A Sweet Treat May Boost Bees' Mood

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June 13, 2017 | 4,861 views

Story at-a-glance

  • When bees were given a drop of sugar water, it cut their decision-making time in half when presented with a confusing problem
  • When bees were attacked by a fake spider, sugared-up bees resumed foraging behaviors faster than the sugar-free bees, suggesting they had a more optimistic outlook
  • When the researchers blocked the feel-good chemical dopamine in the bees’ brains, the changes seen with the sugar disappeared, which suggests changes in mood, not energy, were responsible

By Dr. Becker

Do insects such as bumblebees express emotions like fear and excitement? Charles Darwin certainly thought so, noting in his book, "The Expression of the Emotions in Man and Animals," that "Even insects express anger, terror, jealousy and love by their stridulation."1

Stridulation refers to the act of producing a sound, typically by rubbing two body parts together, but researchers writing in the journal Science figured out another way to determine if bees show emotions: by monitoring their decision-making behavior. If a bee is happy, they surmised, it would be more likely to show a positive bias when making decisions while the opposite would hold true if the bee was feeling more down.

Perhaps the first intriguing aspect of the study is the fact that bees can be readily trained — in this case to associate a blue "flower" with a sugar water treat and a green flower with no reward. From there, researchers took it a step further to evaluate the potential for bee emotions, with fascinating results.

A Sweet Treat May Bring Out Optimism in Bees

The trained bees were next presented with a new scenario: a flower with an intentionally confusing blue-green color. The bees took a while to decide what to do, taking about 100 seconds to either enter the tunnel connected to the blue-green flower (or not). Half of the bees were given a bit of incentive — a drop of sugar water — to see what would happen. Those bees cut their decision-making time in half, spending just 50 seconds at the tunnel entrance before entering.

Did the sugar-rushed bees simply experience a boost in energy? The researchers don't think so, as all of the bees (even those that did not get the sugar) traveled at similar speeds and for similar lengths of time. Instead, the researchers attribute the difference to a primitive feeling of optimism.

In another experiment, the researchers set the bees up to be attacked by a fake spider, then gave half of the bees the sugar-water treat. The sugared-up bees resumed foraging behaviors faster than the sugar-free bees. The researchers also used a special solution to block the feel-good chemical dopamine in the bees' brains, and when this occurred the changes seen with the sugar treat were no longer apparent.

This suggests changes in mood, not energy, may indeed have been behind the bees' changes in decision-making behavior.2 According to the journal Science:

"The authors report decision-making behavior in bumblebees that is analogous to optimism in humans and may reflect positive affect in both humans and other species. Moreover, the behavior appears to depend on the activity of dopamine, a neurotransmitter involved in the processing of reward in humans."

How Intelligent Are Bees?

In the insect world, bees may be a brainy bunch, capable of learning how to use tools and even passing such skills down to future generations. In one study, bees were successfully trained to move a ball to a specific location in order to get a food reward.3

Other bees learned the skill either by watching other bees or a fake "ghost bee" perform the task, although they learned best by watching other bees do it. The bees also demonstrated what the researchers described as "unprecedented" cognitive flexibility, as they didn't just copy other bees' behavior. Instead, they made more efficient use of tools when possible, choosing balls that were closer to the target instead of moving them over long distances, for instance.

It's not surprising when you consider the mass efficiency of a typical bee hive, where close to 80,000 bees (depending on the season) work together to further the interests of the hive as a whole.

Bees Communicate Via the 'Waggle Dance'

When a forager bee returns to the hive with a new spot to find valuable nectar or pollen, she will communicate the precise location of the flowers to her hive, allowing more forager bees to quickly mobilize and take advantage of the precious floral resource. The carefully choreographed dance begins with the bee moving at a precise angle, which reveals the direction of the flowers in relation to the sun. Next, she waggles her abdomen to relate the distance of the flowers; the more waggling, the farther away the flowers are.

The bees also use their sense of smell to figure out what type of flower the pollen came from, helping them to identify their location when flying about.4 In 2014, researchers "eavesdropped" on more than 5,000 waggle dances, looking for differences in foraging behavior by season.5

They were able to successfully decode the dances, revealing not only that the bees communicate valuable information to their hive but also that they travel much farther distances to get their food during the summer than they do in the spring or fall. Study supervisor Frances Ratnieks, professor of apiculture at Sussex University, told The Guardian:6

"There is an abundance of flowers in the spring from crocuses and dandelions to blossoming fruit trees. And in the autumn there is an abundance of flowering ivy. But it is harder for them to locate good patches of flowers in the summer because agricultural intensification means there are fewer wildflowers in the countryside for bees.

… The bees are telling us where they are foraging so we can now understand how best to help them by planting more flowers for them in the summer."

Unfortunately, bees need all the help they can get, as their numbers are dwindling due to industrial agriculture, urban development, diseases and parasites and more.

If you'd like to help support this valuable and complex species, grow native plants, especially those that provide nectar and larval food for pollinators, in your yard while reducing your use of pesticides and other agricultural chemicals, which may harm bees and other pollinators.

[+]Sources and References [-]Sources and References

  • 1 Science September 30, 2016
  • 2 Science News September 29, 2016
  • 3 DVM 360 April 4, 2017
  • 4 National Geographic, World’s Weirdest: Honey Bee Dance Moves
  • 5 PLOS One April 2, 2014
  • 6 The Guardian April 3, 2014