Presence and distribution of stolbur phytoplasmas insect vectors in ‘Lambrusco’ vineyards in Northern Italy.

During 2007/2009 a survey was carried out in 25 vineyards of a grape-growing area in Northern Italy to detect and identify the presence of possible insect vectors of the ‘bois noir’ phytoplasmas (stolbur group) in Lambrusco variety. The leaf/planthopper population was monitored weekly by sticky traps, and sweep nets on herbaceous vegetation and “frappage” on grapevine carried out in the middle and on the border of vineyards from June to September. Captured insects were identified and analyzed with molecular analyses to detect the presence of stolbur phytoplasmas. Identified Cixiidae were Hyalesthes, Cixius and Reptalus. The most abundant species were Hyalesthes obsoletus Signoret (98% of the 761 Hyalesthes genus captured), Cixius cunicularis L. (over 93% of the 273 Cixius captured) and Reptalus panzeri Löw (65% of all the 177 Reptalus captured). Scattered specimens of H. luteipes Fieber, C. nervosus L., C. caledonicus China and R. quinquecostatus Dufour where also identified. The best way to catch the insects was using the sweep net for Hyalesthes and Reptalus (over 97% of H. obsoletus and 78% of Reptalus captured) whereas the “frappage” was the best method for Cixius (64% of all captures). Most of the insects were captured in the vineyard borders (95% Hyalesthes, 72% Reptalus and 60% Cixius). Phytoplasma presence as determined by nested-PCR/RFLP analyses on 16S ribosomal and tuf genes allow identifying stolbur phytoplasmas in different percentages according with species.