Abstract
Sir Vincent Wigglesworth proposed in his seminal work on insect cuticle lipids that lipids are involved in cuticle hardening. In brief, in histological experiments, he demonstrated the presence of lipids as a component of cuticulin, a "hard amber material of the insect cuticle." The molecular evidence for this postulate awaits demonstration. In the present work, we examined the cuticle of larvae lacking the function of the cuticle lipid transporter Snustorr (Snu) by nanoindentation with atomic force microscopy in order to analyze the role of lipids on cuticle hardness in the fruit fly Drosophila melnoagaster. Compared to wild-type larvae, we found that the Young's modulus is 10 times reduced in snu mutant larvae that lack cuticulin at their surface. Thus, this simple result supports the finding of Sir Vincent Wigglesworth that lipids contribute to cuticle hardness in insects.
