Preliminary results on putative vectors of 'Candidatus Phytoplasma solani' in Bois noir-affected vineyards in Franciacorta (Lombardy region, North Italy)

Bois noir phytoplasma (BNp) strains are transmitted by the planthopper Hyalesthes obsoletus Signoret (Homoptera: Cixiidae), a polyphagous insect living preferentially on weeds. In vine-growing areas where H. obsoletus is absent, the presence of BNp implies the existence of alternative vectors. Recently, Reptalus panzeri has been reported as a natural vector of BNp in Serbian vineyards. In the present study, field surveys and molecular analyses were carried out in a BN-affected vineyard in Franciacorta (Lombardy region, North Italy) in 2013 to identify putative insect vectors. Insects (1100 specimens) were captured by entomological net and sticky traps from May to October. Phenotypic analysis by stereomicroscope allowed the identification of 42 taxonomic groups at different levels (26 species and 16 genera), grouped in 624 pools for molecular detection. Specific PCR-based amplification of stamp gene revealed the presence of BNp in 64 analysed pools (10%) belonging to 20 taxonomic groups (15 species and 5 genera). Further analyses will be carried out to (i) characterize the BNp strains identified in insect specimens by stamp gene sequence and compare with strains identified in grapevines and weeds, (ii) determine the transmission capability by trials performed in controlled conditions.