Undergraduate Research Journal

Glassy-Winged Sharpshooter Population Survey and Xylella fastidiosa
Detection
Candice A. Sanscartier 1 , Arinder K. Arora 2 , Genet M. Tulgetske 2 , Thomas A. Miller 2
1
Department of Bioengineering
2
Department of Entomology
University of California, Riverside
ABSTRACT
Across the United States from California to Florida and as far north as Virginia, grapevines
are succumbing to Pierce’s Disease (PD) which currently infects more than 30% of grapevines
and is a threat to the $30 billion 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 insect vector is a leafhopper,
Glassy-Winged Sharpshooter (GWSS, Homalodisca vitripennis). GWSSs are able to survive
in mild to scorching temperatures and can feed on the woody stems of plants, making them
an optimal vector of the pathogen. In the summer, GWSS populations explode, creating the
greatest period of X. fastidiosa infection of grapevines. During summer, 2010, we performed a
survey on unsprayed grapevines on the UCR campus to determine patterns of GWSSs visiting
the plants and their infection status. Insects were collected on yellow sticky traps from late
June to late October. All insects were surface sterilized, the DNA was extracted, and real-time
PCR was used to test for presence of X. fastidiosa. GWSS visitation to the plants was highest
in midsummer. From 112 insects collected, 83 were tested for X. fastidiosa and approximately
76% were found to be positive. These results indicate that many of the GWSSs feeding on the
unsprayed grapevines are infected with X. fastidiosa, placing the plants at high risk of infection.
Mentors
Faculty Mentor: Thomas A. Miller (top)
Graduate Student Mentor: Arinder Arora (lower left)
Postdoctoral Mentor: Genet M. Tulgetske (lower right)
Department of Entomology
Candice joined my laboratory as a volunteer shortly after she
took my Freshman Advising Seminar in Fall of 2009. From
the beginning, Candice fit into our lab very well. She learned
quickly from Lab Manager Genet Tulgetske, and soon came to
be reliable and dependable so we hired her part time. After becoming familiar with our projects,
she selected one, Pierce’s Disease of grapevines, and asked if she could work on that on her
own. She monitored the population of the vector insect, Homalodisca vitripennis, a leafhopper,
and provided reports to the granting agency. Now in her third year, Candice received grant
support from the campus’ Undergraduate Research Grants and other scholarships. She is also
mentoring other undergraduates who followed her example. She does PCR analyses for the
presence of the pathogen in the vector insects causing Pierce’s Disease in our research vineyard
at Agricultural Operations. At the 2012 UCR Symposium for Undergraduate Research,
Scholarship, and Creative Activity, a grape and wine industry representative praised her poster
as work that was critically important to the industry. Candice caught the research “bug” early on
and is planning to attend graduate school. As a junior, she already acts and talks like a graduate
student and now, is publishing. She has a very bright future.
A U T H O R
Candice A. Sanscartier
Bioengineering
Candice Sanscartier is a junior
majoring in Bioengineering. She is an
active member and upcoming officer
of the Biomedical Engineering Society.
Candice joined Dr. Miller’s entomology
lab as a freshman majoring in
Biology. She changed her major to
Bioengineering, although continued
to work in Dr. Miller’s lab. During
her freshman year, she worked under
the mentorship of graduate student,
Arinder Arora, investigating symbiotic
control of Pierce’s Disease, caused by
the bacterium, Xylella fastidiosa. She
then initiated her own project using
molecular and field techniques to
survey Glassy-Winged Sharpshooter
population patterns and infection
rates in local Southern California
grapevines. Candice was awarded two
UCR Undergraduate Research Grants
to support her research and presented
her results at multiple symposia and
conferences. Candice thanks her
mentors, Dr. Miller, Arinder Arora, and
Dr. Genet Tulgetske for their guidance
and encouragement.
U C R U n d e r g r a d u a t e R e s e a r c h J o u r n a l 3 1