Active Processes in Insect Hearing

Abstract

Active mechanical processes in hearing are not restricted to vertebrates: as shown by recent research, such processes are found in insects as well. The investigation of these amplificatory processes in insect hearing has scarcely begun. Many questions are outstanding, including perhaps the most intriguing one, that is, whether, reflecting the need for sensitive hearing, the mechanisms that effect active amplification in the ears of insects and vertebrates are related or have evolved independently. In either case, the discovery of active auditory processes in insects means that the structurally diverse hearing organs of insects can now be used to investigate the mechanisms and the structural basis of these processes and their physical implementation into ears. The scopeof this chapter is to reviewour current knowledgeof activemechanical processes in insect hearing. Starting with a brief description of the anatomy of insect ears and auditory mechanosensory cells, evidence for the existence of active auditory mechanics in insects is summarized and information about its cellular and molecular basis is discussed. Readers interested in more-detailed accounts on the anatomy, the physiology, the genetics, and the evolutionary history of hearing in insects may want to refer to some recent reviews dedicated to these topics (Hoy and Robert 1996; Eberl 1999; Yager 1999; Caldwell and Eberl 2002; Jarman 2002; Robert and Gopfert 2003, 2004) and to a volume on hearing in insects that has appeared earlier in this series (Hoy et al.1998).