Leonid Frantsevich, Aihong Ji, Zhendong Dai, Jintong Wang,
Ludmila Frantsevich, Stanislav Gorb
Adhesive properties of the arolium of a lantern-fly, Lycorma
delicatula (Auchenorrhyncha, Fulgoridae)
Journal of Insect Physiology 2008, 54: 818Ц 827.
Abstract. The arolium in Lycorma delicatula is
shaped as a truncated pyramid, tapering proximally. The base or the terminal area
is corrugated, forming parasagittal wrinkles (period 1.5Ц5.0 mm), which are supported
from inside by cuticular dendrites. Side faces of the arolium are made up of sclerotized
dorsolateral plates. When claws slip on a smooth substrate and pronate, the dorsolateral
plates diverge and expand the sticky terminal area. The real contact area with
the glass plate was recognized by light reflection on its periphery. This area
was measured and shown to be smaller when the leg was pressed perpendicularly
to the substrate (0.02 mm^2) than when it was sheared in a direction parallel
to the substrate (0.05 mm^2). Attachment forces were measured with the aid of
dynamometric platforms during pulling of active insects from horizontal or vertical
glass surfaces. Normal adhesive force (about 9Ц12 mN) was much less than friction
force during sliding with velocity of 6Ц17 mm/s (50Ц100 mN); however, when expressed
in tenacity per unit contact area the difference was less pronounced: 170 and
375Ц625 mN/mm^2, respectively. Sliding of the arolium during shear displacement
was shown to be oscillatory in frame-by-frame video analysis. Relaxative oscillations
consisted of periodical sticks-slips of the arolium along the glass surface.
Videos (in AVI format)
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Measurement of the adhesion force (the normal component) with a force platform.
Measurement of the friction (the tangential component, ten times stronger)
with a balance.
Stick-slips of the arolium
on the glass surface in Lycorma delicatula.
View the film as a whole and afterwards frame by frame.
Sliding of the leg occurs at each third frame
Stick-slips of the arolium on the glass surface in Lycorma delicatula.
View the film at a normal frame rate and afterwards frame by frame or the slow
version in the next window. Sliding of the leg occurs at each third frame.
Stick-slips of the arolium on the glass Ц frame by frame.
The lantern fly firmly holds a hairy bottom surface of a Magnolia grandiflora
leaf with the claws.
The lantern fly is unable to adhere to the waxy top surface of the leaf.