The functional implications of pronotum microstructure on surface friction in beetles

Biomimicry is a discipline that seeks solutions from nature by imitating biological functions or structures, and numerous species have become objects of biomimicry for various purposes. This study analyzed the pronotum microstructure of two Coleopteran species (Onthophagus japonicus and Dorcus titanus) to evaluate their function and role in the movement. Optical microscopy and scanning electron microscopy (SEM) were used to examine the surface biological traits and microstructural characteristics, respectively. Based on the SEM images and microstructure size information (width, distance, and length), we created a geometrical surface that mimicked the beetle's rough pronotum surface and conducted a finite element analysis to explore the influence of microstructure on surface friction. Both D. titanus and O. japonicus had rough surfaces, and O. japonicus had setae in its microstructure pit. Finite analysis showed that an insect surface mimicking concave and convex surfaces required less force than a plain surface, indicating that beetles might improve their body movement and antifouling function through microstructures during movement in dense complexes. The biological and mechanical characteristics of beetles are the focus of extensive research in the field of biological engineering due to their potential utility in numerous domains, including ecology and industry. Thus, further studies on biological engineering research are needed to further understand of application of beetles' characteristics.