Cooperator:

On California’s North Coast, plant species in natural habitats adjacent to vineyards, namely riparian areas, are non-crop hosts of Xylella fastidiosa (Xf). The importance of a riparian host as a pathogen reservoir is related to its ability to support pathogen populations and its attractiveness to the vector, Graphocephala atropunctata (blue-green sharpshooter [BGSS]). We quantified BGSSs on five species (California blackberry, California grapevine, elderberry, Himalayan blackberry, periwinkle) of naturally-established plants adjacent to vineyards. We assessed the ability of the same species to support Xf, using controlled inoculations of potted plants kept in screenhouses in the field. No species were characterized by both an abundance of BGSSs and a high frequency of Xf detection. A 71 % frequency of Xf detection in periwinkle suggests that, regardless of having the fewest BGSS (0.4 nymphs and 0.9 adults per sample), infrequent visitations may result in a high acquisition rate. California grapevine supported eight times as many nymphs and three times as many adults as periwinkle, suggesting that frequent visitations may offset its significantly lower infection rate (19%). California blackberry, elderberry, and Himalayan blackberry are likely less important pathogen reservoir because Xf was infrequently detected in their tissues and they hosted few BGSSs