Meeting Abstract

P2.159  Tuesday, Jan. 5  Maximum flight performance in bumblebees reared under variable hypobaria BUCHWALD, Robert*; DUDLEY, Robert; University of California, Berkeley; University of California, Berkeley rbuchwald@gmail.com

Many bumblebee taxa are distributed across pronounced elevational gradients, but the effects of associated variation in environmental conditions on morphology and flight performance are not fully understood. Altitudinal ascent is associated with reduction in ambient temperature, air pressure, and oxygen availability, and bumblebees may be particularly sensitive to such changes given their high in-flight metabolic rates and tracheal respiration. In order to examine how bumblebees respond to the challenges of flight at high elevation, we reared bumblebee colonies (Bombus impatiens) at three experimentally imposed air pressures corresponding to sea level, and altitudes of 1500 m and 3000 m. Mature colonies were exposed to hypobaric conditions, and individuals then reared from eggs to adulthood were tested for maximum vertical force production in hovering flight. Measured morphological parameters included total mass, flight muscle mass, and wing length. No differences among normo- and hypobaric treatments were found in morphological parameters or in load-lifting capacity, suggesting that this bumblebee species does not respond in these measures to changes in ambient air pressure.