They Do Not Bumble Around: Bumblebees Select Optimal Route to Collect Nectar

For the first time the bumblebees have been tracked in order to study how they select the most favourable route to collect nectar from multiple flowers and then return safely to their nest.

They choose and use trial and error to find the most efficient route between flowers over large distances.

 A study on the bumblebees was published in Sept 18 PLOS Biology. It was led by Professor Lars Chittka and Dr Mathieu Lihoreau from Queen Mary's School of Biological and Chemical Sciences along with other colleagues. These scientists carried out their study with Harmonic Radar Group at Rothamsted Research.

The team set up five artificial flowers in a 1km diameter field. Each flower was fitted with a motion triggered webcams and had landing platforms with drops of sucrose in the middle. The motion-triggered web cams and tiny bumblebee-mounted radar transponders were deployed to track the bumblebees.

They studied that the bees showed individuality. Each bee had a favoured arrival and departure direction.

"Using mathematical models, we dissected bees' learning process and identified how they may decipher this optimal solution without a map. Initially, their routes were long and complex, revisiting empty flowers several times," Dr Lihoreau explained.

"But, as they gained experienced, the bees gradually refined their routes through trial and error. Each time a bee tried a new route it increased its probability of re-using the new route if it was shorter than the shortest route it had tried before. Otherwise the new route was abandoned and another was tested.

"After an average of 26 times each bee went foraging, which meant they tried about 20 of the 120 possible routes, they were able to select the most efficient path to visit the flowers, without computing all the possibilities."

Prior to this Chittka and his colleagues had showed that bees were able to  learn the shortest route possible to navigate between flowers in the lab. But this is the first time they have been able to observe this behaviour in natural conditions and to describe how bees may optimize their routes.

"The speed at which they learn through trial and error is quite extraordinary for bumblebees as this complex behaviour was thought to be one which only larger-brained animals were capable o