Applying the five domains to farmed black soldier fly, house fly, and yellow mealworm welfare

Abstract Trillions of insects are currently farmed as food and feed around the globe. The insects as food and feed industry can provide opportunities for greater food security and increase agricultural sustainability through waste remediation and a circular bioeconomic model. Currently, little is known about the welfare of the insect mini-livestock at the heart of this growing industry. Recent neurobiological and behavioral data suggest at least some insects are plausibly sentient and may feel pain. When animals may be sentient, the precautionary principle suggests we consider their welfare to avoid unnecessary suffering. Alongside the ethical imperative to consider farmed insect welfare, producers may also see economic benefits through enhanced productivity or product quality, improved consumer acceptance, and greater opportunities for product differentiation. Insects farmed as food and feed may be subjected to practices that induce morbidity, mortality, stress, or otherwise cause negative affect during rearing, transportation, and slaughter or depopulation. Furthermore, farming practices may not always provide adequate opportunity for animals to experience positive affective states, e.g., through behavioral expression. Where these practices occur, they may represent welfare concerns. This review examines what is known about the welfare of three insects farmed as food and feed (black soldier flies, houseflies, and yellow mealworms) based on the Five Domains Framework (nutrition, physical health, environment, behavior, and mental state). Although welfare research is beginning to pick up pace for these species, we identify significant gaps in our knowledge, representing opportunities for greater research attention and producer–academic partnership.