Metabolic Flexibility in Insects: Patterns, Mechanisms, and Implications

The evolutionary success of insects may be partly attributed to their profound ability to adjust metabolism in response to environmental stress or resource variability at a range of timescales. Metabolic flexibility encompasses the ability of an organism to adapt or respond to conditional changes in metabolic demand and tune fuel oxidation to match fuel availability. Here, we evaluate the mechanisms of metabolic flexibility in insects that are considered short-term, medium-term, and long-term responses. We describe mechanisms that enhance metabolic flexibility by intermediary metabolites, transcription, tissue resculpting, the nervous system and hormone response, and more permanent genetic adaptations. We consider how metabolic flexibility may provide fitness advantages in diverse environmental conditions, and how this might be related to population dynamics, fundamental niches, and shifting geographic ranges. We conclude by discussing how mechanisms of metabolic flexibility might have broad implications for the management of pests and disease vectors and for the conservation of rare species in an era of rapid change.