Wound-induced increases in the glucosinolate content of oilseed rape and their effect on subsequent herbivory by a crucifer specialist

Damage to the oilseed rape plant (Brassica napus L.) by the cabbage stem fl ea beetle, Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae) induces systemic changes to the glucosinolate profile, most noticeably an increase in the concentration of indole glucosinolates. When jasmonic acid was appli ed to the cotyledons of the plant, a similar effect was observed. Feeding t ests with artificial substrates compared a glucosinolate fraction from jasm onic acid-treated plants with a similar fraction from untreated plants. In these tests, alterations to the glucosinolate profile increased the feeding of a crucifer-specialist feeder (P. chrysocephala). However, in whole plan t tests, P. chrysocephala did not feed more on the jasmonic acid treated pl ants than on the controls. This implies that other aspects of the damage re sponse are being induced by the jasmonic acid treatment and having a negati ve effect on subsequent herbivory.