Analysis of free forward flight ofSchistocerca gregaria employing telemetric transmission of muscle potentials

Abstract

The free flight of mature female Schistocerca gregaria loaded with a transmitter device has been video-monitored for short periods of time in the laboratory. Several flight parameters, such as body angles to horizontal and to flight path, ascent angle, and flight speed, have been analysed. These flight parameters and their interrelationships coincide with those revealed during steady free flight in the field (Baker et al. 1981. J Comp Physiol 141:233–237). Therefore, these short free flights in the laboratory represent free autonomous flight performance, but offer the possibility of controlling environmental conditions. During free flight, the firing patterns of four selected powerful depressor and elevator muscles of the fore- and hindwings were obtained by a transmitter device fixed to the prothorax of the locust. Based on the recruitment of individual motor units, a correlation of the muscle-specific activity with the aerodynamic flight parameters can be accomplished. Wing-beat frequency is positively correlated to ascent angle and to speed. The recruitment of the motor units of the forewing muscles shows a correlation with some of the flight parameters, whereas the hindwing muscles are activated in a rather immutable pattern. This argues for the importance of the forewings for maneuvering, whereas the hindwings mainly serve to provide the basic power output in flight. J. Exp. Zool. 284:119–129, 1999. © 1999 Wiley-Liss, Inc.