Meghan Barrett

Background: Allodynia (pain in response to normally non-noxious stimuli) and hyperalgesia (increased sensitivity to painful stimuli) are well-established indicators of pain sensitization after tissue damage in vertebrates. These phenomena may also offer valuable insights into nociceptive processing in invertebrates. We assessed behavioural evidence for allodynia and hyperalgesia following two types of peripheral injury (tarsus amputation or burning) and sham treatment in black garden ants ( Lasius niger , Hymenoptera: Formicidae). At 20 min, 24 h, and 96 h post-anaesthesia, a ramping hot plate assay with sublethal, but increasingly noxious, temperatures was used to assess allodynia and hyperalgesia. Locomotor speed and proportion of time spent moving were quantified to detect increased responsiveness at normally non-noxious temperatures (allodynia) or exaggerated responses at higher temperatures (hyperalgesia). Results: We observed an earlier onset of responsiveness in ants with tarsus amputations and burns compared to controls, consistent with allodynia, which was stronger and more consistent in tarsus-amputated ants and at later time points. Evidence for hyperalgesia was limited and time-dependent: amputated ants showed a steeper response increase at higher temperatures at earlier time points, but not at 96 h. Burn-treated ants showed less consistent evidence of allodynia and no evidence of hyperalgesia. Conclusions: These findings suggest that sensitization extends beyond the acute injury phase and align with broader evidence for chronic, pain-like processing in insects. As a new injury model in insects, the burn treatment needs to be refined, or the underlying mechanisms may be different to those involved in classic, amputation-induced sensitization.

Trillions of black soldier fly (BSFL; Hermetia illucens; Diptera: Stratiomyidae) and yellow mealworm (YML; Tenebrio molitor; Coleoptera: Tenebrionidae) larvae are slaughtered annually for feed. Slaughter standard operating procedures (SOPs) that protect welfare and product quality are essential to ethical and economical industry practice. This study defines humane (≤1 second time-to-death) slaughter SOPs for hot water immersion of BSFL and YML. We assessed isothermal critical thermal maxima in water from 32, or 40, to 100 °C in YML and BSFL, respectively. We used Weibull probability-based models to characterize survival as a function of processing time at different temperatures, describing the time–temperature conditions required for humane slaughter. We blanched larvae under: 1) a SOP resulting in a ∼1 minute time-to-death for 99% of larvae; 2) a SOP resulting in ≤1 second time-to-death for 99% of larvae; and 3) 99.5-100 °C. We compared ash, protein and fat, pH, water activity, lipid oxidation, and color change. Water temperatures kept above 81.3 °C (BSFL ≤ 0.16 g), and 78.3 °C (YML ≤ 0.12 g), are predicted to result in humane slaughter for >99% of larvae - though, further research is needed to develop SOPs for larger larvae. The humane SOPs have neutral or beneficial impacts on quality. We recommend producers adopt a 2 °C buffer (BSFL: 83.3 °C; YML: 80.3 °C). Finally, we provide an energy balance model that producers can use to determine the larvae:water ratio and temperature that results in humane slaughter in their facility.

Asia has served as a home for insect farming for millennia, including the oldest known insect domestication event (sericulture). Beyond Asia’s traditional insect farming practices, Asian countries have also led the world in many recent insect farming innovations. Asian nations are major players in the insects as food and feed, traditional medicine, waste management, beekeeping, shellac and sericulture industries (among others). Trillions of insects are now farmed or otherwise managed each year across these growing industries. Recent research into insect sentience (which some philosophical traditions regard as important for moral consideration) has suggested that at least some insects may plausibly be sentient, leading to calls from industry and academia alike for insect welfare to be considered on farms. In addition, many philosophical and moral traditions that are prominent in Asia emphasise respect for all life irrespective of sentience, including the just treatment of insects. Here, we briefly review what is currently known about insect welfare in the sericulture, beekeeping and food and feed or waste management industries in Asia. We consider the unique political and sociocultural contexts of insect farming in Asia and how they influence ethical and economic dialogues regarding insect welfare. We conclude with future directions for the study of insect welfare in Asia, the application of its principles to relevant industries and the sociocultural and political factors that may shape local decision-making.

