Meeting Abstract
The mango stem-borer (Batocera rufomaculata) is a large beetle (body mass up to 7.5 gr) capable of long dispersal flights to find suitable host trees. A previous study has shown that: 1) in flight-mills, the beetles are capable of flying distances >20 km without replenishing energy reserves, and 2) smaller beetles (body mass< 3 gr) tend to fly larger distances compared to larger individuals. To study the aerodynamic and physiological mechanisms enabling long-distance flights, we examined the tethered flight of these beetles in a wind-tunnel. The aerodynamic power and drag force of the flying beetles were analyzed from the kinetic energy and velocity profiles, respectively, measured in the wake of the insect using Stereo-PIV. The data were compared to quasi-steady aerodynamic forces and power output estimated from the flapping kinematics, or measured directly with force transducers connected to the tethered insects. The kinetic energy balance of the flow field of the insect matched mechanical power estimates from quasi-steady modelling. Both estimation methods gave values of aerodynamic muscle mass-specific power that is approximately 65% of the aerodynamic mass-specific power of other insects, with asynchronous flight muscles, during hovering. The drag estimates from the wake velocity profiles matches the drag of the beetles as measured with the force transducers. Thus, the results link the unsteady wake of the forward flying insect to its mechanical power output. The low mass-specific power output during forward flight is likely instrumental in long distance flights by ensuring the demands are adequately met by the substrate supply rate to the flight muscles, thus delaying their fatigue.
