The role of surface chemistry for the super-hydrophobicity of the springtail Orchesella cincta (Insecta:Collembola).

Collembola are ancient arthropods living in soil with extensive exposure to dirt, bacteria and fungi. To protect from the harsh environmental conditions and to retain a layer of air for breathing when submerged in water, they have evolved a superhydrophobic, liquid repelling cuticle surface. The non-fouling and self-cleaning properties of springtail cuticle make it an interesting target of biomimetic materials design. Recent research has mainly focused on the intricate microstructures at the cuticle surface. Here we study the role of the cuticle chemistry for the Collembola species Orchesella cincta (Collembola, Entomobryidae). We find that the cuticle loses its hydrophobic properties after rinsing with dichloromethane. Sum frequency generation spectroscopy, time of flight secondary ion mass spectrometry in combination with high-resolution mass spectrometry shows that a nanometer thin triacylglycerol containing wax layer at the cuticle surface is essential to keep the anti-wetting properties. Removal of the wax layer exposes chitin, terpenes and lipid layers in the cuticle.