How many emotions do you think bees feel? Surely, they feel some positive emotion after discovering food or pollen. But did you know that when a bee discovers food or pollen, it returns to the hive and displays a complex dance informing the other bees of its location? We tend to overlook the intelligence of other species on this planet, especially invertebrates, like bees, who we depend on for food.¹ Please, save the bees.

Three takeaways to tell your friends:

• Bees, like humans, contain monoamine neurotransmitters like dopamine and serotonin, and after simulating a predator attacking the hive, bees contain significantly less of these neurotransmitters.²
• Researchers trained bees to associate one odor with nectar and another with less sweet or bitter nectar.²
• After simulating a predator attacking the hive, bees were presented with the two odors again, yet were significantly less “excited” at the odor associated with the less sweet or bitter liquid than bees who didn’t experience an attack.²

You know, it’s easy to train animals to respond to rewards. Just ask Ivan Pavlov, the founder of classical conditioning.³ He found that dogs often salivate at the smell of meat. So, he started ringing a bell when presenting the meat, causing the dogs to associate the bell with food, so the dogs began to salivate to the bell in anticipation of food.³ He took an involuntary response (salivation) to a stimulus (meat) and prompted it by associating the stimulus (meat) with another stimulus (bell). That is classical conditioning. In today’s study, the researchers classically conditioned bees to study their emotions.

Bees enjoy sugary liquids like dogs enjoy meat. Using that information, researchers set up a training protocol. Bees learned to associate two distinct odors with a liquid presented simultaneously. With odor #1, the liquid was sweet and pleasant to the bees, but with odor #2, the liquid was bitter.² As expected,⁴ bees learned to extend their tongue (proboscis) more to odor #1 and less to odor #2. Now, the fun begins.

Now that the bees have associated the odors with reward and punishment, the researchers wanted to know how they would react following a simulated predator attack, like one from a honey badger.⁵ Therefore, the researchers shook the bees, like a honey badger shaking the hive, for 60 seconds and then presented the odors while measuring the percentage of bees that extended their tongues.² There was no discernible difference in tongue extensions between shaken and unshaken bees with odor #1.² With odor #2, significantly fewer bees extended their tongues after being shaken compared to the amount of unshaken bees that extended their tongues.² Given this result, researchers believe that, following a traumatic event, the bees were less interested in the bitter liquid than before a traumatic event.

Then, they repeated the experiment using different liquids associated with odor #2, not just bitter. When both liquids associated with the odors were sugary, but the liquid associated with odor #1 contained more sugar, the bees still showed pessimistic behaviors toward the less sugary liquid associated with odor #2 after being shaken, more so than the unshaken bees.² Thus, bees display pessimistic behavior toward less sugary and bitter liquids following a perceived predator attack.

The bees’ neurotransmitter levels support the pessimism against the liquid associated with odor #2. Yes, bees do have neurotransmitters; in fact they have monoamine neurotransmitters, like us. Specifically, bees use dopamine and serotonin—among others—to send signals in their brains.⁶ After being shaken for 60 seconds, the bees’ levels of three neurotransmitters had significantly decreased: dopamine, serotonin, and octopamine.² Therefore, the decrease in neurotransmitter levels supports the pessimistic behavior shown by the bees, similar to how depressed people have less available serotonin.

In summary, following a perceived predator attack, bees display signs of pessimism and experience significantly lower levels of certain neurotransmitters. At what point can we say they feel emotions?

Note: As I write this, sitting on the ground outside, I witnessed something quite related. An ant picked up a dead ant and carried it to the nest. So, I took a break to read up on the phenomenon. When they die, ants release a pheromone (oleic acid), which alerts other ants to remove the dead ant from the colony.⁷ The dead ants are placed in a waste area near the colony (middens), protecting the colony from disease.⁷ That is likely what occurred. An ant reacting to pheromones, no more. Good job worker ant.

REFERENCES:

1.         Khalifa SAM, Elshafiey EH, Shetaia AA, El-Wahed AAA, Algethami AF, Musharraf SG, et al. Overview of Bee Pollination and Its Economic Value for Crop Production. Insects. 2021;12(8).

2.         Bateson M, Desire S, Gartside SE, Wright GA. Agitated honeybees exhibit pessimistic cognitive biases. Curr Biol. 2011;21(12):1070-3.

3.         Ivan Petrovich Pavlov. Conditioned reflexes; an investigation of the physiological activity of the cerebral cortex, by I.P. Pavlov. translated and edited by G.V. Anrep. New York, Dover Publications; 1927.

4.         Bitterman ME, Menzel R, Fietz A, Schafer S. Classical conditioning of proboscis extension in honeybees (Apis mellifera). J Comp Psychol. 1983;97(2):107-19.

5. Begg CM, Begg KS, Du Toit JT, Mills MGL. Sexual and seasonal variation in the diet and foraging behaviour of a sexually dimorphic carnivore, the honey badger (Mellivora capensis). Journal of Zoology. 2003 Mar;260(3):301–16.

6. Chen YL, Hung YS, Yang EC. Biogenic amine levels change in the brains of stressed honeybees. Arch Insect Biochem Physiol. 2008;68(4):241-50.

7. Do Ants Have Funerals? Why Ants Carry Their Deceased | Cake Blog [Internet]. http://www.joincake.com. Available from: https://www.joincake.com/blog/why-do-ants-carry-dead-ants/