An international perspective on a global challenge: Investigating Potato virus Y transmission in the U.S. and Europe

As technology and transportation create a global community, researchers are increasingly aware of the need to address widespread crop production challenges using an international perspective. Specific diseases and pests have become universal problems. Potato virus Y (PVY), which is vectored by aphids, has persisted as a problematic disease in potatoes and related crops worldwide. Though the virus is well established in many countries, there have been shifts in the strains dominating each region. For example, the strains present in the United States have shifted from PVY^O to PVY^NO or PVY^NTN. In contrast, in Europe, PVY^N is already dominant. Multiple alternative weed hosts have been identified in Europe, which may have contributed to strain dominance. In an effort to understand shifts in strains, a collaborative effort was made to: 1) investigate PVY transmission between known weed hosts and potatoes, and 2) assess vector preferences for healthy or infected plants. Major aphid vectors of PVY, including Myzus persicae L. and Macrosiphum euphorbiae L., were evaluated in transmission studies between potatoes and Chenopodium album L. in both Europe and the U.S. using local PVY strains. Transmission rates for European PVY^N from C. album to potatoes for M. persicae and M. euphorbiae were 44% and 37.5%, respectively. These are similar to the transmission rates reported between potatoes. Vector preferences for healthy and infected C. album were evaluated by releasing 200 M. persicae alates in 1 m³ cages with six infected and six healthy plants. Aphid settling was used to measure preference. The number of aphids settled on each plant was evaluated at 0.5, 2, 4, and 48 h for at least three replications and preferences were analyzed separately for each time period. Aphids were found to have no preference at 0.5, 2, and 4 h, but preferred healthy plants by 48 h (t = 3.18; df = 4; P = 0.034). Aphids may be unable to distinguish between healthy and infected plants early in the host selection process. However, after extended feeding, aphids may leave infected plants and move to healthy hosts, potentially increasing PVY transmission between weeds and surrounding vegetation.