however, is not as rosy, with federal funding likely to be slashed for fighting the Mexfly along the U.S.-Mexican border, where a sterile-fly “buffer zone” exists, and in Baja California, where U.S. and Mexican authorities are trying to squash the citrus-destroying insect.

“It is ironic that we spend all this money on fighting the problem after it occurs and not more on prevention, which is always cheaper,” Routhier said. “It is like fighting fires instead of preventing them.”

While some entomologists believe the Medfly is established in Southern California--the latest infestation was spread through Los Angeles and Orange counties--the Mexfly is not thought to have established itself on this side of the border, said John Worley, a member of the Mexfly Science Advisory Panel.

Worley, also director of the Mexican Fruit Fly Rearing Facility in Mission, Tex., the supplier of sterile flies for eradication programs, said the Mexfly eradication program was bolstered by a plentiful supply of high-quality sterile flies.

Whatever the odds of the Mexfly returning to the Southland, another infestation could lead to more malathion applications by helicopter--and trigger renewed public outcry against possible health hazards from the controversial pesticide.

“We have continued to oppose malathion sprayings and we will keep fighting,” said Sharon Taylor, pesticide reduction director for the Environmental Health Coalition, which was among the several environmental and public-interest organizations that organized opposition to the state sprayings this summer.

Calling the sprayings “human experimentation,” Taylor said her group will continue to push for the release of public health studies on the effects of malathion on humans, as well as advocate pending legislation before Congress to ban aerial applications of the pesticide.

No wild Mexflies, pupae, larvae or eggs have been found in El Cajon since May 5, when two egg-bearing females were trapped near the site where a male fly was discovered April 25, said Jose Aguiar, a Food and Agriculture inspector.

In Compton, one wild fly has been trapped, on July 23, since an infestation was declared there this spring.

Compton’s final release of sterile flies is scheduled for Sept. 21, making a total of 360 million sterile flies that will have been unleashed over the 16-square-mile infested zones in that city and in El Cajon since late June.

The sterile flies are supposed to numerically overwhelm their wild brethren and mate them out of existence.

The quarantines--affecting 73 square miles in El Cajon and 81 square miles in Compton--will be maintained until mid-October, when officials with the state agriculture department, the San Diego County Department of Agriculture, Weights and Measures and the U.S. Department of Agriculture are expected to conclude the eradication project.

Agriculture inspectors who have been checking fruit sold at wholesale, retail and other markets, as well as fruit trees at nurseries, have found only a few minor violations, Aguiar said.

The quarantine, which requires citrus growers and sellers to take extra precautions to protect their fruit from the flies, has been an inconvenience, but county agriculture officials said they have not tallied the cost of those measures.

The Mexfly project cost nearly $600,000 in state and federal funds as of July 31, state agriculture officials said. No current cost estimate was available, but the final figure is expected to exceed several million dollars.