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< Leonid I. Frantsevich >

Leonid I. Frantsevich and Holk Cruse

Leg coordination during turning on an extremely narrow substrate in a bug, Mesocerus marginatus (Heteroptera, Coreidae)

Journal of Insect Physiology 2005, 51: 1092–1104.

Abstract. The turning movement of a bug, Mesocerus marginatus, is observed when it walks upside-down below a horizontal beam and, at the end of the beam, performs a sharp turn by 180°. The turn at the end of the beam is accomplished in three to five steps, without strong temporal coordination among legs. During the stance, leg endpoints (tarsi) run through rounded trajectories, rotating to the same side in all legs. During certain phases of the turn, a leg is strongly depressed and the tarsus crosses the midline. Swing movements rotate to the same side as do leg endpoints in stance, in strong contrast to the typical swing movements found in turns or straight walk on a flat surface. Terminal location is found after the search through a trajectory that first moves away from the body and then loops back to find substrate. When a leg during stance has crossed the midline, in the following swing movement the leg may move even stronger on the contralateral side, i.e. is stronger depressed, in contrast to swing movements in normal walking, where the leg is elevated. These results suggest that the animals apply a different control strategy compared to walking and turning on a flat surface.

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Body-fixed coordinate system

The peculiar body shape of Mesocerus provides good landmarks for the transverse body-fixed axis q through the acute prothoracical “shoulders” and for the longitudinal body axis p through the rostral and caudal body end points. The insect is filmed under a skew mirror: the top image is in the mirror, the bottom one is real. Frame coordinates of any corresponding points in two images are transformed into 3D coordinates in the global space. Landmarks of the body-fixed system are measured in each frame together with leg endpoints. Then 3D global coordinates of the leg endpoint are transformed into 3D body-fixed coordinates.


Leg trajectories

Frame-to-frame leg endpoint coordinates are projected onto the horizontal bodyfixed plane, viewed from the ventral side. All turns are shown as turns to the right (video).

Average stance trajectories of leg endpoints in ten films are rotations to the same side (clockwise in the figure).

When an insect walks on a level ground, it translates its leg during the swing approximately to the same body-fixed point where the leg stood one step ago: there the leg finds the ground. Turning on a twig, the insect would translate its leg to the empty space. Therefore, swing trajectories have the shape of loops in search of the ground (top pair of figures, serial steps during one turn). However, swing vectors from the start point to the finish point form a vector flow rotating also clockwise (bottom pair of figures, ten films overlaid).


Collection of films:

Courtship dances in a fly, Lispe spp.

Stick friction in a lantern fly, Lycorma delicatula

Arolium of a hornet, Vespa crabro

Indirect closing of elytra in a cockchafer, Melolontha

Righting kinematics in beetles (Insecta: Coleoptera)

Leg coordination during turning on an extremely narrow substrate in a bug, Mesocerus marginatus (Heteroptera, Coreidae)

Swimming in the Diving Wasp Prestwichia aquatica (Hymenoptera: Trichogrammatidae)

Kinematics of elytra in beetles

Indirect closing of elytra in various beetles

Double rotation of the opening (closing) elytra in beetles (Coleoptera)

Actuation and performance of the elytron-to-body articulation in a diving beetle


I. I. Schmalhausen Institute of Zoology, 2004-2009