The UK has lost two bumblebee species in the 20th century and several more are now rare or declining. Bumblebees are increasingly recognised as sentient insects, making their population collapse a welfare issue as well as an ecological crisis.
Research by Barron and Klein, and subsequent work by Lars Chittka at Queen Mary University, provides strong evidence that bees have the neurological capacity for subjective experience. Bumblebees show pessimistic cognitive bias after stressful events and positive affect responses to food rewards. This means pesticide exposure, habitat loss, and colony collapse are not merely conservation concerns but potential sources of large-scale invertebrate suffering. Neonicotinoid sublethal effects impair learning and memory, reducing foraging success and likely causing frustration-like states. Colony-level starvation, where entire nests die through insufficient forage, represents significant welfare harm at scale.