9520626 Flying insects vary in the metabolic fuels they use to support energetically costly flight. Flies and bees usually use sugars to fuel flight, while moths and butterflies usually use fat stores. This research will examine metabolic physiology at several levels in a hawkmoth whose heavy body, narrow wings and rapid flight impose high flight costs. Measurement of rates of oxygen consumption and carbon dioxide production during flight will indicate whether sugars or fats are being oxidized. Moths that have fed on sugar-rich nectar will be compared with unfed moths to determine whether fuel use varies with nutritional status. Maximum reaction rates of catabolic enzymes in the carbohydrate and lipid burning pathways of flight muscle will be assayed to determine how feeding and flight performance relate to the moth's underlying metabolic biochemistry. Stable isotope analysis will be used to characterize the contribution of larvally-obtained and adult- obtained resources to egg provisioning. The research will improve understanding of the constraints on activity metabolism and the relative importance of metabolic capacity and fuel availability in limiting performance. Improved understanding of the way energy is allocated between flight and reproduction may increase our understanding of the population dynamics of flying insects.
