Predator-induced stress responses in insects: A review

Note: Conceptual framework in graphical abstract adapted from Cohen et al. (2012). [Display omitted] •Predation risk induces the octopamine-adipokinetic hormone (OAH) axis in insects.•Studies must account for taxon- and sensory-specific differences in prey responses.•The insect stress response to predation mirrors that observed in vertebrates.•A physiological network perspective helps compare responses across predator-prey systems.•Best practices for studying predator-induced stress in insects are presented. Predators can induce extreme stress and profound physiological responses in prey. Insects are the most dominant animal group on Earth and serve as prey for many different predators. Although insects have an extraordinary diversity of anti-predator behavioral and physiological responses, predator-induced stress has not been studied extensively in insects, especially at the molecular level. Here, we review the existing literature on physiological predator-induced stress responses in insects and compare what is known about insect stress to vertebrate stress systems. We conclude that many unrelated insects share a baseline pathway of predator-induced stress responses that we refer to as the octopamine-adipokinetic hormone (OAH) axis. We also present best practices for studying predator-induced stress responses in prey insects. We encourage investigators to compare neurophysiological responses to predator-related stress at the organismal, neurohormonal, tissue, and cellular levels within and across taxonomic groups. Studying stress-response variation between ecological contexts and across taxonomic levels will enable the field to build a holistic understanding of, and distinction between, taxon- and stimulus-specific responses relative to universal stress responses.