Meeting Abstract
The Mango stem-borer, Batocera Rufomaculata, is an invasive species accidently introduced into Israel in the early 1950’s and is one of its largest beetle species. Females lay eggs in the stems of Ficus trees and the boring larvae tunnel through the stem causing substantial damage to the host tree before emerging as flying adult. Adult beetles may differ in body mass 7-folds (1 – 7 gr) as a direct result of food availability and quality during larval growth. Research conducted at our lab has shown that smaller beetles, that developed on a poor diet, have higher long-distance flight endurance compared to large beetles, that developed on a richer diet, thus suggesting that smaller beetles are more efficient flyers. The physiological and biomechanical mechanisms increasing the flight efficiency of smaller beetles are currently unknown. Here, we examined the wingbeat kinematics of small and large beetles flying tethered in a wind-tunnel under increasing wind speed conditions. Flapping kinematics were extracted using two high-speed cameras and a set of two force transducers connected to the tether arm measured the forces exerted by the beetle during flight. Smaller beetles showed a preference for flight at lower wind speed. Nevertheless, the smaller beetles generated more lift per body mass than larger beetles at the preferred speed of larger beetles. Furthermore, the aerodynamic power per lift was lower in the smaller beetles indicating their higher flight efficiency. Measurements on revolving beetle wings have shown that larger ones require a higher power input/lift than smaller ones. This data suggests that smaller beetles possess elevated flight capabilities facilitating their dispersal from the less favorable environments in which they developed.
