|Van De Veire, Jacqueline - Jackie|
|PERRING, THOMAS - University Of California|
Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/10/2020
Publication Date: 4/28/2020
Citation: Backus, E.A., Cervantes, F.A., Van De Veire, J.A., Burbank, L.P., Perring, T. 2020. Sharpshooter feeding behaviors controlling Xylella fastidiosa inoculation are represented by the EPG X Wave. Entomological Society of America Annual Meeting. Available: https://esa.confex.com/esa/2020intl/meetingapp.cgi/Search/0?sort=Relevance&size=10&page=1&searchterm=Backus
Technical Abstract: Xylella fastidiosa (Xf) is a plant bacterium that causes lethal scorch diseases in crops such as grape, olive, citrus, and ornamentals. The mechanism of Xf inoculation by sharpshooter leafhoppers has been hypothesized to be due to egestion (ejection) of bacteria from colonization sites in the functional foregut into grape xylem cells during feeding. Electropenetrography (EPG) can be used to observe these vector behaviors in real time because the sharpshooter X wave represents combined salivation and egestion. This report provides preliminary data supporting that the X wave also represents Xf inoculation into grape. Clean blue-green sharpshooters were allowed to feed on artificial diets containing ~107 Xf cfu for 2.5 to 7 hours. Each insect was then allowed to make a single, EPG-recorded stylet probe into a small grapevine petiole. Two treatments were used: 1) feeding was interrupted before a mature xylem vessel was reached and the X wave was performed, and 2) the insect was allowed to reach a mature xylem cell and perform two to four X waves. qPCR was used to detect bacteria in the treated plants. Bacteria were detected in 19 (28%) of the 67 insect-probed plants, with 95% of those positive plants from the X wave treatment. Thus, results to date support that the X wave represents Xf inoculation behaviors, and that a single stylet probe can initiate a qPCR-positive, systemic, symptomatic Pierce’s disease infection. If future tests continue to support the hypothesis, then EPG can be used to identify grapevine resistance to vector inoculation behaviors.