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

Püffel, Frederik; Johnston, Richard; Labonte, David

doi:10.1098/rsos.221066

Cited by 23 publications

(48 citation statements)

References 152 publications

(315 reference statements)

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“…In order to make the implications of this difference in flexural rigidity tangible, we calculated the expected deflection for two plates of the same area, but of different thickness and moduli, approximated by T hc and E I , respectively, for a forager with a cuticle brightness of b RGB = 0.15 and a callow with b RGB = 0.5. Under the same load, equal to half of the maximum muscle stress extracted for closely related A. cephalotes majors [83], the resulting deflection of callow cuticle is 17 times higher than for dark cuticle; absolute values of deflection are estimated in the electronic supplementary material. These results invite another hypothesis why callows 'underperform' when biting, in addition to continued muscle growth and physiological development (figure 4a).…”

Section: (B) Flexural Rigidity and The Mechanical Demands On The Head...mentioning

confidence: 99%

Developmental biomechanics and age polyethism in leaf-cutter ants

et al. 2023

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Many social insects display age polyethism: young workers stay inside the nest, and only older workers forage. This behavioural transition is accompanied by genetic and physiological changes, but the mechanistic origin of it remains unclear. To investigate if the mechanical demands on the musculoskeletal system effectively prevent young workers from foraging, we studied the biomechanical development of the bite apparatus in Atta vollenweideri leaf-cutter ants. Fully matured foragers generated peak in vivo bite forces of around 100 mN, more than one order of magnitude in excess of those measured for freshly eclosed callows of the same size. This change in bite force was accompanied by a sixfold increase in the volume of the mandible closer muscle, and by a substantial increase of the flexural rigidity of the head capsule, driven by a significant increase in both average thickness and indentation modulus of the head capsule cuticle. Consequently, callows lack the muscle force capacity required for leaf-cutting, and their head capsule is so compliant that large muscle forces would be likely to cause damaging deformations. On the basis of these results, we speculate that continued biomechanical development post eclosion may be a key factor underlying age polyethism, wherever foraging is associated with substantial mechanical demands.

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Section: (B) Flexural Rigidity and The Mechanical Demands On The Head...mentioning

confidence: 99%

Developmental biomechanics and age polyethism in leaf-cutter ants

et al. 2023

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“…First, the distance between mandible markers and a derived joint centre is highly consistent across the kinematic space (figure 4c); second, fitting a single rotational axis to data from opening angles larger than 68 resulted in small and randomly distributed residuals of the cost function defined by equation (2.3) (figure 4e); and third, the standard deviation of the residuals and the distance metrics in this region of the kinematic space were small, and comparable to those obtained from a physical hinge joint model (figure 4e). The orientation of the dominant axis defines the plane of rotation, and thus determines the magnitude of the mechanical advantage of the force transmission system [25,33,35,41], the possible mandibular gape with respect to the head-or bodyfixed anatomical planes [25,33,41], and the angle between apodeme and effective in-lever [41]. All these parameters play a crucial role in determining insect bite performance [41].…”

Section: Discussionmentioning

confidence: 99%

“…Is it really plausible that all dicondylic mandibles of winged biting insects are adequately described by the same hinge joint paradigm? Although restriction to a single DoF simplifies neuromechanical control and may increase net bite force by channelling muscle force into two antagonistic muscle pairs [33,35,[39][40][41], it is not free from disadvantages. In mammals, for example, multiple jaw DoFs enable an array of masticatory kinematics, with significant benefits to the ability to nutritionally process food (e.g.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional kinematics of leaf-cutter ant mandibles: not all dicondylic joints are simple hinges

