Posted on 09/10/2012
Bumblebee with radar transponder (photographer: Andrew Martin)
Scientists from Royal Holloway, University of London, Queen Mary, University of London and Rothamsted Research have discovered that bees are able to seek out the most efficient route when foraging between flowers, despite having a number of combinations available to them.
In a paper published in PLOS Biology, the team used radar tracking to show how bumblebees discover flowers, learn their location and use trial and error to find the most efficient route between flowers over large distances.
Arranging artificial flowers in the shape of a pentagon, the team equipped each one with a motion-sensitive camera to record video footage of each visit. In combination with the radar tracking, they were able to collect accurate data on where the bees flew and when they visited each flower from the very start of each bee’s foraging career.
Initially they found that the bees flew long and complicated paths around the field until they located and remembered the positions of all the artificial flowers. As they gained experience, the bees refined their route and visited each flower once before returning back to the nest. The researchers found that the bees continued to tinker with their route on each subsequent foraging trip, and only adopted the new route if it was shorter than those they had previously followed.
Dr Nigel Raine from the School of Biological Sciences at Royal Holloway said: “Although the bees used around 20 of the 120 possible routes to link the five flowers, they were still able to find the most efficient route.”
“To solve the same problem, a person might calculate the length of all possible routes to find the shortest. A bee with a brain the size of a grass seed is unlikely to be doing such complex calculations in its head. Instead our results suggest it is probably comparing the length of its most recent route, to the shortest path it has used so far. Using such a simple rule allows bees to find efficient routes when foraging.”
The team also found that when the flowers were rearranged, the bees gradually explored the landscape for new flowers, found them and incorporated them into new foraging routes.
“This is the sort of challenge bees deal with everyday as the plants in flower change, so bees are continually required to update the best route to find food,” Dr Raine added.
The research was supported by a combined grant from the Wellcome Trust, the Biotechnology and Biological Sciences Research Council, and the Engineering and Physical Sciences Research Council (BB/F52765X/1). The research team included Dr Nigel Raine from the School of Biological Sciences, Dr Mathieu Lihoreau and Professor Lars Chittka from Queen Mary, University of London and Dr Juliet Osborne and her team at Rothamsted Research.
Reference: Lihoreau, M., N. E. Raine, A. M. Reynolds, R. J. Stelzer, K. S. Lim, A. D. Smith, J. L. Osborne and L. Chittka (2012). Radar tracking and motion-sensitive cameras on flowers reveal the development of pollinator multi-destination routes over large spatial scales. PLoS Biology 10: e1001392. doi:10.1371/journal.pbio.1001392. The full text is available here