Transmission of Xylella fastidiosa subsp. pauca ST53 by the sharpshooter Cicadella viridis from different source plants and artificial diets
The sharpshooter Cicadella viridis L. (Hemiptera: Cicadellidae) is the most common sharpshooter in Europe and, given its xylem feeding behaviour, is considered a potential vector of the plant pathogenic bacterium Xylella fastidiosa Wells et al. (Xanthomonadales: Xanthomonadaceae). We tested X. fastidiosa subsp. pauca ST53 (Xfp) transmission capabilities of C. viridis adults, namely i) acquisition efficiency from four host plant species - periwinkle, milkwort, lavender, alfalfa - and from two artificial diets (PD3 and Xfm), ii) inoculation efficiency to periwinkle at different times post acquisition from different plant and artificial diet sources. The main European vector species - Philaenus spumarius - was used as a control. Cicadella viridis was able to acquire Xfp from 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. viridis is 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 sums also to ecological constraints (mainly monocots host plants, humid environments) that make 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 Xf in other agroecosystems, e.g. vineyard and stone fruits grown in humid areas, cannot be excluded.