BIOLOGY AND ECOLOGY OF THE GLASSY-WINGED SHARPSHOOTER IN THE SAN JOAQUIN VALLEY

• Author(s): Daane, Kent; Johnson, Marshall; Fournier, Valarie; Groves, Russell; Hagler, James; Hashim, Jennifer; Luck, Robert; Purcell, Alexander; Shapland, Elaine; Son, Youngsoo; Yokota, Glenn;
• Abstract: We followed glassy-winged sharpshooter (GWSS) preference and age structure on ornamental host plants in Bakersfield, California. Results of an urban survey showed GWSS host utilization varied greatly. This was especially true during the growing season when the mobile GWSS nymphs and adults would frequently shift amongst abutted host plants. While host plant utilization was dynamic, yet there were clear seasonal patterns. In late-fall through mid-winter, GWSS were most commonly found on privet, oleander, and citrus. In late-winter through spring, the preferred hosts were Xylosma, photinia, and flowering pear. In summer, host utilization was most dynamic and often dependent on host condition (such as irrigation). Nevertheless, GWSS adult and nymph summer and early-fall populations were consistently found on Xylosma, photinia, oleander, star jasmine, and Crape myrtle. Controlled experiments with potted host plants found similar results and highlight differences in GWSS feeding and oviposition preferences. Throughout all studies, we sampled the numbers of predators and parasitoids. Emerged parasitoids show Gonatocerus ashmeadi and G. triguttatus were reared from egg masses collected on most host plants, and accounted for a large percentage of summer GWSS mortality. Predators were present, especially spiders, and often observed feeding on GWSS. However, our data has not yet found any one predator species to be consistently associated with GWSS or with a reduction in GWSS densities. Collected predators are being analyzed using immunologically-based assays that employ pest-specific monoclonal antibodies (MAbs) to help identify the key predators of GWSS. During the urban surveys, we collected plant material (e.g., potential vector host plants) and potential insect vectors to determine the incidence of X. fastidiosa. This material was processed in the laboratory using immunocapture DNA extraction to determine the presence of X. fastidiosa. Results show that GWSS collected in urban regions often (10%) carry Xylella fastidiosa, however, it is not the strain that cause PD.
• Publication Date: Dec 2004
• Journal: 2004 Pierce's Disease Research Symposium