D3211: Characterizing the transmission efficiency of Xylella fastidiosa by the sharpshooter Draeculacephala robinsoni

The recent report of the North American sharpshooter Draeculacephala robinsoni in southwestern France and northeastern Spain raises concerns about its possible role in the spread of Xylella fastidiosa (Xf). Proactive research on the sharpshooter phenology, ecology, ethology and transmission of the fastidious bacterium is dramatically needed to promptly devise sustainable management strategies. This project aims at characterizing: i) the transmission efficiency of Xf by D. robinsoni using alfalfa and grapevine as model host plants; ii) the vibrational communication of the sharpshooter, with the goal of developing semiophysicals for behavioral disruption tackling mating and insect-plant interaction. Transmission efficiency of Xf subspecies fastidiosa (ST1) is determined through transmission tests with groups of individuals using different source/recipient plant combinations (alfalfa–alfalfa, alfalfa–grapevine, grapevine–alfalfa, grapevine–grapevine). Additionally, vector-strain specificity is investigated through in vitro acquisition trials using artificial diets of two strains belonging to subspecies fastidiosa and multiplex inoculation to alfalfa and subsequent RNA extraction and transcriptomic analysis to evaluate genotype-specific effects on insect gene expression. Intraspecific communication of D. robinsoni through substrate-borne vibrations is investigated through ethological tests across various social contexts (courtship and mating, rivalry, etc.) and vibrations recordings through a laser Doppler vibrometer. Preliminary findings show that the species uses four distinct, context-specific vibrational signals (two produced by males, two and two by females) to facilitate mating. Females do not initiate signaling unless stimulated by male calls, and mating includes duet establishment, localization, and short copulation (3–10 minutes).