Insect Pigments Research Articles

The chemistry of aphids and scale insects

A general survey of aphids and scale insects is followed by a review of their secondary metabolites, a few of which may be found in museum artifacts or as conservation requisites. Lac resin (which gives shellac of commerce) is based upon complex oligomers of hydroxy acids joined by ether and ester linkages. In addition to a range of minor constituents, the following hydroxy acids have been found: 9, 10, 16-trihydroxypalmitic acid, jalaric acid, and laccijalaric acid. The last two are tricyclic sesquiterpenic aldehyde-acids. The structures of the actual oligomers remain uncertain. Three scale insect pigments have been important as dyestuffs: cochineal (carminic acid), kermes (kermesic acid) and lac dye. All these insect pigments are anthraquinones, and the structures of carminic and kermesic acids, now well established, are given. Lac dye is a rather complex mixture of (at least) three phenolic compounds (erythrolaccins) and four phenolic acids (laccaic acids). Waxes secreted by certain coccids have been used by many peoples, for example in China, in India and in South America. The chemistry of these waxes is reviewed. Other insect products described include honeydew, manna, and carotene and polycyclic quinonoid pigments from aphids. -- AATA

The chain of unexpected discovery: xanthopterin-stimulated renal mitosis.

The authors wish to inscribe this paper to the memory and the genius of Frederick Gowland Hopkins, in Needham's words essentially the founder of modern biochemistry in the United Kingdom [1]· Hopkins's towering contributions have been movingly described in Needham's Centenary Lecture in the University of Cambridge in 1961 and in Dale's great obituary appreciation written for the Royal Society [2]—both works of much piety. Among Hopkins's multifarious interests, none can excel in sheer romance that which dealt with insect pigments, an interest which spanned the greater part of his long life. At the age of seventeen he had just left school when he published a note in The Entomologist of 1878 dealing with the natural history of the bombardier beetle {Brachinus crepitans). A decade later (while he was at Guy's Hospital) came a further paper on the pigments of pierid butterflies, with his suggestion of the importance of the uric acid structure. No fewer than a further four decades were needed before Wieland, again to

Insect pigments—IV. Pteridines and colour in some Hemiptera

Eleven species of Hemiptera Heteroptera were investigated for the presence of pteridines. Isoxanthopterin, violapterin, and 7-methylxanthopterin were identified in some species. Erythropterin was found in all the species examined: its importance in pigmentation of Hemiptera is emphasized.

Mollisin, a naturally occurring chlorine‐containing quinone: Part IV,. Revised structures for cochenillic acid and for the insect pigments, carminic and kermesic acids

Abstract4‐Methoxy‐6‐methylhemimellitic acid and its isomers, 3‐methoxy‐5‐methyltrimellitic and 5‐methoxy‐3‐methyltrimellitic acid have been synthesized. 4‐Methoxy‐6‐methylhemimellitic acid is identical with a degradation product of mollisin methyl ether. Evidence is presented from which it must be concluded that cochenillic acid ‐ a degradation product of the well‐known insect pigments carminic and kermesic acids ‐ considered since 1897 to be 4‐hydroxy‐6‐methylhemimellitic acid is in fact 5‐hydroxy‐3‐methyltrimellitic acid. From this it follows that the current structural formulae of carminic and kermesic acids must be revised.

A light-sensitive yellow pigment from the housefly.

Extraction of house-fly heads with neutral phosphate buffer yielded a dark brown solution from which a number of pigments were separated, either wholly or partially, by chromatography on a column of calcium phosphate mixed with celite. One of the pigments was light-sensitive, and had a yellow color, with a spectral absorption maximum at 437 mmicro in phosphate buffer at pH 6.5. Several consecutively eluted fractions from each chromatogram of the house-fly head extract showed the characteristic absorption curve of this pigment with no trace, spectroscopically, of the other pigments of the extract. The products of bleaching the pigment at pH 6.5 had an absorption curve showing plateaus at 440 to 460 mmicro and 350 to 360 mmicro and an inflection at about 250 mmicro. Above pH 8.0 the pigment bleached in the dark giving an absorption maximum at about 380 mmicro, and inflections at 290 mmicro and at about 250 mmicro. With 2.5 to 5 N HCl or H(2)SO(4) an absorption maximum at 470 to 475 mmicro was obtained with either the unbleached or the bleached pigment. With sulfosalicylic acid, ethanol, or heating at 100 degrees C., a part of the pigment was precipitated, leaving a light-stable yellow supernatant. This light-sensitive house-fly pigment cannot as yet be identified with any of the previously known insect pigments or with the photosensitive pigments of other animals, though these latter compounds exhibit some similarity in their spectroscopic properties.

Bacterial Origin of Some Insect Pigments

THE literature on symbiosis, as summarized in Buchner's1 latest book, refers almost entirely to histological and cytological findings. Little work seems to have been done on the isolation of the symbiotes, and less still on their physiological role in insect metabolism. Koch2 was the first to prove that the symbiote of Sitodrepa panicea provides a growth-promoting factor or vitamin for this insect. With regard to Cicadella viridis, I have published two3,4 communications showing that the insect contains two bacteria : one on culturing produces a greenish-yellow pigment, identical with the colour of the insect, and the other -carotene which is apparent at least on the legs of the males. In the female, -carotene is reduced to the colourless vitamin A, which is needed by the insect.

The origin of pigments in insects and the rôle of genes

The origin of pigments in insects and the rôle of genes

Pigments of Lepidoptera

I WAS about to pen some remarks on Mr. Perry Coste's recent articles on this subject, when a letter from Mr. Gowland Hopkins in the last number of NATURE (p. 581) expressed substantially the same views as those which I had arrived at. I write now rather to support Mr. Hopkins in his strictures than to offer any fresh criticisms of my own. The articles on “Insect Colours” published in these columns are, as the author states, to be regarded in the light of an abstract of a series of more extended papers published in the Entomologist. The papers in the latter publication from their title led us to suppose that Mr. Coste had made some contribution to our knowledge of the chemistry of insect pigments. I read them from month to month in the hope of getting new light on this subject, which is of such general interest to both chemists and biologists: I regret to say that I have been grievously disappointed. The experiments thus far described amount simply to the fact—not altogether astonishing—that strong chemical reagents modify the colours of Lepidopterous pigments or in some cases dissolve them out of the wings. The bearing of these observations on the chemistry of the pigments is so remote as to be practically useless until we know something of the chemical nature of these pigments. The methods adopted by Mr. Coste are not likely to advance our knowledge in this direction very much, and it is certainly remarkable that in treating of yellows he makes no reference1 to the only real contribution to the chemistry of Lepidopterous pigments, viz. the experiments made by Mr. Hopkins, and published in the Proceedings of the Chemical Society in 1889. Mr. Coste is no doubt acquainted with those South American Papilios with a large red spot on the hind wing, which spot loses its red colour and becomes of a brilliant metallic bluish green when the wing is tilted so that the incident and reflected rays form a very wide angle. The colour is in this case doubtless a mixed result, partly due to pigment and partly to interference. Now, anyone who has observed this and other similar colour phenomena in insects might describe his observations as contributions to the physics of insect colours. If he thought proper to adopt this course, he would be misleading physicists. The observation of the bare facts is as much a contribution to the physics of insect colours as the statement that a rainbow can be seen in the sky is a contribution to the physics of illuminated water-drops. It seems to me that Mr. Coste's experiments bear the same relationship to the chemistry of insect colours that the mere observation of interference colours in insects bears to the physics of insect colours.