Contribution of Noncolonizing Aphids toPotato Virus YPrevalence in Potato in Idaho

Potato virus Y (PVY) is a major concern for potato production in the United States given its impact on both crop quality and yield. Although green peach aphid, Myzus persicae (Sulzer), is the most efficient PVY vector, it may be less abundant in potato-growing areas of Idaho relative to non-potato-colonizing aphid vectors of PVY that may disperse from nearby cereal fields and other crops. A field study was conducted during 2012-2013 to examine if noncolonizing aphids disperse to nearby potato fields as cereal crops dry down before harvest. The aphid fauna was sampled weekly in four different potato fields in south-central and southeastern Idaho using yellow sticky traps and yellow pan traps. Potato fields were chosen with an adjacent cereal field such that the prevailing westerly wind would facilitate aphid dispersal from cereal fields to potato. Non-potato-colonizing aphids sampled included 10 cereal aphid species, the most abundant of which were Rhopalosiphum padi L. and Metopolophium dirhodum (Walker). More than 35 species from noncereal hosts also were found. Overall, green peach aphid abundance was relatively low, ranging from 0.5-2.5% of the total aphid capture between years and among fields. In both years and all locations, cereal aphid abundance peaked in mid- to late July (cereal ripening stage) and decreased thereafter as cereal crops dried. PVY prevalence in the potato fields increased following these increases in aphid abundance. This study suggests that cereal aphids and other noncolonizing aphids are important contributors to PVY prevalence in potato in southern Idaho.