Time-lapse three-dimensional imaging of crack propagation in beetle cuticle

The female locust has a unique mechanism for digging in order to deposit its eggs deep in the ground. It utilizes two pairs of sclerotized valves to displace the granular matter, while extending its abdomen as it propagates underground. This ensures optimal conditions for the eggs to incubate, and provides them with protection from predators. Here, two major axes of operation of the digging valves are identified, one in parallel to the propagation direction of the ovipositor, and one perpendicular to it. The direction-dependent biomechanics of the locust major, dorsal digging valves are quantified and analyzed, under forces in the physiological range and beyond, considering hydration level, as well as the females age, or sexual maturation state. Our findings reveal that the responses of the valves to compression forces in the specific directions change upon sexual maturation to follow their function, and depend on environmental conditions. Namely, in the physiological force range, the valves are resistant to mechanical failure. In addition, mature females, which lay eggs, have stiffer valves, up to roughly nineteen times the stiffness of the pre-mature locusts. The valves are stiffer in the major working direction, corresponding to soil shuffling and compression, compared to the direction of propagation. Hydration of the valves reduces their stiffness but increases their resilience against failure. These findings provide mechanical and materials guidelines for the design of novel non-drilling excavating tools, including 3D-printed anisotropic materials based on composites.

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“…The fracture topography implies on a brittle material 40 , agreeing with the force-displacement curves of the dry valves (Fig. 3 e,f).…”

Section: Mechanical Failuresupporting

confidence: 83%

The Biomechanics of the Locust Ovipositor Valves: a Unique Digging Apparatus

Das

Gershon

Bar‐On

et al. 2021

Preprint

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“…Based on this model, the microtrichia cuticle must have a stiffness of at least 0.3–0.4 GPa, similar to the stiffness of wood and bone ( Vincent and Wegst, 2004 ), to prevent any side contact (for an angle to the disc surface of 40° to 50°; see Figure 7 ). It is not unlikely that the microtrichia cuticle is even stiffer: sclerotised cuticles can have an elastic modulus of up to 20 GPa ( Vincent and Wegst, 2004 ; Wegst and Ashby, 2004 ; Sykes et al, 2019 ). This supports our idea that microtrichia can maintain tip contact during interactions with rough surfaces and could serve a similar function to stiff remora spinules.…”

Section: Discussionmentioning

confidence: 99%

Extreme suction attachment performance from specialised insects living in mountain streams (Diptera: Blephariceridae)

Kang

White

Chen

et al. 2021

eLife

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Suction is widely used by animals for strong controllable underwater adhesion but is less well understood than adhesion of terrestrial climbing animals. Here we investigate the attachment of aquatic insect larvae (Blephariceridae), which cling to rocks in torrential streams using the only known muscle-actuated suction organs in insects. We measured their attachment forces on well-defined rough substrates and found that their adhesion was less reduced by micro-roughness than that of terrestrial climbing insects. In vivo visualisation of the suction organs in contact with microstructured substrates revealed that they can mould around large asperities to form a seal. We have shown that the ventral surface of the suction disc is covered by dense arrays of microtrichia, which are stiff spine-like cuticular structures that only make tip contact. Our results demonstrate the impressive performance and versatility of blepharicerid suction organs and highlight their potential as a study system to explore biological suction mechanisms.

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“…Developmental imaging of internal and nanometric structures is challenging in complex living organisms, as many high-precision anatomical techniques require destructive imaging, necessarily implying that the same material cannot be repeatedly imaged through development. Other noninvasive techniques such as nanoCT theoretically have a minimum resolution of 50nm, although in practice currently around 120 nm (Sykes et al, 2019); they also lack capacity to image structure within dense continuous materials.…”

Section: Accepted Articlementioning

confidence: 99%