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

• Author(s): Hix, Raymond; McGuire, Michael; Puterka, Gary;
• Abstract: The glassy-winged sharpshooter (GWSS) Homalodisca coagulata is native to the southeastern United States (Young 1958) 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. PD has been a problem in California for more than 100 years, but the GWSS is a more effective vector of X. fastidiosa because it can feed on the xylem of seemingly dormant woody stems. Unlike sharpshooters native to California, GWSS can reproduce in grape. 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 2001a). These spots are then scraped off during egg lying. 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 2001a). Many leafhopper species produce brochosomes, but only females are known to produce the rod shaped brochosomes (Rakitov 2000). As reported here in 2001, data from the intercept traps and colored plates clearly indicated that GWSS are attracted to yellow as well as orange. Attraction to these colors was statistically significant (Hix 2001b) and demonstrated that even though the AM type trap may have reliability issues, it is clearly not a blunder trap.
• Publication Date: Dec 2002
• Journal: 2002 Pierce's Disease Research Symposium