Kang,

Püffel,

Labonte

2023

Phil. Trans. R. Soc. B

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Insects use their mandibles for a variety of tasks, including food processing, material transport, nest building, brood care, and fighting. Despite this functional diversity, mandible motion is typically thought to be constrained to rotation about a single fixed axis. Here, we conduct a direct quantitative test of this ‘hinge joint hypothesis’ in a species that uses its mandibles for a wide range of tasks: Atta vollenweideri leaf-cutter ants. Mandible movements from live restrained ants were reconstructed in three dimensions using a multi-camera rig. Rigid body kinematic analyses revealed strong evidence that mandible movement occupies a kinematic space that requires more than one rotational degree of freedom: at large opening angles, mandible motion is dominated by yaw. But at small opening angles, mandibles both yaw and pitch. The combination of yaw and pitch allows mandibles to ‘criss-cross’: either mandible can be on top when mandibles are closed. We observed criss-crossing in freely cutting ants, suggesting that it is functionally important. Combined with recent reports on the diversity of joint articulations in other insects, our results show that insect mandible kinematics are more diverse than traditionally assumed, and thus worthy of further detailed investigation. This article is part of the theme issue ‘Food processing and nutritional assimilation in animals’.

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“…In order to compare the morphology across ants of different body sizes, the muscle volume, Physiological Cross-Sectional Area (PCSA), and fiber length were normalized: , and . In the absence of detailed information on the force-length properties of the involved muscles (Püffel et al, 2023), we define PCSA as . Information on the body mass was lacking for some ants.…”

Section: Methodsmentioning

confidence: 99%

“…. In the absence of detailed information on the force-length properties of the involved muscles (Püffel et al, 2023), we define PCSA as…”

Section: Scalingmentioning

confidence: 99%

Parallel and divergent morphological adaptations underlying the evolution of jumping ability in ants

Aibekova

Katzke

Allman

et al. 2023

Preprint

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Jumping is a rapid locomotory mode widespread in terrestrial organisms. However, it is a rare specialization in ants. Forward jumping has been reported within four distantly related ant genera: Gigantiops, Harpegnathos, Myrmecia, and Odontomachus. The temporal engagement of legs/body parts during jump, however, varies across these genera. It is unknown what morphological adaptations underlie such behaviors, and whether jumping in ants is solely driven directly by muscle contraction or additionally relies on elastic recoil mechanism. We investigate the morphological adaptations for jumping behavior by comparing differences in the locomotory musculature between jumping and non-jumping relatives using x-ray micro-CT and 3D morphometrics. We found that the size-specific volumes of the trochanter depressor muscle (scm6) of the middle and hind legs are 3-5 times larger in jumping ants, and that one coxal remotor muscle (scm2) is reduced in volume in the middle and/or hind legs. Notably, the enlargement in the volume of other muscle groups is directly linked to the legs or body parts engaged during the jump. Furthermore, a direct comparison of the muscle architecture revealed two significant differences between in jumping versus non-jumping ants: First, the relative Physiological Cross-Sectional Area (PCSA) of the trochanter depressor muscles of all three legs were larger in jumping ants, except in the front legs of O. rixosus and M. nigrocincta; second, the relative muscle fiber length was shorter in jumping ants compared to non-jumping counterparts, except in the front legs of O. rixosus and M. nigrocincta. This suggests that the difference in relative muscle volume in jumping ants is largely invested in the area (PCSA), and not in fiber length. There was no clear difference in the pennation angle between jumping and non-jumping ants. However, the length of hind legs relative to body length was longer in jumping ants. Based on direct comparison of the observed vs. possible work and power output during jumps, we surmise that direct muscle contractions suffice to explain jumping performance, in two species, but elastic recoil is likely important in one. We suggest that increased investment in jumping-relevant musculature is a primary morphological adaptation that separates jumping from non-jumping ants. These results elucidate the common and idiosyncratic morphological changes underlying this rare adaptation in ants.

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

Cited by 23 publications

References 152 publications

Developmental biomechanics and age polyethism in leaf-cutter ants

Developmental biomechanics and age polyethism in leaf-cutter ants

Three-dimensional kinematics of leaf-cutter ant mandibles: not all dicondylic joints are simple hinges

Parallel and divergent morphological adaptations underlying the evolution of jumping ability in ants

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