Comparison of forced mating behaviour in four taxa of Anonconotus, the Alpine bushcricket

Forced or coercive copulation is known to occur in a variety of insect taxa but until recently, this behaviour had not been recorded in crickets and bushcrickets (Orthoptera: Ensifera). The aim of the present study was to investigate forced mating behaviour in four taxa of Anonconotus Camerano 1878 (Orthoptera: Tettigoniidae), comparing the recently documented forced mating behaviour in the Alpine bushcricket Anonconotus alpinus ghilianii with those of Anonconotus alpinus alpinus, Anonconotus pusillus and Anonconotus baracunensis occidentalis under both laboratory and semi-natural field conditions. In all four taxa, males did not sing to attract females, but instead initiated copulation by stalking the female before leaping onto her and using the sharply pointed cercal spurs to maintain a hold on the female's abdomen. In A. a. ghilianii and A. a. alpinus, the positioning of the male's hind legs appeared to impede the movement of the female's hind legs during copulation. In Anonconotus baracunensis, the duration of copulation was considerably longer than in the other species, lasting a mean of 153 min in the laboratory and 40 min in field enclosures (compared with a mean of 7-9 min in the other taxa). This longer duration of copulation, which occurred following spermatophore attachment, is interpreted as functioning to prolong ejaculate transfer by preventing the female from eating the external portions of the spermatophore. In support of this, male A. baracunensis were found to produce a significantly greater ejaculate mass compared with the other Anonconotus taxa. We propose that members of the genus Anonconotus would make an excellent novel model system for the study of forced copulation from a sexual conflict perspective.