The first detection of grapevine's “flavescence doree” (FD) in Switzerland and the application of the mandatory control measures date back to 2004. The use of buprofezin allowed an optimal control of the insect vector Scaphoideus titanus. However, buprofezin has been banned since 2019 raising the need for an alternative control strategy. Assuming a slow S. titanus population growth in the first post-treatment years, the Swiss Canton of Ticino received the permission to suspend the mandatory insecticide treatments for two consecutive years, before resuming the insecticide sprayings with pyrethrins in the third year. This study aimed at assessing the impact of the suspension and resumption of treatments on the population dynamics of S. titanus and the consequences on the FD incidence in vineyards. The mean captures of S. titanus specimens increased eleven fold over the two-year period of treatment suspension, while the subsequent pyrethrins applications did not bring the populations back to the pre-suspension level. Nevertheless, the overall increments were not statistically significant (p > 0.05) mostly due to the variability in population density among vineyards. However, and most importantly, the incidence of infected grapevines remained stable. Under specific frame conditions, such as low initial vector populations and cultivation of less susceptible cultivars, adaptive management options may represent a possible alternative control strategy for an extensive use of insecticide applications in the vineyard agroecosystem.
