Meeting Abstract

126.2  Tuesday, Jan. 7 13:45  Unravelling the insect flight motor using in vivo time-resolved x-ray tomography WALKER, SM*; TAYLOR, GK; University of Oxford, UK; University of Oxford, UK simon.walker@zoo.ox.ac.uk

Flies are among the smallest and most agile of all flying animals. Their wings are driven indirectly by large power muscles, which cause cyclical deformations of the thorax that are amplified through the intricate wing hinge. This mechanism leaves little scope for control and wingbeat asymmetries are instead produced using an array of tiny steering muscles, which attach directly onto the components of the wing hinge. Little is known about the mechanics of these steering muscles due to the difficulty in measuring fast-moving, micron-scale structures, which are also hidden from view by the thoracic shell. Here we present time-resolved microtomography of blowflies, Calliphora vicinia, flying in a synchrotron beamline. This technique allows us to visualize and measure the three-dimensional movements of the steering muscles and place them in the context of the deforming thoracic structures that they actuate. The insects were rotated rapidly during experiments, producing compensatory asymmetric wing movementsm, and we compared the muscle kinematics and thoracic movements between low- and high-amplitude wingbeats. Our visualizations reveal mechanisms not foreseen by earlier electrophysiological and anatomical studies. The tendons of some steering muscles buckle on every wingbeat to accommodate high amplitude motions of the wing hinge. Other steering muscles absorb kinetic energy from an oscillating control linkage, which we hypothesise plays in important role in power management. Our results show that the steering muscles operate through a diverse range of nonlinear mechanisms, and represent the first four-dimensional visualizations of an organism’s internal movements on sub-millisecond and micron scales.