Farmed yellow mealworm (Tenebrio molitor; Coleoptera: Tenebrionidae) welfare: species-specific recommendations for a global industry

Yellow mealworms (Tenebrio molitor; Coleoptera: Tenebrionidae) are currently the most farmed holometabolous insect species in the insects as food and feed industry, with over 300 billion individual mealworms reared annually. Yellow mealworm larvae are being developed for potential uses as human protein, pet, livestock and fish feed, reclamation of mycotoxin-contaminated grains, and more. Insect welfare is of great interest to consumers, producers, and academics; yet no studies have considered the species-specific welfare concerns of farmed yellow mealworms under current industry conditions. Following a model for considering farmed insect welfare, we review yellow mealworm biology and its relationships to welfare in commercial rearing facilities, including: interspecific interactions (predators, parasites, and pathogens), abiotic conditions (temperature, hydration, atmospheric gasses, lighting), nutrition (including pollutants, plastics, and hormones), intraspecific concerns (genetics, morphological defects, cannibalism, density, mating and oviposition needs, and handling-associated stress), and slaughter and depopulation methods (including anesthesia and stunning). From this review, we identify practical recommendations for improving current welfare concerns in the industry and mitigating future concerns that may appear as the industry continues to grow. Finally, we discuss future research directions that are necessary to better understand the welfare of this species.