The transmission of potato virus Y by aphids of different vectoring abilities

SUMMARY Adult apterae of Myzus persicae and Macrosiphum euphorbiae that did not transmit potato virus YN (PVYN) in a first test were as likely to transmit the virus in a subsequent test as those that did transmit on the first occasion. Only 16% of M. persicae that were allowed a single acquisition probe into a leaf infected with both PVYO and PVYN transmitted both strains, 37% transmitted either PVYO or PVYN and 47% did not transmit. There was no difference in the duration of probes that did or did not result in virus transmission. Statistical models were fitted to data on the frequency of transmission of PVYO, PVYN or both PVYO and PVYN by M. persicae and by aphids of poorer vector species, M. euphorbiae and Rhopalosiphum padi. Transmission of the two viruses ocurred independently of each other and consequently transmission of both was rare with M. euphorbiae and R. padi. Mineral oil applied to leaves infected with both strains diminished the frequency of transmission by M. persicae. Fitted models suggested that the aphids that probed through the oil droplets on leaves treated 30 min previously did not transmit virus, and that 24 h later, when the droplets had spread, aphids probing through them could transmit but with a decreased ability.