Bois noir is a disease of the grapevine yellows complex. It is associated with ‘Candidatus Phytoplasma solani’, an obligate pathogenic bacterium transmitted to grapevine by Hyalesthes obsoletus and Reptalus panzeri, polyphagous insect vectors living mainly on broadleaf weeds. The occurrence of bois noir in vine-growing areas where the population density of these vectors is low implies the existence of alternative vectors. In this study, conducted in Franciacorta (North Italy), eight new insect vectors of ‘Ca. P. solani’ to grapevine have been identified by vineyard surveys, transmission trials in controlled conditions, and molecular analyses. Interestingly, the new vectors Euscelis incisus and Dicranotropis hamata live preferentially on grassy weeds (Figure). These findings highlight that bois noir epidemiology in vineyard agro-ecosystems is more complex than previously known, opening up new perspectives in the disease management.
Figure: Euscelis incisus (a) and Dicranotropis hamata (b), two new insect vectors living preferentially on grassy weed.
Quaglino F., Sanna F., Moussa A., Faccincani M., Passera A., Casati P., Bianco P.A., Mori N. (2019) Identification and ecology of alternative insect vectors of ‘Candidatus Phytoplasma solani’ to grapevine. Scientific Reports 9, 19522.