LEAF WAXINESS AND THE PERFORMANCE OF LIPAPHIS-ERYSIMI (KALTENBACH) (HOMOPTERA, APHIDIDAE) ON 3 BRASSICA CROPS

The amount of wax on leaf surfaces was determined for waxy and low-wax phenotypes of three Brassica crops: oilseed rape, kale, and collards. The effects of these phenotypes were assessed on the fecundity, settling time, and biomass increase of the mustard aphid, Lipaphis erysimi (Kaltenbach), a pest of oilseed rape. Leaves of the waxy phenotype of each Brassica had about twice as much wax as the low-wax phenotype, but the amount of wax had no effect on any of the three measures of aphid performance. Lipaphis erysimi was more fecund and produced a higher biomass on the rape than on the collards, but settled more quickly on the collards than on rape. If the waxiness of oilseed rape is altered to increase crop resistance to other pests, the pest status of L. erysimi is unlikely to be affected.