Foot morphology and substrate adhesion in the Madagascan hissing cockroach, Gromphadorhina portentosa

Abstract

Insects are successful terrestrial organisms able to locomote over a wide range of obstacles and substrates. This study investigated how foot morphology (tarsal structure) correlates with substrate adhesion and ecological niche in the Madagascan hissing cockroach, Gromphadorhina portentosa Schaum (Blattaria: Blaberidae). Using light and scanning electron microscopy, the morphology of the different structures of the tarsus of G. portentosa was analysed. Using an Instron® universal testing machine, a series of peak force experiments were then conducted to record the force required to lift the cockroaches off different substrates. G. portentosa was pulled off 10 different substrates, which consisted of smooth Perspex; Perspex scored at 1cm intervals; Perspex hatched at 1 cm, 0.5 cm, and 1 mm intervals; Perspex abraded with fine grade sandpaper; Perspex abraded with coarse grade sandpaper; wood; glass; and Teflon. A clear relationship was seen where an increase in scoring on the Perspex caused a decrease in adhesive ability of G. portentosa. This may be due to there being adequate contact area for the attachment of the pads and to allow the claws to engage. The results obtained suggest that to achieve the greatest adhesion to substrates, G. portentosa uses a combined effect of both adhesive pads and pretarsal claws. Adhesion to a wide range of substrates appears to be an adaptation to life as a wingless forest floor dweller.

Observations of shear adhesive force and friction of Blatta orientalis on different surfaces

“…In general, claw-mediated adhesive insects can attach to a horizontal or vertical surface only by interlocking and so the adhesive abilities increase with the surface roughness [5,19,20], in agreement with our observations. In particular, the claw-mediated adhesion occurs when the surface asperity size is comparable or larger than the claw tip diameter [3,4,51], here estimated to be 12.3 µm.…”

“…Many authors have studied a multitude of insects, especially thanks to the availability of microscopic analysis instruments (Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM)), in order to understand and measure their adhesive abilities; in the course of the last decades, beetles [1][2][3][4][5][6], aphids [8][9][10], flies [7,11,12], bugs [13], ants [14][15][16][17], cockroaches [18][19][20][21][22][23][24], spiders [25][26][27] and geckos [28][29][30][31][32][33][34][35][36][37][38] have been extensively studied.…”

“…In particular, the shear adhesive force, and so the shear safety factor (sSF) obtained dividing the shear adhesive by the body weight force, thus an apparent friction coefficient, was previously determined for few living animals through different techniques [20] as reported in Table 1.…”

Versatility of Turing patterns potentiates rapid evolution in tarsal attachment microstructures of stick and leaf insects (Phasmatodea)

“…The smooth attachment systems of other insects likewise lack such an additional level of nanostructures [5,6]. For example, representatives of Orthoptera [39,40], Hymenoptera [46][47][48], Plecoptera [49] and Blattodea [50,51] possess smooth attachment pads, sometimes with a microstructure as in the AMS of Phasmatodea, but without structures at other hierarchical levels. By contrast, fibrillar attachment devices, which consist of deformable setae [6,7,11], often include another level of hierarchical structures on these setae, as in spiders [52,53], Coleoptera [54][55][56] or Diptera [57][58][59].…”

Localization of Biobotic Insects Using Low-Cost Inertial Measurement Units

“…These roaches grow to be approximately 60 mm long and 30 mm wide, with a payload capacity of approximately 15 g [15]. They use a combination of pretarsal claws and adhesive pads to cling to and move on a wide variety of surfaces [18], with top speeds of several cm/s. Their exoskeleton is a compliant structure, allowing them to fall from heights and squeeze under obstacles [19] without issue.…”