DEVELOPMENT OF TRAPPING SYSTEMS TO TRAP THE GLASSY-WINGED SHARPSHOOTER HOMALODISCA COAGULATA ADULTS AND NYMPHS IN GRAPE (AVF V107)

• Author(s): Hix, Raymond; McGuire, Michael; Puterka, Gary;
• Abstract: The glassy-winged sharpshooter (GWSS) Homalodisca coagulata is native to the southeastern United States where it is a known vector of various strains of the bacterium Xylella fastidiosa. Since its introduction into California, it has become established in large numbers in certain areas. Pierces disease has been a problem in California for more than 100 years, but the GWSS is a more efficient vector of X. fastidiosa because it is a stronger flier than native California sharpshooters, and it can feed on the xylem of seemingly dormant woody stems. The wine industry in Temecula, CA has been seriously impacted by Pierces disease (PD) losing about 30% of its vineyards to date. The combination of PD and GWSS in California poses a serious threat to the grape industries. About 98,000 acres of table grapes are currently cultivated in California with 14,000 acres of table grapes in the Coachella Valley (Riverside County). The Coachella Valley has a history of PD and there is currently a high population of glassy-winged sharpshooters. The combination of the bacterium and new vector creates a serious disease threat to grape in the area. A similar situation has occurred in Kern County, California as well. One of the crucial components and cornerstones of integrated pest management is the monitoring for the presence and density of a pest. Proper detection methods allow for optimum integration of biological, cultural, physical, chemical and regulatory measures to manage a pest. Yellow sticky traps have been used extensively in the southeastern U.S. for monitoring leafhoppers including GWSS in peach (Ball, 1979) and citrus (Timmer et al., 1982). However, the reliability of these methods to detect the GWSS in California is questionable, and traps specifically designed for GWSS do not currently exist. To compound the situation, current methods are not standardized. For example, different sizes and shades of yellow sticky traps are being used in monitoring programs. The AM designation on certain traps actually refers to the apple maggot for which the trap was designed. Furthermore, the relationship of trap catches to actual populations of GWSS in grape or citrus are currently unknown. Trap designs based on the behavior and biology of the insect in question have a much higher chance of success than relying on trial and error of traps designed to monitor other insects. Female GWSS secrete and deposit brochosomes on the forewings just prior to egg laying (Hix, 2001). These spots are then scraped off during egg laying. Furthermore, white spots are secreted before each egg mass is laid, and female GWSS can only produce rod shaped brochosomes after mating. It is therefore feasible to relate preovipositional females with white spots and residues to egg masses in associated vegetation analysis. The white spots are very visible on females caught in traps (Hix, 2001). Many leafhopper species produce brochosomes, but only females are known to produce the rod shaped brochosomes.
• Publication Date: Dec 2001
• Journal: 2001 Pierce's Disease Research Symposium