Adult diet strongly affects cuticle thickness and its injury resistance in the insect Narnia femorata (Hemiptera: Coreidae)

Arthropods are the most diverse phylum on earth, accounting for up to 90% of animal species. The cuticular exoskeleton has played a vital role in their evolutionary success, but we know surprisingly little about the factors influencing its development, structure, and biomechanical properties. In this study, we examined whether and how nutrition affects the cuticle after an insect has completed its final molt into the adult stage. We found that a high-quality adult diet provided to the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae), over three weeks led to 4.1-times thicker cuticle with 3.7-times greater injury resistance relative to those that consumed a poor, but still ecologically relevant, diet. We further discovered that a high-quality adult diet allowed compensation for a sub-optimal juvenile diet. The cuticle of males was more injury resistant than that of females, as expected due to the aggressive male competition in this species. Altogether, our results show that, even after the final molt, nutrition can strongly influence the development and properties of the arthropod cuticle, a phenomenon that likely has drastic fitness-related consequences for locomotion, predator-prey interactions, and resource acquisition.