First Report of Impatiens Necrotic Spot Tospovirus (INSV) in Israel

In January 1999, Anemone coronaria L. imported from Europe and grown in open fields near Jerusalem in Israel developed foliar ringspots and foliar necrosis. Within a few weeks of the first appearance of these symptoms, further anemone plants in the surrounding area were affected and seriously damaged. Impatiens necrotic spot tospovirus (INSV) was detected in affected plants by enzyme-linked immunosorbent assay (ELISA; anti-INSV monoclonal antibodies were provided by H. T. Hsu, USDA, Beltsville, MD, and a polyclonal antibody to INSV was purchased from Loewe, Otterfing, Germany). Crude sap extracted from symptomatic tissue was mechanically transmitted to Emilia spp., Petunia hybrida, Nicotian glutinosa, N. benthamiana, and N. rustica plants that developed symptoms characteristic of INSV infection (1). ELISAs of leaf sap extracted from anemone plants and mechanically inoculated indicator plants gave a strong positive reaction to INSV. Leaf-dip preparations prepared from leaf samples of anemone plants were analyzed by transmission electron microscopy (TEM). Virus particles typical of a tospovirus were observed in samples taken only from symptomatic plants. TEM studies with ultrathin sections of infected anemone and Emilia spp. leaves revealed the presence of tospovirus-like particles. This first report of INSV interception in Israel brings the count of the Tospovirus members in Israel to three, including tomato spotted wilt virus (TSWV), which was found in the past to infect anemone and other ornamental crops, and the Iris yellow spot tospovirus, infecting onion (2). INSV is known to occur in Europe and in the U.S., mostly in flowers grown in greenhouses. The virus is transmitted by the Western flower thrips (WFT; Frankliniella occidentalis Pergande). Although all infected plants were destroyed, precautions to prevent further introduction of the virus must be made. INSV might spread by the WFT, which is abundant in Israel year round, and might also infect other greenhouse or field crops. References: (1) M. Daughtrey et al. Plant Dis. 81:1220, 1997. (2) A. Gera et al. Plant Dis. 82:127, 1998.