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Bumblebees Quickly Learn Best Paths to Sweet Flowers

The views expressed are those of the author and are not necessarily those of Scientific American.


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bumblebees learn shortest routes to flowers

Image courtesy of Andrew Martin

Bumblebees, it turns out, don’t bumble. Using tiny radar tracking devices, motion-activated cameras and artificial flowers, scientists have learned how the bees themselves quickly learn the best routes to take when they go foraging from flower to flower. In fact, their cognitive competence in this area seems to match that of bigger-brained animals.

A team of researchers from Queen Mary University of London outfitted a colony of buff-tailed bumblebees (Bombus terrestris) with miniscule harmonic radio sensors and plastic number tags. They trained the bees to feed on artificial flowers that offered a perch and a sugar solution in the center. The colony’s nest box, positioned in a large field on a British estate, was then situated near five of these artificial flowers. The flowers were arranged in a pentagon shape, with each one 50 meters from the next, which is many times the distance a bumblebee can see. That arrangement prevented the subjects from following each other or spotting the next flower. The “flowers” were watched by motion-sensing video cameras to capture each bee’s feeding. The researchers also chose to complete the experiment in October, when local flowers would have faded and not tempt the bees away from the experimental ones.

“Initially, their routes were long and complex, revisiting empty flowers several times,” Mathieu Lihoreau, of the university’s School of Biological and Chemical Sciences and co-author on the study, said in a prepared statement. “But, as they gained experience, the bees gradually refined their routes.” And they did so quickly. After only an average of 26 outings, the bees had tried only about 20 of the 120 different possible foraging routes—and reduced their total flight distance by roughly 80 percent.

Previous studies had shown similar learning curves in smaller areas the laboratory, but this was the first to demonstrate it in a more realistic scale the wild. The bees in this wild-scenario actually outperformed their lab counterparts, who only improved to about 75 percent of the optimal feeding flight. The findings were published online September 20 in PLoS Biology.

The learning appeared to be primarily 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,” Lihoreau said. “Otherwise, the new route was abandoned and another route was tested.”

These findings are a new cognitive laurel for these impressive insects. “The speed at which they learn through trial and error is quite extraordinary,” Lihoreau’s colleague Lars Chittka, said in a prepared statement. “This complex behavior was thought to be one which only larger-brained animals were capable of.” The study does not explore whether bees were developing mental maps of the foraging area, as humans, sharks and even, arguably, octopuses do. But simply using heuristics seems to get them pretty far (by cutting down massively on time spent buzzing through the air).

Although this navigation seems to be a no-brainer for the bees, we humans needed mathematical algorithms to analyze and understand the elegance of their behavior. “This is a really exciting result because it shows that seemingly complex behaviors can be described by relatively simple rules, which can be described mathematically,” Chris Rawlings, head of Computation and Systems Biology at Rothamsted Research, said in a prepared statement. “This means we can now use mathematics to inform us when been behavior might be affected by their environment and to assess, for example, the impact of changes in the landscape.”

The bees, themselves, seemed resistant to change, especially if it meant a reduction in especially fruitful destinations. “If we removed a flower, bees continued looking at that location—even if it was empty for an extended period of time,” Chittka said. “It seems bees don’t easily forget a fruitful flower.”

Katherine Harmon Courage About the Author: Katherine Harmon Courage is a freelance writer and contributing editor for Scientific American. Her book Octopus! The Most Mysterious Creature In the Sea is out now from Penguin/Current. Follow on Twitter @KHCourage.

The views expressed are those of the author and are not necessarily those of Scientific American.





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