Transmission of Xylella fastidiosasubsp. pauca ST53 by the Sharpshooter Cicadella viridisFrom Different Source Plants and Artificial Diets

The sharpshooter Cicadella viridisL. (Hemiptera: Cicadellidae) is the most common sharpshooter in Europe and, given its xylem feeding behavior, is considered a potential vector of the plant pathogenic bacterium Xylella fastidiosaWells et al. (Xanthomonadales: Xanthomonadaceae). We tested X. fastidiosasubsp. pauca ST53 (Xfp) transmission capabilities of C. viridisadults, namely 1) acquisition efficiency from four host plant species—periwinkle, milkwort, lavender, alfalfa—and from two artificial diets (PD3 and Xfm), 2) inoculation efficiency to periwinkle at different times post acquisition from different plant and artificial diet sources. The main European vector species—Philaenus spumariusL. (Hemiptera: Aphrophoridae)—was used as a control. C. viridiswas able to acquire Xfpfrom periwinkle, milkwort, and lavender, although with low efficiency (3–16%) and from artificial diets (23–25%). Successful inoculation on periwinkle was extremely rare, being observed only three times, following feeding on milkwort plant and PD3 artificial diet sources. Our study shows that C. viridisis not a relevant vector of Xfp, given the very low transmission rate in controlled conditions, and the inability to feed on olive. The low efficiency reported here correlates with ecological constraints of the vector (mainly monocots host plants, humid environments) that make it difficult to forecast a relevant role in dispersing X. fastidiosa, at least within the present distribution of the exotic bacterium in Europe. However, a possible role of this species in spreading Xfin other agroecosystems, e.g., vineyard and stone fruits grown in humid areas, cannot be excluded.