A bending wave simulator for investigating directional vibration sensing in insects

Substrate vibrations are important in social and ecological interactions fo r many insects and other arthropods. Localization cues include time and amp litude differences among an array of vibration detectors. However, for smal l species these cues are greatly reduced, and localization mechanisms remai n unclear. Here we describe a method of simulating the vibrational environm ent that facilitates investigation of localization mechanisms in small spec ies. Our model species was the treehopper Umbonia crassicornis (Membracidae ; length I cm), which communicates using bending waves that propagate along plant stems. We designed a simulator consisting of a length of dowel and t wo actuators. The actuators were driven with two time signals that created the relationship between slope and displacement characteristic of steady-st ate bending wave motion. Because the surface of the dowel does not bend, as would a natural stem, close approximation of bending wave motion was limit ed to a region in the center of the dowel. An example of measurements of th e dynamic response of an insect on the simulator is provided to illustrate its utility in the study of directional vibration sensing in insects. (C) 2 001 Acoustical Society of America.