State wipes out Medflies

Those sterile male flies have done it again -- they’ve helped state agriculture officials overcome a persistent pest.

The California Department of Food and Agriculture declared victory Thursday over Mediterranean fruit fly infestations in three counties: Los Angeles, Santa Clara and Solano. That means there are no remaining Medfly infestations in the state, the agency said.

The Los Angeles County quarantine is no longer being enforced and is expected to be formally lifted within days, once paperwork is completed. Quarantines in Santa Clara and Solano counties already have been lifted.

The Mediterranean fruit fly is one of many pests that threaten agriculture and residential gardens in California. As travel and commerce increase worldwide, the variety of pests breaching the U.S. border is on the rise.

State and farm officials, for example, are now concerned about the Asian citrus psyllid, a tiny insect that can carry a disease that kills citrus trees. It has been discovered just blocks south of the border in Tijuana, sending shock waves through the California citrus industry.

The disease, known as citrus greening, has already killed tens of thousands of acres of orange groves in Florida and has the potential to ruin much of California’s $1.2-billion-a-year citrus-growing business.

State officials say the Mediterranean fruit fly can infest more than 260 types of fruits and vegetables. It lays eggs in the produce, rendering it inedible.

California has put more than $500 million and tons of insecticides into eradicating exotic fruit flies during the last four decades, according to state and federal officials.

“The Medfly is a pest that poses a serious threat to California agriculture,” said state Secretary of Food and Agriculture A.G. Kawamura. “I would like to thank the residents and growers who helped us eradicate these infestations by cooperating with the three quarantines.”

The most recent quarantines were put into place in 2007. The Los Angeles County quarantine covered 103 square miles in the Rolling Hills/Rancho Palos Verdes area.

In all three affected counties, state and federal agriculture officials took a biological approach to eradicating the pest: They released sterile male Medflies in the area. Females mate with sterile males but don’t produce any offspring and the insects die out, ending the infestation.

The California Department of Food and Agriculture and the U.S. Department of Agriculture have relied on the release of sterile Medflies almost exclusively since 1996.

In the early 1980s, then-Gov. Jerry Brown endured harsh public criticism over the aerial spraying of the chemical pesticide malathion over parts of the Bay Area to eradicate the state’s first Medfly infestation.

Los Angeles County battled the pest in the late 1980s and early ‘90s, becoming something of a Medfly hot spot.

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jerry.hirsch@latimes.com