The extraordinary success of social insects is partially based on division of labour, i.e. individuals exclusively or preferentially perform specific tasks. Task preference may correlate with morphological adaptations so implying task specialization, but the extent of such specialization can be difficult to determine. Here, we demonstrate how the physical foundation of some tasks can be leveraged to quantitatively link morphology and performance. We study the allometry of bite force capacity in Atta vollenweideri leaf-cutter ants, polymorphic insects in which the mechanical processing of plant material is a key aspect of the behavioural portfolio. Through a morphometric analysis of tomographic scans, we show that the bite force capacity of the heaviest colony workers is twice as large as predicted by isometry. This disproportionate ‘boost’ is predominantly achieved through increased investment in muscle volume; geometrical parameters such as mechanical advantage, fibre length or pennation angle are likely constrained by the need to maintain a constant mandibular opening range. We analyse this preference for an increase in size-specific muscle volume and the adaptations in internal and external head anatomy required to accommodate it with simple geometric and physical models, so providing a quantitative understanding of the functional anatomy of the musculoskeletal bite apparatus in insects.

群居昆虫的非凡成功部分基于劳动分工，即个体专门或优先执行特定任务。任务偏好可能与形态适应相关，因此意味着任务专业化，但这种专业化的程度可能很难确定。在这里，我们演示了如何利用某些任务的物理基础来定量连接形态和性能。我们研究了Atta vollenweideri切叶蚁（多态性昆虫）咬合力能力的异速生长，其中植物材料的机械加工是行为组合的关键方面。通过断层扫描的形态测量分析，我们发现最重的蚁群工蚁的咬合力能力是等距预测的两倍。这种不成比例的“提升”主要是通过增加对肌肉体积的投资来实现的。机械优势、纤维长度或羽状角度等几何参数可能受到维持恒定下颌张开范围的需要的限制。我们分析了这种对特定尺寸肌肉体积增加的偏好，以及通过简单的几何和物理模型来适应它所需的内部和外部头部解剖结构的适应性，从而提供了对昆虫肌肉骨骼咬合装置的功能解剖结构的定量理解。