S1-5.5 Jan. 6 Drawing inspiration from insect breathing and heaving conventional wisdom: Convective tracheal and air sac mechanisms in Drosophila visualized with x-ray imaging. HALE, ME*; WATERS, JS; LEE, WK; SOCHA, JJ; FEZZAA, K; WESTNEAT, MW; Univ. of Chicago; Arizona State Univ.; Argonne National Laboratory; Argonne National Laboratory; Argonne National Laboratory; Field Museum firstname.lastname@example.org
Since the early work of Steve Vogel on tethered flight, Drosophila has been a model for the biomechanics of movement. Recent advances in phase contrast imaging using synchrotron x-rays have provided opportunities to examine internal mechanics of respiratory movements in this species. The mechanism of gas exchange in small insects, such as fruit flies, has conventionally been viewed as a process driven by diffusion, with the role of convection being limited to autoventilation in the thoracic air sacs during flight. We observed three different convective mechanisms in the head and thorax of non-flying Drosophila that suggest an important role of convection in these small animals. First, we observed that head air sacs expand and collapse during the proboscis extension reflex (PER) indicating, as suggested by Lehmann and Heyman (J. Exp. Biol. 208, 3645), that PER can generate convection. Second, we recorded a long duration, low frequency inflation and deflation of the head air sacs that was not associated with visible motion (i.e. was not autoventilatory). Third, we discovered that tracheal tubes in the anterior thorax expand and collapse during periods of inactivity, indicating that convection in the thorax can be used in non-flight situations. We suggest that convective air transport is used for gas exchange even in some small insects for which diffusion alone has been thought to be sufficient. Supported by the University of Chicago under section H.28 of its contract W-31-109-ENG-38 to manage Argonne National Laboratory with a Board of Governors Seed Grant to MEH and WKL.