Meeting Abstract

98.4  Saturday, Jan. 7  Dragonfly versus fruit fly: Biomechanics, behavior and strategy during aerial predator-prey encounters COMBES, S.A.*; RUNDLE, D.E.; IWASAKI, J.M.; Harvard University scombes@oeb.harvard.edu

Despite extensive research on the ecology and population dynamics of predator-prey systems, our understanding of the physical interaction between animals and the factors that determine the outcome of an encounter remains limited. We performed over 3000 controlled predation trials to assess how the capture success of dragonflies (Libellula cyanea) hunting fruit flies (Drosophila melanogaster) is affected by environmental conditions and prey behavior. We also analyzed 50 high-speed videos of predation encounters to understand how the flight mechanics of both predator and prey affect the outcome. We find that the flight performance of fruit flies in our natural, outdoor enclosure differs significantly from previously published accounts of Drosophila flight capabilities in the laboratory. In addition, the pursuit strategy and capture success of dragonflies is highly dependent on prey behavior. Fruit flies perform a series of random turns (saccades) during normal cruising flight, but the speed and curvature of these turns varies between individuals. Rather than adopting the most direct route to interception, dragonflies approach their prey from below, optimizing their ability to visually track prey and minimizing the likelihood of being detected. Fruit flies that perform frequent, rapid saccades are more difficult for dragonflies to approach in this manner, and occasionally detect the approaching predator in time to initiate evasive maneuvers. Overall, dragonflies are more successful at capturing fruit flies that perform slow, moderate turns during cruising flight. These results highlight the difficulty of fully understanding complex flight behaviors such as predation and escape through experiments performed in artificial settings or by eliciting these behaviors with artificial stimuli.