Adult nutrition strongly affects insect cuticle thickness and injury resistance

Arthropods are the most diverse phylum on Earth, accounting for approximately 90% of animal species. The cuticular exoskeleton has played a vital role in their evolutionary success, but we know surprisingly little about the external factors influencing its development, structure and biomechanical properties. This omission is critical because cuticle is involved in almost every biological function in this massive group of organisms. In this study, we examined how an ecologically relevant difference in early adult diet affected the insect cuticle. We discovered that high-quality food provided to the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae), over the first three weeks of adult life led to a 4.1 times thicker cuticle with 3.7 times greater injury resistance relative to those that consumed a poor diet. Cuticle thickness and injury resistance scaled positively with body size. Males kick and wrestle with each other in this species, and we found that the cuticle of males was more injury resistant than the cuticle of females. This work highlights that nutrition during adulthood can strongly influence the development and properties of the arthropod cuticle, a phenomenon that likely has profound fitness-related consequences for locomotion, predator-prey interactions and resource acquisition.