VARIATION IN CUTICULAR HYDROCARBONS ACROSS A HYBRID ZONE IN THE GRASSHOPPER CHORTHIPPUS-PARALLELUS

Two subspecies of the meadow grasshopper Chorthippus parallelus form a hybrid zone across the mountains of the Pyrenees. The subspecies differ, amongst several other traits, in the composition of their cuticular hydrocarbons. These compounds are thought to be involved in chemical communication during courtship. Here we report that cuticular hydrocarbon composition differs between the sexes and that a narrow dine for cuticular hydrocarbons separates the subspecies. The dine centre is displaced 15 km north of the majority of dines reported for other characters. This unusual lack of coincidence is discussed with reference to its possible causes and its consequences for the sexual communication system of Chorthippus parallelus.