DEFINITIVE EVIDENCE FOR CUTICULAR PHEROMONES IN A CRICKET

The Orthoptera include many species established as important model sys tems in the study of animal behaviour, particularly in relation to com munication and mating systems. Although most interest has focused on a uditory communication, increasing circumstantial evidence suggests tha t there may be a widespread additional communication channel in the fo rm of cuticular contact pheromones. Using the field cricket, Gryllus b imaculatus, we conducted a behavioural assay which demonstrated that m ales can distinguish the sex of conspecifics using such a Channel. Mal e response to females (courtship song) was completely abolished by usi ng an organic solvent to remove cuticular hydrocarbons and associated compounds from a stimulus female. It was subsequently restored by pain ting the washed female with the dissolved extract. This technique cont rols for the possibility, inherent in previous tests, that the lack of response to washed body parts might be due to the washing process its elf. The composition of the cuticles of males and females was analysed using gas chromatography. This revealed that the two sexes differ mar kedly in the quantities of the majority of the compounds found in the cuticular extract thar had previously been shown to be used in mate re cognition. This suggests that mate recognition is likely to be due to the relative concentrations of several cuticular compounds, rather tha n a single 'sex pheromone'. It supports previous assertions of the exi stence of contact pheromones in the Orthoptera, suggesting that they m ay be widespread in this group. (C) 1997 The Association for the Study of Animal Behaviour.