Meeting Abstract

37.2  Monday, Jan. 5  Antennae mediate an abdominal flexion response to body rotations in the hawkmoth Manduca sexta HINTERWIRTH, A.J.*; DANIEL, T.L.; University of Washington; University of Washington ahinterw@u.washington.edu

The crepuscular moth Manduca sexta does not rely on vision alone for flight control. It uses mechanosensory information from its antennae to mediate rapid responses to aerodynamic disturbances (Sane et al. 2007). Specifically, antennae may act as vibrational gyroscopes detecting Coriolis forces that occur when a moth undergoes rotational motion. However, there are no data that clearly show moths respond to pure rotational motion stimuli in absence of any other inputs, such as visual or wind stimuli. To address the role of antennae as sensors of body rotations, we developed an experimental setup that allows us to investigate the respective influences of the visual and rotational mechanosensory systems. We tether a moth in an LED visual arena that can be mechanically rotated (after Sherman & Dickinson, 2003). Visual or mechanical rotations can thereby be presented independently, or in any arbitrary phase with respect to each other. At the same time, we monitor two behavioral responses: abdominal flexion and wing trajectory. Our results show that antennae mediate abdominal flexion as a response to pure mechanical rotations. The angle of flexion increases when the rotational velocity is increased (up to 250 deg/s). Moreover, removing the antennal flagellum diminishes the response significantly, in many cases completely (Mean reduction to ~18% of control groups gain, N=14 animals). The abdominal response, however, can be rescued by gluing back a flagellum on each antennal base, as long as mechanoreceptors on the scape and pedicel are left intact. (Rescue to ca. 70% of the control groups gain in 7 of 8 animals in which antennal re-attachment was performed.) These results thus provide strong evidence for the antennal gyroscope hypothesis.