Impact of Orientus ishidae on “flavescence dorée” emergence in the vineyards of riparian ecosystems

In this study the polyphagous status of Orientus ishidae was confirmed by showing that the leafhopper is able to lay eggs, hatch and develop on different deciduous trees of a riparian ecosystem, including the grapevines of neighbouring vineyard plots. It was demonstrated that, in such habitat, the main source plants for the phytoplasma acquisition are the alder trees. Leafhoppers collected on alders were mainly infected by FD phytoplasma genotypes M50 (map-FD1) and M38 (map-FD2) and were able to efficiently transmit it back to alder plants. However the same individuals could not transmit to grapevine after 42 forced transmission trials. These results and the detection of only one M38 infected grapevine stock over a 5 year period of extensive monitoring in neighbouring vineyards, suggest a low transfer frequency of phytoplasmas from alder to grapevine by O. ishidae.