Reductions in insect biodiversity are widely documented and result from numerous pressures that operate from local to global scales. Identifying and synthesizing information on these drivers has become a central focus of research over the past decade, yet existing reviews often emphasize a limited set of well-established threats. Here, we provide a policy-oriented review of the drivers of insect decline, structured explicitly around the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) assessment framework and accompanied by statements of confidence to facilitate direct uptake into biodiversity assessments. We integrate evidence on both widely recognized drivers and a broader suite of pressures that remain comparatively understudied. The impacts of large-scale drivers of insect decline, such as land-use change and climate change, are well established and broadly align with those seen to threaten other taxa. Yet, many other threats, such as insecticides and light pollution (among others), pose disproportionate harm to insects but are not fully understood and remain important areas of research. It is also the case that most insect populations are experiencing multiple stressors simultaneously, and the combined effects of these pressures remain unclear. Despite this uncertainty, many threats to insect biodiversity are largely understood, and we know enough to form broad expectations for future responses and to develop action plans.

Insect science is a dynamic and continually evolving field, driven equally by the methods we develop, critique and use and the philosophies that guide our investigations, interpretations and applications. Advances in technologies and techniques allow us to study insects at unprecedented spatial, temporal and molecular scales, revealing deeper insights into the mechanisms by which they shape our ecosystems, society and human health. At the same time, evolving philosophical perspectives are continuously advancing how we design our experiments, consider our animals, infer new phenomena and share our findings. Together, methods, philosophies and ethics form the critical foundations of insect science from which progress across entomology ultimately arises. Sharing and reflecting on these approaches is essential for innovation in entomology to extend beyond individual laboratories and subdisciplines to benefit the wider scientific community. These interdisciplinary advances are, however, typically scattered across journals, disciplines and informal exchanges, often struggling to find a suitable home, limiting their visibility and impact. To address this need, the Royal Entomological Society has launched a new journal dedicated to methods and philosophies across insect science. Approaches in Entomology: Methods, Philosophies, and Ethics provides a dedicated forum for the dissemination, evaluation and development of innovative approaches across the full breadth of insect science with a particular emphasis on methods, philosophies and ethical dialogues.

Nociception, the capacity to detect tissue‐damaging stimuli, such as noxious chemicals or high heat, is increasingly studied across insect orders and life stages, informing our understanding of its adaptive value and molecular mechanisms. The black soldier fly (Hermetia illucens; Diptera: Stratiomyidae) is widely recognized as the star of the growing insects as food and feed industry. Black soldier fly larvae (BSFL) are reared at high densities that, combined with their extraordinary collective metabolism, can sometimes generate lethal overheating on farms. Data on the thermal nocifensive capabilities of BSFL could inform our understanding of larval behaviours during overheating events (and potential welfare impacts of thermal methods of slaughter) and provide a comparative datapoint to the well‐studied vinegar fly (Drosophila melanogaster; Diptera: Drosophilidae). Accordingly, we adapted global and local thermal nociception methods from larval vinegar flies for use with BSFL. We find that global assays (akin to boiling) adapt easily to both first‐ and late‐instar BSFL, that BSFL exhibit slightly different nocifensive behaviours than last‐instar vinegar fly larvae and that BSFL have higher thresholds (thrashing begins at 39.70°C in late‐instar BSFL versus 26.6°C in D. melanogaster). In contrast, the classical local nociception assay did not adapt easily to BSFL; hence, we modified the assay to test a time‐bounded, continuous exposure to the temperature probe instead of response latency. This assay generated a unique, gradual pattern of increasing responsiveness to the probe in late‐instar BSFL (>95% responsiveness above 66°C) rather than the sharp cutoff in responsiveness at 52°C demonstrated in D. melanogaster during response‐latency assays. Altogether, these protocols open the door for standardized research on BSFL thermal nociception for fundamental and applied purposes.

