Experimental and molecular evidence of R eptalus panzeri as a natural vector of bois noir

Bois noir ( BN ) is an economically important grapevine yellows disease induced by the stolbur phytoplasma and principally vectored by the cixiid H yalesthes obsoletus . This study addresses the involvement of other planthoppers and/or leafhoppers in BN epidemics in the S outh B anat district of northeastern S erbia, by performing transmission experiments and multilocus typing of stolbur phytoplasma isolates to determine the vector‐related characteristics of the disease. Transmission trials were conducted with adults of two cixiid congeners, R eptalus panzeri and R . quinquecostatus , which were found to harbour stolbur phytoplasma in the vineyards under study. A molecular characterization of stolbur phytoplasma isolates was performed by sequence analysis and/or RFLP typing of the two housekeeping genes tuf and sec Y and the two membrane proteins stamp and vmp1 . Transmission trials with naturally infected R . panzeri adults from either the BN ‐infected vineyards or maize redness ( MR )‐affected maize fields revealed a high stolbur phytoplasma transmission efficiency to grapevines. In contrast, experiments conducted with stolbur‐positive R . quinquecostatus originating from BN ‐infected vineyards, provided no evidence for a vector role of this species. Seven stolbur phytoplasma genotypes, all of which were tuf ‐b types, were detected among the grapevine‐ and insect‐associated field samples according to the tuf / sec Y / vmp1 / stamp typing. STOL g was the genotype most frequently found in naturally infected grapevine (42%), as well as R . panzeri originating from the vineyards (85%) and maize fields (98%). The same genotype was found in all experimental plants inoculated by R . panzeri , confirming its vectorship of the disease.