Flavescence dorée phytoplasma detected in Clematis vitalba and Dictyophara europaea
Studies were carried out from 2002 to 2007 in Italy and the Balkans to better understand the relationships between isolates of flavescence dorée phytoplasma (EPPO A2 List) found in clematis (Clematis vitalba) and grapevine (Vitis vinifera). A total of 399 clematis and 107 grapevine samples were collected from Italy and the Balkans. Analysis showed that 36% of the clematis plant samples were infected by phytoplasmas which, in grapevine, are associated with flavescence dorée. It is noted that infected clematis plants were also found in areas where flavescence dorée has never been reported (such as Macedonia, Croatia and parts of Italy and Serbia). In addition, extensive surveys were carried out in Italy (8 sites in Veneto) and Serbia (10 sites) to obtain information on potential insect vectors present in the field. Hemipteran species were collected (sweep net) from infected plants of clematis and grapevine, and also from grass species in meadows. When examining all potential vectors of flavescence dorée (other than the known vector Scaphoideus titanus), only Dictyophara europaea (Auchenorrhyncha: Dictyopharidae) was found to be infected by flavescence dorée phytoplasma. The pathogen was detected in 20 specimens (out of 180 – 11%) of Scaphoideus titanus, and in 18 specimens (out of 527 – 3.4%) of D. europaea. S. titanus was consistently found in grapevine (although some individuals were caught on clematis) while D. europaea was caught on both grapevine and clematis. Preliminary transmission experiments showed that D. europaea can transmit flavescence dorée phytoplasma to grapevine and, therefore suggested that it could be an occasional vector of flavescence dorée phytoplasma from clematis to grapevine. In the past, it was thought that only grapevine and S. titanus were involved in the disease epidemiology, but these results showed that other hosts and vectors may also play a role.
Filippin L, Jović J, Cvrković T, Forte V, Clair D, Toševski I, Boudon-Padieu E, Borgo M, Angelini E (2009) Molecular characteristics of phytoplasmas associated with Flavescence dorée in clematis and grapevine and preliminary results on the role of Dictyophara europaea as a vector. Plant Pathology 58(5), 826-837.