Transmission of () and () by the Cottony Grape Scale, (Hemiptera: ).

The cottony grape scale is a scale insect colonizing grapevine; however, its capacity as a vector of grapevine viruses is poorly known in comparison to other scale species that are vectors of viral species in the genera and . The ability of to transmit the ampeloviruses [GLRaV]-1, -3, and -4, and the vitivirus (GVA), to healthy vine cuttings was assessed. The scale insects used originated from commercial vine plots located in Alsace, Eastern France. When nymphs sampled from leafroll-infected vineyard plants were transferred onto healthy cuttings, only one event of transmission was obtained. However, when laboratory-reared, non-viruliferous nymphs were allowed to acquire viruses under controlled conditions, both first and second instar nymphs derived from two vineyards were able to transmit GLRaV-1 and GVA. This is the first report of GLRaV-1 and GVA transmission from grapevine to grapevine by this species.