Meeting Abstract

52.5  Thursday, Jan. 5  Load lifting with asymmetric wings in the hawkmoth (Manduca sexta) FERNANDEZ, M.J.*; GUO, M.; HEDRICK, T.L.; University of North Carolina at Chapel Hill; University of North Carolina at Chapel Hill; University of North Carolina at Chapel Hill

In nature, wing damage is common in insects, resulting in wing asymmetries. Recently, we found that despite damaged wings, hawkmoths are able to maintain flight stability during hovering through neural modulation of muscle activity. Moths have to constantly steer to counteract the torque produced by the wing asymmetry. Therefore, we expect to see a cost to this constant steering on other aspects of flight performance such as maximum lift production. In this study we determined these costs by measuring (1) maximum load lifting capability and (2) oxygen consumption and carbon dioxide production during hovering flight in hawkmoths (Manduca sexta). We tested three cases: (a) symmetric undamaged wings, (b) asymmetric with one wing clipped, and (c) symmetric with both wings clipped. We found kinematic differences between the asymmetric wings including increased wingbeat frequency with wing area reduction and increased stroke amplitude on the clipped wing compared to the unclipped wing. Although force production is proportional to second moment of wing area, we expected to find a larger decrease in the maximum vertical force exerted by the moths in case (b) than would be predicted by the reduction in area alone. Indeed, we found a greater reduction in vertical force than expected from the change in wing area alone. Furthermore, when wing area is further reduced by clipping both wings symmetrically, vertical force production does not decrease below the levels measured for asymmetric clipping. We suggest that there is a significant cost in control in addition to the cost of the total reduced wing area seen in our asymmetric and symmetric wing clipping treatments.