Prevalence of Flavescence Dorée PhytoplasmaInfected Scaphoideus titanus in Different Vineyard Agroecosystems of Northwestern Italy

Quantitative estimates of vector populations and their infectivity in the wild and in cultivatedcompartments of agroecosystems have been carried out to elucidate the role of the wild compartmentin the epidemiology of Flavescence dorée (FD). Seven sites were selected for the investigations in thePiedmont Region of Italy. They were characterized by a high variety of agricultural and ecologicallandscape features, and included a vineyard surrounded by wild vegetation. In order to describeabundance and prevalence of FD-infected vectors in the cultivated and wild compartments of thevineyard agroecosystem, adults of Scaphoideus titanus were collected by yellow sticky traps inside andoutside the vineyard over the period July 10th-September 9th, 2015. They were counted and singlyanalyzed for the presence of FD phytoplasmas by PCR. Multifactorial correlations among vectorpopulation level, prevalence of infected insects inside and outside the vineyards, disease prevalencein cultivated and wild Vitis plants, and location of wild Vitis plants with respect to the vineyardwere analyzed. Abundance of S. titanus adults significantly decreased from the end of July onwards,particularly inside the vineyard (average range 22.7 2.5 insects/trap). Percentage of FD-positiveS. titanus was significantly higher outside the vineyard (up to 48% on average) compared to insidethe vineyard (up to 34% on average), and increased during the season in both compartments.