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United States Department of Agriculture

Agricultural Research Service

Title: Where, When and How Do Ingestion and Other Feeding Behaviors of the Glassy-Winged Sharpshooter Allow Inoculation of Xylella Fastidiosa?

Authors
item Backus, Elaine
item Joost, P - UNIV OF CALIF-RIVERSIDE
item Shugart, Holly

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: October 6, 2005
Publication Date: December 5, 2005
Citation: Backus, E.A., Joost, P.H., Shugart, H. 2005. Where, when and how do ingestion and other feeding behaviors of the glassy-winged sharpshooter allow inoculation of xylella fastidiosa? Proceedings of the 2005 Pierce's Disease Research Symposium. p.85-88.

Interpretive Summary: Many nagging questions about the mechanisms of transmission of Xylella fastidious (Xf) by glassy-winged sharpshooter (GWSS) exist, hindering development of predictive epidemiological models for ultimate GWSS impact on California crops, as well as rapid development of resistant crops. Efforts this year focused on developing research infrastructure, such as simultaneous availability of plants, insects and bacteria, and protocols for the experiments. All protocols for electrical penetration graph (EPG)-monitoring of identified probes, including artificial termination of probes, marking of probe locations, and recovery of tissues and processing for CLSM, have been perfected. In addition, a protocol for observing GFP-Xf as it exits stylets has been developed, wherein a wired GWSS that has acquired GFP-Xf is monitored while probing transparent artificial diet. Views of its stylets and salivary sheath are simultaneously video-captured and synchronized with EPG waveforms.

Technical Abstract: Many nagging questions about the mechanisms of transmission of Xylella fastidious (Xf) by glassy-winged sharpshooter (GWSS) exist, hindering development of predictive epidemiological models for ultimate GWSS impact on California crops, as well as rapid development of resistant crops. This new grant seeks to complete our answer to these questions. Only five months of funding from this grant was available to Backus this year, due to bureaucratic hurdles. Nonetheless, we were able to accomplish significant work with support from Backus’s in-house ARS funds. Efforts focused on developing research infrastructure, such as simultaneous availability of plants, insects and bacteria, and protocols for the experiments. We now receive monthly shipments of adult GWSS, housed in a CDFA-approved quarantine facility at CSU Fresno, fed on greenhouse-reared cowpea, sorghum and grape. We also maintain green fluorescent protein (GFP)-transformed Xf in colony and are mechanically inoculating it into grape (cv. ‘Cabernet Sauvignon’) on a regular basis. GWSS are caged on these acquisition plants for 6-8 days, and are assayed for presence and location of bacteria using protocols we developed for confocal laser scanning microscopy (CLSM). All protocols for electrical penetration graph (EPG)-monitoring of identified probes, including artificial termination of probes, marking of probe locations, and recovery of tissues and processing for CLSM, have been perfected. In addition, a protocol for observing GFP-Xf as it exits stylets has been developed, wherein a wired GWSS that has acquired GFP-Xf is monitored while probing transparent artificial diet. Views of its stylets and salivary sheath are simultaneously video-captured and synchronized with EPG waveforms. Preliminary results show that GFP-Xf is present and visually resolvable following injection by the stylets into artificial diet, but synchronization between video and EPG recording of behavior was not perfect in these earliest tests. The experiment to determine the time course of inoculation and movement of GFP-Xf from the site of injection is about to begin.

Last Modified: 12/22/2014
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