Abstract booklet - gtö – Society for Tropical Ecology

100 PARALLEL SESSION HALL H III | ECOLOGICAL NETWORKSPARALLEL SESSION HALL H IV | ANIMAL PLANT INTERACTION 101WEDNESDAY 12:15 Hall H IIIlevel and hence no clear sign for convergent species trait-habitat evolution atthe global scale. Species trait–habitat relation patterns rather varied betweencontinents, which highlights the importance of recent historical effects and localsite filters in shaping trait-habitat relations and hence determining functionalcomposition in local communities. These results highlight the importance ofintegrating trait-habitat links into analyses of biological communities as thiswould enhance predictive power and general usefulness of species assemblyrules in community ecology and macro-ecology. Convergence studies can alsoyield general models for predicting fundamental community patterns and theyprovide essential tools for large scale species distribution models if trait-habitatlink information is included.PARALLEL SESSION WEDNESDAY 10:00, Hall HIV:ANIMAL PLANT INTERACTIONChair: Georg ZizkaDELAYED INDUCTION OF PLANT DEFENCES BY LEAF-CUTTINGANTS: UNVEILING THE SECRETS OF A KEY HERBIVORE?Rainer Wirth 1 , Martin Tremmel 2 , Jörg Stephan 1 , Christian Kost 31Department of Plant Ecology and Systematics, University of Kaiserslautern,Kaiserslautern, DE, wirth@rhrk.uni-kl.de, 2 Present address: Department ofChemical Ecology, University of Bielefeld, Bielefeld, DE, 3 Max Planck Institute forChemical Ecology, Jena, DELeaf-cutting ants (LCAs) are omnipresent features of neotropical landscapesthat drastically influence present-day forest structure and composition. Theseants are known as polyphagous, yet highly selective herbivores. The factors thatgovern their selection of food plants, however, remain poorly understood. Wehypothesized that the induction of anti-herbivore defences by attacked foodplants, which are toxic to either ants or their mutualistic fungus, should affectfood plant selection and elucidate a series of hitherto unresolved questions onthe ants’ foraging behavior. To test this ‘induced defence hypothesis’, we usedlima bean (Phaseolus lunatus), a plant that - upon herbivore attack - emitsmany volatile organic compounds (VOCs) with known anti-fungal or antrepellenteffects. While a 20% removal of a plant’s total leaf area by workersof the LCA Atta colombica did not influence its VOC emission rate after 24 h,extending the damage treatment to a total of 4 d significantly increased VOCemission levels in damaged plants relative to controls. In contrast, leaf loss dueto a chewing herbivore of approximately 15% of a plant’s total leaf area wasalready sufficient to significantly increase VOC emission levels within 24 h. Indual choice bioassays, foraging workers were strongly attracted to plants thathave been damaged mechanically or by LCAs 24 h ago. On the other hand,strong induction levels of experimental plants after treatment with the planthormone jasmonic acid or, alternatively, 4 d of LCA feeding strongly repelledLCA foragers relative to control plants. These findings offer two valuableinsights in the foraging ecology of LCA. First, they support the ‘induced defencehypothesis’ that predicts a strong effect of inducible anti-herbivore defences onthe foraging behaviour of LCAs. Second, the delayed activation of the plant’santi-herbivore defences observed after LCA damage is a novel mechanismused by an herbivore to quickly remove larger quantities of leaf material beforebeing recognized by the plant. In this way, a LCA colony can maximize its intakeof plant biomass suitable for the cultivation of its mutualistic fungus.WEDNESDAY 10:00 Hall H IVgtöSociety for Tropical Ecology | Gesellschaft für Tropenökologie e.V. Status and future of tropical biodiversity | Frankfurt, 21 - 24 February 2011gtö