Rapid hormonal rise in honey bees due to heat-shock is mitigated by a primer pheromone

Honey bee workers undergo age-related task transitions, with the shift from nursing to foraging modulated by the primer pheromone ethyl oleate (EO). The amount of this pheromone is high in foragers, and it presumably suppresses the programmed increase of juvenile hormone (JH) titers in younger honey bees when foragers are present. However, there is no direct evidence of whether this pheromone can modulate JH titers. Here, we show that while heat stress elevated JH levels in isolated honey bee foragers, this effect was absent when bees were housed in groups. Moreover, when isolated honey bee foragers were under heat stress and EO was directly applied (5.5 mg per glass vial) a similar modulation in JH was observed as in grouped bees. These results identify a novel role for EO in mitigating physiological stress, and highlight pheromonal communication as a mechanism of social buffering that enhances colony resilience to environmental stress. Our simple thermal stress assay provides a valuable tool for future investigations into endocrine regulation and colony resilience.