Acoustic Communication and Differences in the Biology of Two Sibling Species of Grasshoppers, Acrotylus insubricus and A. patruelis

In Israel, sexually mature adults of the sibling species of grashoppers Acrotylus insubricus (Scopoli) and A. patruelis (Herrich-Shaffer) occur both allopatrically and sympatrically. To distinguish between the 2 species in areas of sympatry and to help resolve their confused taxonomy, nonmorphological criteria were sought. The mating and acoustic behavior of these species and some aspects of their biology were therefore studies.

No species-specific differences in mating or acoustic behaviour were found. Stridulatory songs of the 2 species were similar for all parameters studied, as was substrate drumming, studied both as airborne sound and solidborne sound (i.e., substrate vibrations). No response to playback of either form of sound, or of substrate vibrations as such, was obtained under the conditions of our experiments.

Under identical conditions of incubation, eggs of A. patreulis hatched in a significantly hsorter time than those of A. insubricus, and gave rise to uniformly grey nymphs differing from the black-headed, light-bodied nymphs of the latter species. Under "no-choice" laboratory conditions, F1 hybrids were obtained from each of teh reciprocal parental crosses. Songs of hybrid males could not be distinguished from those of the parent species.