A growing animal ingests food from the environment and distributes the assimilated energy between chemical energy stored in synthesized biomass and energy spent on metabolic processes, including food processing, maintenance, activity and overhead costs for growth. Under food restriction, the growth rate is usually decreased. However, the extent of this reduction may be influenced by a potential trade-off with maintenance metabolism. The latter seems to be down-regulated under food restriction in some animals and up-regulated in others. Recently, the Maintenance-Growth Model (MGM) was developed for ontogenetic and post-mature growth, including several aspects not considered by common mechanistic growth models, most importantly the division of maintenance costs into and parts, where the latter can be up- or downregulated under food restriction. Using empirical data, MGM has been calibrated and successfully applied to an insect growing under ad libitum conditions. Here, the model is further calibrated to newly collected individual data for the same species growing under two different regimes of food restriction, complemented with previously collected data for food-limited cohorts. We find that two alternative model scenarios of MGM are able to generate rather good predictions of observed growth under food restriction, assuming either upregulated maintenance or decreased effective assimilation (assimilation minus energy spent on processing and searching food). We find the latter scenario least plausible, implying that the current study provides the first indication for the occurrence of upregulated maintenance in an insect species when food is scarce, an unexpected result that requires further investigation. The inclusion of maintenance regulation in MGM enables the new growth model to be used in the modelling of life-history dependent trade-offs between maintenance, growth and maturation for various other species.

中文翻译：

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一种新的个体生长机制模型表明，当昆虫食物稀缺时，维持成本就会上调

生长中的动物从环境中摄取食物，并在合成生物质中储存的化学能和代谢过程消耗的能量之间分配吸收的能量，包括食物加工、维护、活动和生长的间接成本。在食物限制下，生长速度通常会降低。然而，这种减少的程度可能会受到与维持代谢的潜在权衡的影响。后者似乎在某些动物的食物限制下下调，而在另一些动物中则上调。最近，维护生长模型（MGM）是针对个体发育和成熟后生长而开发的，包括常见机械生长模型未考虑的几个方面，最重要的是将维护成本分为 和 部分，其中后者可以向上或向下在食品限制下下调。利用经验数据，MGM 已被校准并成功应用于在随意条件下生长的昆虫。在这里，该模型进一步校准为新收集的在两种不同食物限制制度下生长的同一物种的个体数据，并补充了之前收集的食物限制群体的数据。我们发现，假设上调维持或降低有效同化（同化减去用于加工和寻找食物的能量），MGM 的两种替代模型场景能够对食物限制下观察到的生长产生相当好的预测。我们发现后一种情况最不可信，这意味着当前的研究首次表明，当食物稀缺时，昆虫物种的维持上调，这是一个意想不到的结果，需要进一步调查。 MGM 中包含的维持调节使得新的生长模型能够用于对其他各种物种的维持、生长和成熟之间依赖于生活史的权衡进行建模。