Dehydroabietic acid, an aromatic abietane diterpenoid, attracts termite workers

Subterranean termites primarily use decaying wood as both nest material and food, and the worker caste is responsible for searching for new wood. Because brown-rotted wood contains (Z,Z,E)-3,6,8-dodecatrien-1-ol, which is a trail pheromone component in Reticulitermes termites, it is considered that this compound attracts termite workers. However, while the trail pheromone allows passing workers to continue to move along it, it is unlikely to attract them from a distance. Therefore, workers should use other attractants derived from decaying wood as cues to locate it. In this study, we found that an aromatic abietane diterpenoid in termite culture medium made from brown-rotted Japanese red pine (Pinus densiflora) attracted workers of the Japanese subterranean termite Reticulitermes speratus (Kolbe) (Isoptera: Rhinotermitidae). Gas chromatography analyses and behavioral assays revealed that the n-hexane extract of the medium contains dehydroabietic acid, which is a resin component of various conifers, and this compound attracts workers. These results strongly suggest that R. speratus workers mainly use this compound as a cue to locate brown-rotted pinewood in nature. Our study contributes to the understanding of the mechanisms of wood detection in termites.