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Frantsevich L.,Schmalhausen Institute of Zoology
Zoology | Year: 2012

Voluntary movements of the prothorax and the elytra in tethered flying beetles and manually induced movements of these parts in fresh dead beetles were recorded in 30 species representing 14 families. Participation of prothoracic elevation in the closing of the elytra was demonstrated in three ways. (i) The elevation was always simultaneous with elytral closing, in contrast to depression and elytral opening; a rare exception occurred in Lucanus cervus, whose elytra sometimes started to close before the cessation of wing strokes and the elevation of the prothorax. (ii) The manipulated elevation always induced closing of the spread elytra; the mechanical interaction between the hind edge of the pronotum and the roots of the elytra is a universal mechanism of closing the elytra in beetles. (iii) The prevention of pronoto-elytral contact in live beetles by the excision of the hind edge of the pronotum in front of the root prevented elytral closing after normal flight. Exceptions to this rule included some beetles that were able to close their elytra after such an excision: tiger beetles and diving beetles (seldomly) and rose chafers (always). This ability in Adephaga may be explained by attachments of the muscle actuating the 4th axillary plate, which differ from the attachments in Polyphaga. Cetoniinae open their elytra only by a small amount. It is proposed that their small direct adductors in combination with the elasticity of the sclerites are enough to achieve elytral closing without additional help from the prothorax. © 2012 Elsevier GmbH. Source


Frantsevich L.,Schmalhausen Institute of Zoology
Journal of Experimental Biology | Year: 2010

Actuation of the closing of the elytra was previously ascribed to intrinsic muscles in the mesothorax. We investigated closing (1) by loading or arrest of some thoracic segments in a tethered flying beetle, (2) by animation, i.e. passive motion of preparations of the thorax simulating the action of some muscle, and (3) by excision of some parts of sclerites or cuts across certain muscles. We found out that depression of the prothorax, necessary to unlock the elytra, precedes their opening but elevation of the prothorax is synchronous with the closing. The closing is retarded if the elevation is retarded by loading; if the elevating prothorax is clamped, then the closing is also arrested or hindered; animation of the elevation of the prothorax in the dead animal is enough for the closing of the previously spread elytra; the closing is prevented if a piece at the hind edge of the pronotum, positioned in front of the root of an elytron, is excised. This excision also prevents closing in the in vivo experiments. Mechanical interaction between the elytron and the prothorax is limited to the contact point between the posterior edge of the pronotum and the lateral apophysis of the root. Thus, the elevation of the prothorax is the indirect and main mechanism of the closing in Melolontha. ©2010. Published by The Company of Biologists Ltd. Source


Frantsevich L.,Schmalhausen Institute of Zoology
Journal of Bionic Engineering | Year: 2011

We recorded transient movements, i.e. opening and closing, of beetle elytra. The beetles were tethered from below and filmed under a skew mirror; two markers were glued on each elytron at the apex and at the base. Body-fixed 3D traces of the apical and basal markers were reconstructed. The trace of the basal marker was, as a rule, non-parallel to the apical trace. The costal edge of the elytron uniformly supinated in the course of adduction of the apical marker. We found two essential attributes of double rotation: (1) the elytron to body articulation is approximately a spherical mechanism; (2) transient opening and closing possess single degree of freedom. The double rotation was modeled with two mechanisms: (1) a flexagon model of the Haas and Wootton's type simulated the elytral movement relative to the movement of one facet of the flexagon; (2) a screw and nut model provided traces as two sectors of a helical thread, one sector was phase shifted with respect to other one. Screw guideways in a spherical mechanism give rise to discrepancies. Exact solution for a spherical mechanism with two guideways was proposed. The modeling revealed the attribute (3): the elytron is actuated by two linked but differently directed drives. Experimental investigations on the elytron to body articulation may be oriented at search of those mechanisms. © 2011 Jilin University. Source


Klymenko S.I.,Schmalhausen Institute of Zoology
Vestnik Zoologii | Year: 2010

Based on the analysis of morphological characteristics of related species of the genus Eurytoma, several groups of cryptic species poorly distinguishing by external morphology, but clearly confined to certain hosts are shown to have morphological differences of male genitalia that are highly species-specific and can be useful for identification of cryptic species of the genus Eurytoma (E. rosae Nees, E. strigifrons Thomson, and E. jaceae Mayr species complexes). Source


Frantsevich L.,Schmalhausen Institute of Zoology
Journal of Insect Physiology | Year: 2012

Transient movements of the elytra (opening and closing) were filmed in beetles tethered from below. A total of 39 specimens of 18 species representing 11 families were examined. Bright markers glued to the elytra were traced frame by frame. Body-fixed 3D traces of apical and shoulder markers were reconstructed. Shapes of traces reflected different steps of elytral movement and different types of flight. Flat circular arcs were fitted to scattered traces using the least square method. The rotation axis of the apical marker was always directed at the contralateral side. The trace of the shoulder marker was, as a rule, non-parallel to the apical trace. Usually, the shoulder marker on the costal edge of the elytron uniformly supinated in the course of adduction of the apical marker. Traces of opening and closing coincided, hence the double rotation of the elytron had one degree of freedom. The elytron to body articulation in beetles is, presumably, a spherical mechanism with two separate but linked drives for a broad swing during opening (closing). © 2011 Elsevier Ltd. Source

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