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 diff er, amongst several other traits, in the composition of their cuticula r hydrocarbons. These compounds are thought to be involved in chemical communication during courtship. Here we report that cuticular hydroca rbon composition differs between the sexes and that a narrow dine for cuticular hydrocarbons separates the subspecies. The dine centre is di splaced 15 km north of the majority of dines reported for other charac ters. This unusual lack of coincidence is discussed with reference to its possible causes and its consequences for the sexual communication system of Chorthippus parallelus.