Transmission of ‘Candidatus Phytoplasma solani’ by Reptalus quinquecostatus (Hemiptera: Cixiidae)

Transmission trials were carried out using Reptalus quinquecostatus (Cixiidae), a potential vector of ‘Candidatus Phytoplasma solani’ (‘Ca. P. solani’), to assess its ability to inoculate the phytoplasma to periwinkle (Catharanthus roseus), grapevine (Vitis vinifera), lavandin (Lavandula × intermedia) and tobacco (Nicotiana tabacum). Detection, genotyping and comparison of ‘Ca. P. solani’ strains carried by R. quinquecostatus showed that R. quinquecostatus carried a higher diversity of ‘Ca. P. solani’ than Hyalesthes obsoletus, major known vector of ‘Ca. P. solani’ strains. Molecular analyses also showed the presence of a new strain only in grapevines and R. quinquecostatus. ‘Ca. P. solani’ was successfully inoculated to periwinkles by R. quinquecostatus, but no transmission was achieved to the other tested plants. The ability to transmit ‘Ca. P. solani’ to plants and observations of adults feeding on grapevines in vineyards consolidate the hypothesis that R. quinquecostatus is a specific vector of ‘Ca. P. solani’ strains. Moreover, the discovery of a new genotype present in R. quinquecostatus and not in H. obsoletus, vector also present on grapes, suggests that R. quinquecostatus should have a direct role in ‘Ca. P. solani’ epidemiology. Overall, even if R. quinquecostatus has a minor or no role in ‘Ca. P. solani’ transmission from weeds to grapevines, it can have an indirect role in Bois Noir epidemiology. This planthopper can contribute to maintain an alternative ‘Ca. P. solani’ cycle in weeds even in the absence of H. obsoletus preferentially by maintaining pathogen reservoirs in wild compartments neighbouring susceptible crops.