CARD, G; DICKINSON, MH; California Institute of Technology; California Institute of Technology: Three dimensional kinematic analysis of flight initiation in Drosophila melanogaster

One of the most complex and important maneuvers a fly must perform is the initiation of flight. Relatively little is known about how this action is achieved given the extreme rapidity of the movement and the limited video technology previously available. In earlier studies (Trimarchi and Schneiderman, J. Zool., Lond. 1995: 235, 211-222), two distinct takeoff behaviors were identified. In Type 1 takeoffs, the fly first elevates and rotates its wings in preparation for flight, then depresses the wings simultaneously with extension of the mesothoracic legs. In Type 2 takeoffs, the fly jumps with its legs before the wings are elevated, so wing motion does not begin until the fly is airborne. New video technology has allowed us to look at flight initiation in more detail than possible previously. In this study, Drosophila were filmed in three dimensions at 6,000 Hz with a pixel resolution of 512 X 512. Both voluntary and visually stimulated takeoffs were recorded and analyzed. High resolution comparison of these two types of takeoff showed that use of the wings during the jumping phase of takeoff is important for the stabilization of flight: flight initiation without prior raising of the wings results in the fly tumbling through the air until the wings are unfolded and can be used to establish controlled flight. Furthermore, while Type 2 takeoffs were previously correlated with visually elicited escape responses and Type 1 takeoffs with �voluntary� (non-stimulated) flight initiation, we observe that some visual stimuli result in wing elevation prior to takeoff jump (Type 1). Our kinematic analysis thus suggests that rather than correlation with particular stimulus modalities, such as vision or olfaction, the different types of takeoffs may be better correlated with different stimulus parameters, for example the timescale of the stimulus.