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Insects probably feel pain, so farming them should minimize it

UK and Iranian scientists say insects probably feel pain because they “most likely” have central nervous control of nociception (the detection of painful stimuli). The team looked at previous behavioral, molecular and anatomical neuroscience evidence to reach their conclusions. As discussions of insect farming ramp up in response to climate change and food shortages, including a UN recommendation to farm insects, the scientists warn existing animal welfare protections tend not to cover insects. If insects feel pain, we must start treating them more ethically, they argue, whether in farms, conservation programs or the laboratory.

We stand at an important crossroads of how to feed a human population projected to reach 10 billion by 2050, while conventional livestock farming is a major contributor to climate change. The United Nations recommends mass producing insects for food.

However, ethical implications have not been thoroughly considered, since animal welfare protections tend not to cover insects. We argue that insects most likely have central nervous control over nociception, based on behavioral, molecular and anatomical neuroscience evidence. Such control is consistent with the existence of pain experience, with important implications for insect farming, conservation and their treatment in the laboratory.

Ethical eating – Do insects feel pain? In this review article, the authors argue that insects most likely have central nervous control of nociception (the detection of painful stimuli) and this consistent with the existence of pain experience. The review looks at behavioral, molecular and anatomical neuroscience evidence to support this, and the implications for insect farming, conservation and laboratory treatment in light of calls – by the UN and others – to mass produce insects for food. 

Background

Modulation of nociception allows animals to optimize chances of survival by adapting their behavior in different contexts. In mammals, this is executed by neurons from the brain and is referred to as the descending control of nociception.

Whether insects have such control, or the neural circuits allowing it, has rarely been explored. Based on behavioral, neuroscientific and molecular evidence, we argue that insects probably have descending controls for nociception.

Behavioral work shows that insects can modulate nocifensive behavior. Such modulation is at least in part controlled by the central nervous system since the information mediating such prioritization is processed by the brain.

Central nervous system control of nociception is further supported by neuroanatomical and neurobiological evidence showing that the insect brain can facilitate or suppress nocifensive behavior, and by molecular studies revealing pathways involved in the inhibition of nocifensive behavior both peripherally and centrally.

Insects lack the endogenous opioid peptides and their receptors that contribute to mammalian descending nociception controls, so the authors discuss likely alternative molecular mechanisms for the insect descending nociception controls.

They also discuss what the existence of descending control of nociception in insects may reveal about pain perception in insects and finally consider the ethical implications of these novel findings.