Ability of single aphids to transmit both avirulent and virulent strains of potato leaf roll virus

Abstract

A strain of potato leaf roll virus causing mild symptoms in potato and Physalis floridana was more readily transmitted by peach-potato aphids, Myzus persicae (Sulz.), from these hosts to P. floridana than was a virulent strain. P. floridana plants infected with the avirulent strain seemed immune to subsequent infection with the virulent strain. Single M. persicae, which had fed on plants infected with the avirulent strain and had transmitted it to healthy plants, subsequently acquired and transmitted the virulent strain, apparently as readily as did previously virus-free aphids. Most of the plants infected by means of single aphids carrying both virus strains seemed to contain only one strain, but both strains were recovered from some plants with intermediate-type symptoms. The insect transmission of potato leaf roll virus resembles that of beet curly top virus and differs from that of aster yellows virus.