Identification of a worker aggregation pheromone in the termite Reticulitermes flavipes

The colony organization of social insects is primarily maintained through pheromone-mediated communication. In most subterranean termites, workers forage for new decaying wood resources to expand their nesting areas, and after finding new resources, they exploit and connect the wood resources with tunnels. Since each wood has a different nutritional value and the nutritional requirement of the colony should change from time to time, it would be advantageous for workers to communicate information about the most suitable food source at a given time. However, such a communication mechanism has never been demonstrated. In this study, we identified the chemical profile of the worker aggregation pheromone in the termite Reticulitermes flavipes and revealed that the workers’ response level to aggregation pheromones is influenced by the food type that the workers recently fed on. Bioassays and gas chromatography-mass spectrometry analysis indicated that the pheromone consists of the mixture of 3-ocatanone, fatty acids (myristic acid, pentadecanoic acid, palmitoleic acid, and margaric acid), cholesta-3,5-diene, and cuticular hydrocarbons (including 21 compounds), and these compounds synergistically act as a worker attractant. Furthermore, our bioassays revealed that when workers from the same colony are divided into subpopulations and each subpopulation is fed a different food for two days, workers in each sub-group are attracted to the aggregation pheromone produced by workers on the same food that they were eating. These results suggest that workers of R. flavipes are able to transmit information about the type of food they are eating to their nestmates via their aggregation pheromone.