@article {102566, title = {Wings and halteres act as coupled dual-oscillators in flies.}, journal = {Elife}, volume = {10}, year = {2021}, month = {2021 Nov 16}, abstract = {

The mechanics of Dipteran thorax is dictated by a network of exoskeletal linkages which, when deformed by the flight muscles, generate coordinated wing movements. In Diptera, the forewings power flight, whereas the hindwings have evolved into specialized structures called halteres which provide rapid mechanosensory feedback for flight stabilization. Although actuated by independent muscles, wing and haltere motion is precisely phase-coordinated at high frequencies. Because wingbeat frequency is a product of wing-thorax resonance, any wear-and-tear of wings or thorax should impair flight ability. How robust is the Dipteran flight system against such perturbations? Here, we show that wings and halteres are independently-driven, coupled oscillators. We systematically reduced the wing length in flies and observed how wing-haltere synchronization was affected. The wing-wing system is a strongly-coupled oscillator, whereas the wing-haltere system is weakly-coupled through mechanical linkages which synchronize phase and frequency. Wing-haltere link acts in a unidirectional manner; altering wingbeat frequency affects haltere frequency, but not vice-versa. Exoskeletal linkages are thus key morphological features of the Dipteran thorax which ensure wing-haltere synchrony, despite severe wing damage.

}, issn = {2050-084X}, doi = {10.7554/eLife.53824}, author = {Deora, Tanvi and Sane, Siddharth S and Sane, Sanjay P} } @article {16561, title = {Mechanics of the thorax in flies.}, journal = {J Exp Biol}, volume = {220}, year = {2017}, month = {2017 Apr 15}, pages = {1382-1395}, abstract = {

Insects represent more than 60\% of all multicellular life forms, and are easily among the most diverse and abundant organisms on earth. They evolved functional wings and the ability to fly, which enabled them to occupy diverse niches. Insects of the hyper-diverse orders show extreme miniaturization of their body size. The reduced body size, however, imposes steep constraints on flight ability, as their wings must flap faster to generate sufficient forces to stay aloft. Here, we discuss the various physiological and biomechanical adaptations of the thorax in flies which enabled them to overcome the myriad constraints of small body size, while ensuring very precise control of their wing motion. One such adaptation is the evolution of specialized myogenic or asynchronous muscles that power the high-frequency wing motion, in combination with neurogenic or synchronous steering muscles that control higher-order wing kinematic patterns. Additionally, passive cuticular linkages within the thorax coordinate fast and yet precise bilateral wing movement, in combination with an actively controlled clutch and gear system that enables flexible flight patterns. Thus, the study of thoracic biomechanics, along with the underlying sensory-motor processing, is central in understanding how the insect body form is adapted for flight.

}, issn = {1477-9145}, doi = {10.1242/jeb.128363}, author = {Deora, Tanvi and Gundiah, Namrata and Sane, Sanjay P} } @article {861, title = {Biomechanical basis of wing and haltere coordination in flies.}, journal = {Proc Natl Acad Sci U S A}, volume = {112}, year = {2015}, month = {2015 Feb 3}, pages = {1481-6}, abstract = {

The spectacular success and diversification of insects rests critically on two major evolutionary adaptations. First, the evolution of flight, which enhanced the ability of insects to colonize novel ecological habitats, evade predators, or hunt prey; and second, the miniaturization of their body size, which profoundly influenced all aspects of their biology from development to behavior. However, miniaturization imposes steep demands on the flight system because smaller insects must flap their wings at higher frequencies to generate sufficient aerodynamic forces to stay aloft; it also poses challenges to the sensorimotor system because precise control of wing kinematics and body trajectories requires fast sensory feedback. These tradeoffs are best studied in Dipteran flies in which rapid mechanosensory feedback to wing motor system is provided by halteres, reduced hind wings that evolved into gyroscopic sensors. Halteres oscillate at the same frequency as and precisely antiphase to the wings; they detect body rotations during flight, thus providing feedback that is essential for controlling wing motion during aerial maneuvers. Although tight phase synchrony between halteres and wings is essential for providing proper timing cues, the mechanisms underlying this coordination are not well understood. Here, we identify specific mechanical linkages within the thorax that passively mediate both wing-wing and wing-haltere phase synchronization. We demonstrate that the wing hinge must possess a clutch system that enables flies to independently engage or disengage each wing from the mechanically linked thorax. In concert with a previously described gearbox located within the wing hinge, the clutch system enables independent control of each wing. These biomechanical features are essential for flight control in flies.

}, keywords = {Animals, Biomechanical Phenomena, Diptera, Microscopy, Electron, Scanning, Wings, Animal}, issn = {1091-6490}, doi = {10.1073/pnas.1412279112}, author = {Deora, Tanvi and Singh, Amit Kumar and Sane, Sanjay P} }