Induction of cotton extrafloral nectar production in response to herbivorydoes not require a herbivore-specific elicitor

The production of extrafloral nectar is thought to represent an indirect pl ant defense, as it allows plants to recruit natural enemies which can prote ct the plant against herbivore attacks. In previous work we demonstrated th at plants may show a strong increase in extrafloral nectar secretion in res ponse to herbivory. Here we address the question of whether this induction is herbivory-specific, or simply a general response to tissue damage. We co mpared the level of induction in Gossypium herbaceum (L.) (Malvaceae) follo wing either herbivory by Spodoptera littoralis (Boisduval) (Lepidoptera; No ctuidae) or mechanical damage with and without the addition of S. littorali s regurgitate. Both herbivore feeding and mechanical damage significantly r aised nectar production. No difference in volume or pattern of nectar secre tion was found between natural and mechanical damage, nor between artificia lly damaged plants treated with regurgitate or water. Our findings indicate that the induction of extrafloral nectar secretion constitutes a general r esponse by the plant to tissue damage, rather than representing a herbivory -specific mechanism. The costs and benefits of such a non-specific strategy for the plant are discussed.