Incidence of the cabbage aphid, Brevicoryne brassicae L. in potato crops in India and its efficiency for transmission of potato virus Yo

Potato crops are infected by a large number of aphid-transmitted viruses resulting in yield loss and degeneration of seed stocks. These viruses are transmitted by a large number of colonizing and non-colonizing aphids. The non-colonizing aphid species are mainly responsible for the spread of non-persistent viruses like potato virus Y (PVYo). The cabbage aphid, Brevicoryne brassicae L, an important pest of cruciferous crops, is a non-colonizing aphid visiting potato crops transiently. We evaluated the relative prevalence of cabbage aphids in potato crops at four locations namely, Jalandhar (Punjab), Shimla (Himachal Pradesh), Modipuram (Uttar Pradesh) and Kalyani (West Bengal), where most of the seed and ware potato production is carried out in India. The cabbage aphids constitute an appreciable proportion (3.57% to 19.04%) of the aphid population on potato plants at these locations. The cabbage aphids were found to successfully acquire and transmit the PVYo from and to potato plants. The virus transmission efficiency came out to be 11.25%, with a relative efficiency factor (REF) of 0.13, in comparison to the peach-potato aphid, Myzus persicae (Sulzer). This is the first report of B. brassicae being a vector of PVYo in India. Therefore, isolation of seed potato crops from cruciferous crops or stringent management of the aphids on the latter is necessary for production of healthy seed potatoes.