We have suspected for some time that bumblebees were surprising creatures, but new research from Queen Mary University of London adds an unexpected piece: these furry insects are capable of interpreting a sort of visual Morse code, distinguishing short and long flashes of light to orient themselves towards a sugary reward. This is not a trivial ability: it means that bumblebees possess a form of time processing, an ability that until now we thought was almost exclusive to vertebrates.
Scientists have devised a system that is as simple as it is ingenious. Two light signals were positioned in front of the bumblebees of the Bombus terrestris species: one with a longer duration and one more rapid. Varying the times – for example 5 seconds vs 1 second or 2.5 seconds vs 0.5 seconds – was associated with two opposite outcomes: a sugar reward or a bitter quinine solution. The insects quickly understood which duration led to a reward and which led to a decidedly unpleasant experience.
Unrewarded memory and decisions
The most surprising part comes when the researchers completely removed any odor or presence of sugar. Despite the absence of the reward, the bumblebees continued to choose the “correct” light signal more often, the one that had previously been associated with the sweet substance. Evidence that clearly indicates how these insects were not simply following an olfactory trail, but had learned and memorized the temporal pattern. A behavior that reveals learning, generalization and decision-making abilities that are more complex than imagined.
Why bumblebees are able to process visual signals of different durations remains a mystery. In their natural environment they do not encounter similar flashes of light, yet they are able to interpret them as if they had always possessed this faculty.
Scientists hypothesize that this ability derives from the evolution of mechanisms useful for other purposes, such as movement in space, orientation or perhaps primitive forms of communication.
Another possibility is that this ability is simply a consequence of the basic properties of neurons, a kind of intrinsic function of the nervous system. For now, it remains a fascinating puzzle that opens up new questions about the cognitive world of insects.
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