Resolving the structure and composition of weevils cuticular scales and diamond photonic crystals

Insects have developed 3D photonic crystals to produce colours without pigments. They diversified their colours via similar cuticular compositions (chitin and proteins). It is unknown how insects form such photonic crystals. Therefore, we apply to perform studies on the scales of three differently coloured Pachyrhynchus weevils. We used SEM and found these three Pachyrhynchus weevils develop 3D diamond photonic crystals in each scale and tune the crystal size and orientations to produce different colours. We hypothesize that such differences in domain colours at microscales are accompanied by specific variations in compositions of the cuticles such as the crystallinity of chitin and proteins and ratio of chitin/protein which will be elucidated by using XRD/XRF and FTIR. This work will pave the way for understanding self-organization processes of diamond photonic crystals in the cuticular scales of Pachyrhynchus weevils.