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Title: Exploration for biological control agents in the native range of the glassy-winged sharpshooter.

item Goolsby, John

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 11/5/2005
Publication Date: 12/5/2005
Citation: Goolsby, J., Setamou, M. 2005. Exploration for biological control agents in the native range of the glassy-winged sharpshooter. Proceedings of CDFA Pierce's Disease Control Program Research Symposium, December 5-7, 2005, San Diego, California. p. 318-320.

Interpretive Summary: Homalodisca vitripennis, glassy-winged sharpshooter (GWSS), is native to the southeastern U.S., including Texas, and is an invasive pest in California where it is the primary vector for the lethal bacterial disease in grapes, Xylella fastidiosa, called Pierce’s Disease. A new initiative to study the ecology of GWSS in its native non-crop habitat is underway. Several sites in southeastern Texas have been selected each with stands of native Vitis spp. (grapes). Monthly trapping will be used to determine the phenology of GWSS and other related sharpshooter insects. Several methods including hand collection, egg and nymphal sentinels, sweeping, and baits will be used to assess the diversity of biological control agents at each location. Since previous biological control efforts have focused on egg parasitoids of GWSS, these exploration efforts will emphasize discovery of parasitoids that attack the nymphal (immature) stages of GWSS. The family of flies, Pipunculidae, the big-headed flies, are known to be parasitoids of nymphal sharpshooters and show promise as biological control agents because they are known to cause high levels of mortality to sharpshooters and other leafhoppers in both natural and agricultural settings

Technical Abstract: The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is native to Northeastern Mexico and the Southeastern U.S., and the origin of the invasive California populations is reported to be Texas. Most of the entomological and epidemiological information regarding this pest are derived from its status as a vector of Pierce’s Disease, Xyllela fastidosa, in cultivated hosts. Much less is known about the field ecology and phenology of GWSS and its natural enemies in its native habitat in the Southeastern U.S. Recent surveys in the native range and research on biological control agents has focused on egg parasitoids of GWSS. Gonatocerus spp. egg parasitoids have been collected from the native range of Texas, Florida, and Northeastern Mexico, and released in California where several species are now established. Nymphal parasitoids of H. coagulata are thought to exist, but have not been documented from the native range. Our studies are aimed at finding nymphal parasitoids of GWSS in native range that can be used as biological control agents in California. Parasitoids in the families Dryinidae and Pipunculidae may be the most suitable candidates if they have a sufficiently narrow host range to warrant release in California. In addition, the nymphal parasitoids must be able to cope with the lack of immature hosts during the winter when only adults are available. Many species of Pipunculidae are known to over winter as pupae which may make them pre-adapted to California agroecosystem.