Abstract:
Mechanical factors can play an important role in insect-plant interactions. I will show examples of ant-plant interactions that are strongly determined by biomechanical adaptations. In the mutualism between ants and Macaranga trees, slippery waxy stems protect the specialized, 'wax-running' ant partners against generalist competitors that are unable to climb the stems. Macaranga wax barriers not only act as filters favoring specialist over generalist ants but also represent an ecological isolation mechanism leading to host specificity in this ant-plant system. The presence or absence of wax barriers has a variety of further implications on the biology of Macaranga-ant associations. I will show results of studies on the proximate mechanisms of slipperiness and wax-running capacity. In another ant-plant symbiosis, 'barriers' formed by the carnivorous pitcher plant Nepenthes bicalcarata are circumvented by the ant Camponotus schmitzi. Here, the capacity to escape the plant traps is not only based on superior attachment but also on the exceptional swimming behavior of this ant species.