Bumblebees live in annual colonies with complex social structures, and their welfare is affected by pesticides, habitat loss, and disease at both individual and colony levels.
Bumblebee welfare spans multiple levels - individual bees, colonies, and populations - and welfare harms at each level interact in important ways. Individual bees are capable of learning, remember flower types and locations, and may experience something analogous to positive states when foraging successfully. Sub-lethal pesticide exposure impairs navigation and memory, causing bees to become lost and die away from the colony - an individual welfare harm that scales to colony productivity loss. At colony level, pathogen infections including those spread by commercially reared bumblebees imported for greenhouse pollination can devastate wild populations. The commercial bumblebee industry, while providing economic value through crop pollination, has been implicated in the spread of Nosema bombi and trypanosomes to wild bumblebees with which escaped colony workers interact. Habitat loss reduces floral diversity, creating nutritional stress that weakens immune systems and increases disease susceptibility. The cascade from individual welfare harm to colony failure to population decline represents a multi-level welfare challenge requiring solutions at each scale.