Development of Trapping Systems to Trap the Glassy-Winged Sharpshooter Homalodisca Coagulata Adults and Nymphs in Grape

Four trap types in addition to Pherocon AM traps and clones were field tested in 2001 for the ability to catch the glassy-winged sharpshooter Homalodisca coagulata (GWSS). Traps were deployed in citrus groves and grape vineyards with known high populations in addition to groves and vineyards with low populations. Trap types tested included flight intercept traps (5 colors), plates (11 colors), colored discs (12 colors), and nymph traps (3 colors). Traps were checked weekly and visual count of egg masses, nymphs, and adults were made. Trapped GWSS were sexed, and females with forewing spots of brochosomes or residue were noted. The 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 and demonstrated that even though the AM type trap may have reliability issues, it is clearly not a ?blunder trap.? Traps reliability stems from three key issues. First, the glue is not sticky enough on the AM trap (and clones) especially above 90E F. Second, the reflected wavelengths (8) below 500 nanometers are somewhat repellent to GWSS. Finally, dusty conditions can shorten the AM traps effectiveness from two weeks to 1 week or less, and temperatures above increased the probability of escape.

The yellow and orange colored plates with Stickem Special Holdfast formulation were very successful in catching adult GWSS. Yellow plates caught statistically more GWSS than AM traps while orange traps usually caught more than the AM traps. The interesting thing is that the yellow plates were more reliable at catching GWSS at low population levels than the AM traps. The nymph traps reliably caught 1st through 5th instar nymphs in moderate to low populations. These traps are easy to deploy in grape canes in situations where it could take hours of searching to locate nymphs. Low populations of GWSS nymphs in a vineyard may pose threats of moving X. fastidiosa from vine to vine within trellises. Flourescent yellow and canary yellow intercept traps attracted large numbers but the collection mechanism only caught about 15%of the bugs that encountered the panels, which made the traps unreliable. However, intercept traps were capable of catching live insects and may have utility when a better capture devise is incorporated.
Additional progress was made in determining that adult and nymphs are attracted to upper UV, and certain wavelengths in the yellow and orange ranges. The preliminary data indicated relationships between the number of ovipositional females trapped and oviposition in associated vegetation.

Female GWSS secrete and deposit brochosomes on the forewings just prior to oviposition. These spots are then scraped off during oviposition. 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 suggesting they are looking for a place to lay eggs.

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