Cucurbit Genetics Cooperative Report 18:44-44 (article 21) 1995
Specificity of Transmission of Melon Yellowing Viruses by Trialeurodes vaporariorum and Bemisia tabaci
C. Soria, A.I. L. Sese, and M.L. Gomez-Guillamon
Experimental Station La Mayora, 29759 Algarrobo-Costa, Malaga SPAIN
In 1982. symptoms of melon-yellowing disease were detected in melon (Cucumis melo L.) crops cultivated under plastic greenhouses in the southwest of Spain (Soria and Gomez-Guillamon. 1989). The approximately 950 nm long closterovirus causal agent involved in these outbreaks is transmitted semipersistently by the greenhouse whitefly Trialeurodes vaporariorum West. (2,5). However., from 1989, we observed a pronounced increase of the populations of Bemisa tabaci at the same time as a decrease in the populations of Trialeurodes vaporariorum (1). B. tabaci transmits semipersistently another clostero-like particle approximately 790 nm long, and this appears to be responsible for the melon-yellowing disease that affects present-day melon crops in this area (3).
The fact that the two viruses are both clostero-like particles (2, 3) and also the similarity of the symptomatologies of the yellowing diseases they produced in melon crops led us to design and carry-out a simple experiment to test for possible specificity of the transmission of one of the two viruses by one or the other of the two whitefly species. We attempted to transmit both types of virus using as vectors the two whitefly species, Trialeurodes vaporariorum and Bemisia tabaci. eighty groups of approximately 50 insects were used in this work. Twenty groups of each whitefly species were allowed to feed on one of the two sources of inoculum for 48h. At the end of this period, each group of whiteflies were transferred to healthy melon plants at the two-trueleaf stage and allowed to feed for 72h. After this period, the flies were removed and the plants were transferred to a greenhouse and kept within a fly-proof mesh to wait the appearance of symptoms. The controls were ten C. melo plants which had never had contact with the two vector species. At the 15th day following the three-day inoculation period, the leaves on which the whiteflies were feeding were eliminated to prevent subsequent infection.
In the experiments that used T. vaporariorum as vector fifty-five percent of the plants were infected and showed symptoms of disease produced by the virus associated with T. Vaporariorum, but no plants were infected with the virus associated with B. Tabaci. In the experiments with the B,. tabaci vector, ninety-five percent of the plants were infected with the melon-yellowing virus associated with this species, but no plants were infected with the virus associated with T. vaporariorum. These results of this present work clearly demonstrated the specificity of the transmission of a single melon-yellowing-disease virus by each whitefly species.
Acknowledgement: We wish to thank David W. Schofield for translating the manuscript. This work has been financed by the CICYT project AGF92-1064.
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- Jorda-Gutierrez, C., M.L. Gomez-Guillamon,, M. Juarez, and A. Alfaro-Garcia. 1993. Clostero-like particles associated with a yellows disease of melon in south-eastern Spain. Plant Pathology 42:722-727.
- Sese, A.I.L., M.L. Gomez-Guillamon, and J.R. Diaz-Ruiz. 1994. Appearance of a possible new melon yellowing disease in Spain. Cucurbit Genetics Cooperative 17:72-73.
- Soria, C. and M.L. Gomez-Guillamon. 1989. Transmission of the causal agent of a muskmelon yellowing disease. Cucurbit Genetics Cooperative 12:40.
- Soria, C. M.L. Gomez-Guillamon, and J.E. Duffus. 1991. Transmission of the agent causing a melon yellowing disease by the greenhouse whitefly, Trialeurodes vaporariorum in southeast Spain. Neth, J. Pl. Path. 97:289-296.