Meeting Abstract

59.4  Saturday, Jan. 5  Perturbation compensation in hovering flight HEDRICK, TL; University of North Carolina at Chapel Hill thedrick@bio.unc.edu

Biological locomotor systems are often lauded for their robustness, or their ability to reject perturbations to their trajectory or orientation. However, the underlying properties of organisms that enable robustness are not well understood but likely involve both active changes to the neuromuscular inputs to the locomotor system as well as passive mechanical responses effects. Here I report the response of the hawkmoth Manduca sexta to continuous perturbation via asymmetric wing reduction. As a proxy for naturally occurring wing damage, the most distal 18% of wing area was removed following the recording of a baseline bout of hovering flight. This represents a 40% reduction in 2nd moment of area of the wing and therefore an approximately 40% reduction in lift generated by it during hovering flight. Additionally, wing reduction also obliterates the more distal campaniform sensilla, thought to be wing deformation detectors with a role in maintaining coordinated muscle contraction during flight. This damage was sufficient to provoke rapid failure in a simulation of hawkmoth flight, but the live moths were able to resume flight shortly after wing reduction. Compensation for asymmetric wing reduction in live moths took the form of a 15% increase in wingbeat frequency, a reduction in anterior-posterior wing sweep on the undamaged side and an increase in wing sweep on the damaged side; other wing motion parameters remained within the range typical of symmetric flight. The existence of responses in both the damaged and undamaged wings implies an active neural component, but simulations demonstrate that much of the kinematic response may be driven by muscle force-velocity properties. Thus, in this instance, compensation for continuously applied perturbation is likely managed by both neural and passive components.