The effect of surface anisotropy in the slippery zone of Nepenthes alata pitchers on beetle attachment

The slippery zone in pitchers of the carnivorous plant Nepenthes alata bears scattered prominent lunate cells and displays continuous epicuticular crystalline wax coverage. The aim of this study was to examine the influence of the surface anisotropy, caused by the shape of lunate cells, on insect attachment ability. Traction tests with ladybird beetles Coccinella septempunctata were performed in two types of experiments, where surface samples of (1) intact pitchers, (2) chemically de-waxed pitchers, and (3) their polymer replicas were placed horizontally. Beetle traction forces were measured when they walked on test surfaces in either an upward (towards the peristome) or downward (towards the pitcher bottom) direction, corresponding to the upright or inverted positions of the pitcher. On intact pitcher surfaces covered with both lunate cells and wax crystals, experiments showed significantly higher forces in the direction towards the pitcher bottom. To distinguish between the contributions, from claw interlocking and pad adhesion, to insect attachment on the pitcher surfaces, intact versus claw-ablated beetles were used in the second type of experiment. On both de-waxed plant samples and their replicas, intact insects generated much higher forces in the downward direction compared to the upward one, whereas clawless insects did not. These results led to the conclusion that, (i) due to the particular shape of lunate cells, the pitcher surface has anisotropic properties in terms of insect attachment, and (ii) claws were mainly responsible for attachment enhancement in the downward pitcher direction, since, in this direction, they could interlock with overhanging edges of lunate cells.

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Surface roughness rather than surface chemistry essentially affects insect adhesion

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.7.139 ◽

2016 ◽

Vol 7 ◽

pp. 1471-1479 ◽

Cited By ~ 30

Author(s):

Matt W England ◽

Tomoya Sato ◽

Makoto Yagihashi ◽

Atsushi Hozumi ◽

Stanislav N Gorb ◽

...

Keyword(s):

Surface Roughness ◽

Surface Chemistry ◽

Coccinella Septempunctata ◽

Traction Force ◽

Dominant Factor ◽

Chemical Compositions ◽

Specific Chemical ◽

Chemical Surface ◽

Ladybird Beetles ◽

Attachment Ability

The attachment ability of ladybird beetles Coccinella septempunctata was systematically investigated on eight types of surface, each with different chemical and topographical properties. The results of traction force tests clearly demonstrated that chemical surface properties, such as static/dynamic de-wettability of water and oil caused by specific chemical compositions, had no significant effect on the attachment of the beetles. Surface roughness was found to be the dominant factor, strongly affecting the attachment ability of the beetles.

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Effect of Substrate Stiffness on the Attachment Ability in Ladybird Beetles Coccinella septempunctata

Bio-inspired Structured Adhesives - Biologically-Inspired Systems ◽

10.1007/978-3-319-59114-8_4 ◽

2017 ◽

pp. 47-61 ◽

Cited By ~ 1

Author(s):

Lars Heepe ◽

Dennis S. Petersen ◽

Lisa Tölle ◽

Jonas O. Wolff ◽

Stanislav N. Gorb

Keyword(s):

Coccinella Septempunctata ◽

Substrate Stiffness ◽

Ladybird Beetles ◽

Attachment Ability

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Influence of ambient humidity on the attachment ability of ladybird beetles (Coccinella septempunctata)

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.7.123 ◽

2016 ◽

Vol 7 ◽

pp. 1322-1329 ◽

Cited By ~ 16

Author(s):

Lars Heepe ◽

Jonas O Wolff ◽

Stanislav N Gorb

Keyword(s):

Environmental Conditions ◽

Coccinella Septempunctata ◽

Dry Adhesive ◽

Ladybird Beetle ◽

Ambient Humidity ◽

Ladybird Beetles ◽

Significant Difference ◽

Attachment Ability ◽

Adhesive Fluid

Many insects possess adhesive foot pads, which enable them to scale smooth vertical surfaces. The function of these organs may be highly affected by environmental conditions. Ladybird beetles (Coccinellidae) possess dense tarsal soles of tenent setae, supplemented with an adhesive fluid. We studied the attachment ability of the seven-spotted ladybird beetle (Coccinella septempunctata) at different humidities by horizontal traction experiments. We found that both low (15%) and high (99%) relative humidities lead to a decrease of attachment ability. The significantly highest attachment forces were revealed at 60% humidity. This relationship was found both in female and male beetles, despite of a deviating structure of adhesive setae and a significant difference in forces between sexes. These findings demonstrate that not only dry adhesive setae are affected by ambient humidity, but also setae that stick due to the capillarity of an oily secretion.

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Insect attachment on crystalline bioinspired wax surfaces formed by alkanes of varying chain lengths

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.5.116 ◽

2014 ◽

Vol 5 ◽

pp. 1031-1041 ◽

Cited By ~ 10

Author(s):

Elena Gorb ◽

Sandro Böhm ◽

Nadine Jacky ◽

Louis-Philippe Maier ◽

Kirstin Dening ◽

...

