Mediterranean fruit fly infestations in the Escondido and Fallbrook areas of San Diego County, Calif., have been eradicated, ending quarantines that began in late 2009.

The eradication of the infestations means San Diego County is now free from Mediterranean fruit fly infestations.

“Fruit flies are dangerous pests for California farming and backyard gardens,” said A.G. Kawamura, secretary of the California Department of Food and Agriculture (CDFA). “I would like to thank the residents of San Diego County who helped us eradicate these infestations by cooperating with the quarantines.”

To eradicate the pest, agricultural officials employed weekly aerial releases of approximately 2.5 million sterile medflies over the core of each quarantine area. Fertile female flies in the environment mate with the sterile male flies but produce no offspring, ultimately resulting in eradication of the pest.

The sterile medflies came from the joint CDFA-U.S. Department of Agriculture rearing facility in Los Alamitos, which prepared hundreds of millions of sterile flies weekly for release over the Los Angeles Basin. The pest has been introduced repeatedly by international travelers who bring infested produce with them.

In the Escondido area, the 77-square-mile quarantine was declared after the detection of a mated female medfly in a local trap in September 2009. The quarantine was lifted on Aug. 13.

In Fallbrook, the 79-square-mile quarantine was declared after the detection of three medflies in local traps in October and November 2009. The quarantine was lifted on July 30.

The Mediterranean fruit fly threatens agriculture plus residential gardens in California. As travel and commerce increase worldwide, the variety and frequency of pests breaching California’s border are also on the rise.

The pest can infest over 260 types of fruits and vegetables threatening California’s crops and exports plus urban and suburban landscaping and gardens.

A permanent infestation could result in estimated annual losses of $1.3 billion to $1.8 billion.