We’ve long thought of insects as instinctive, mindless creatures with robot-like responses to the world and all of its impulses.
But the closer we look, the more surprisingly complex behaviors we find Bees communicate through dance to incredible acts of ant cooperation, and now we have mounting evidence that these little creatures that rule our world can also experience pain.
nociception – the sensory nervous system’s detection of unpleasant stimuli, including chemical burns, sharp cuts and pressure from bruises – elicits a variety of physiological and behavioral responses in animals. One of them can be the perception of pain.
It is well documented that insects have avoidant responses to potentially harmful contact.
In addition, experiments in 2019 showed that the frequently studied fruit fly, Drosophila, showed symptoms of chronic pain after researchers removed the fruit fly’s leg. After the fruit fly was fully healed, the researchers found that the fruit fly’s contralateral leg became hypersensitive.
The authors attributed this to the loss of the fly “Pain Brake” Mechanism in his nervous chord. A pain-braking mechanism calms pain perception, but in the fruit flies, when the sensory nerves were overstimulated, it killed the brake entirely.
But as well as bacteria move away from unpleasant stimuliIdentifying pain in other lives is not as easy as looking for a negative reaction to a harmful contact. In order to consciously register a feeling of pain, we need a complex physiological system that is connected to our brain maybe even emotions.
In mammals, the nociceptors (pain receptors) send an alarm of bad stimuli to our brain, where neurons generate the negative and subjective, physical and emotional feeling of pain.
Studies show that nociception and pain can be regulated independently and have identified distinct systems for the regulation of each.
These systems have yet to be fully identified in insects.
“A hallmark of human pain perception is that it can be modulated by nerve signals from the brain,” says Queen Mary University neurobiologist Matilda Gibbons said news week.
“Soldiers sometimes don’t even notice serious injuries on the battlefield because the body’s own opiates suppress the nociceptive signal. We therefore asked whether the insect brain contains the neural mechanisms that would make experiencing a pain-like perception plausible, and not just simple nociception.”
Gibbons and colleagues reviewed the scientific literature and found several indications that this mechanism is present in insects.
While they lack the genes for them Opioid receptors that down-regulate pain in usduring traumatic events, they make other proteins that could serve the same purpose.
Behavioral evidence also suggests that insects have molecular pathways that suppress responses to noxious contact, for both their peripheral and central nervous systems. For example, the presence of a sugar solution suppresses the normal avoidance of unpleasant stimuli by bumblebees.
Anatomically, insects have descending neurons from the brain to the part in their nerve cord where their defense response to harmful touch originates.
In addition, the tobacco hawkmoth even uses mitigation behavior after a wound, such as nursing.
Each of these things may not be definitive on its own, but taken together they seem to suggest that insects have some sort of pain response control system similar to ours.
“We argue that insects most likely have central nervous control over nociception based on behavioral, molecular and anatomical neuroscientific evidence,” the team concludes a statement. “Such control is consistent with the existence of pain experience.”
However, because insects are a large and diverse group, it is entirely possible that the complexity of their nociceptive regulation and potential pain sensations also vary widely between them.
However, the prospect of their pain raises important ethical questions for further investigation – especially with regard to the planned mass housing of these animals in the future.
“We are at an important crossroads in how to feed a human population that is projected to reach 10 billion by 2050,” the researchers said to say.
“While conventional animal husbandry is a major contributor to climate change, the United Nations recommends mass-producing insects for food. However, ethical implications have not been thoroughly considered as animal welfare typically does not cover insects.”
This study was published in Proceedings of the Royal Society B: Biological Sciences.