Cabbage (Brassica oleracea var. Capitata) fails to show wound-induced defence against a specialist and a generalist herbivore?

Abstract

This paper presents tests of a model of wound-induced defence in herbaceous plants. Many studies have reported both chemical changes in leaves and changes in the behaviour and/or physiology of herbivores as a result of wounding leaves. These studies and others have led to the development of various models to explain wound-induced effects both in terms of plant response and herbivore behaviour. The model under test was proposed by Edwards and Wratten (1987) and predicts that wounding a plant will cause herbivores (1) to take more meals of a smaller size and/or consume less foliage overall (2) grow more slowly and (3) be more mobile. These predictions were tested in cabbage Brassica oleracea L. Var. Capitata cv. Pixie) with Pieris brassicae L. (Lepidoptera: Pieridae) as a herbivore specialising on cabbage, and Spodoptera littoralis Boisd. (Lepidoptera: Noctuidae) as a generalist herbivore. Both insects showed some reduction in consumption of leaves from upper parts of the plant, but no change in meal size. There were no effects on the growth or mobility of either species as a result of wounding foliage. These results are discussed in relation to the predictions of the model.