Xiphinema rivesi from Slovania Transmit Tobacco ringspot virus and Tomato ringspot virus to Cucumber Bait Plants.

The dagger nematode, Xiphinema rivesi Dalmasso, a member of the X. americanum group, was detected in 2002 for the first time in Slovenia and for the fourth time in Europe (4). X. rivesi is a vector of at least four North American nepoviruses including Cherry rasp leaf virus (CRLV), Tobacco ringspot virus (TRSV), Tomato ringspot virus (ToRSV), and Peach rosette mosaic virus (PRMV) (1,2). All of these viruses are included on the EPPO and EU lists of quarantine organisms, but none of the Xiphinema species found in Europe have been reported to transmit these nepoviruses. Three virus isolates, including TRSV (from Lobelia spp.; virus collection of the Plant Protection Service, Wageningen, The Netherlands), ToRSV (grapevine isolate PV-0381; DSMZ, Braunschweig, Germany), and Arabis mosaic virus (ArMV) (from Vinca spp.; virus collection of the Plant Protection Service), were used in transmission tests with a population of X. rivesi found in Slovenia. X. rivesi is not known to transmit ArMV and this virus was included as a check. The nematodes were extracted from peach orchard soil collected near the village of Dornberk, and transmission tests fulfilled the set of criteria proposed by Trudgill et al. (3). Cucumis sativus cv. Eva, grown in a growth chamber at 25°C, was used as acquisition hosts and transmission bait plants. The acquisition hosts were mechanically inoculated and showing systemic symptoms before the introduction of nematodes. Noninoculated acquisition plants were included as controls. After a 10-day acquisition feeding period, the nematodes were transferred to healthy bait plants and allowed a 14-day inoculation feeding period. X. rivesi transmitted TRSV and ToRSV but not ArMV. TRSV and ToRSV bait plants developed systemic symptoms 4 to 6 weeks after the nematodes were transferred. Transmission of TRSV and ToRSV was confirmed by testing leaf and root sap of bait plants in a double antibody sandwich (DAS)-ELISA. High virus concentrations were detected in the roots and leaves of TRSV and ToRSV symptomatic plants. DAS-ELISA on bait plants from nematodes that had been allowed to feed on ArMV-infected or the virus-free control acquisition plants gave negative results. No symptoms appeared on bait plants used for ArMV transmission or the control bait plants. To our knowledge, this is the first report of transmission of TRSV and ToRSV with a Xiphinema population from Europe. References: (1) D. J. F. Brown et al. Phytopathology 84:646, 1994. (2) L.W. Stobbs et al. Plant Dis. 80:105, 1996. (3) D. L. Trudgill et al. Rev. Nematol. 6:133, 1983. (4) G. Urek et al. Plant Dis. 87:100, 2002.