Biochemistry and biosynthesis of insect pigments

Abstract

abstract. The functional role and commercial importance of insect pigments have been studied for well over a century. They are classified into those synthesized by insects, which include anthraquinones, aphins, pterins, tetrapyrroles, ommochromes, melanins and papiliochromes, and those sequestered from their host plants, the antioxidative carotenoids and water-soluble flavonoids. They can also be categorized into those that are produced by cyclization of linear precursors, e.g. anthraquinones, aphins and tetrapyrroles and those derived from cyclic precursors such as pterins, ommochromes, melanins and anthocyanins. Anthraquinones and aphins are derived by cyclization of linear polyketides via successive condensation of simple carboxylic acid metabolites and occur in two major Superfamilies of Hemiptera, the Coccoidea and Aphidoidae, respectively. Ommochromes, tetrapyrroles and melanins are derived from different amino acid precursors, tryptophan, glycine and tyrosine, respectively. Apart from providing body colouration, ommochromes are visual pigments, melanins act as a protectant against UV and tetrapyrroles facilitate oxygen transport to cells. Papiliochromes are synthesized using both, the essential amino acids tyrosine and tryptophan. Pterins are derived from guanosine triphosphate (GTP) and are also present in ommatidia of eyes. The sequestered pigments, anthocyanins and carotenoids, are synthesized from phenylalanine and by condensation of two isoprene units, respectively, in plants. The biosyntheses of chemochromes in insects are governed by a complex set of enzymes, pathways and genetics. This review provides a comprehensive understanding of the molecules that are not only responsible for the striking colours but also provide functional benefits for insects. The commercially important pigments are also discussed.

Transcriptome profiling in the damselfly Ischnura elegans identifies genes with sex-biased expression

“…The biosynthesis pathway and annotation details are given in Additional file 2: Figure S2 and Additional file 1: Sheet 16. Carotene and xanthophyll, together constituting carotenoid pigments, are lipid soluble, containing no nitrogen and absorb light with green and blue wavelengths, which is producing a green, blue-green, blue and red colour to the insect integument and haemolymph [54]. Carotenoids play an important role in antioxidation, photoreception and colouration [50, 54].…”

“…Carotene and xanthophyll, together constituting carotenoid pigments, are lipid soluble, containing no nitrogen and absorb light with green and blue wavelengths, which is producing a green, blue-green, blue and red colour to the insect integument and haemolymph [54]. Carotenoids play an important role in antioxidation, photoreception and colouration [50, 54]. However, none of the genes in this pathway were uniformly differentially expressed between the sexes.…”

Spiders have rich pigmentary and structural colour palettes

“…S1) than 3OH-kynurenine and cannot be detected by Raman, but have been successfully detected by SERS (Smyth et al, 2011). Pterins are abundant in insects (Shamim et al, 2014), and a previous genomic study suggested that pterins could be synthesized de novo in spiders (Croucher et al, 2013). Therefore, pterins could also be responsible for the colour production of these yellow setae.…”

Cuticular Hydrocarbon Profiles Differentiate Tropical Fire Ant Populations (Solenopsis geminata, Hymenoptera: Formicidae)

“…Insect body color is primarily attributed to the existence of pigment molecules in the cuticle or underlying epidermis, which include anthraquinones, aphins, pterins, tetrapyrroles, ommochromes, melanins, carotenoids and flavonoids . Among these compounds, pterins, melanins and carotenoids are involved in the formation of black, yellow, red, orange pigments .…”