Research involving insects currently falls outside the scope of animal welfare legislation in the United Kingdom ; however, many institutions in the United Kingdom require submission of procedures involving insects to their internal ethics review board. Here, we have surveyed UK institutions to assess what proportion require ethics applications for work with insects. Further, we surveyed entomologists working at UK institutions to understand when requirements first came about at their institution and (if applicable) their experiences with ethics review, including feedback received, resources used/desired and their self‐reported confidence in submitting applications. In addition, we assessed entomologists' perception of the influence of ethics review on research quality and their general attitudes and values towards the ethical treatment of insects in research and the process of ethics review. Our data demonstrate that just over half of UK institutions (51.6%) require ethics review for research with insects starting in 2008, with a steady trend towards increasing institutional requirements over time. Entomologists currently submitting are largely confident in their applications (68.8%, confident) but the majority believe that resources like training on ethics in the insect context and greater research on insect welfare would be helpful. Entomologists largely believed that ethics applications had either a positive effect (44.6%) or no effect (39.6%) on research quality; early‐career entomologists were more likely to report a positive effect of ethics review on study quality. Qualitative responses suggest the entomological community has diverse values and attitudes towards the ethical treatment of insects in research.

Nociception, the capacity to detect tissue-damaging stimuli such as noxious chemicals or high heat, is increasingly studied across insect orders and life stages, informing our understanding of its adaptive value and molecular mechanisms. The black soldier fly (Hermetia illucens; Diptera: Stratiomyidae) is widely recognized as the star of the growing insects as food and feed industry. Black soldier fly larvae (BSFL) are reared at high densities that, combined with their extraordinary metabolism, can generate lethal overheating on farms. Data on the thermal nocifensive capabilities of BSFL could inform our understanding of larval behaviors during overheating events (and potential welfare impacts of thermal slaughter), and provide a comparative datapoint to the well-studied vinegar fly (Drosophila melanogaster; Diptera: Drosophilidae). Accordingly, we adapted global and local thermal nociception methods from larval vinegar flies for use with BSFL. We find that global assays (akin to boiling) adapt easily to both first and sixth instar BSFL, that BSFL exhibit slightly different nocifensive behaviors than last instar vinegar fly larvae, and that BSFL have higher thresholds (thrashing begins at 39.70 C in last instar BSFL versus 26.6 C in D. melanogaster). In contrast, the classical local nociception assay did not adapt easily to BSFL; a modified version generated a unique, gradual pattern of increasing responsiveness to the probe in sixth instar BSFL (>95% responsiveness above 66 C) rather than the sharp cutoff in responsiveness at 52 C demonstrated in D. melanogaster. Altogether, these protocols open the door for standardized research on BSFL thermal nociception for fundamental and applied purposes.

Feeder animals—live animals such as mice, fish and invertebrates used as feed for other species—often far exceed the number of exhibit animals at zoological institutions. While there are extensive species‐specific guidelines for the care of exhibit animals, the guidelines that exist for animals used as feed are brief and offer relatively few species‐specific recommendations. This state of affairs increases the risk of compromised welfare—which is especially concerning given growing evidence of sentience in fish and some invertebrates. As zoological institutions continue to advance toward evidence‐based, welfare‐focused practices, it is imperative that institutions recognize and address the welfare of feeder animals. Current and future generations of scientists need to focus on validating welfare indicators for common feeder species, developing welfare assessments for feeder animals, and routinely monitoring and refining practices to enhance the welfare of feeder animals. Given the sheer volume of feeder animals used across institutions, even modest improvements could have a profound cumulative impact on animal welfare.

Intraspecific variation in behavior is associated with variable brain resource allocation patterns: There is frequently increased tissue investment in discrete regions that support fitness‐relevant cognitive abilities. However, the relationships between tissue volume and actual cell numbers have rarely been explored for insects due to methodological hurdles recently addressed via the application of isotropic fractionation. In solitary desert Centris pallida (Hymenoptera: Apidae) bees, there are two major levels of intraspecific variation: sex (males vs. females) and male morph (as a result of alternative reproductive tactics, large morph and small morph males rely on scent or sight, respectively, for mate location). Using isotropic fractionation, we separately analyzed optic lobe (OL) and central brain (CB) cell numbers of males and females to determine the impacts of sex and morph on brain cell allometry. Female bees’ brains were bigger and had higher cell numbers and cell densities than males of the same size. In both sexes, total brain cell number increased with brain size, driven by increases in OL cell numbers. Between male morphs, we found that OL masses were relatively larger in small‐morph males, consistent with the relationship between body size and OL volumes reported in prior studies. However, small‐morph C. pallida males had fewer total cells (as represented by cell nuclei) and reduced cell density, in their OLs. Together, these data suggest that there is intraspecific and brain‐region‐specific variation in brain cell numbers and that variation in brain tissue volume may not match other levels of neural organization like brain cell numbers/densities.