Monitoring Scaphoideus titanus with emphasis on spatio-temporal distribution allows to improve control in fragmented viticultural areas

Abstract: A severe outbreak of Flavescence dorée (FD) was recorded in the territory of the
Consortium “Prosecco Superiore Conegliano Valdobbiadene” (Veneto region, Italy) in
2019-2020. From 2021 to 2024, a project investigated the factors that may have contributed to this issue, namely the efficacy of control strategies against Scaphoideus titanus, the abundance of vector populations, their spatio-temporal aggregation patterns, and the possible role of adjacent woody vegetation as sources of infestation. Monitoring vineyards showed high S. titanus populations densities in 2021 indicating low efficacy of control measures. Efficacy trials showed that commonly used systemic insecticides were less effective than some pyrethroids. Following the use of pyrethroids, vector abundance declined from 2022 onwards. In 2021, spatial distribution analysis of S. titanus populations in four study areas revealed significant aggregations of both nymphs and adults. Adult spatial distribution was not associated with adjacent woody vegetation, but with contiguous S. titanus and FD infested vineyards. In 2023 and 2024, S. titanus aggregation patterns declined markedly, coinciding with reduced vector population densities. As a consequence, FD incidence decreased from 9.6 % (2021) and 14.6 % (2022) to 3.7 % (2023) and 0.5 % (2024). A similar approach in monitoring S. titanus populations and FD incidence was followed in the Prosecco DOC territory. An ad hoc insecticide strategy was conducted to minimize the number of vector hotspots, improving FD control. Results suggest that an area-wide management strategy is essential to maintain S. titanus and FD at acceptable levels.