42.3 Thursday, Jan. 5 Flight Decisions: Target Orientation, Landing, and Obstacle Avoidance in Fruit Flies VAN BREUGEL, Floris*; DICKINSON, Michael; California Institute of Technology; University of Washington email@example.com
Landing behavior is one of the most critical, yet least studied, aspects of insect flight behavior. In order to safely land, an insect must recognize a visual feature, navigate towards it, decelerate, and extend its legs in preparation for touchdown. Although previous studies have focused on the visual stimuli that trigger these different components – relying extensively on tethered preparation - none have been able to characterize the full sequence of landing behavior in freely flying insects. By using a real-time 3D tracking system in conjunction with high speed video recordings, we were able to study landing behavior in freely flying Drosophila from the moment they first recognized a visual target to the point of touchdown. This analysis was made possible by a custom-built feedback system that actively maintained the fly in the focus of the high speed camera. The results suggest that landing is comprised of three distinct behaviors. First, the flies actively turn towards the target via directed body saccades. Next, the flies begins to decelerate is at a point determined by the rate and extent of retinal expansion. Finally, they extend their legs when the visual target reaches a threshold retinal size of approximately 60 deg. Non-landing flies also actively turn towards the target until the retinal size of approximately 30 deg is reached, at which point they make a directed evasive saccade away from the target. Collectively, the results provide insight into the organization of sensory motor modules that underlie landing behavior in insects.