Inter- and intrapopulation effects of sex and age on epicuticular composition of meadow grasshopper, Chorthippus parallelus

We analyzed patterns of variation in cuticular lipids across and within five populations of the meadow grasshopper Chorthippus parallelus. This revealed considerable differences between the sexes and between populations and differences in the pattern of sexual dimorphism between populations. The presence of sexual dimorphism and the extent of differences between populations suggests that divergence has been driven by sexual selection acting through a contact pheromone on the cuticle. However, those lipids that differ most between the sexes are not the same as those that vary the most between populations, suggesting that sexual selection alone is not responsible for driving divergence in cuticular composition. We also examined differences in cuticular composition with adult age, revealing that the proportion of all but one of the 14 lipid classes we identified changes significantly with age in at least one population. Overall the pattern of variation with age is fairly consistent across populations, with the proportion of shorter-chain compounds increasing with age.