Behavioral bioassays of termite trail pheromones : Recruitment and orientation effects of cembrene-A inNasutitermes costalis (Isoptera: Termitidae) and discussion of factors affecting termite response in experimental contexts.

The monocyclic 14-membered ring diterpene, cembrene-A, previously identified as a nasutitermitine trail pheromone, was tested for its effectiveness as a trail pheromone inNasutitermes costalis. Artificial trails prepared from serial dilutions of racemic cembrene-A over a concentration range of 10(-1)-10(-6) mg/ml were ineffective in recruiting termites. Serial dilutions of racemic cembrene-A ranging in concentration from 10(-1) to 10(-5) mg/ml produced an orientation effect. Chiral cembrene-A produced recruitment in soldiers at 10(-1) and 10(-3) mg/ml and was less ineffective in recruiting workers. Soldiers always showed a lower and more variable recruitment response to chiral cembrene-A than to sternal gland extracts. The behavioral response to both chiral and racemic cembrene-A was different in quantity and quality from that observed for sternal gland extract. Based on the results of these behavioral tests, cembrene-A appears to be a generalized nasute orientation pheromone which may show recruitment properties at unnaturally high concentrations.