Population Dynamics of the Glassy-Winged Sharpshooter and Xylella fastidiosa Infection Rates in a Multi-year Grape Plot Survey
Authors:Arinder Arora, Matt Daugherty, Candice Sanscartier, Genet Tulgetske
Mentor:Thomas Miller, Professor of Entomology, University of California Riverside
Across the United States, grapevines are succumbing to Pierce’s Disease (PD), which currently infects more than 30% of America’s 30 billion dollar wine industry. PD is caused by the bacterial pathogen, Xylella fastidiosa, which blocks water from flowing through the xylem of plants. Affected grapevines develop leaves that are discolored and dried out, and usually die within 2-5 years. X. fastidiosa is transmitted by xylem feeding insects. The most effective vector is the leafhopper, Glassy Winged Sharpshooter (GWSS). GWSS are most commonly found in mild to scorching temperatures and are able to feed on the woody stems of plants which make it an optimal vector for the pathogen. In the summer, GWSS populations explode, creating the greatest period of infection of grapevines. During the summers of 2010- 2012, we performed surveys on unsprayed grapevines in the Agricultural fields on the UCR campus. During this three year Entomology study, we examined the patterns of GWSS visitations on the plants and their X. fastidiosa infection status. Insects were collected on yellow sticky traps checked weekly during the emergence season of late April to late October. All insects were surface sterilized, the bacterial DNA was extracted, and real time PCR was used to test for X. fastidiosa. Although population visitations vary greatly from year to year, we were able to gather information on the GWSS population dynamics. Like insect visitation, analyses of X. fastidiosa infection frequencies for 2010 and 2011 also show great variation between seasons. The insect collection data for the 2012 season, although still being analyzed, show high population visitation for the GWSS. Further discussion will include additional analysis of infection rates, as well as other factors that influence insect population and bacterial infection patterns, such as gender, plot location and plant genotype.