Detection of mycoplasmalike organisms in Scaphoideus titanus Ball reared on flavescence dorée infected grapevine by dot hybridizations using DNA probes

Grapevine flavescence dorée (FD) is known to be associated with mycoplasmalike organisms (MLO) seemingly spread in the vineyards by the leafhopper Scaphoideus titanus Ball which occurs in Northern Italy. The study was carried out for two years in order to check for the presence of MLOs in this insect using dot hybridization with biotinylated MLO-DNA probes. The DNA extracted from 11 of 15 groups of S. titanus reared on symptomatic vines showed hybridization signals with probes pAY and pG at 52°C. Three of 5 groups of insects reared on symptomless vines (FD-infected in the past) and two groups of insects reared on vines which had never showed symptoms were also positive. These results show the possibility to detect the presence of MLO potentially related with FD disease in an insect population with DNA probes. A relationship between the presence of MLO-infected insects and the maintenance of the disease through the years in the field appears also possible.