The effect of seasonal temperatures on the physiology of the overwintered honey bee.

Honey bee physiology follows an annual cycle, with winter bees living ten times longer than summer bees. Their transition can be disrupted by climate change. Several climate factors, mainly temperature, may contribute to the global losses of winter bees. We simulated global warming by maintaining constant temperatures of 25°C (Group 25) and 35°C (Group 35) in rooms around hives from June to October, while a Group control experienced natural conditions. Colony performance was assessed in August and September. In February, workers were examined for physiological traits (acinus size and lipid content in the fat body) and molecular markers (vg and JHAMT), along with potential markers (ilp1, ilp2, TOR1, and HSP70). Our findings suggest that temperature decreases around winter worker broods from Group 25 in the fall led to their different physiological states related to aging in winter compared to Group 35 workers. Changes in bees from Group 35 the end of diapause were detected with an upregulation of HSP70, ilp2, and TOR1 genes. These signs of winter bees in response to summer global warming could lead to the development of strategies to prevent bee losses and improve the identification of physiological states in insect models.