Bumble bee collecting pollen. Click through to see what Lihoreau's experiment looked like.
Credit: Veer Images
Bumblebee (Bombus terrestris audax) visiting artificial flower array.
Credit: Mathieu Lihoreau
LONDON: Considering their brain size, bumblebees use surprisingly complex problem-solving techniques to save energy whilst foraging for food.
Researchers in the UK have shown that bees are capable of adapting their flight path to reduce energy use when foraging, despite not having a full idea of the space around them. It also asks questions about what we know about the foraging patterns of other animals.
The bees achieve this by a technique known as 'gradual optimisation'. Mathieu Lihoreau, who led the research team at Queen Mary, London University, said, "Despite having tiny brains, bees effectively used gradual optimisation (comparing several different routes), to solve this famously complex routing problem which still baffles mathematicians 80 years after it was first posed."
Hunting for food
The Bumblebee (Bombus terrestris), has such a small brain that scientists assumed it would apply the simplest approach possible to finding nectar: constantly flying from one flower to the closest flower (known as the 'nearest-neighbour strategy'). This also applies to many other foraging animals, although previous research has shown that some primates are capable of sussing out better routes.
Now we have a much clearer picture of how bees decide which pattern to follow when collecting nectar. Instead of working towards the nearest plant, bees will take the overall distance of their route into account and work towards the shortest journey.
The team discovered this by arranging six artificial flowers, each with equal amounts of nectar, in a specific flight arena. It was deliberately set up so that it would be a significant diversion for the bees if they used a 'nearest-neighbour' policy. To make sure that the results were not a fluke, they recorded 80 foraging bouts, keeping track of which flowers were visited and also the order in which they were harvested.
Trial and error
The findings, published today in Biology Letters, show that over the 640 different flower visits, the bees considerably reduced the amount that they would have to fly overall. This was done by learning which routes worked out quicker than others as they went along.
The bees almost never applied the 'nearest-neighbour' strategy, instead remembering the relative distances between the flowers, and eventually calculating the shortest route.
This revealed that bees are able to solve complex routing problems by learning, without needing a sophisticated idea of the actual space between each individual flower. The process, known as 'traplining', could also be used by other foraging creatures.
Do bees like rewards?
Andrew Thomas Charlton, an ecologist from the University of Aberdeen in Scotland who was not involved in this study, praised the experiment. "This work has been needed for a long time; our lack of knowledge about traplining animals needed to be redressed," he said. But he added that it would be dangerous to assume that all animals would repeat this behaviour, highlighting the need to repeat this test with other foraging creatures, like birds and bats.
Charlton also noted possible discrepancies between results that were collated in a laboratory, and what actually happens in the wild, which could be solved through further research.
Lihoreau, who is now based at the University of Sydney, and his team are now expanding the study to include the varying levels of pollen found in different flowers to determine whether bees take the rewards offered by more pollen-rich plants into account.
