TRANSMISSION OF THREE NORTH AMERICAN ISOLATES OF PLUM POX VIRUS: IDENTIFICATION OF APHID VECTORS AND SPECIES-SPECIFIC TRANSMISSION FROM INFECTED STONE FRUITS

Authors: GILDOW, FRED - PENN STATE UNIV; Damsteegt, Vernon; Stone, Andrew; Schneider, William; Luster, Douglas - Doug; LEVY, LAURENE - USDA, APHIS

Submitted to: Acta Horticulture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2004
Publication Date: 9/1/2004
Citation: Gildow, F., Damsteegt, V.D., Stone, A.L., Schneider, W.L., Luster, D.G., Levy, L. 2004. Transmission of three north american isolates of plum pox virus: identification of aphid vectors and species-specific transmission from infected stone fruits. Acta Horticulture 657:207-212

Interpretive Summary: Plum pox virus is transmitted by several aphid species in different areas of Europe. We tested 13 aphid species found in the U.S to determine which species could be vectors and how they transmitted the virus. Seven aphid species transmitted isolates of the plum pox potvirus (PPV), found in Pennsylvania, with different levels of efficiency. Aphids were allowed to feed on infected peach leaves or pea leaves to acquire the virus. Following a short acquisition time, aphids were allowed to move over to healthy peach or pea seedlings to transfer the virus. The most effective vectors were the green peach aphid, the spirea aphid, the black peach aphid, and the black bean aphid. Efficient aphid vectors transmitted to more than 80% of test plants; inefficient vectors transmitted to less than 5% of the test plants. One species, the brown citrus aphid, is not found in geographic areas where stone fruits are grown, but transmitted the virus at more than 35% efficiency. Differences were noted in aphid ability to transfer virus from peach leaves versus peach fruit. The green peach aphid and spirea aphid were able to transmit PPV effectively from infected fruit to healthy peach seedlings.

Technical Abstract: North American populations of 13 aphid species were tested for their ability to transmit isolates of plum pox potyvirus recovered from infected trees in Adams, Franklin, and York Counties, PA. Seven species, Aphis fabae, A. spiraecola, Brachycaudus persicae, Metopolophium dirhodum, Myzus persicae, Rhopalosiphum padi and Toxoptera citricida transmitted PPV in unrestricted probing tests utilizing Colmo pea as both the PPV source and transmission bioassay indicator. A. spiraecola and M. persicae were the most efficient vectors with 86% and 83% of 100 seedlings infected when infested with 25-50 aphids each. M. dirhodum and R. padi only occasionally transmitted PPV to pea (2%). Although T. citricida was an effective vector (36% in pea), it is restricted to Florida and does not occur in major stone fruit growing areas of North America. The six aphids that did not transmit PPV included Acyrthosiphum pisum, Aphis glycines, Aulacorthum solani, Macrosiphum euphorbiae, Rhopalosiphum maidis, and Sitobion avenae. When given an acquisition period on PPV-infected peach seedlings and then allowed an unrestricted inoculation period on healthy peach seedlings, M. persicae, A. spiraecola, A. fabae, and B. persicae transmitted PPV to 63%, 31%, 38%, and 32% of the seedlings, respectively. When acquisition fed on infected peach fruit and allowed an unrestricted probing period on peach seedlings, the same aphid species transmitted PPV to 50%, 35%, 0%, and 0% of seedlings, respectively, in replicated tests. In summary, Pennsylvania isolates of PPV were transmitted effectively by indigenous aphid populations, were acquired and transmitted from fruit collected from infected orchard trees over two growing seasons, and had different degrees of transmission efficiency when acquired from foliar or fruit tissues.