Transmission of Six Ampeloviruses and Two Vitiviruses to Grapevine by Phenacoccus aceris

Grapevine leafroll disease is caused by grapevine leafroll-associated viruses (GLRaVs). These viruses are common in vineyards worldwide and often associated with vitiviruses that are involved in the rugose wood complex of grapevine. Ten mealybug species are known as vectors of one or several of these grapevine viruses, including the apple mealybug Phenacoccus aceris which is widespread in Holarctic regions and able to transmit Grapevine leafroll-associated virus-1 and -3 (GLRaV-1 and -3). Our aim was to characterize the transmission features of leafroll viruses by Phenacoccus aceris in order to better understand the contribution of this mealybug to leafroll epidemics. Results showed that Phenacoccus aceris is able to transmit GLRaV-1, -3, -4, -5, -6, and -9 to grapevine but not GLRaV-7. This is the first report of GLRaV-6 transmission by a mealybug. Also, for the first time it was shown that Phenacoccus aceris could vector vitiviruses Grapevine virus A (GVA) and Grapevine virus B (GVB). First instar nymphs were the most efficient stage in transmitting GLRaV-1, -3, and GVA. This research sheds light on the transmission biology of grapevine viruses by Phenacoccus aceris and represents a step forward to leafroll disease management.Grapevine leafroll disease is caused by grapevine leafroll-associatedviruses (GLRaVs). These viruses are common in vineyards worldwideand often associated with vitiviruses that are involved in the rugose woodcomplex of grapevine. Ten mealybug species are known as vectors of oneor several of these grapevine viruses, including the apple mealybugPhenacoccus aceris which is widespread in Holarctic regions and able totransmit Grapevine leafroll-associated virus-1 and -3 (GLRaV-1 and -3).Our aim was to characterize the transmission features of leafroll virusesby Phenacoccus aceris in order to better understand the contribution ofthis mealybug to leafroll epidemics. Results showed that Phenacoccusaceris is able to transmit GLRaV-1, -3, -4, -5, -6, and -9 to grapevine butnot GLRaV-7. This is the first report of GLRaV-6 transmission by amealybug. Also, for the first time it was shown that Phenacoccus aceriscould vector vitiviruses Grapevine virus A (GVA) and Grapevine virus B(GVB). First instar nymphs were the most efficient stage in transmittingGLRaV-1, -3, and GVA. This research sheds light on the transmissionbiology of grapevine viruses by Phenacoccus aceris and represents a stepforward to leafroll disease management