Sound or Vibration, an Old Question of Insect Communication

Abstract

About one hundred years ago, one of the pioneers of bioacoustics, Johann (Ivan, Joannes) Regen, born in Slovenia and living later in Vienna, investigated acoustic communication in crickets and bushcrickets. Despite many convincing results, he had a difficult dispute with a physiologist Otto Ernst Mangold to prove his ideas about airborne sound communication in insects. Eventually, he succeeded to persuade him with a series of imaginative experi- ments. However, his findings are by far not valid for all groups of insects. When I started to investigate acoustic communication in Heteroptera with my students and coworkers about half a century later, the question of their communication channel was not clear. After some critical experiments, it became evident that they emit and receive substrate-borne vibrational signals. Similar experiments were per- formed with ‘‘small cicadas’’ by Ichikawa, Strübing and Traue, who also came to the conclusion that they use substrate vibration as a communication channel. Nowadays, we know that the majority of Hemiptera and also many other insects use the vibrational channel for acoustic communication, some others use true sound or near field airborne vibrations, but not to forget acoustic signalization in aquatic and semiaquatic insects. However, some insects apparently use both channels for acoustic communication or orientation.