Diffusione del virus BlScV sul mirtillo gigante americano

In 2004, infections of Blueberry scorch virus (BlScV) were detected for the fi rst time outside North America on Vaccinium corymbosum (Ericaceae) in Piedmont (NW Italy). Since 2009, however, virus was found also in Trentino on V. corymbosum and on a new host species: V. ashei. Overall, four infected fi elds in Piedmont and three in Trentino were identifi ed. Molecular analysis on the two strains, from Piedmont and from Trentino, showed two distinct epidemics are now present in Italy: the Piedmont isolates belong to a BlScV strain similar to isolates from the East Coast of Canada and the US, whereas the Trentino isolates are very similar to an American strain from Washington State on the West Coast of the US. In its area of origin, the virus is transmitted by Ericaphis scammelli (Hemiptera: Aphididae) in a non-persistent fashion. In 2005-2010, fi eld surveys were carried out to monitor aphid populations in seriously infected highbush blueberry crops in Piedmont. Moreover, experiments were set up to evaluate aphid transmission ability in laboratory and fi eld trials. E. scammelli was the predominant aphid species in the investigated highbush blueberry crops with population levels varying in relation to the locality and the year. However, in transmission trials, E. scammelli proved not to be a very effi cient vector of BlScV.