Influence of Grapevine Cultivar on the Second Generations of Lobesia botrana and Eupoecilia ambiguella

Grapevine cultivar can affect susceptibility to Lobesia botrana and Eupoecilia ambiguella with important implications on control strategies. A four-year study was carried out in north-eastern Italy on 10 cultivars (Cabernet Sauvignon, Carmenere, Chardonnay, Merlot, Refosco dal Peduncolo Rosso, Rhine Riesling, Sauvignon Blanc, Terrano, Tocai Friulano and Verduzzo Friulano) grown in the same vineyard to assess whether the cultivar affects second-generation population levels of the two vine moths and L. botrana larval age composition. The influence of bunch traits measured at the peak of egg hatching on demographic parameters was also evaluated. Over the four years, L. botrana significantly prevailed over E. ambiguella in nine cultivars. Chardonnay and Tocai Friulano were the most infested cultivars and Merlot was the least infested. At the sampling date, the age composition of L. botrana varied with cultivar, with the larvae being significantly older on Chardonnay and younger on Carmenere, Merlot and Verduzzo Friulano. Older larval age was significantly associated with higher bunch compactness. Larval infestation was not significantly influenced by either bunch compactness or berry volume, which suggested a more important role for contact and volatile substances mostly originating from the berries. These results allow for the improvement of Integrated Pest Management strategy against vine moths.