Wax Blooms in Tenebrionid Beetles of the Namib Desert: Correlations with Environment

Abstract

Twenty—six species of adult Namib tenebrionid beetles belonging to the tribes Adesmiini and Zophosini have an extracuticular wax bloom covering either part or all of their body surface. These species occur in the dunes, dry river bed, and adjacent gravel plains of the central Namib. The percentage of species possessing a wax bloom increases from the coastal fog desert to the inland hot dry desert. The amount of bloom and its distribution over the integument also increase in a similar manner along the climatic gradient. Despite considerable diversity in coloration and patterns of the wax blooms, the chemical composition of the lipid components showed little variation. Hydrocarbons were the predominant lipid class, with the size of constituent molecules ranging from 19 to 40 carbon atoms. In all species tested, n—alkanes were more abundant than branches alkanes. Odd—numbered carbon chains (e.g., C27, C29, C31) comprised the bulk of the hydrocarbon fractions. The possible functional roles of these blooms in water balance, thermoregulation, predator avoidance, and chemical communication are discussed.

Gold bugs and beyond: a review of iridescence and structural colour mechanisms in beetles (Coleoptera)

“…Vukusic et al (2007) described particularly bright white reflectance in the melolonthine scarab Cyphochilus; this whiteness arises from fine (5 nm diameter) unordered cuticular filaments on the interior of scales, which in cross section form a slender but extremely effective array of scattering structures. Several desert tenebrionid species are white or pale blue due to scattering from wax filaments that prevent water loss, reduce radiation absorption and provide crypsis (Hadley 1979;McClain et al 1985). UV reflectance in beetles is a special case of 'insect white' that also results from broadband scattering (contra Pope & Hinton (1977), who wrongly attributed UV reflectance to pigments).…”

Chemistry, biochemistry, and physiology of insect cuticular lipids

“…The amount and composition of cuticular lipids (primarily hydrocarbon) of 26 species of adult tenebrionid beetles living in the Namib desert was studied [202], and an excellent correlation was found in all cases between the amount of surface wax and the relative humidity and average temperature to which the insect was exposed. Transpiration rates of species with larger amounts of surface lipids were significantly lower than those for species with less surface waxes.…”

Bio-Inspired Photonic Structures: Prototypes, Fabrications and Devices

“…By varying photonic structure characterizations, incident light angle, or the refraction index contrast of the color-produced optical system via the environmental stimuli, reversible coloration changes, which are basically passive, are revealed in fishes, beetles, and birds [39][40][41][42][43][44][45][46]. Most structural basis of SCC are attributed to the one-dimensional (1D) reflectors.…”