Mechanical properties of larval mouthparts of the antlion Euroleon nostras (Neuroptera: Myrmeleontidae) and their correlation with cuticular material composition

Abstract

The diversity of insects can be explained by their ability to fill various ecological niches, which includes the foraging from diverse sources. The cuticle-based feeding structures interact with the food and show adaptations in shape, material composition and mechanical properties to it. In this study, we focus on the mouthparts of a very prominent ambush predator, the antlion larvae of Euroleon nostras. By nanoindentation, we tested the hardness and the Young’s modulus of the mouthparts, which are significantly harder and stiffer than other insect cuticle structures. To gain insight into the origins of the high values, we studied the degree of tanning using confocal laser scanning microscopy. Additionally, we determined the content of transition and alkaline earth metals by energy dispersive X-ray spectroscopy. We found that the proportions of Zn, Mn, Fe, Cu, Ca, Mg, and Si correlate with the mechanical property values. We also conducted experiments on the breaking stress, the puncturing and biomechanical behaviour of the jaws, which highlighted their extraordinary strength. These findings are not only valuable for biologists, but also for material scientists, as they contribute to our understanding of the origins of mechanical property heterogeneities in insect cuticle.