INSECT SENTIENCE: SHOULD WE BE CONCERNED FOR THE WELFARE OF INSECTS? A NEUROBIOLOGICAL PERSPECTIVE

Format of work:

Conference Presentation

Event presented at / Journal Name:

AWRN Workshop on Insects as Mini-Livestock

Speaker / Contact Author's Name:

Dr Meghan Barrett, Indiana University Indianapolis / Insect Welfare Research Society

Speaker / Contact Author's E-mail Address:

meghbarr@iu.edu

• Research aim:

  To review the scientific studies that have been carried out on insect pain and summarise the evidence for pain across six different insect groups in both juveniles and adults.

• Background:

  Trillions of insects are directly impacted by humans each year (farmed, managed, killed, etc.). Over 1.2 trillion insects are already farmed for food and feed, with estimates that over 8 trillion will be farmed by 2030, compared to only 79 billion terrestrial birds and mammals (e.g., chickens, pigs, goats, cows, etc.). Insect welfare is both completely unregulated and infrequently researched despite stronger summarized evidence for pain in some insect groups than in decapod crustaceans – a group already protected by some welfare legislation, such as the 2022 UK Animal Welfare (Sentience) Act based on the findings of the Birch et al. 2021 framework.

• Approach:

  This 75-page publication summarizes over 350 scientific studies on insects to assess the scientific evidence for pain across six insect groups at two developmental time points (juvenile, adult). It uses the Birch et al. 2021 framework, developed in a report commissioned by the UK government on assessing invertebrate sentience, to assess neurobiological and behavioural evidence for pain.

• Key finding:

  We find strong evidence for pain (6/8 criteria; Table 1) in adult insects of two orders (Blattodea: cockroaches and termites; Diptera: flies and mosquitoes). We found more summative evidence for these two groups than has been found for decapod crustaceans (e.g., crabs, which meet 5/8 criteria). Additionally, we find substantial evidence for pain in adult insects of three additional orders (Hymenoptera: bees, ants; Lepidoptera: butterflies; Orthoptera: crickets, grasshoppers). For several criteria, evidence was distributed across the insect phylogeny, providing some reason to believe that certain kinds of evidence for pain will be found in other taxa. No insect group conclusively failed a criterion.

• Industry or policy relevance:

  Welfare concerns have been identified as the result of human activities, including in the insects as food and feed industry. Insects in the industry may face: inhumane slaughter (microwaving, baking), mass outbreaks of disease, cannibalism, starvation, and transport- or handling-induced stress. Many of these concerns are a problem for economic productivity as well.

• Route for practical application:

  Legislators should be aware that there is evidence for sentience in adult insects, warranting an application of the precautionary principle wherever significant welfare concerns arise. Working with insect experts, welfare scientists, and producers can ensure improved welfare for these animals wherever they are managed.

• Confidence in findings and next steps towards realising impact:

  The image in this article (credited to Sajedeh Sarlak) summarises the confidence level for each criterion for adults of each focal insect order. The criterion from left to right are: Nociception, Sensory Integration, Integrated nociception, Analgesia, Motivational trade-offs, Flexible self-protection, Associative learning and Analgesia preference. The orders from top to bottom are Blattodea, Coleoptera, Diptera, Hymenoptera, Lepidoptera and Orthoptera. The colours indicate level of confidence in evidence from Very high confidence (dark green), through to white (very low confidence) and no research (hatched). In most cases where evidence was evaluated, confidence was high or very high. However, further research to fill in the gaps would be beneficial.

Funders:

European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme.

Links to Open Access Publications or DOI:

• https://brill.com/view/journals/jiff/9/2/article-p119_1.xml
• https://www.wageningenacademic.com/doi/10.3920/JIFF2021.0214
• https://osf.io/e92kw/
• https://osf.io/c4qp3/
• https://doi.org/10.1016/bs.aiip.2022.10.001

Citation:

Gibbons M, Crump A, Barrett M, Sarlak S, Birch J, Chittka L (2022). Can insects feel pain? A review of the neural and behavioral evidence. Advances in Insect Physiology.