Morphology, histology, and chemistry of the wings of Tribolium castaneum and Tribolium confusum (Coleoptera: Tenebrionidae)

Abstract

Background: Insect wings are an excessively diverse structures, which have fascinated scientist for centuries. Coleoptera is the largest order in the insect group and the most successful animal on earth (Nature Communications 9(205):1–11, 2018). In order to adapt to the change in the environments, they developed strategies to cope up with different factors. The most distinctive feature of beetles is that the forewings are sclerotized into elytra; from this, they get their formal name (koleos = sheath, pteron = wing). The elytra play an important role in protecting the delicate hindwings and the dorsal surface of the abdomen. Besides its influence on protective the hindwing during flight, the forewings are open enough to allow the hindwings to unfold and function. Result: The structural and mechanical properties in living organisms may improve the understanding of natural solutions and advance the design of novel artificial materials. In this paper, the morphological and histological structure of the wings of two species of beetles, Tribolium castaneum and Tribolium confusum, has been investigated using scanning electron microscopy (SEM). The organic chemical function groups of the wings were detected using Fourier-transformed infrared spectroscopy (FTIR). Both Tribolium species have considerable variations regarding the total thickness, and width of the hemolymph space within the elytra. The elytra of both species bear conspicuous field of trichoid sensilla from dorsal side and numerous gland openings with a pit. The michrotrichia found on the ventral side may have an important role in wing folding. The presence of C–H stretching bands with the prevalence of methylene bands may indicate the presence of long-chain aliphatic acids in surface waxes in T. castaneum. The height of the spikes of the hindwings was remarkable by hydrogen-bonded O–Hand N–H amide stretching vibration and was correlated to the thickness of the wing. Conclusion: Insect wings are a core example of histological and morphological novelty. This study illustrates the morphological and histological structure of both the forewing and hindwing of Tribolium castaneum and Tribolium confusum