Identification and potential application of a putative allomone component in the defensive secretion of a destructive invasive species: the red-necked longhorn beetle, Aromia bungii

The red-necked longhorn beetle, Aromia bungii, is an invasive wood-boring insect that has recently invaded Europe and Japan, seriously damaging stone fruit trees in both native and invaded regions. Rose oxide, including both cis- and trans-isomers, was previously found in the volatiles produced by A. bungii adults, while the inter- and intra-specific behavioral functions of this compound remain unclear. By manually shaking the beetles, a much greater amount of rose oxide was released from the beetles, compared to that released from nondisturbed beetles. Rose oxide was further determined to be original from a white-colored secretion which was immediately sprayed by the beetles that were hand captured or squeezed by tweezers. These findings indicate that this pungent compound putatively has a role as an allomone component released from the defensive secretion by A. bungii adults when threatened, which may be an adaptive defensive strategy against the predation of natural enemies such as insectivorous birds. Y-tube olfactory assays revealed that rose oxide, at a high concentration, was significantly repellent to both sexes of A. bungii adults, suggesting that rose oxide may also have a function in the intraspecific communication of A. bungii. Considering the low price of the commercially available products, this repellent effect of rose oxide may facilitate the development of novel control strategies, such as push-pull strategy, for A. bungii.