|Joost, P - UNV OF CA-RIVERSIDE,CA|
Submitted to: International Auchenorrhyncha Congress
Publication Type: Proceedings
Publication Acceptance Date: June 15, 2005
Publication Date: August 7, 2005
Citation: Backus, E.A., Joost, P.H. 2005. Specific stylet activities by sharpshooters are involved in inoculation of xylella fastidiosa. Proceedings of the 12th. International Auchenorrhyncha Congress. p.P-1 Interpretive Summary: Our work seeks to understand how the feeding of the glassy-winged sharpshooter (GWSS) controls transmission of Xylella fastidiosa, the bacterium that causes Pierce's Disease in grape. One of the main methods we used is electrical penetration graph (EPG) monitoring of insect feeding, a technology similar to electrocardiography. This year's work correlated different waveforms with minute movements of the insect's mouth parts in the plant, and identified two waveforms that are likely involved in X. fastidiosa inoculation. This work will eventually allow us to determine how much and what types of feeding by a sharpshooter on a healthy grape will lead to infection of the plant. This, in turn, will help other scientists assess the risk of spread of the pathogen, and eventually aid in development of new control methods.
Technical Abstract: Our work seeks to understand the stylet penetration behaviors of the glassy-winged sharpshooter (GWSS), and how they interact with Xylella fastidiosa (Xf) to facilitate transmission to grapevine. We use videotaping of feeding on transparent diets, combined with electrical penetration graph [EPG] monitoring to identify most details of feeding. Previous studies in the Backus lab found that the B1, C and N waveforms are associated with inoculation of Xf into susceptible grape plants. This year's work showed that A1 represents the primary formation of the salivary sheath, B1 represents sheath salivation, stylet tip fluttering and probably tasting and B2 represents stylet sawing through the hardened sheath or tough plant material. It is particularly interesting that the B1spikelet burst is dispersed intermittently throughout other pathway waveforms, e.g. between peaks of A1, as well as in continuous durations by itself. This dispersion, plus last year's research finding that B1 was the only pathway waveform associated with Xf inoculation, suggest that the spikelet bursts might represent precibarial valve movement, an important component of a hypothesized inoculation behavior for Xf.