Vector-phytoplasma relationships during natural infection of Hyalesthes obsoletus, Euscelis lineolatus, Neoaliturus fenestratus and Psammotettix alienus captured in vineyard agroecosystems in the Marche region (central-eastern Italy).

Grapevine yellows (GY) associated with phytoplasma constitute a serious phytosanitary problem in many Italian regions. GY spread involves interactions between the vector and the reservoir plants of the phytoplasma. The objective of this study was to determine the role of the planthopper Hyalesthes obsoletus in the diffusion of Bois noir (BN) and other GY, as also for the leafhoppers Euscelis lineolatus, Neoaliturus fenestratus and Psammotettix alienus, which are widespread in the Marche Region and which are known to be, or are under investigation as, phytoplasma vectors. In 2007 and 2008, in vineyard agroecosystems affected by GY diseases, a total of 1,069 leafhopper and planthopper specimens were collected and analyzed. Each of the insect species was infected with phytoplasma. The phytoplasma infection levels varied according to the vineyard agro-ecosystem and the insect species, and they increased through the season. PCR-restriction fragment length polymorphism (RFLP) analysis detected phytoplasma belonging to subgroups 16SrI-B, 16SrI-C and 16SrXII-A (BN) in E. lineolatus, 16SrI-B in P. alienus and 16SrI-B and 16SrI-C in N. fenestratus. H. obsoletus showed only the 16SrXII-A subgroup. No X-disease and phytoplasma associated to the 16SrV group were detected in any of the specimens. The inoculation assays showed the ability of the insect species analyzed to inoculate the phytoplasma, detected in their bodies, into the artificial feeding medium.