Wednesday, February 22, 2012

Buzz Worthy

Photo credit: Dr. Ilia

I thought I would keep the bee topic alive for yet another day.  I’m not sure if this is because I’m hopelessly yearning for spring, or because this was just another article about bees that caught my attention...
Let me just preface the rest of this post by stating that I really don’t know very much about bees. What I do know is that I like honey on my pancakes sometimes instead of maple syrup, bumble bees bite, and that all bees just spend the entire summer zipping around from plant to plant until their stomachs are so full that they have to get back to the nest and empty stock.
They buzz, some bite instead of sting, and when they get within six inches of my body I freeze, cautiously drawing in slow breaths as if I can’t outrun them or, just maybe, they aren’t aware that I’m right in front of them.
Who would’ve thought that when it came down to gathering food, bees were smarter than a sans-technology salesman? Obviously not me, as I just admitted that I thought bumble bees bit people rather than stung them. 
Animals, much like a salesman without GPS, face trouble in collecting sporadically distributed resources.  For the salesman, this might be money.  For bumble bees? Flowers. 
Instead of trying route after route in search of the best option, they simply move to the nearest unvisited resource.  This strategy is called the “nearest-neighbor solution” and it has been found to be used by humans, nonhuman animals, rats and bees.
In their study, “Bees do not use nearest-neighbor rules for optimization of multi-location routes” four scientists from the University of London found opposing support for the “well-known traveling salesman” analogy in which our salesman must find the shortest route that passes each of his customers visiting each just once before returning home: bees are different.
So how does the salesman learn the best route? He could measure and then compare all the lengths, but if he covers a five-mile-radius with more than 35 houses that might be tedious.  (Looks like he’ll rely on a trial and error approach.)
Animals are assumed to rely on simple-trial and error and spatial memory as well.  However, this rule encourages the idea of stable and repeatable multi-location routes or “traplines.”  Traplines are a behavior that increases foraging efficiency, different from the nearest-neighbor method.
These scientists found that the bumble bees don’t rely on the nearest-neighbor method when it yields a less than optimal outcome, but rather they gradually reduce their distance with experience.
For their experiment, worker bees from a single colony were observed for a few trials, foraging on six artificial flowers in an indoor-lit room, spaced in a way that maximized discrepancy between “optimal” and “nearest-neighbor” strategies. After they were able to estimate the crop capacity from the volume of sucrose that had been ingested during observations, they then set each flower’s sucrose solution to one-sixth of the total capacity, ensuring the bees visited each flower.
Results showed that the bees significantly decreased their flight distances, decreased the number of visits to empty flowers and decreased flight duration as they become familiar with the flower setup.  
Most bees minimized their total travel by selecting optimal traplines that relied on gradual learning and spatial memory; they don't follow the nearest-neighbor strategy.
Are bumble bees smarter than a salesman or saleswoman?
No, the point of this post wasn't to suggest that. I was just sharing my new found knowledge: the stinging, seemingly aimless buzzing bumble bees are more cognizant of their surroundings than I, or we, may think. 

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