Variations on a Theme: Cerambycid Beetles Use Lactone Stereoisomers to Optimize Use of Pheromone Chemical Space.

Three different diastereomers of 6-ethyl-3,5-dimethyltetrahydro-2H-pyran-2-one (henceforth lactone) were identified from male-specific volatiles produced by the neotropical cerambycid beetles (subfamily Lamiinae) Atrypanius lignarius (Bates), Oedopeza umbrosa (Germar), and Oreodera glauca glauca (L.). Atrypanius lignarius produced one of the enantiomers of the (3R*,5S*,6S*)-diastereomer, whereas O. umbrosa produced the (3S,5S,6R)-lactone, and O. glauca glauca produced the (3S,5R,6S)-lactone. In field bioassays, the O. umbrosa (3S,5S,6R)-lactone attracted only conspecific adults of both sexes. The racemic (3R*,5S*,6S*)-lactone was strongly attractive to A. lignarius, while also eliciting significant cross-attraction in O. umbrosa and also the lamiine cerambycid Aegomorphus jaspideus (Germar). Although O. glauca glauca was not captured during the trials, possibly because we were unable to carry out bioassays where it had originally been captured, the racemic (3S*,5R*,6S*)-lactone attracted the congener Oreodera quinquetuberculata (Drapiez), as well as A. lignarius, A. jaspideus, and O. umbrosa. These results suggest that the 6-ethyl-3,5-dimethyltetrahydro-2H-pyran-2-one structural motif, which attracted species of three tribes, may be widely shared within the Lamiinae, with species exploiting different stereoisomers to provide some degree of species specificity to their signals.