Bees Can Solve Complex Color Puzzles, Study Finds

Bethany Halford
for National Geographic News
November 1, 2005
As they buzz from blossom to blossom, it might seem that bumblebees need
to see only flowers, honey, and hive. But a new study suggests that
bumblebees have a surprisingly sophisticated visual system.

Through a series of clever experiments, University College London researchers R. Beau Lotto and Martina Wicklein discovered that bees can solve complex color puzzles.

The scientists say the finding may provide new understanding of human vision and guide the development of similar systems for robots. The study appears this week in the Proceedings of the National Academy of Sciences' Online Early Edition.

In bees, as with people, vision has as much to do with the brain as it does with the eye. As Lotto explains, the eye sees by detecting light that falls upon its retina. But, the neuroscientist adds, light that's reflected onto the eye from an object, such as a flower, is constantly changing.

To perceive the flower or anything else, the brain must decipher that light. "If you can understand how something relatively simple like the bee solves these problems, then we can apply that to robotics," Lotto said.

Developing a visual system that deciphers information, he added, "is the most significant obstacle facing robotics."

Color Puzzle

Scientists already knew that bumblebees could distinguish different flowers based on color alone. And they knew that bees could do this under different types of global lighting—a sunny morning or an overcast afternoon, for example.

Researchers assumed that the bees made color distinctions by adapting to the scene's average color.

What scientist didn't know was whether bumblebees could distinguish specifically colored flowers where lighting conditions were more complicated—a forest floor dappled with sunlight, for example.

To better grasp how bees operate in such complex lighting, Lotto and Wicklein set up a bumblebee puzzle.

The duo built an array of 64 Plexiglas "flowers." The array was then divided into 4 panels of 16 flowers. In each panel, light filters gave four flowers different colors: ultraviolet yellow, blue, yellow, and green.

The pair backlit each panel with either blue, yellow, or green light or a shade visible to insects known as UV-yellow.

Lotto and Wicklein then placed a sugar solution at every blue flower. This trained forager bees to selectively visit the blue blossoms amid the riot of multicolored, plastic flowers.

Once trained, the bees were given what Wicklein, an expert on insect biology and behavior, describes as a "multiple-choice exam." The researchers rearranged the blossoms and removed all traces of the sugar solution.

When they let the bumblebee foragers loose on the array, the insects showed a preference for visiting the blue flowers.

Even when the scientists backlit the flowers with a color of light the bees had never seen before, the bugs still made a beeline for the blue blossoms.

"We were kind of surprised," Wicklein said of the insects' performance. "It's a hard task, but it looks as if bumblebees can solve the problem very easily."

Contextual Clues

So how do the bees pick out the blue flowers amid a kaleidoscope of choices?

"What we've discovered is that the way the bees are solving this problem is that they're using relationships between the flowers," Lotto said. Whether it's within the context of a backlit green array or a backlit yellow array, the bees survey the panel and go for the bluest looking flower.

Dale Purves, director of Duke University's Center for Cognitive Science, said via e-mail that the "highly imaginative" study is important because it shows "that relatively simple invertebrates use the same empirical strategy that humans employ."

"The ability to manipulate the environment of bees in ways that would be impossible in human studies promises many additional insights about the deeper nature of vision across a wide range of animals," he added.

Because the bees are able to tackle such a complex task and have only a million neurons in their tiny brains, Lotto thinks robots could evolve a similar system.

One of his students has already created a virtual bee computer program, like the matrix described in the study, that's populated with virtual bees. In the virtual system, the bees evolve their ability to use color relationships. Those that can pick out the blue flowers eat, live, and reproduce. Those that can't starve and die off.

"In this next year we're trying to take those virtual robots into the real world," Lotto said.

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