A bending wave simulator for investigating directional vibration sensing in insects

Substrate vibrations are important in social and ecological interactions for many insects and other arthropods. Localization cues include time and amplitude differences among an array of vibration detectors. However, for small species these cues are greatly reduced, and localization mechanisms remain unclear. Here we describe a method of simulating the vibrational environment that facilitates investigation of localization mechanisms in small species. Our model species was the treehopper Umbonia crassicornis (Membracidae; length 1 cm), which communicates using bending waves that propagate along plant stems. We designed a simulator consisting of a length of dowel and two actuators. The actuators were driven with two time signals that created the relationship between slope and displacement characteristic of steady-state bending wave motion. Because the surface of the dowel does not bend, as would a natural stem, close approximation of bending wave motion was limited to a region in the center of the dowel. An example of measurements of the dynamic response of an insect on the simulator is provided to illustrate its utility in the study of directional vibration sensing in insects.