Fertility-associated pheromones, chemical signals delineating ovarian development, were favourably selected in the course of evolution because it is in the best interest of both the signallers (in recruiting help from other colony members) and the receivers (in assisting them to reach an informed decision of how to maximize fitness). Such signals therefore should constitute honest, deception-proof indicators of ovarian development, suggesting, theoretically, that the processes of ovarian development and signal production are irreversibly coupled. Here we demonstrate that these processes can be uncoupled by treating queenless (QL) honeybee callow workers with methoprene, a juvenile hormone (JH) analog. While methoprene effectively inhibited ovarian development, it neither inhibited Dufour's fertility signal nor the mandibular glands' dominance signal. In fact, there was even a slight augmentation of both in the methoprene-treated bees. Thus, although fertility and fertility signals are tightly associated, they can be uncoupled by experimental manipulation. These results are consistent with the hypothesis that ovarian development and fertility-associated signal production are triggered by a common event/signal (e.g. queen pheromone disappearance) but comprise different regulatory systems. The evolutionary implication is that these two traits have evolved independently and may have been co-opted to emphasize the reproductive status of workers in the competition for reproduction.
Bibliographical noteFunding Information:
This research was supported by The Israel Science Foundation founded by the Israel Academy of Sciences (ISF grant # 720/04 to Abraham Hefetz). We thank Shiri Shnior, Tovit Simon and Shani Inbar for their technical assistance. Josef Kamer and Haim Efrat from the Tzrifin Apiary for assistance in establishing the experimental hives, and Naomi Paz for editorial assistance.
- Primer pheromones
- Reproductive competition
- Worker reproduction