Male-produced sex pheromone in Tribolium confusum: Behaviour and investigation of pheromone production locations

It is generally accepted that mating in flour beetles of the genus Tribolium is mediated by a male-produced aggregation pheromone. The pheromone production site in T. castaneum is believed to be glands on the ventral side of the femur. Behavioural experiments with the confused flour beetle T. confusum were conducted using extracts of beetles and different body parts as well as live beetles to investigate the responses to the complete odour bouquet released from the beetles. In our experiments, females but not males were attracted to male-produced volatiles, corresponding to the definition of a sex pheromone rather than an aggregation pheromone. SEM pictures confirm the occurrence of glands on all three pairs of legs of male T. confusum, but behavioural experiments show that females are attracted not only to extracts of male legs but also to whole body extracts and extracts of bodies without legs. These data suggest that in this species attractive compounds are produced not only in the glands on the femurs but also at multiple locations. Thus the pheromone systems involved in mating of flour beetles may be more complex than previously reported and differ among closely related species.