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Vector Relations

Specificity of the Helper-Component-Mediated Aphid Transmission of Three Potyviruses Infecting Muskmelon. H. Lecoq, Chargés de Recherches, Station de Pathologie Végétale, and Station d'Amélioration des Plantes Maraichères, I.N.R.A., Domaine Saint Maurice, 84140 - Montfavet, France; M. Pitrat, Chargés de Recherches, Station de Pathologie Végétale, and Station d'Amélioration des Plantes Maraichères, I.N.R.A., Domaine Saint Maurice, 84140 - Montfavet, France. Phytopathology 75:890-893. Accepted for publication 28 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-890.

Aphids (Myzus persicae) transmitted purified watermelon mosaic virus 1 strain of papaya ringspot virus (WMV 1), watermelon mosaic virus 2 (WMV 2), and zucchini yellow mosaic virus (ZYMV) in the presence of extracts from plants infected by the homologous virus and which contained helper component (HC). When heterologous combinations were tested, some degree of specificity was revealed in the virus-HC interaction even though in all cases some transmission occurred. WMV 1-HC allowed high transmission rates of WMV 2 but not of ZYMV, WMV 2-HC permitted high transmission rates of ZYMV and slightly less of WMV 1, while ZYMV-HC was efficient in promoting WMV 2 transmission but not that of WMV 1. When two viruses were mixed in the presence of one HC some competition did occur. In five of the six combinations tested, transmission rates of the homologous virus from the mixture were not significantly different (although usually slightly less) from that observed when alone, while transmission rates of the heterologous virus from the mixture were drastically reduced (four to six times). In these cases, a competition seemed to occur in favor of the homologous virus. When WMV 2 and ZYMV were mixed with WMV 2-HC the situation was different: ZYMV transmission rate was not affected by the presence of WMV 2, but the WMV 2 transmission rate was significantly reduced. In this case, competition also occurred but in favor of the heterologous virus. The high affinity between ZYMV and WMV 2-HC may provide some epidemiological advantage to ZYMV.