|Gildow, Fred - PENN STATE UNIV.|
|Levy, Laurene - USDA, APHIS|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 13, 2004
Publication Date: August 1, 2004
Citation: Gildow, F., Damsteegt, V.D., Stone, A.L., Schneider, W.L., Luster, D.G., Levy, L. 2004. Plum pox in north america: identification of aphid vectors and a role for fruit in virus spread. Phytopathology. 94:868-874. Interpretive Summary: Plum pox (sharka) is the most devastating, aphid-transmitted, virus disease affecting stone fruits. It causes loss in fruit quality and quantity, and affects interstate and international trade in nursery stock and ornamental species. Eradication of the disease from the U. S. requires knowing which aphids are able to transmit the virus and how they do it. Aphid species were collected from peach orchards in Pennsylvania, colonized at the Pennsylvania State University insectary, and tested for their ability to transmit plum pox potyvirus (PPV) at the USDA BSL-3 containment facility at Fort Detrick. Five species from the orchards including the green peach aphid, spirea aphid, black peach aphid, black bean aphid, and the bird-cherry oat aphid transmitted PPV from peach to peas. The brown citrus aphid also transmitted PPV efficiently although it does not exist in areas where plum pox has been reported. When peach seedlings were used as a test species in place of peas, the aphids were able to transmit more effectively from peach leaves than from peach fruit. However, evidence obtained that aphids readily feed on peach fruit and that the peach fruit could serve as a virus source for long distance dispersal will require re-evaluation of methods of handling fruit from infected trees.
Technical Abstract: Thirteen aphid species, many collected from peach orchards as migrants, were tested for their ability to transmit three Pennsylvania isolates of plum pox virus (PPV) collected in Adams (PENN-3), Franklin (PENN-4), and York (PENN-7) County, PA. Five species: Aphis fabae, Aphis spiraecola, Brachycaudus persicae, Myzus persicae, and Rhopalosiphum padi transmitted PPV in transmission tests using Colmo pea as bioassay host. Toxoptera citricida, from Florida, also was an effective vector but does not occur in major stone fruit growing states. Species not transmitting PPV in parallel tests included Acyrthosiphon pisum, Aphis glycines, Aulacorthum solani, Macrosiphum euphorbiae, Metopolophium dirhodum, Rhopalosiphum maidis, and Sitobion avenae. When given a 3-day probing access period simultaneously on PPV-infected peach seedlings and healthy peach seedlings, M. persicae, A. spiraecola, A. fabae, and B. persicae transmitted PPV to 63%, 31%, 38%, and 32% of the healthy seedlings, respectively. When given a similar probing period on PPV-infected peach fruit and healthy peach seedlings, the same aphid species transmitted PPV to 50%, 35%, 0%, and 0% of seedlings, respectively. Results support the hypothesis of secondary PPV spread by indigenous aphids in Pennsylvania, and suggest that PPV-infected fruit could act as a virus source for long distance dispersal.