Can Ips typographus (L.) (Col., Scolytidae) smell the carrion odours of the dead beetles in pheromone traps? Electrophysiological analysis

Head‐space samples of Ips typographus dead beetles taken from pheromone traps were tested by combined gas chromatography and electroantennographic detection (GC–EAD) on the antennae of the same species, and identified by GC‐mass spectroscopy (MS). The GC‐EAD analysis showed that antennae of both sexes responded to 1‐hexanol and verbenone from the aeration samples, while the typical and strong carrion odours from the dead beetles such as dimethyl disulphide, 3‐methyl‐1‐butenol (isoamyl alcohol), 2,5‐dimethyl pyrazine and isovaleric acid elicited no antennal responses. The EAD active compounds, 1‐hexanol and verbenone, have been shown in earlier studies to be inhibitory on attraction of I. typographus to pheromone traps. Thus, the decreased catching efficacy of pheromone traps with many dead beetles might be the result of the release of 1‐hexanol and verbenone from the dead beetles, but not to the typical carrion smells which are strongly detected by the human nose.