Keyword(s):

Surface Roughness ◽

Experimental Studies ◽

Three Dimensional ◽

Coccinella Septempunctata ◽

Fold Reduction ◽

Adhesive Pads ◽

Highly Hydrophobic ◽

Chain Lengths ◽

Attachment Ability ◽

Insect Attachment

The impeding effect of plant surfaces covered with three-dimensional wax on attachment and locomotion of insects has been shown previously in numerous experimental studies. The aim of this study was to examine the effect of different parameters of crystalline wax coverage on insect attachment. We performed traction experiments with the beetle Coccinella septempunctata and pull-off force measurements with artificial adhesive systems (tacky polydimethylsiloxane semi-spheres) on bioinspired wax surfaces formed by four alkanes of varying chain lengths (C36H74, C40H82, C44H90, and C50H102). All these highly hydrophobic coatings were composed of crystals having similar morphologies but differing in size and distribution/density, and exhibited different surface roughness. The crystal size (length and thickness) decreased with an increase of the chain length of the alkanes that formed these surfaces, whereas the density of the wax coverage, as well as the surface roughness, showed an opposite relationship. Traction tests demonstrated a significant, up to 30 fold, reduction of insect attachment forces on the wax surfaces when compared with the reference glass sample. Attachment of the beetles to the wax substrates probably relied solely on the performance of adhesive pads. We found no influence of the wax coatings on the subsequent attachment ability of beetles. The obtained data are explained by the reduction of the real contact between the setal tips of the insect adhesive pads and the wax surfaces due to the micro- and nanoscopic roughness introduced by wax crystals. Experiments with polydimethylsiloxane semi-spheres showed much higher forces on wax samples when compared to insect attachment forces measured on these surfaces. We explain these results by the differences in material properties between polydimethylsiloxane probes and tenent setae of C. septempunctata beetles. Among wax surfaces, force experiments showed stronger insect attachment and higher pull-off forces of polydimethylsiloxane probes on wax surfaces having a higher density of wax coverage, created by smaller crystals.

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The effect of surface anisotropy of Si(001)2 × 1 on hollow formation in the initial stage of oxidation as studied by reflection electron microscopy

Surface Science ◽

10.1016/0039-6028(89)90467-6 ◽

1989 ◽

Vol 220 (1) ◽

pp. 131-136 ◽

Cited By ~ 31

Author(s):

Hisatoshi Kahata ◽

Katumichi Yagi

Keyword(s):

Electron Microscopy ◽

Surface Anisotropy ◽

Initial Stage ◽

Reflection Electron Microscopy ◽

Effect Of Surface

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The Coccinellidae (Coleoptera) from Fuerteventura, Canary Islands

Zootaxa ◽

10.11646/zootaxa.4646.1.6 ◽

2019 ◽

Vol 4646 (1) ◽

pp. 101-123 ◽

Cited By ~ 1

Author(s):

JERZY ROMANOWSKI ◽

PIOTR CERYNGIER ◽

JAROSLAV VĚTROVEC ◽

KAROL SZAWARYN

Keyword(s):

Canary Islands ◽

Coccinella Septempunctata ◽

North African ◽

The North ◽

Ladybird Beetles

During this study, Coccinellidae were collected and observed at 25 sites located along the coast and inland of the island of Fuerteventura during 2016 and 2017. A total of 2825 Coccinellidae specimens belonging to 22 species was recorded, of which 11 species are newly recorded from Fuerteventura. In the case of three species taxonomical decisions are proposed. Scymnus incisus (Har. Lindberg, 1950) is transferred to the genus Nephus Mulsant and placed in the nominate subgenus as Nephus (Nephus) incisus (Har. Lindberg, 1950), comb. nov. Scymnus medanensis Eizaguirre, 2007, is redescribed and placed in the subgenus Pullus Mulsant. Coccinella algerica Kovář, 1977, is synonymized with Coccinella septempunctata Linnaeus, 1758, syn. nov. We propose retaining the taxonomic distinction of the North African and Canarian populations of this species as the subspecies Coccinella septempunctata algerica Kovář, stat. nov. Nephus peyerimhoffi (Sicard, 1923) is deleted from the list of ladybird beetles inhabiting the Canary Islands.

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Contributions of lunate cells and wax crystals to the surface anisotropy of Nepenthes slippery zone

Royal Society Open Science ◽

10.1098/rsos.180766 ◽

2018 ◽

Vol 5 (9) ◽

pp. 180766 ◽

Cited By ~ 1

Author(s):

Lixin Wang ◽

Dashuai Tao ◽

Shiyun Dong ◽

Shanshan Li ◽

Yu Tian

Keyword(s):

Atomic Force Microscope ◽

Surface Topography ◽

Friction Force ◽

Body Length ◽

Structural Features ◽

Large Displacements ◽

Surface Anisotropy ◽

Atomic Force ◽

Microstructure Examination ◽

Wax Crystals

Nepenthes slippery zone presents surface anisotropy depending on its specialized structures. Herein, via macro–micro–nano scaled experiments, we analysed the contributions of lunate cells and wax crystals to this anisotropy. Macroscopic climbing of insects showed large displacements (triple body length within 3 s) and high velocities (6.16–20.47 mm s −1 ) in the inverted-fixed (towards digestive zone) slippery zone, but failed to climb forward in the normal-fixed (towards peristome) one. Friction force of insect claws sliding across inverted-fixed lunate cells was about 2.4 times of that sliding across the normal-fixed ones, whereas showed unobvious differences (1.06–1.11 times) between the inverted- and normal-fixed wax crystals. Innovative results from atomic force microscope scanning and microstructure examination demonstrated the upper layer of wax crystals causes the cantilever tip to generate rather small differences in friction data (1.92–2.72%), and the beneath layer provides slightly higher differences (4.96–7.91%). The study confirms the anisotropic configuration of lunate cells produces most of the anisotropy, whereas both surface topography and structural features of the wax crystals generate a slight contribution. These results are helpful for understanding the surface anisotropy of Nepenthes slippery zone, and guide the design of bioinspired surface with anisotropic properties.

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