Meeting Abstract

50.3  Saturday, Jan. 5  Strain patterns on an antenna: are moth antennae tuned? MYHRVOLD, C.A.*; FOX, J.L.; SANE, S.P.; DANIEL, T.L.; Princeton University; University of Washington; National Center for Biological Science, Bangalore, India; University of Washington jessfox@u.washington.edu

Insects rely on mechanosensory feedback to maintain stable flight. For example, a recent study by Sane et al. (2007) demonstrated that mechanical forces on hawkmoth (Manduca sexta) antennae are detected by sensory neurons and play a crucial role in navigation. However, due to the small size and geometric complexity of the antenna, it is difficult to physically measure forces and strain patterns as they occur in vivo. Here, we used a finite element model (FEM) of a male moth antenna to examine the 3-D patterns of strain at the base of the vibrating antenna as a moth executes an aerial maneuver. The FEM combines antennal geometry with experimentally measured values of flexural stiffness, natural resonance frequency, and damping properties of the antenna. We subjected the FEM to motions that mimic those we have measured experimentally. From these simulations, we computed the strain at the FEM base, where antennal mechanosensors are located. For a simulated turn about the yaw axis, the mean peak value of the normal (orthogonal to the long axis) component of the elastic strain tensor was over four times as high when the FEM was rotated at 5 rad/s compared to a control rotation at 0 rad/s. When angular velocity was increased from 5 to 10 rad/s, however, the mean peak value decreased significantly (by 29%). Live moths tethered to a rotating motor while flapping, showed similar changes in antennal motions. Thus, moth antennae may be �tuned� to respond best to Coriolis-specific frequencies and angular velocities.