Nutrition affects stress resistance in African honeybees (Apis mellifera scutellata

1. Nutrition plays an important role in physiological stress resistance and by adjusting their intake of key nutrients, such as protein and carbohydrate, many animals can better resist stress. 2. Poor nutrition may contribute to the widespread and on-going declines of honeybee populations by increasing their vulnerability to abiotic (e.g. pesticides) and biotic (e.g. diseases) stressors. However, we do not know how nutrition affects stress resistance in social insects such as honeybees. 3. Here, we examined how exposure to the toxic secondary metabolite nicotine, a neurotoxin that shares structural similarities with the neonicotinoid pesticides, and low temperatures affected nutrient regulation in honeybees using the Geometric Framework of nutrition. 4. Groups of queenless, newly emerged worker bees were given diets containing specific ratios of protein and carbohydrate to determine, first, how toxin exposure and ambient temperature affected their nutrient intake and, secondly, how nutrition affected survival under stress. 5. We find that low temperatures and nicotine interacted to reduce survival in African honeybees that ate low protein, high carbohydrate diets. However, bees fed a high protein diet were better able to survive insult with these interacting stressors. 6. Although protein conferred a survival benefit in honeybees exposed to these dual stressors, when allowed to self-select their diet, caged workers did not shift their intake towards a higher protein food to improve their survival under these stressful conditions. 7. We discuss the possible constraints on nutrient regulation in honeybees and the role that diet could play in their decline.

营养在生理应激耐受性中扮演着至关重要的角色。通过调整对蛋白质和碳水化合物等关键营养素的摄入，众多动物能够更有效地抵抗压力。不良的营养状况可能加剧蜜蜂数量的持续下降，这种下降趋势普遍存在，并可能因增加其对抗非生物因素（如农药）和生物因素（如疾病）的脆弱性而加剧。然而，我们尚不清楚营养如何影响诸如蜜蜂等社会性昆虫的应激耐受性。在本研究中，我们运用营养的几何框架，探讨了暴露于有毒次生代谢物尼古丁（一种与烟碱类农药结构相似的神经毒素）和低温如何影响蜜蜂的营养调节。实验中，未成熟的无王蜂群被给予了特定比例的蛋白质和碳水化合物饮食，以确定首先，毒素暴露和环境温度如何影响其营养摄入；其次，营养如何影响在应激条件下的生存率。我们发现，低温和尼古丁的相互作用降低了食用低蛋白、高碳水化合物饮食的非洲蜜蜂的生存率。然而，食用高蛋白饮食的蜜蜂在面对这些相互作用的应激因素时，更能耐受侵害。尽管蛋白质为暴露于这些双重应激因素的蜜蜂提供了生存上的益处，但当被允许自主选择饮食时，笼养工蜂并未调整其摄入量，以转向更高蛋白的食物来改善在压力条件下的生存率。我们讨论了可能限制蜜蜂营养调节的因素以及饮食在蜜蜂数量下降中所扮演的角色。