Identification of volatile potato sesquiterpenoids and their olfactory detection by the two-spotted stinkbug Perillus bioculatus

The predaceous stinkbug Perillus bioculatus is attracted towards volatiles emitted by damaged potato plants. Whereas mechanically damaged plants lost attractiveness 1 h after damage was indicted, attraction was long-lasting when the plants were damaged by Colorado potato beetles Leptinotarsa decemlineata, a prey of P. bioculatus. A range of sesquiterpenoids was previously shown to be induced upon beetle damage. In order to evaluate the potential role of sesquiterpenoids in the attraction response, volatiles from damaged potato plants were collected and analyzed with GC-MS and GC-EAG. The antennae of P. bioculatus responded to beta-caryophyllene, alpha-humulene, (E)-beta-farnesene, (-)-germacrene D, and germacrene D-4-ol. Two sesquiterpenes that coeluted, alpha-zingiberene and bicyclogermacrene, together also elicited olfactory responses of P. bioculatus, whereas the individual compounds did not. The response of P. bioculatus to a variety of sesquiterpenes at low dosages suggests a role for these compounds in prey detection of this stinkbug.