Foxglove, Digitalis purpurea: An Eco-feast Plant for Bumble Bee Conservation in the Northwestern Himalayas

Bumble bees (Bombus spp.) are key pollinators in Himalayan ecosystem, but habitat degradation and floral resource scarcity threaten their population. Foxglove, Digitalis purpurea, an introduced plant with deep corolla, is an important source of pollen and nectar for bees and harbors four species of bumble bees viz. Bombus haemorrhoidalis, Bombus tunicatus, Bombus simillimus, and Bombus eurythorax in the Jammu region of the Northwestern Himalayas. The nest count and abundance of B. tunicatus and B. simillimus were significantly higher in patches with D. purpurea plantation (p < 0.05) as compared to control patches. The individuals of B. tunicatus and B. simillimus foraging on the flowers of D. purpurea were vigorous in terms of body length and body weight (p < 0.05) as compared to the individuals foraging on other habitat patches. A strong positive correlation was found between the corolla lengths of the examined flower species and the tongue lengths of nectar-gathering bumble bees (r = 0.89). Besides, long-tongued Bombus species are attracted to flowers of D. purpurea due to the deep corolla and higher nectar production (p < 0.05). The D. purpurea is recommended as an eco-feast plant for bumble bee conservation, and its plantation in the pollinator gardens will ensure efficient pollination services by the bumble bees. Hence, this study provides the first scientific evidence of the role of D. purpurea in bumble bee conservation in the Indian Himalayas.