Functional Role of Ant Microsculpturing in Abrasion Resistance

The success of insects in global ecosystems is linked to the functions provided by the exoskeleton, also known as the cuticle. In addition to the basic functions of structure and protection, the cuticle is often covered with ornate micro sculpturing patterns that range from simple ridges to complex net-like patterns. Yet the functions of these patterns are relatively unknown. This study explores the potential of striated cuticle patterns to provide abrasion resistance using the harvester ant, Pogonomyrmex badius, as a model. Harvester ants are famous for digging some of the most complex nests in the animal world, often reaching several meters deep in sandy soils. Previous research has shown that digging these nests can abrade the cuticle and increase the risk of desiccation, so we hypothesize that cuticle micro sculpturing might aid in abrasion resistance. We collected a series of minor and major workers from five colonies of the southeastern harvester ant, Pogonomyrmex badius, and measured the width of ridge patterns found on their heads. We imaged each sample using a Nikon Z5 and StackShot Macro Rail and measured ridge and inter-ridge width using ImageJ software. We found that micro sculpturing patterns in Pogonomyrmex badius fell within a narrow range that was smaller than the average size of a sand grain. This indicates that ridges may function as an exclusionary mechanism that prevents sand from fully contacting the exoskeleton.