Stridulatory pattern generation in acridid grasshoppers: metathoracic interneurons in Stenobothrus rabicundus (Germar 1817)

Stridulation was elicited in tethered gomphocerine grasshoppers of the spec ies Stenobothrus rubicundus in order to identify interneurons of the stridu lation pattern generator, and describe their morphological and physiologica l properties. Nine types of such neurons could be found and characterized; eight of those could additionally be compared to corresponding neuron types previously known from other species. As shown in detail for one selected t ype, the neurons of the stridulation pattern generator are very similar in their anatomical appearance, and possess similar physiological qualities at least in two species with similar stridulation patterns. Stridulation inte rneurons of species with largely different stridulatory motor patterns have a similar morphology, but show a different activation timing throughout th e stridulation. Nevertheless, special properties such as resetting or initi ation capability of certain stridulation interneurons seem to be conserved throughout the species. The results suggest that the stridulation pattern g enerator of different species consists of a uniform set of interneurons tha t change their activity pattern to produce species-specific song movements.