The effect of Drosophila suzukii attack during grape drying process in Veneto Region (north-eastern Italy)

Abstract: The presence and harmfulness of Drosophila suzukii (Matsumura) on grapes was noticed in Veneto Region (north-eastern Italy). For red wines obtained using dried grapes, the damage caused by D. suzukii can be intense due to the possible increase in pathogen infections during the withering process. In order to evaluate the effects of D. suzukii infestation during the withering process, two autochthonous varieties, i.e. Rondinella and Corvina, used for the production of the well-renowned Amarone and Recioto wines, were considered. Berries showed a natural weight loss during withering, but a further decrease was observed in damaged grapes, which was positively correlated with the intensity of the Drosophilidae attack. Moreover, D. suzukii infestation influenced the acetic acid bacteria and Botrytis cinerea development. In Rondinella a high acetic acid production and a putative development of B. cinerea in the “noble rot” was observed. In Corvina the lower amount of fungal metabolites suggested a development of sour rot instead of B. cinerea. Implications for D. suzukii management in the storage house during the drying process is discussed.