WOUND-INDUCED CHANGES IN TOMATO LEAVES AND THEIR EFFECTS ON THE FEEDING PATTERNS OF LARVAL LEPIDOPTERA

Several studies have shown changes in the pat terns of damage from fee ding insects associated with changes in palatability and overall consu mption as a result of wound-induced chemical changes in plants. This p aper describes how the pattern of feeding damage made by the larvae of Spodoptera littoralis Boisd. (Lepidoptera: Noctuidae) on tomato is af fected by changes in palatability of the leaves. Two sorts of response s to leaves from plants that had received prior damage were observed. Larvae offered a choice of leaves tended to take fewer meals on leaves from previously-wounded plants than on control leaves, frequently rej ecting the former after sampling them. On wounded plants this rejectio n behaviour was associated with a shift in feeding site towards the ba se of the plant. However, starved larvae offered only a single excised leaf readily ate leaves from wounded plants but took shorter meals on these leaves than on controls. Although it was not directly tested it is possible that this difference in response reflected chang es in fo od selectivity with a differing level of satiation. The results are co nsidered in relation to the adaptive significance of the plant of chan ges in within-plant distributions of herbivore damage.