Scaphoideus titanus fitness on grapevine varieties with different susceptibility to Flavescence dorée phytoplasma

Scaphoideus titanus (Ball) is a Nearctic leafhopper (Cicadellidae: Deltocephalinae),monophagous on Vitis spp., naturalized in European vineyards since the 20th century. Following its introduction and establishment in Europe, S. titanus became themain vector of Flavescence dorée phytoplasma (FDp) to grapevine. FDp causes heavyeconomic losses to viticulture in Europe. The control of the disease mainly relies oninsecticide applications against the vector and on the removal of infected plants. Theexploitation of plant resistance or tolerance against pathogens and pests can represent a valuable tool for a more sustainable viticulture. The first step in identifyingresistance traits in grapevine varieties towards S. titanus is the evaluation of insectfitness parameters on different grapevine genotypes. Therefore, in this work, nymphmortality and developmental time, adult survival and prolificacy of S. titanus havebeen studied on three grapevine varieties, characterized by different susceptibility toFD. Scaphoideus titanus showed highest fitness when reared on Barbera, whereas theworst performances were recorded on Moscato, with a significant reduction in nymphand adult survivals, a slowed nymph development, and a decreased number of available eggs. On Brachetto, S. titanus showed an intermediate level of fitness parameters.Consistently with previous studies on feeding behaviour, Barbera is the most suitablehost for the FD-vector. The high suitability of Barbera for S. titanus may partly explainthe high susceptibility to FD of this variety. On the contrary, the low suitability ofMoscato, poorly susceptible to FD, may be due to antibiosis and antixenosis defencemechanisms that act against S. titanus.