Aster yellows phytoplasma in grapevines : identification of vectors in South Africa

Abstract

Since the discovery of aster yellows phytoplasma on grapevine in South Africa in 2006, a concerted effort by various research groups to identify the vector(s) was co-ordinated by Winetech. This included qualitative and quantitative surveys for two years of leaf- and planthoppers occurring in vineyards in affected areas, testing specimens of leaf- and planthopper species for the presence of aster yellows phytoplasma with PCR, transmission experiments, and relating presence of leaf- and planthoppers in the field to the time of disease transmission. Twenty-eight leaf- and planthopper species/species groups have been recorded from vineyards in aster yellows-infected regions. The four most abundant species/species groups were Acia lineatifrons (Naudé), Austroagallia spp., Cicadulina spp. and Mgenia fuscovaria (Stål) (Hemiptera: Cicadellidae). Austroagallia spp. and M. fuscovaria repeatedly tested positive for the presence of AY. Results of transmission experiments and a field trial to determine leaf-/planthopper abundance in vineyards along with time of transmission in the field suggest that M. fuscovaria is a vector of aster yellows phytoplasma in South Africa. The concerted effort between industry and researchers allowed for fast identification of a potential vector of aster yellows phytoplasma in South Africa.