STUDIES ON MALE DRONES YIELD NEW INSIGHTS INTO THE MECHANISM UNDELYING ODOR-MEDIATED SOCIAL BEHAVIOR IN THE HONEY BEE (Apis mellifera L.)

Open Access
- Author:
- Villar, Gabriel
- Graduate Program:
- Entomology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 05, 2016
- Committee Members:
- Christina Grozinger, Dissertation Advisor/Co-Advisor
Thomas Charles Baker, Committee Chair/Co-Chair
Heather M Hines, Committee Member
N/A, Committee Member
Victoria Anne Braithwaite-Read, Outside Member - Keywords:
- Honey bee
Drone
Pheromone
Chemical Ecology
Behavior
Olfaction - Abstract:
- Understanding how chemical signals cause specific changes in behavior, and how these behavioral responses are modulated (possibly due to modifications to the complexity of the signal, how it is detected and/or processed by the olfactory system, and how distinct physiological states of the receiver may impact receptivity to a signal) remain outstanding questions in the fields of chemical ecology and neuroethology. Here I employed comparative studies in honey bees, and primarily utilized drones, to gain new insights into the mechanisms that underlie odor-mediated behavior in this eusocial insect. We have identified that the mechanisms driving maturation-related differences in behavioral receptivity to the queen are likely based in the central brain, not in the peripheral nervous system. This is in contrast with sex-associated differences in response to the queen, which appear to have a significant basis in the periphery (Chapter 2). In Chapter 3, we tested the theory that social pheromones may have evolved from sex pheromones. Our findings on the sex and social pheromone 9-ODA did not support this theory, as we found that the pathways in which 9-ODA affect worker and drone physiology and behavior are likely shared. In testing this theory we also identify a new primer pheromone in honey bees that affects males, a relatively rare biological phenomenon. Pheromone communication in honey bees regulates the social environment and is based on the complexity of the pheromone signal and differential processing based on the receiver’s caste and physiological state. Pheromone profile shifts in response to changes in the queen reproductive physiology further modulate social responses in workers. In Chapter 4 we demonstrate that drones are also receptive to these changes and propose that this may be a mechanism driving drone-queen interactions in and out of the colony. In Chapter 5, we identify the compounds produced in the drone mandibular gland and confirm their biological activity. This is a critical first step in understanding how drones are navigating their social environment. In considering these findings, multiple significant conclusions emerge. First, drones are engaging in their social environment through a more complex chemical communication system than the research community has previously anticipated. Drones are receptive to the same pheromones as workers and are able to respond accordingly to different aspects of pheromone complexity (compounds, blend specificity, and now, profile shifts). Furthermore, they may also be producing their own pheromones, elaborating on the already complex communication system of honey bees. Going forward, drones are likely to prove their value as a resource in advancing our understanding of social behavior and its underlying odor-mediated mechanisms.