The locomotor apparatus of one of the smallest beetles – The thoracic skeletomuscular system of Nephanes titan (Coleoptera, Ptiliidae)

Yavorskaya, Margarita; Beutel, Rolf G.; Farisenkov, S. E.; Polilov, Alexey A.

doi:10.1016/j.asd.2019.01.002

Cited by 21 publications

(30 citation statements)

References 26 publications

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“…Such outstanding values can be linked to two factors: structural features and kinematics of the wings, and size and efficiency of muscles. Physical characteristics of the musculature of Ptiliidae have not been studied, but it is known that miniaturization does not considerably increase relative volumes of muscles in beetles, in contrast to dipterans, where miniature species have membranous wings and very large flight muscles (8). The power of flight muscles depends on both volume and some structural features (9), but this aspect has not yet been studied in any ptilopterous insects, and the contribution of muscles to the flight efficiency of microinsects requires further study.…”

Section: Discussionmentioning

confidence: 99%

“…This structure can reduce wing mass compared to that of a membranous wing of the same size, thus reducing inertial losses; at the same time, the permeability of bristled wings at low Reynolds numbers is very low, creating aerodynamic forces similar to those of membranous wings of the same size (10,12). Bristled (compared to membranous) wings make use of the clap and fling mechanism more efficiently: smaller forces are required to draw such wings apart (13,14); this is especially important, as the flight cycle of Ptiliidae includes not only the upper clap above the body but also the lower clap under the body (8). Features of this wing cycle may strongly increase aerodynamic efficiency: The wing moves back at a high angle of attack relative to the body and to the direction of movement during both upstroke and downstroke, while, in other miniature insects, the downstroke is directed forward and mostly creates drag-based lift (5).…”

Section: Discussionmentioning

confidence: 99%

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Extraordinary flight performance of the smallest beetles

Farisenkov

Lapina

Petrov

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Size is a key to locomotion. In insects, miniaturization leads to fundamental changes in wing structure and kinematics, making the study of flight in the smallest species important for basic biology and physics, and, potentially, for applied disciplines. However, the flight efficiency of miniature insects has never been studied, and their speed and maneuverability have remained unknown. We report a comparative study of speeds and accelerations in the smallest free-living insects, featherwing beetles (Coleoptera: Ptiliidae), and in larger representatives of related groups of Staphylinoidea. Our results show that the average and maximum flight speeds of larger ptiliids are extraordinarily high and comparable to those of staphylinids that have bodies 3 times as long. This is one of the few known exceptions to the “Great Flight Diagram,” according to which the flight speed of smaller organisms is generally lower than that of larger ones. The horizontal acceleration values recorded in Ptiliidae are almost twice as high as even in Silphidae, which are more than an order of magnitude larger. High absolute and record-breaking relative flight characteristics suggest that the unique morphology and kinematics of the ptiliid wings are effective adaptations to flight at low Reynolds numbers. These results are important for understanding the evolution of body size and flight in insects and pose a challenge to designers of miniature biomorphic aircraft.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Extraordinary flight performance of the smallest beetles

Farisenkov

Lapina

Petrov

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…thrips (Thysanoptera). They are active fliers, which implies that bristled wings produce enough force to support the animal body weight and propel it through the air (Yavorskaya et al 2019;Cheng and Sun 2018;Zhao et al 2019). Considering the bristled morphology as a biological adaptation, it is important to look into the potential benefits and penalties from the mechanical standpoint.…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

Aerodynamic performance of a bristled wing of a very small insect

et al. 2020

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Aerodynamic force generation capacity of the wing of a miniature beetle Paratuposa placentis is evaluated using a combined experimental and numerical approach. The wing has a peculiar shape reminiscent of a bird feather, often found in the smallest insects. Aerodynamic force coefficients are determined from a dynamically scaled force measurement experiment with rotating bristled and membrane wing models in a glycerin tank. Subsequently, they are used as numerical validation data for computational fluid dynamics simulations using an adaptive Navier–Stokes solver. The latter provides access to important flow properties such as leakiness and permeability. It is found that, in the considered biologically relevant regimes, the bristled wing functions as a less than $$50\%$$ 50 % leaky paddle, and it produces between 66 and $$96\%$$ 96 % of the aerodynamic drag force of an equivalent membrane wing. The discrepancy increases with increasing Reynolds number. It is shown that about half of the aerodynamic normal force exerted on a bristled wing is due to viscous shear stress. The paddling effectiveness factor is proposed as a measure of aerodynamic efficiency. Graphic abstract

