A Comparative Study of Mating Behaviour in Some Neotropical Grasshoppers (Acridoidea)

Aspects of premating and mating behaviour in several South American grasshopppers (Acridoidea) are described and compared. Examples of communication by acoustical, visual and chemical means are given.

Acoustic signals are emitted only by species of the subfamilies Gomphocerinae, Acridinae, Romaleinae and Copiocerinae. Each subfamily has distinct sound-producing mechanisms, and the songs occur in different behavioural contexts. In Gomphocerinae and Acridinae the sexes recognize and attract each other by species-specific songs produced by a femuro-tegminal stridulatory mechanism. In contrast, Romaleinae produce a simple song by rubbing the hindwings against the forewings. These songs are similar in different species and no attraction of females could be demonstrated, but the behaviour may function in male-male interaction and during copulation. Sexual pheromones also play a role in this subfamily. Acoustic activity during copulation has been observed in Aleuasini (Copiocerinae), but its function is still unclear.

No sound production at all exists in the Leptysminae, Rhytidochrotinae, Ommatolampinae, Melanoplinae, Proctolabinae and Bactrophorinae, but conspicuous movements of hindlegs (kneewaving) and antennae were observed. In some species these form part of a soundless courtship display.

Ecological constraints have little influence on the basic mating strategies: romaleine, gomphocerine and melanopline grasshoppers often coexist in various habitats, but show the divergent behaviour patterns characteristic of their respective subfamilies. Intrinsic factors of female reproductive physiology seem to be more important: a hormonally controlled reproductive cycle in gomphocerine females provides for only few short copulations, while romaleine females copulate frequently and longer. In Gomphocerinae and Acridinae, receptive females are rare (male-biased operational sex ratio) which leads to intense competition among males. It is hypothesized that this could be responsible for the high diversification of song and courtship patterns in these subfamilies.