Submitted to: Australian and New Zealand Entomological Societies Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/6/2017
Publication Date: 9/17/2017
Citation: Burbank, L.P., Sisterson, M.S., Krugner, R., Stenger, D.C. 2017. Detection and typing of Xylella fastidiosa from glassy-winged sharpshooter for Pierce’s disease epidemiology. Presented at Australian and New Zealand Entomological Societies Conference, Sept 17-20, 2017, Terrigal, Australia
Technical Abstract: Epidemiology of Pierce’s disease of grape, caused by the bacterial pathogen Xylella fastidiosa (Xf), is largely dependent on populations of insect vectors such as the invasive glassy-winged sharpshooter (GWSS) (Homalodisca vitripennis). In the grape-growing regions of the southern San Joaquin Valley of California, disease and vector control are complicated by the presence of other crops such as citrus which can serve as alternate feeding hosts for GWSS. To determine the time of year that GWSS are most likely to spread Xf in vineyards, and to improve the efficacy of area-wide pest control programs, surveys were conducted to identify number and location of Xf-positive GWSS in vineyards and citrus orchards throughout the growing season. Xf was detected in GWSS heads using TaqMan probe-based quantitative PCR (qPCR). Xf-positive GWSS were most prevalent in vineyards during late summer when the pathogen was readily detectable in grapevine, but were found in citrus throughout the winter when grapevines are dormant. As multiple Xf strains with different host ranges are endemic to the San Joaquin Valley, sequence typing was conducted using Xf genes amplified directly from GWSS heads which had tested positive for Xf by qPCR. The dominant Xf genotype identified in the GWSS samples matched the genotype of strains isolated from grapevines systemically infected with Xf in the vineyards studied. This suggests that TaqMan qPCR methods can be used to efficiently evaluate localized pathogen presence and seasonal dynamics from field-collected insects.