Frictional properties of contacting surfaces in the hemelytra-hindwing locking mechanism in the bug Coreus marginatus (Heteroptera, Coreidae)

Abstract

The structure and function of the hemelytra-to-hindwing locking mechanism of the bug Coreus marginatus were analysed. The system consists of a cuticular protrusion in the ventral side of the hemelytra, which locks the subcostal border of the hindwing in flight. The speed and distance slid by both surfaces against one another during flight were assessed using a combination of high-speed video recordings and a 2D geometrical model. The friction coefficient between sliding surfaces was assessed using a micromanipulator, coupled with force transducers. This was done under three experimental conditions: freshly dissected, air dried and rehydrated ethanol preserved samples. The results showed a high speed of sliding, approximately 0.18 m s(-1), with a relatively low friction coefficient (0.2 micro). There was no evident difference in the friction measured under the various treatments, with the exception of the rehydrated condition, which was lower. The surface morphology of the wing locking mechanism, namely outgrowths of one part having rounded edges, and completely flat surface on the counterpart, effectively aids in the reduction of friction at the microscopic level. The structure is effective even dry, and after being preserved in ethanol, suggesting that no cuticle secreted lubrication substance is responsible for its effectiveness. The ultrastructure presumably confers mechanical stability to the system under the high load it is subjected to in flight.

Unzipping bird feathers

“…Forewing microhook arrays holding the hindwings of the bug Coreus marginatus in flight can be separated from the hindwing at a force of 0.8 mN. The array consists of numerous (more than 20) 40 -60 mm long hooks [18]. The number of wing hooks holding fore-and hindwings together correlates with the flight distance for bees [19].…”

The acoustic mechanics of stick–slip friction in the California spiny lobster (Panulirus interruptus)

“…Similar to the spiny lobsters, a liquid layer was present in this frictional system; however, based on their s estimates, the surface asperities exceeded the height of the liquid layer, such that the surface dynamics were determined by the rubbery behaviour of the ant's foot pad rather than fluid dynamics. In contrast, the dry frictional system of a heteropteran wing-locking mechanism has an average k of 0.1-0.2 when slid at a maximum velocity of 18.6·cm·s -1 , to which the authors draw a comparison with 'Babbitt alloy sliding over steel' (Goodwyn and Gorb, 2004).…”

“…While the transitions between static and sliding friction are key to many biological movements (e.g. Goodwyn and Gorb, 2004;Niederegger and Gorb, 2006;Scherge and Gorb, 2001), biological sound production generated through periodic stick-slip frictional movements is both unusual and understudied. Here, we characterize the acoustic mechanics of stick-slip friction in the California spiny lobster (Panulirus interruptus) (Fig.·1) using a combination of kinematics, acoustic analyses and mechanical friction tests.…”

Biological attachment devices: exploring nature's diversity for biomimetics

“…The dragonfly head arrester (figure 3b ) mechanically secures the head at two additional points during pairing or feeding (Gorb 1999b) and provides high mobility of the head in flight, when the head is involved in the flight control as a mechanosensory organ (Mittelstaedt 1950). Some animals attach their fore wings to hind wings in flight, in order to be supported by a larger area in flight (functional diptery; Perez Goodwyn & Gorb 2004). Probably the most interesting aspect of the last example is that such an articulation remains immobile in one direction, but provides sliding of the fore wing relatively to the hind wing in the other direction (figure 3a).…”