Eumelanin and pheomelanin are predominant pigments in bumblebee (Apidae:Bombus) pubescence

Abstract

BackgroundBumblebees (Hymenoptera: Apidae: Bombus) are well known for their important inter- and intra-specific variation in hair (or pubescence) color patterns, but the chemical nature of the pigments associated with these patterns is not fully understood. For example, though melanization is believed to provide darker colors, it still unknown which types of melanin are responsible for each color, and no conclusive data are available for the lighter colors, including white.MethodsBy using dispersive Raman spectroscopy analysis on 12 species/subspecies of bumblebees from seven subgenera, we tested the hypothesis that eumelanin and pheomelanin, the two main melanin types occurring in animals, are largely responsible for bumblebee pubescence coloration.ResultsEumelanin and pheomelanin occur in bumblebee pubescence. Black pigmentation is due to prevalent eumelanin, with visible signals of additional pheomelanin, while the yellow, orange, red and brown hairs clearly include pheomelanin. On the other hand, white hairs reward very weak Raman signals, suggesting that they are depigmented. Additional non-melanic pigments in yellow hair cannot be excluded but need other techniques to be detected. Raman spectra were more similar across similarly colored hairs, with no apparent effect of phylogeny and both melanin types appeared to be already used at the beginning of bumblebee radiation.DiscussionWe suggest that the two main melanin forms, at variable amounts and/or vibrational states, are sufficient in giving almost the whole color range of bumblebee pubescence, allowing these insects to use a single precursor instead of synthesizing a variety of chemically different pigments. This would agree with commonly seen color interchanges between body segments across Bombus species.

Exposure to a competitive social environment activates an epigenetic mechanism that limits pheomelanin synthesis in zebra finches

“…Pheomelanin shows a distinctive Raman spectrum comprising three diagnostic bands located at 500, 1,500 and 2,000 cm −1 , and eumelanin shows different spectra with other diagnostic bands (Galván & Jorge, ; Galván et al, ; Polidori, Jorge, & Ornosa, ; Wang et al, ). In the flank feathers of male zebra finches, we only detected Raman signal from pheomelanin together with bands that can be assigned to keratin (Hsu, Moore, & Krimm, ).…”

Females mate with males with diminished pheomelanin‐based coloration in the Eurasian nuthatch Sitta europaea

“…In each feather, we obtained five Raman spectra from different barbs and barbules. Pheomelanin shows a distinctive Raman spectrum comprising three diagnostic bands located at 500, 1500 and 2000 cm -1 , and eumelanin shows different spectra with other diagnostic bands , Galván and Jorge 2015, Wang et al 2016, Polidori et al 2017). In the nuthatch feathers, we only detected Raman signal from pheomelanin, together with bands that can be assigned to keratin (Hsu et al 1976) (Fig.…”

WASTE FROM THE HARVESTING OF BUTTON MUSHROOM (Agaricus bisporus) AS A SOURCE OF NATURAL MELANIN

“…Melanins have been isolated from a variety of phylogenic sources: animals (Mbonyiryivuze et al 2015;Polidori et al 2017;Sun et al 2017), plants (Wang et al 2006;Kannan and Ganjewala 2009;Cuevas-Juárez et al 2014), bacteria (Kurian et al 2014;Laxmi et al 2016;El-Naggar and El-Ewasy 2017) and fungi (Harki et al 1997;Suryanarayanan et al 2004;Ye et al 2011;Łopusiewicz 2018). Melanins are commonly represented as black and brown pigments, high molecular weight heterogenous polymers derived from the oxidation of monophenols and the subsequent polymeryzation of intermediate o-diphenols and their resulting quinones (Solano 2014).…”