Differences in PVY transmissibility by three aphid vectors in Idaho potato fields

Potato virus Y (Potyvirus: Potyviridae) (PVY), the most economically important virus affecting the seed and commercial potato production in the United States, is vectored by several potato colonizing and non colonizing aphid species in a non persistent manner. Transmission of PVY by Myzus persicae (Sulzer), Macrosiphum euphorbiae (Thomas) and Rhopalosiphum padi L. (Homoptera: Aphididae) from two sources of virus inoculum was monitored under field conditions during the summers of 2006, 2007 and 2008. The inoculum sources were potato, Solanum tuberosum (Linnaeus), and hairy nightshade, Solanum sarrachoides (Sendtner), an annual solanaceous weed occurring in potato fields in Idaho. Six treatments consisting in the combination of vector species and inoculum sources plus two controls were replicated three times in a randomized complete block design and evaluated. Potato plots were caged to prevent the effect of external factors. Initial infection and percentage of infected plants three weeks after placement of the treatment were evaluated through leaf samples processed with DAS-ELISA. In the three years, transmission of PVY by the three aphid vectors was higher in plots that had a PVY-infected hairy nightshade plant as source of virus inoculum than in plots that had a PVY-infected potato plant.  Both M. persicae and M. euphorbiae transmitted PVY at higher rates than R. padi, regardless of the inoculum source. Thus, hairy nightshade is an important component in the potato-pathosystem affecting the epidemiology of PVY in Idaho and should be included in the PVY management plan.