Abstract

In greenhouse studies, apterous turnip aphids, Lipaphis erysimi (Kaltenbach), reared on ‘Shogoin’ turnip had a longer prereproductive period, produced fewer progeny, and were smaller than their counterparts reared on ‘Purple Top White Glob’ (PTWG) turnip. Similarly, alate aphids reared on radish and placed on turnip as prereproductive adults, produced fewer progeny on Shogoin than on PTWG. Experiments in which apterous aphids were reared on one cultivar and transferred to the other as prereproductive adults suggested that the resistance of Shogoin operates primarily against the reproductive adult turnip aphid.

In 3 field plantings, turnip aphids were 3X more abundant on PTWG than on Shogoin in the one planting in which well-established aphid populations were observed. The green peach aphid, Myzus persicae (Sulzer), and the cabbage aphid, Brevicoryne brassicae (L.), were significantly more abundant on Shogoin than on PTWG in one planting, but not in 2 others. Larvae of the diamondback moth, Plutella xylostella (L.), were significantly more abundant on Shogoin than PTWG in 2 of the 3 experimental plantings.

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