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; Pryor, Murry; 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. Averaging data across all sampling sites and collection dates, grape, citrus, apple, Xylosma, cherry and flowering pear were the most preferred ovipositional sites. GWSS nymphs were most often collected on oleander, flowering pear, Xylosma, crabapple, Abelia, and crape myrtle. Adults were most often collected on oleander, Xylosma, pyracanthum, crape myrtle, and crabapple. Over the 3 year period, population patterns were clearly evident: new egg masses were first found in mid-March, followed by a strong April-May oviposition period, the resulting nymph and adult GWSS populations follow in sequence. A summer decline in GWSS density was primarily the result of high egg parasitism during the second oviposition period. Throughout the field survey, we sampled resident GWSS predators and parasitoids. Emerged parasitoids were primarily Gonatocerus ashmeadi. Predators were primarily spiders and the Argentine ant. In 2004-05, we manipulated combinations of GWSS host plant species, to investigate year-long GWSS survival and age structure. Treatments were: citrus, euonymus, grape, oleander, crape myrtle, citrus and grape, and oleander and crape myrtle. Only in the combination of citrus and grape was there an increase in GWSS density. During the urban surveys, we also collected plant material (e.g., potential vector host plants) and potential insect vectors to determine the incidence of Xylella fastidiosa (Xf). This material was processed in the laboratory using immunocapture DNA extraction to determine the presence of Xf. Results showed that GWSS collected in urban regions often (10%) carried Xf, however, it was not the strain that causes Pierces disease.
• Publication Date: Dec 2005
• Journal: 2005 Pierce's Disease Research Symposium