Can Bees Feel Pain?
We all know that some bee species are able to deliver a sting that to varying degrees, humans and animals may experience as painful.
But what about bees, could they feel pain if they are harmed in any way, for example, due to predator attack or human behaviour?
How Science Shows It's Likely Bees Feel Pain
Whenever I have unfortunately seen a worm cut in half (accidentally or deliberately) the reaction of the worm (a frantic wriggle) has long convinced me the worm felt it.
Whilst we may understand more easily the distress calls of a pet when in pain, I saw no reason to dismiss invertebrates as being immune to the feeling consequences of a swat, just because they are so small and we're not on the same wavelength!
Consequently, my approach to all creatures is to avoid causing pain to any, and to help or rescue any I can from potentially harmful situations.
It may seem that my stance is sentimental, but it turns out my concerns were probably justified all along.
Nociception And Pain
Nociception is the sensory nervous system's sensitivity to harmful/painful or potentially harmful or painful stimuli, and the resulting defence responses that are triggered as a result.
Nociception and pain are different things, since pain is a subjective interpretation or experience of the stimuli and differs between individuals.
For example, my pain experience of a bee sting might be different from someone else's.
Nevertheless, since bees cannot describe their experience of pain to us, observing clues provided by nociception responses can give an indication of a pain response and therefore, an experience of pain.
In her 2019 published study indicating that fish experience pain, Sneddon1 beautifully explains why:
"In order to survive, animals must avoid injury and be able to detect potentially damaging stimuli via nociceptive mechanisms. If the injury is accompanied by a negative affective component, future behaviour should be altered and one can conclude the animal experienced the discomfort associated with pain."
- Lynne U. Sneddon
Pain experience in bees
Since bees cannot describe their experience of pain to us, one way scientists can identify whether bees experience pain, is:
- by examining physiological responses, or
- by assessing whether future behaviours of bees are altered or adapted in some way, after coming into contact with a potential threat or negative stimulus.
Chittka describes some of these experiments in his book, The Mind Of A Bee2.
For example:
- Threat simulation
An experiment simulating the threat of a predator (crab spiders) recorded that bumble bees learned to avoid flowers in which crab spiders were detected, and altered their behaviour on approach to the flowers. - Negative association
In another experiment, honey bees were trained to associate an odour with either a sweet or unpleasant reward.
Half of the bees were then subjected to a vigorous shaking in a piece of laboratory equipment called a vortecizer, in order to mimic a predator attack.
Bees that had been subjected to the vigorous shaking were less likely to accept an 'ambiguous stimulus' (that for example, combined both odours) than the non-shaken bees.
This led the researchers to conclude the shaken bees displayed a pessimistic cognitive bias as a result of the simulated predator attack.
Do honey bees feel pain after stinging?
When a honey bee stings a large animal or a human, the barbed sting becomes lodged in the skin, and the bee's abdomen is torn away as any attempt is made to remove the bee.
The sting remains behind in the skin, and continues to pump venom, but the bee obviously dies.
The question might reasonably be asked: "if stinging is suicidal for honey bees, why does this not deter them from doing it?"
It seems the answer lies in the strong pheromone emitted by guard bees that stimulates a strong defensive reaction. After all, honey bees have evolved responses to all kinds of predator attacks on their nests, from badgers, to bears and birds, as well as other invertebrates such as hornets, all intent on consuming the honey and brood within.
It appears this pheromone not only recruits other honey bee workers to defend the nest, it also makes the guard bees more aggressive whilst making them insensitive to bodily harm.
It is also proposed that the surge of honey bee pheromone may even flood their system with a pain killer, since it has been found that the more alarm pheromone bees are exposed to, the less they respond to electric shock (Núñez et al, 19973).
If all this seems far fetched, Chittka2 points out that in intense life or death situations, soldiers have been shown to apparently subdue the experience of pain from severe injuries, during intense fight and flight situations in battle.
Consequences?
Evidence of pain response has been recorded not only in bees, but also in other insects (and indeed, many other invertebrates).
For example, lepidopteran larvae (caterpillars), such as the large moth, Manduca sexta, Drosophila (fruit fly) larvae, molluscs such as Aplysia (a genus of sea slugs), a snail (Helix), octopus (Adopus), crayfish (Astacus), hermit crab (Pagurus), and shore crab (Hemigrapsus) have all been shown to experience pain4.
Invertebrates are all too often viewed as insignificant, even despite the important role they play in the environment. They are sometimes mistakenly believed not to suffer pain. As I explained in my review of Chittka's book, we are increasingly being shown evidence that bees are sentient beings.
Knowing this, scientists may rethink their laboratory techniques, and we citizens may think twice before swatting or squishing bees or other invertebrates.
References
1. Sneddon LU. Evolution of nociception and pain: evidence from fish models. Philos Trans R Soc Lond B Biol Sci. 2019 Nov 11;374(1785):20190290. doi: 10.1098/rstb.2019.0290. Epub 2019 Sep 23. PMID: 31544617; PMCID: PMC6790376.
2. Chittka, Lars: The Mind Of A Bee, Princeton University Press, 2022. ISBN: 9780691236247. Chittka quotes a number of research papers in his book, not listed in this article. Please see his book for further details.
3. Núñez, Josué A., L. O. Almeida, Norberto Balderrama and Martin Giurfa. “Alarm Pheromone Induces Stress Analgesia via an Opioid System in the Honeybee.” Physiology & Behavior 63 (1997): 75-80.
4. Walters ET. Nociceptive Biology of Molluscs and Arthropods: Evolutionary Clues About Functions and Mechanisms Potentially Related to Pain. Frontiers in Physiology. 2018 ;9:1049. DOI: 10.3389/fphys.2018.01049. PMID: 30123137; PMCID: PMC6085516.
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