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“…The elytra are in many cases, including ladybird beetles 14 and featherwing beetles, closed before wing folding. The muscle involved in the closing of each elytron is M. prophragma-mesophragmalis (IIdlm1, also known as M28 47 ); this muscle is retained in Ptiliidae 12 . With the elytra fully or partly closed, the folding of the wings proceeds as follows.…”

Section: Discussionmentioning

confidence: 99%

“…The unfolding of the wings is triggered by the opening of the elytra. The opening movements of each elytron are facilitated by the following muscles: M. mesonoto-phragmalis, M. mesonoto-coxalis anterior, M. mesonoto-coxalis posterior, and M. mesepimero-subalaris (IIdlm2 IIdvm4, IIdvm5, and IItpm10, respectively; also known as M29, M40, M40, and M35, respectively 47 ); all these muscles are retained in Ptiliidae 12 . The subsequent anteriad movement of each wing is facilitated by M. metanepisterno-axillaris and M. metepimero-axillaris tertius 16 : IIItpm7 and IIItpm 9, respectively; also known as M71b and M71a, respectively 47 ); all these muscles are retained in Ptiliidae 12 .…”

Section: Discussionmentioning

confidence: 99%

Miniaturization re-establishes symmetry in the wing folding patterns of featherwing beetles

Petrov

Farisenkov

Polilov

2020

Sci Rep

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Most microinsects have feather-like bristled wings, a state known as ptiloptery, but featherwing beetles (family Ptiliidae) are unique among winged microinsects in their ability to fold such wings. An asymmetrical wing folding pattern, found also in the phylogenetically related rove beetles (Staphylinidae), was ancestral for Ptiliidae. Using scanning electron, confocal laser scanning, and optical microscopy, high-speed video recording, and 3D reconstruction, we analyze in detail the symmetrical wing folding pattern and the mechanism of the folding and unfolding of the wings in Acrotrichis sericans (Coleoptera: Ptiliidae) and show how some of the smaller featherwing beetles have reverted to strict symmetry in their wing folding. The wings are folded in three phases by bending along four lines (with the help of wing folding patches on the abdominal tergites) and locked under the closed elytra; they unfold passively in two phases, apparently with the help of the elasticity provided by resilin unevenly distributed in the wing and of convexities forming in the cross-sections of the unfolding wing, making it stiffer. The minimum duration of folding is 3.5 s; unfolding is much more rapid (minimum duration lowest recorded in beetles, 0.038 s). The folding ratio of A. sericans is 3.31 (without setae), which is greater than in any beetle in which it has been measured. The symmetrical wing folding pattern found in A. sericans and in all of the smallest ptiliids, in which ptiloptery is especially pronounced, is the only known example of symmetry re-established during miniaturization. This direction of evolution is remarkable because miniaturization is known to result in various asymmetries, while in this case miniaturization was accompanied by reversal to symmetry, probably associated with the evolution of ptiloptery. Our results on the pattern and mechanisms of wing folding and unfolding can be used in robotics for developing miniature biomimetic robots: the mechanisms of wing folding and unfolding in Ptiliidae present a challenge to engineers who currently work at designing ever smaller flying robots and may eventually produce miniature robots with foldable wings.

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The locomotor apparatus of one of the smallest beetles – The thoracic skeletomuscular system of Nephanes titan (Coleoptera, Ptiliidae)

Cited by 21 publications

References 26 publications

Extraordinary flight performance of the smallest beetles

Extraordinary flight performance of the smallest beetles

Aerodynamic performance of a bristled wing of a very small insect

Miniaturization re-establishes symmetry in the wing folding patterns of featherwing beetles

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