Medfly Found in San Bernardino County, Santa Teresa Area

CDFA has established a 72-square mile quarantine zone. Compiled by staff

Published on: Oct 17, 2005

The California Department of Food and Agriculture has established a 72-square mile quarantine zone in San Bernardino County, in the Rancho Cucamonga area, following the detection of a Mediterranean fruit fly infestation.

To date, four wild Medflies and larvae have been detected in the area. This is the first Medfly infestation in San Bernardino County since 1993.

In addition to Rancho Cucamonga, the quarantine area includes portions of Ontario, Upland and Montclair. Ontario International Airport is within the quarantine boundary. In addition, the California Department of Food and Agriculture is scheduled to begin aerially releasing sterile Mediterranean fruit flies in a 10-square mile region of San Jose, following the detection of two Medflies in the Santa Teresa area.

The sterile Medflies will be brought in from the joint CDFA/USDA rearing facility in Los Alamitos, which prepares hundreds of millions of sterile flies weekly for release over the Los Angeles Basin. For the San Jose project, 2.5 million sterile Medflies will be released weekly. The flies, sterile males, have a proven track record in Southern California of breeding with wild females to help achieve eradication.

"This program is a great example of research and science working to benefit the public and the environment," says CDFA Secretary A.G. Kawamura. "It wasn’t very long ago that a Medfly infestation meant spray treatments by helicopter. A lot of Bay Area residents probably remember that. Now we have a solution that relies largely on biological control. It’s a great example of progress offered by integrated pest management principles."

The sterile project, called the Preventive Release Program, was introduced in 1996 and has been instrumental in redefining Medfly response in California. It has also dramatically reduced the number of infestations. Between 1987 and 1994, an average of 7.5 Medfly infestations were discovered each year in California. Since the Preventive Release Program began in 1996, there have been just four infestations. The last Medfly infestation in San Jose was in 1992.

In addition to the sterile releases, CDFA is conducting ground treatments in a 200-meter radius—about one-eighth of a mile—from the locations of the two detections. The substance being utilized is the organic compound Naturalyte (active ingredient: spinosad), a naturally occurring extract from bacteria.

The Medfly can infest over 260 types of fruits and vegetables, causing severe impacts on California agricultural exports and backyard gardens. A permanent infestation would result in estimated annual losses of $1.3 billion to $1.8 billion.

Agricultural shipments from the San Bernardino County quarantine zone will be limited by specific regulations designed to minimize movement of potentially infested commodities. In addition, people moving through the quarantine zone are urged not to remove fruits and vegetables from the area.

An eradication program for the Medfly is already underway, consisting of increased releases of sterile male flies in the San Bernardino County area and ground treatments within a 200-meter radius of the finds, which is approximately one-eighth of a mile.