Origin of a sudden mass occurrence of the stolbur phytoplasma vectorHyalesthes obsoletus(Cixiidae) in Austria

The grapevine disease ‘bois noir’ is widespread in European viticulture, but in many regions there is a lack of correspondence between disease spread and abundance of the main insect vector, the planthopper Hyalesthes obsoletus. This was the situation in Austria until 2012, when a mass occurrence of the vector was observed on Urtica dioica, a new host plant for the vector and reservoir plant for the pathogen, stolbur phytoplasma, in this area. Here we analyse the origin of the Austrian vector populations using genetic markers. The origin was unambiguously assigned to two regional populations, and two causes for the population expansion: immigration of East Central European populations and l…