A biomechanical model for the relation between bite force and mandibular opening angle in arthropods

Area of Science:

• Biomechanics
• Ecology
• Evolutionary Biology

Background:

• Bite forces are crucial for animal mating, fighting, and feeding behaviors.
• Arthropod feeding habits have significant ecological and economic impacts.
• Knowledge gaps exist regarding how arthropod bite apparatus morphology and physiology influence bite performance and variation with mandible gape.

Purpose of the Study:

• To develop a biomechanical model linking bite force and mandibular opening angle.
• To validate the model using morphological data from *Atta cephalotes* (leaf-cutter ants).
• To explore the model's utility in extracting physiological properties, quantifying bite force specialization, and assessing morphology vs. physiology contributions.

Main Methods:

• Derivation of a first-principles biomechanical model for bite force and mandibular gape.
• Validation using computed tomography (CT) scans of *Atta cephalotes* musculoskeletal bite apparatus at varying mandible opening angles.
• Integration with *in vivo* bite force measurements.

Main Results:

• The biomechanical model accurately predicts geometric relationships.
• Leaf-cutter ants exhibit specialized morphology and physiology for extreme bite forces (approx. 2600x body weight).
• The study quantifies muscle physiological properties and discusses relative contributions of morphology and physiology to bite force.

Conclusions:

• A quantitative understanding of morphology-physiology-performance links is established for insect mandibles.
• This framework facilitates comparative studies on arthropod bite apparatus.
• Advances knowledge of arthropod behavior, ecology, and evolution through biomechanical insights.