SOME EFFECTS OF VIRUS SOURCE AND ACQUISITION FEEDING ON THE APHID TRANSMISSION OF POTATO LEAF ROLL AND TURNIP LATENT VIRUSES

Abstract

Upper whole leaves from the same or different Physalis floridana Rydb. plants provided about equally good sources of potato leaf roll and turnip latent viruses for young nymphs of Myzus persicae (Sulz.). Half leaves infected with potato leaf roll virus varied as much as whole leaves, but half leaves infected with turnip latent virus differed the least of all sources tested. Newly detached leaves were better sources of potato leaf roll virus than those detached for 3 or 7 days, and leaves from plants that showed early symptoms of infection were better sources than those from plants that showed later symptoms. This was not true for sources of turnip latent virus.In serial transfer work that began with single nymphs, the number of plants infected with potato leaf roll virus increased as aphid time on the virus source increased, although a similar increase did not result with turnip latent virus. Some aphids differed by 5 days or more in the time they first transmitted either virus after leaving the source. No aphids lived for longer than 12 serial transfers or 13 days after leaving the virus source.