News › BeeNav - Bumblebees cleverly calculate efficient routes

Bumblebee with radar tag

20 September 2012

Scientists have discovered that bumblebees have developed a remarkable ability to quickly find the most efficient route through flower patches, when foraging.

In a paper published today in PLOS Biology, scientists in the Psychology Division at Queen Mary College London, working with scientists from the Harmonic Radar Group at the world renowned Rothamsted Research have suggested that bumblebees are able to solve complex dynamic routing problems by using simple learning heuristics, a behaviour previously thought to be complex and one which only larger-brained animals were capable of.

Rothamsted scientist and co-author Dr Andy Reynolds said "Bees quickly develop circuits (traplines) that visit flowers in a manner that minimizes overall travel distance. This is much like the traveling salesman in the famous and fiendishly difficult-to-solve mathematical problem of how to take the shortest path between multiple destinations. We showed how this complex routing problem can be solved by small-brained animals without requiring 'map-like' memory."

The UK based scientists used motion-triggered webcams and tiny bumblebee-mounted radar transponders to track bumblebees (Bombus terrestris) on artificial flowers. The "flowers" had landing platforms with drops of sucrose in the middle and the researchers tracked the sequence of flower visits during consecutive foraging bouts. It was found that bumblebees found the closest flowers first and added new flowers during subsequent bouts.

The scientists believe that through trial and error, combining exploration with learning from previous bouts, the bumblebees progressively adjust their routes as they find shorter paths. 'Traplines' (efficient route) linking the artificial flowers were established after an average of 26 foraging bouts, which entailed trying only about 20 of the 120 possible routes. In contrast to computers, bees did not find the absolute shortest route in the simple experimental arrangement. But they came very close, especially considering that they explored only a small fraction of the possible routes, and established traplines relatively rapidly.

Head of Computational and Systems Biology at Rothamsted research, Professor Chris Rawlings added "This is an exciting result because it shows that seemingly complex behaviours can be described by relatively simple rules which can be described mathematically. This means we can now use mathematics to inform us when bee behaviour might be affected by their environment and to assess, for example, the impact of changes in the landscape".

So next time you are unsure of the most efficient route to your destination, just ask a bumblebee.

Publication

› Radar Tracking and Motion-Sensitive Cameras on Flowers Reveal the Development of Pollinator Multi-Destination Routes over Large Spatial Scales (10.1371/journal.pbio.1001392)

Contacts

› Andy Reynolds and Jason Lim

Notes to Editors

To keep the bees' focus on the artificial flowers, the experiments were done in October, when natural sources of nectar and pollen were scarce. To make the bees want to find all five flowers, each sucrose drop was only enough to fill one fifth of a bumblebee's crop. And to keep the bees from finding one foraging site from another visually, the flowers were arranged in a pentagon that was 50 m on each side, which is more than three times as far as bumblebees can see.

Besides shedding light on how bees develop traplines, this work suggests that small-brained animals can use simple methods to solve complex routing problems without the need for cognitive maps of spatial relationships, as has been suggested.

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Sponsored by Government, BBSRC's budget for 2011-12 is around £445M which it is investing in a wide range of research that makes a significant contribution to the quality of life in the UK and beyond and supports a number of important industrial stakeholders, including the agriculture, food, chemical, healthcare and pharmaceutical sectors.

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