Time-restricted foraging under natural light/dark condition shifts the molecular clock in the honey bee, Apis mellifera

ABSTRACT

Honey bees have a remarkable sense of time and individual honey bee foragers are capable of adjusting their foraging activity with respect to the time of food availability. Although, there is compelling experimental evidence that foraging behavior is guided by the circadian clock, nothing is known about the underlying molecular mechanisms. Here we present for the first time a study that explores whether time-restricted foraging under natural light-dark (LD) condition affects the molecular clock in honey bees. Food was presented in an enclosed flight chamber (12 m × 4 m × 4 m) either for 2 hours in the morning or 2 hours in the afternoon for several consecutive days and daily cycling of the two major clock genes, cryptochrome2 (cry2) and period (per), were analyzed for three different parts of the nervous system involved in feeding-related behaviors: brain, subesophageal ganglion (SEG), and the antennae with olfactory sensory neurons. We found that morning and afternoon trained foragers showed significant phase differences in the cycling of both clock genes in all three tissues. In addition, the phase differences were more pronounced when the feeder was scented with the common plant odor, linalool. Together our findings suggest that foraging time may function as a Zeitgeber that might have the capability to modulate the light entrained molecular clock.

KEYWORDS:

• Honey bees
• time-restricted foraging
• clock genes
• olfactory cues
• food entrainment

Supplemental material

Supplemental data for this article can be accessed here.

Acknowledgements

We thank Ravi Boyapati for helping in sample collection and Ebi Antony George for helping in statistical analysis. We also thank Sheeba Vasu, Sruthi Unnikrishnan, and members of the bee group for valuable comments on earlier versions of the manuscript.

Conflict of interest statement

The authors declare that there is no conflict of interest.

Additional information

Funding

R.J. was supported by Indian Council of Medical Research (ICMR) fellowship; A.B. was supported by NCBS-TIFR institutional funds No. 12P4167.