Fig. 1. Gas chromatographs (FID) with coupled electroantennograms (EAD) from Colorado potato beetles in response to volatiles emitted over a 3 h test period by an undamaged potato plant (A), a mechanically damaged potato plant (B), 10 female beetles feeding on a potato plant (C) and 10 male beetles feeding on a potato plant (D). EADs in A, C and D were recorded from female antennae; the EAD in B was recorded from a male antenna. A, nonanal; B, 2-phenyl ethanol; CPB I, male-specific compound; IS, internal standard (10 ng of decane); Sesquiterpene region, retention times of various sesquiterpenes. No differences were observed between EADs of male and female antennae.