Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2012
Publication Date: August 1, 2012
Citation: Backus, E.A., Krugner, R. 2012. Effects of plant water stress on vector feeding behaviors that control acquisition and inoculation of Xylella fastidiosa. Phytopathology. 102(S4):8. Technical Abstract: Xylella fastidiosa (Xf) is an economically important pathogen of grapevine (Pierce’s disease), stone fruits, nursery trees, and ornamental plants (various scorch diseases) in California. The bacterium is transmitted by sharpshooter leafhopper vectors, such as the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar). Vector feeding behaviors directly control Xf acquisition and inoculation. The present study tested whether plant water stress affects vector performance of acquisition and/or inoculation behaviors. Feeding behaviors on well-watered vs. water-stressed plants were recorded using electrical penetration graph (EPG); plants studied were almond, Prunus dulcis, and citrus, Citrus sinensis cv ‘Navel.’ EPG waveforms representing pathway phase (searching for xylem), X waves (xylem contact, likely to control Xf inoculation), and waveform C (ingestion of xylem fluid, Xf acquisition) were analyzed. Results showed that xylem-sap ingestion per insect as longer on well-watered than water-stressed plants. Numbers of X waves per insect also were higher when plants were well-watered. Thus, both acquisition and inoculation behaviors were decreased on water-stressed plants. These findings support other studies suggesting that diminished irrigation can impact Pierce’s disease epidemiology by reducing bacterial acquisition and/or inoculation by the vector.