Beyond causing bee deaths, pesticide exposure at sub-lethal doses impairs navigation, learning, immune function and reproduction in bees, representing a widespread and underappreciated welfare problem.
The welfare implications of sub-lethal pesticide exposure in bees extend well beyond colony-level population effects. Individual bees experiencing pesticide-induced navigation impairment may become lost and die isolated from the colony. Immune suppression from pesticide exposure leaves bees more vulnerable to pathogens, increasing disease mortality. Learning impairments affect foraging efficiency and food security for the colony. If insects are capable of any form of welfare-relevant experience, which increasing evidence suggests is plausible, then widespread chronic sub-lethal pesticide exposure represents a welfare problem on an enormous scale affecting billions of individual animals.