Transmission efficiency of different non-persistent viruses infecting melon by four aphid species

Transmission experiments of different isolates of Cucumber mosaic virus (CMV), Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV) were conducted using established colonies of Aphis gossypii Glover, Myzus persicae (Sulzer), A. fabae Scopoli and A. craccivora Koch as vectors. The transmission procedure used provided an estimate of the virus transmission efficiency for each aphid species. Two different virus isolates/aphid clones were tested for each virus species using the most efficient aphid species as vector. A. gossypii was the most efficient vector of CMV (100 ± 0%), while M. persicae showed the highest efficiency of transmiting WMV (67.9 ± 28.5%) and ZYMV (96.4 ± 3.6%). Both WMV and ZYMV showed variability in their transmission efficiency by aphids. No significant differences were found in the efficiency of the two CMV isolates tested. No differences were observed in the vector transmission ability between clones of each aphid species tested. Results of our transmission studies together with previously known information on the temporal and spatial patterns of virus epidemics in melon crops in Spain suggest that CMV is mainly transmitted by a colonising aphid such as A. gossypii. In contrast, WMV is mainly transmitted by non-colonising transient aphid species such as M. persicae that alight on melon crops during late spring.