Insects, pain, sentience and welfare

In 2021 a LSE report, Birch et al defined 8 practical criteria for assessing sentience in invertebrates, such as a demonstrable capacity for nociception and adaptive behavioural responses, evidence of learning and memory, consistent motivational states that affect decision making, and neurophysiological correlates suggestive of conscious processing. A recent article in The Biologist points to a growing body of behavioural and neural evidence showing that many orders of insects may meet the criteria for sentience. Counter-arguments to insect sentience include the possibility that "pain" responses are simple reflexes, and that current evidence does not conclusively demonstrate subjective experience in most insect taxa. However, there is a growing call for precautionary improvements in welfare practice, such as in  2023 when the Eurogroup for Animals issued a Scientific Declaration on Insect Sentience and Welfare, while recognising scientific uncertainty about the degree and distribution of insect sentience.  Yet despite the huge scale of insect use in research and industry, welfare considerations for insect use in research remains largely unregulated. 

Why does this impact entomology and vector research?

A recent study published in Ecological Entomology looked at entomologists' knowledge and attitudes toward insect welfare in research and education, demonstrating that many entomologists lack formal training or guidance on insect welfare, and that attitudes vary widely depending on species, research context, and perceived sentience.

The authors used a mixed‑methods approach with online questionnaire distributed to practicing entomologists and educators. The survey collected demographic and professional background data, self‑reported knowledge of insect welfare concepts and guidelines, attitudes toward welfare across different insect taxa and research contexts, and details of institutional training and policies. Question formats combined Likert scales, multiple‑choice items, and open‑ended questions to capture both quantitative measures of awareness and qualitative explanations of reasoning and practice. The findings demonstrated that entomologists showed variable knowledge and attitudes toward insect welfare, with key take aways being:

• Knowledge gaps exist among entomologists. Many researchers and educators lack formal training or accessible guidelines on insect welfare.
• Welfare concern is uneven across taxa. Greater empathy is directed at pollinators and charismatic insects while disease vectors such as mosquitoes receive less welfare consideration.
• Research context shapes attitudes. Behavioural and ecological scientists report higher welfare awareness than professionals focused on pest control or operational vector management.
• Institutional guidance is inconsistent. Few institutions provide clear, species‑specific protocols for the care, handling, and humane euthanasia of insects used in research and training.
• Work burden and increased costs. The study also reported respondents' concerns about the potential regulatory and practical consequences of formalising insect welfare standards, including burdens on research workflows, compliance costs, and implications for teaching and pest‑control operations.

The variance and gaps in knowledge, practices and attitudes have implications for public health, affecting experimental validity. For example, stress and poor handling of insects may produce unreliable results in experimental studies, and could impact public trust as lack of transparency in vector control programs could hinder community acceptance and cooperation.

Key considerations include:  

• Experimental validity. Stress, suboptimal housing, and rough handling alter vector behaviour, longevity, pathogen susceptibility, and transmission metrics used in risk models.
• Reproducibility improves with standardized welfare practices. Consistent husbandry and humane handling reduce uncontrolled variance across labs and field teams.
• Ethical conduct affects community engagement. Public acceptance of interventions that involve release, manipulation, or mass rearing of vectors hinges on transparent welfare standards.
• Regulatory and funding landscapes are shifting. Anticipating stricter oversight and societal expectations avoids delays to vector control projects and protects institutional reputation.

What are some practical recommendations for disease vector research and control?

There are existing, tried and tested examples we can learn from on developing and adopting practical welfare protocols, using appropriate monitoring and experimental design. Looking at housing density, temperature, humidity, feeding regimes, handling methods, and humane endpoints for key vectors such as Aedes, Anopheles, Culex, Phlebotomos, Simulium etc (and let us not forget those non-insect vectors, such as snails and crustaceans) and implementing good record-keeping practices of these factors could greatly reduce uncontrolled variance between laboratories, mass‑rearing facilities, and field teams. E.g.

• Monitoring colony health with behavioural and physiological welfare indicators, and documenting corrective actions and interventions that reduce stress during production.
• Identifying the handling artifacts that could alter behaviour, survival, or vector competence.
• Standardising capture, transport, holding, and release procedures to minimise mortality, physiological impairment, and behavioural bias that would affect surveillance accuracy or release efficacy.
• Embedding training on minimising handling stress, recognising welfare indicators, humane euthanasia techniques, and consistent husbandry into entomology, vector control, and public‑health training programmes.

If implemented carefully, with input from researchers, educators and professionals working in vector research and control to ensure manageable and affordable practices, these practical steps on animal welfare could help establish good standardizes, preferred practice for vector welfare in public health, improving both research outcomes and vector management and control methodologies. And crucially communicating these welfare practices and safeguards clearly to regulators, funders, and affected communities could help build and strengthen trust for interventions involving live vectors, such as sterile‑male or gene‑drive releases.

Main image by James Gathany, CDC, source A New Model for Predicting Outbreaks of West Nile Virus. Gross L, PLoS Biology Vol. 4/4/2006, e101. https://dx.doi.org/10.1371/journal.pbio.0040101. Permission to use under Creative Commons license.