Mechanics, Metabolism and Menosporinae: An Integrative Analysis of Dragonfly Flight Performance

I present an integrative, multi-level study of inter- and intraspecific variability in dragonfly flight performance, and relate this to ecological fitness traits. My studies show how changes in dragonfly body size are accompanied by complementary changes in wing beat kinematics, the dynamic contractile performance of flight muscles, and the geometry of their associated skeletal levers. These changes appear to be required to maintain a universally constant thrust-to-weight ratio across the size range of contemporary dragonflies. In addition, I demonstrate how, within the species Libellula pulchella , flight performance is affected by variation in flight muscle substrate utilization, myofibrillar protein composition and myofibrillar protein quality. Moreover, this thesis describes how a natural protozoan (gregarine) infection of L. pulchella intestines not only negatively affects these characteristics of flight muscles, but also impairs systemic nutrient metabolism and its endocrine control. These infection-associated symptoms affect the competitive behavior of male L. pulchella in the field, and thus ultimately male mating success and fitness. I relate my studies on insect physiology and performance to key scientific challenges in mammalian biology. My analyses of the host-parasite interaction between L. pulchella and gregarines demonstrate that insects can naturally develop metabolic and inflammatory disease symptoms that closely resemble those of prevalent mammalian disease, and thus present new potential avenues through which to explore such diseases.