Biological Control of Glassy-Winged Sharpshooter (GWSS)

PROBLEM: GWSS has spread rapidly in Ventura and Santa Barbara counties threatening citrus, avocado, and grapes.

SIGNIFICANCE: Tree crops are rendered unmarketable by heavy frass. Grapes are killed by Pierce’s disease vectored by GWSS. A variety of efforts, including genetically engineered resistant cultivars, parasite mass rearing, etc. are being heavily funded. However, the potential to leverage the effectiveness of the natural or mass–reared sharpshooter enemies by habitat manipulation has received little attention as a potential suppressive technique.

STRATEGY: Continue to observe ecology of GWSS and associated natural enemy complex and potential trap crops, report findings in the community and look for growers willing to participate in a demonstration.

ACCOMPLISHMENTS:

• Confirmed the potential role of natural enemies in GWSS suppression:
• Observed 95%+ rates of parasitism in some Ventura County orchards.
• Observed nearly universal association between green lacewing and GWSS, including voracious feeding by lacewing larvae on egg masses.
• Confirmed potential for certain plant species to differentially attract the pest.
• Observed potential trap crops including non–egg–laying aggregations on fennel and tree tobacco.
• Observed strong preference for corn as an egg–laying site.