Scientists Release Wasps to Fight Grapevine Pest

RIVERSIDE —  Scientists this week began releasing tiny wasps that they hope will stop a pest threatening California’s $33-billion wine industry.

Three hundred egg wasps were released in orange groves in Riverside County. In the wild, the young of the tiny, stingerless, Mexican wasp devour the eggs of the glassy-winged sharpshooter.

Sharpshooters, which have infested areas of 11 counties, can carry the bacteria that cause Pierce’s Disease, a grapevine blight.

It has caused $40 million in losses in Riverside County’s Temecula area.

Testing of the wasp began in Temecula and will later include areas of Ventura, Kern, Tulare and Fresno counties, state agriculture officials said.

If the egg wasps prove effective, they will be bred for release throughout the infested areas in a bid to halt the pest’s expansion. Researchers at the University of California, Riverside, are beginning a breeding program that eventually could produce thousands of wasps a day, said Larry Bezark, chairman of the Pierce’s Disease Advisory Task Force in Sacramento. However, university entomologist David Morgan said, that will take months.

“At the moment, we are still in the construction and experimental stages,” Morgan said. “We probably won’t be releasing wasps in big numbers until next year.”

A $30-million-plus eradication program begun earlier this year has included monitoring and ground spraying of pesticide.