Relationships between , Its Herbaceous Hosts and Bois Noir Epidemiology in Northern Italian Vineyards.

is the vector of " Phytoplasma (. P.) solani," the causal agent of grapevine yellows Bois noir (BN). The relationships among the planthopper, its main herbaceous hosts as phytoplasma reservoirs ( and ) and BN spreading were studied in northern Italy. In two areas the relationship between host plants and the phenology and survival of planthopper adults was investigated in potted plants and in field conditions. Moreover, ecology, newly symptomatic grapevine occurrence and ". P. solani" -types' presence were studied in two vineyards (2014-2019). An earlier occurrence of adults on than and better adult survival of the originating host were observed. When was prevalent, the vector occurred almost exclusively along the ditch outside the vineyard. amount varied widely from year to year and nymphal mortality due to late frosts was supposed. In one vineyard, the amount of newly symptomatic grapevines was significantly correlated with vector abundance in the previous year. The ". P. solani" -type was influenced by vector population levels on the two hosts. Since the abundance of populations on the two hosts influences BN epidemiology and dynamics and the ". P. solani" -type, this must be considered in BN control strategies.