The CDFA Pierce’s Disease Control Program uses biological control as one of its methods for reducing the spread and damage caused by the glassy-winged sharpshooter (GWSS). Biological control involves using living organisms such as predators, parasitoids, and pathogens to reduce the populations of a target pest. In the case of GWSS, the biological control agents are tiny wasps which feed on and destroy the eggs of GWSS. The PDCP has collected and evaluated several different species of wasps from the USA and Mexico to find species which show promise for controlling GWSS in California. Of these, four closely-related species are currently being reared and released by the Program. The wasps are reared in the PDCP insectary located in Arvin and are then released at selected locations. Over the life of the program, more than 2.3 million biocontrol agents have been released at 67 sites in 11 counties.
In addition to being used for biological control purposes, some of the GWSS and wasps collected and reared by the Biocontrol Unit have been provided to scientists for use in research projects. One project involves developing lab analytical methods for identifying which types of wasps parasitized and killed GWSS egg masses. This technology will make it easier to evaluate the effectiveness of the different wasp species being released and help focus efforts on those biocontrol agents which are most effective in the field.