ABSTRACT
The constant presence of various species of Diptera Drosophilidae, and in particular of Drosophila fasciata Meigen, on grapes affected with ‘grapevine sour-rot’, leads to believe that the insect plays an important role in the diffusion and development of the disease, present in many vineyards of Lombardy.
Grapevine sour-rot is an alteration produced by yeasts and bacteria that penetrate into the grape through wounds; they are constantly joined by some Drosophilidae attracted by the strong smell of acetic acid and of ethyl acetate. Researches carried out on various viticultural areas of Lombardy have led to point out how, together with Drosophila fasciata Meigen, also Drosophila funebris Fabr. and Drosophila fenestrarum Fall, are present.
In order to verify the role of these insects in the transport of the grapevine sour-rot agents, the yeast attractiveness towards the vinegar flies has been measured by tests through a proper olfactometre. Laboratory data confirm that a group of yeasts separated from bunches affected with grapevine sour-rot prove to be particularly attractive towards Drosophila adults. Moreover, tests on transmission by adults and the finding of yeast in the feeding channel of all the development phases of vinegar fly, demonstrate how the insect is particularly important for the spreading of the disease.
