Arcus as a tensegrity structure in the arolium of wasps (Hymenoptera: Vespidae)

Frantsevich, Leonid; Gorb, Stanislav N.

doi:10.1078/0944-2006-00067

Cited by 42 publications

(34 citation statements)

References 12 publications

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“…On the smooth substrate, claws slip over the substrate and drift apart, and the arolium spreads and presses to the substrate (Snodgrass 1956;Federle et al 2001;Frantsevich and Gorb 2002). Similar behavior of the tarsal chain is described for flies (Niederegger and Gorb 2003).…”

Section: Introductionmentioning

confidence: 80%

Insect walking techniques on thin stems

Gladun

Gorb

2007

Arthropod-Plant Interactions

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The attachment ability of insects on surfaces are associated not only with the micro-and nanostructure of the adhering part of an attachment device, but also with the global scale kinematics responsible for contact formation and release. In the present study, the locomotory techniques of several representatives of insects from four different orders (Orthoptera, Heteroptera, Coleoptera, and Hymenoptera), possessing different types of attachment structures, are described. The study is based on video recordings of insects walking on a flat surface and on cylindrical rods of various thickness, imitating plant stems. Attachment devices of tarsi and pretarsi were visualized using Scanning Electron Microscopy. The results show a different manner in the use of adhesive structures on substrates with various curvatures. Insects bearing attachment pads on proximal tarsomeres usually touch flat and curved substrates using all tarsomeres, whereas insects with their attachment devices on the distal tarsomeres usually walk on flat surfaces using the distal tarsomeres of the overextended tarsus. On substrates, with diameters comparable to or larger than the tarsus length, insects walk above the stem by clasping the stem with the bent tarsi. On thin stems, insects clasp the stem between their tarsi and hang under the stem. Thus, on thin and thick rods, forces applied to attachment organs act in opposite directions. There are two methods of leg positioning for walking on a rough flat substrate. In the first case, the tarsus is straightened and the rough substrate is gripped between the claws and the proximal complex of attachment devices (tarsal euplantulae, fossulae spongiosa, and terminal spurs of tibiae). In the second case the tibia does not touch the substrate; the insect is supported only by distal tarsomeres. The tarsus is in an overextended condition. On rods, with diameters comparable to or larger than the tarsus length, insects walk by clasping the stem with the bent tarsi. This posture is characteristic for the majority of insects independent of the tarsal position they normally use while walking on a plane. If the rod's diameter is smaller than the tarsus length, walking insects usually clutch it between contralateral tarsi. Using such a posture they are supported by interlocking or by strong friction, generated by attachment devices of the proximal tarsomeres, and do not use attachment devices of the pretarsus. Contact with the substrate is reinforced due to the coordinated contralateral clutch using all supporting legs. It is concluded that the use of different types of attachment structures correlates with locomotory techniques.

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Section: Introductionmentioning

confidence: 80%

Insect walking techniques on thin stems

Gladun

Gorb

2007

Arthropod-Plant Interactions

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“…By contrast, the smooth arolium cuticle in ants and other Hymenoptera is probably not a hydrostat, because it is not isolated by the epidermis, and adjoins a large, fluid-filled compartment inside the arolium [4]. Here, lateral expansion of the contact area is achieved in a completely different way, via a U-shaped endoscelerite of the arolium, the arcus, which helps to translate a pull along the leg into a lateral expansion [4,5,9,26]. Our results suggest that the ants' unfolding mechanism is more confined to purely proximal pulls, whereas the stick insects' mechanism can be triggered for a wider range of pulling angles.…”

Section: Discussionmentioning

confidence: 99%

Rapid preflexes in smooth adhesive pads of insects prevent sudden detachment

Endlein

Federle

2013

Proc. R. Soc. B.

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Many insects possess adhesive organs that can produce extreme attachment forces of more than 100 times body weight but they can rapidly release adhesion to allow locomotion. During walking, weaver ants (Oecophylla smaragdina) use only a fraction of their maximally available contact area, even upside-down on a smooth surface. To test whether the reduced contact area makes the ants more susceptible to sudden and unexpected detachment forces, for example, by rain or wind gusts, we investigated the reaction of untethered ants to rapid horizontal displacements of the substrate. Highspeed video recordings revealed that the pad's contact area could more than double within the first millisecond after the perturbation. This contact area expansion is much faster than any neuromuscular reflex and therefore represents a passive 'preflex', resulting from the mechanical properties and geometrical arrangement of the (pre-)tarsus. This preflex reaction protects ants effectively against unexpected detachment, and allows them to use less contact area during locomotion. Contact area expanded most strongly when the substrate displacement generated a pull along the axis of the tarsus, showing that the ants' preflex is direction-dependent. The preflex may be based on the ability of Hymenopteran adhesive pads to unfold when pulled towards the body. We tested Indian stick insects (Carausius morosus), which have smooth pads that lack this motility. Similar to the ants, they showed a rapid and direction-dependent expansion of the contact area mainly in the lateral direction. We propose that the preflex reaction in stick insects is based on the reorientation of internal cuticle fibrils in a constant-volume system, whereas the ants' pad cuticle is probably not a hydrostat, and pad extension is achieved by the arcus, an endoscelerite of the arolium.

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“…Also, a certain stiffness in the tarsus and the pretarsus segments is necessary for the tarsal chain to work properly, and avoid curling and detaching from the ground (Clemente and Federle, 2008;Frantsevich and Cruse, 1997;Frantsevich and Gorb, 2004). Third, the use of the claw retractor muscle on a smooth surface may be due to the fact that the arolium, as a pretarsal attachment pad, is also driven by this muscle (Federle et al, 2001;Frantsevich and Gorb, 2002). On smooth surfaces the activity of the retractor unguis may thus not indicate use of the claws but rather deployment and preload/shear of the arolium as an attachment pad for smooth surfaces.…”

Section: Discussionmentioning

confidence: 99%

Activity of the claw retractor muscle in stick insects in wall and ceiling situations

Bußhardt

Gorb

Wolf

2011

Journal of Experimental Biology

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SUMMARYThe activity of the middle part of the claw retractor muscle was examined in two species of stick insects (Carausius morosus and Cuniculina impigra). We performed electromyographic recordings while the animals were standing on a smooth or a rough surface of a platform in horizontal, vertical or inverted positions, as well as during rotations of the platform. We recorded tonic and phasic motor units. The tonic units were active all the time without significant differences in spike frequency, regardless of the position of the animals (although there was a tendency for higher discharge frequencies to occur during platform rotations). The phasic units were active almost exclusively during platform movement. In contrast to the tonic units, we detected significant differences in the activities of the phasic units; namely, higher spike frequencies during rotations compared with the stationary phases, especially for rotations into 'more awkward' positions. A comparison of the two species revealed no difference in muscle activity, despite differences in the animals' tarsal attachment structures. The same was true when comparing the muscle activity of the two species on both the smooth and the rough surfaces.

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Arcus as a tensegrity structure in the arolium of wasps (Hymenoptera: Vespidae)

Cited by 42 publications

References 12 publications

Insect walking techniques on thin stems

Insect walking techniques on thin stems

Rapid preflexes in smooth adhesive pads of insects prevent sudden detachment

Activity of the claw retractor muscle in stick insects in wall and ceiling situations

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