SOUND-PRODUCING ORGANS AND MECHANISM OF SONG PRODUCTION IN FIELD CRICKETS OF THE GENUS ACHETA FABRICIUS (ORTHOPTERA, GRYLLIDAE)

Abstract

A comparative study of the sound-producing organs of Acheta rubens, A. assimilis, a "northern spring species" (NSS), and A. pennsylvanicus reveals that the size of tegmen, harp, resonator, and file have no taxonomic value. The tooth-number in the file, however, is a useful additional character in the identification of males of different species of Acheta.The stridulatory organs of both the tegmina are equally efficient. The removal of the lateral or apical parts of either or both tegmina does not affect the modulation quality of the song, it only lowers the intensity. At the time of stridulation only about one-third of the tile is engaged by the scraper and it is the inward movement of the tegmina that produces the song. The kind of song depends on the elevation of the tegmina. A pulse is produced when the tegmina move inward, followed by a non-pulse period due to outward movement of the tegmina. Each pulse consists of a number of 'spikes' (seen in audiospectrographs) each of which is formed by a tooth being struck.