Identifying a model host for Xylella fastidiosa transmission by spittlebugs

One of the factors stalling studies on the transmission biology of Xylella fastidiosa by spittlebugs is the lack of model host plant species for transmission trials. Here, we performed transmission and Electropenetrography (EPG) trials with Philaenus spumarius and X. fastidiosa pauca ST53 on eight candidate model host plant species, namely alfalfa, basil, common amaranth, lavender, periwinkle, rosemary, sunflower, and tobacco. Spittlebugs transmitted the bacterium to alfalfa, periwinkle, rosemary, tobacco and basil, with periwinkle and tobacco showing the highest inoculation rates. In a significant number of alfalfa and basil plants, inoculation was not followed by persistent systemic infection. Tobacco (lowest spittlebugs survival), and basil and sunflower (shortest xylem ingestion), were the least suitable for the spittlebug among the plant species tested. Xylella fastidiosa-positive spittlebugs performed egestion (the inoculation behavior) more frequently than negative individuals, and far later in the probe (ca. 60 min after the first stylets insertion) than previously reported for sharpshooters (ca. 5 min). Overall, periwinkle was the best model host among the ones tested. Besides fundamental research, this plant species could be used for insect vectors infectivity screening in large-scale surveys aimed at determining X. fastidiosa presence in a given area.