Meeting Abstract
Flies are able to quickly change direction during flight and these manoeuvres require concurrently rapid changes in wing kinematics. However, due to its anatomy, the indirect flight musculature cannot produce sufficiently asymmetrical wing movements by itself. Instead, other mechanisms must be used; one example being the gear change mechanism. This involves a mechanical interaction between two cuticular structures: the radial stop (RS), found proximally on the underside of the wing’s radial vein, and the pleural wing process (PWP) which protrudes laterally from the ventral part of the wing hinge. The RS can interact with the PWP during the downstroke in several ways: bypassing it entirely, locking into one of the dorsal grooves of the PWP, or hooking behind it, each altering wing movement. The shapes of the PWP and RS also differ across species, potentially varying the effects on the wing kinematics. It has previously been noted in hoverflies that the alula (a small, proximal part of the wing) changes between a flipped and flat state relative to the rest of the wing at the same time as wing kinematic changes, and so it has been hypothesised that it is an indirect indicator of the state of RS-PWP interaction. We have examined the RS-PWP interaction through recording high-speed macro videos of tethered Calliphora vicina (amongst other species) with simultaneous recordings of the three-dimensional wing kinematics. Our data quantifies the effects of these interactions on wing kinematics and the result of the differing structural shapes amongst species. Our results also show greater variety in RS-PWP interactions than previously thought, and evaluate the utility of the alula as an indicator of the gear change mechanism.
