How dancing honey bees keep track of changes in their environment

Honey bee colonies are able to adjust and reallocate their foraging resources efficiently when foraging conditions in their environment change. This is achieved by two mechanisms: in the short term, bees who had previously foraged at a food source make occasional return visits to that food source and resume foraging if its quality improves; in the long term, foraging bees use the waggle dance to transmit information about the quality and location of newly found food sources to their colony mates.

HFSP Program Grant holders David Sumpter and Madeleine Beekman and colleagues
authored on Tue, 24 April 2012

The ability to efficiently reallocate foraging resources in a rapidly changing environment can be of vital importance to a honey bee colony. Previously, two complementary mechanisms have been identified by which bees can effectively switch between food sources when their relative quality changes. One of these mechanisms is the waggle dance, a symbolic language used by foraging bees to relay information about the quality and location of a particular food source to their colony mates. When the quality of a food source increases, the duration and intensity of the waggle dances increase with it. The other mechanism is inspection, where bees that had previously stopped foraging at a food source keep making occasional return visits to that food source and resume foraging if its quality improves.

Figure: Bees foraging at a high quality feeder. Some of the bees are marked with feeder-specific colors

In order to study the relative importance of the waggle dance and inspector bees, we used a combination of field experiments and mathematical modeling. To test the importance of dance language on the colony’s ability to adapt to changing foraging conditions, we needed to prevent the bees from transferring directional information. We achieved this by eliminating the cues dancing bees usually use to orient the dance. We used a white sheet to diffuse light and prevent the bees from orienting towards polarised light, and placed the hive on its side (horizontally) to eliminate gravitational cues. Without dance language information, bees should not be able to track changes in their environment at the colony level. Our results suggest that even a large reduction in the ability of bees to pass on directional information has a negligible effect on colony level response to changes in food quality.

We then used a state-based mathematical model to examine the experimental results. Introducing inspector bees into the model, we were able to replicate the results of the experiments and see that colonies are able to successfully allocate their resources to the best available food source in the short term even without dance language information. The model also predicts that over a longer period of time, when the inspector bees cease making return visits to their previous food sources, the colony will not be able to switch to the best food source once dance information is removed. This implies that the waggle dance is particularly important in helping colonies reallocate foraging resources when environmental changes occur over longer time periods.

Our results show that a combination of individual memory, in the form of inspector bees, and collective communication, in the form of the waggle dance, can interact to allow a social insect colony to adapt to changes on both short and long time scales.

Text by Boris Granovskiy

Reference

How dancing honey bees keep track of changes: the role of inspector bees.  Boris Granovskiy, Tanya Latty, Michael Duncan, David J. T. Sumpter, Madeleine Beekman. Behavioral Ecology 23(3):588-596doi:10.1093/beheco/ars002

Pubmed link