The use of first-axillary steering muscles in Drosophila roll control*

Like balancing a meter stick on the tip of your finger, flapping flight is an inherently unstable dynamical system. In order to navigate changing wind conditions and evade determined fly swatters, fruit flies have evolved a stability reflex which can correct for mid-flight perturbations on the timescale of wingbeats (~30 ms). About the fly's most unstable degree of freedom, roll, these corrections begin within 5ms, one of the fastest reflexes in the animal kingdom. Previous investigations have shown that this reflex is well-modeled using a proportional integral controller. We now seek to elucidate the underlying mechanisms of neural control within the wing motor system which make this possible. Using a combination of mid-flight mechanical perturbations and neural manipulation via optogenetics, we investigated the role of the first axillary steering muscles during corrections for perturbations about the fly's body roll axis. We find that both of the first axillary steering muscles drive wing kinematic changes necessary for roll correction, and place this in context of the fly's roll controller.