Deans Carrie, Hutchison William
Department of Entomology, University of Minnesota, St. Paul, MN, United States.
Front Insect Sci. 2023 Jul 20;3:1105531. doi: 10.3389/finsc.2023.1105531. eCollection 2023.
The ability of living organisms to acquire the nutrients needed to carry out required physiological functions has important consequences for fitness. However, an organism must not simply meet the requirements for individual nutrients, but must ingest an optimal balance of multiple nutrients. Despite this, animals rarely consume truly balanced resources, and instead commonly feed selectively across multiple unbalanced resources to reach an optimal balance, i.e., intake target. Nutritional research has predominantly focused on the behavioral strategies employed during nutrient regulation, as well as the fitness consequence of failing to meet intake targets, but little work has been done on the temporal aspects of this process. For instance, within what timeframe must organisms reach their intake target before a fitness cost is incurred? Hours, days, weeks?
In this study, we investigated how nutrient regulation interval impacts consumption and performance in adult female spotted-wing Drosophila (Drosophila suzukii). Females were constrained to either a protein- orcarbohydrate-biased diet over different time intervals and at different schedules, while control flies were constrained to one diet for the entire feeding period.
Regulation interval had a significant impact on feeding behavior and consumption. Total consumption was highest on the shorter interval treatments, where diets were alternated more frequently, and declined as the interval period increased. The relative consumption of both diets was statistically-different across intervals and was higher for the carbohydrate-biased diet. Consumption of the protein-biased diet was more variable across intervals and was more strongly impacted by the daily timing of diet switches. Performance data showed that shorter regulation intervals led to longer fly lifespans, a result commonly observed in studies exploring the impacts of diet macronutrient ratio variability on performance.
These results show that the temporal aspects of nutrition, such as feeding intervals and the timing of resource availability, can have strong impacts on feeding behavior, nutrient regulation, and fitness. These results provide an insight into how consumers may deal with changes in host phenology, the availability of hosts, and changes in nutrient availability within hosts. Understanding these mechanisms will be important for predicting responses to changes in nutrient cycling and resource availability mediated by natural and anthropogenic habitat modifications, such as global climate change.
生物体获取进行所需生理功能所需营养物质的能力对其适应性具有重要影响。然而，生物体不仅要满足个体营养物质的需求，还必须摄取多种营养物质的最佳平衡。尽管如此，动物很少消耗真正平衡的资源，而是通常在多种不平衡的资源中进行选择性觅食，以达到最佳平衡，即摄入目标。营养研究主要集中在营养调节过程中所采用的行为策略，以及未达到摄入目标所产生的适应性后果，但关于这一过程的时间方面的研究却很少。例如，生物体必须在多长时间内达到其摄入目标才会产生适应性成本？几小时、几天、几周？
在本研究中，我们调查了营养调节间隔如何影响成年雌性铃木氏果蝇（Drosophila suzukii）的摄食和性能。雌性果蝇在不同的时间间隔和不同的时间表下被限制在以蛋白质或碳水化合物为主的饮食中，而对照果蝇在整个摄食期都被限制在一种饮食中。
调节间隔对摄食行为和摄入量有显著影响。在较短的间隔处理中，即饮食交替更频繁时，总摄入量最高，并且随着间隔期的增加而下降。两种饮食的相对摄入量在不同间隔之间存在统计学差异，且以碳水化合物为主的饮食摄入量更高。以蛋白质为主的饮食摄入量在不同间隔之间变化更大，并且受饮食切换的每日时间影响更强。性能数据表明，较短的调节间隔导致果蝇寿命延长，这一结果在探索饮食常量营养素比例变异性对性能影响的研究中经常观察到。
这些结果表明，营养的时间方面，如摄食间隔和资源可利用的时间，会对摄食行为、营养调节和适应性产生强烈影响。这些结果为消费者如何应对宿主物候变化、宿主可利用性以及宿主体内营养可利用性的变化提供了见解。了解这些机制对于预测由自然和人为栖息地改变（如全球气候变化）介导的营养循环和资源可利用性变化的响应将非常重要。
