Infectivity of aphids bred on virus-infected cauliflower plants

Caged cauliflower plants infected with either cabbage black ring spot virus (CBRSV) or cauliflower mosaic virus (ClMV) were colonized with Myzus persicae or Brevicoryne brassicae. Winged and wingless aphids that voluntarily flew or walked from these plants were transferred singly to healthy cauliflower or other brassica seedlings to compare their feeding behaviour and ability to transmit the viruses. Wingless aphids settled to probe more readily than winged, and B. brassicue was initially more restless than M. persicae. ClMV was more readily transmitted than CBRSV by both species, and B. brassicae rarely transmitted CBRSV. Wingless aphids transmitted less often than winged ones, and no wingless B. brassicae transmitted CBRSV, although they did ClMV. Fewer aphids transmitted CBRSV from old plants than from young ones, but plant age had little effect on ClMV transmission.