Definitive evidence for cuticular pheromones in a cricket

The Orthoptera include many species established as important model systems in the study of animal behaviour, particularly in relation to communication and mating systems. Although most interest has focused on auditory communication, increasing circumstantial evidence suggests that there may be a widespread additional communication channel in the form of cuticular contact pheromones. Using the field cricket, Gryllus bimaculatuswe conducted a behavioural assay which demonstrated that males can distinguish the sex of conspecifics using such a channel. Male response to females (courtship song) was completely abolished by using an organic solvent to remove cuticular hydrocarbons and associated compounds from a stimulus female. It was subsequently restored by painting the washed female with the dissolved extract. This technique controls for the possibility, inherent in previous tests, that the lack of response to washed body parts might be due to the washing process itself. The composition of the cuticles of males and females was analysed using gas chromatography. This revealed that the two sexes differ markedly in the quantities of the majority of the compounds found in the cuticular extract that had previously been shown to be used in mate recognition. This suggests that mate recognition is likely to be due to the relative concentrations of several cuticular compounds, rather than a single 'sex pheromone'. It supports previous assertions of the existence of contact pheromones in the Orthoptera, suggesting that they may be widespread in this group.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour