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Insect pigments—IV. Pteridines and colour in some Hemiptera
7. Insect Physiol., t 966, Vol. 12, pp. 123 to 127. Pergamon Press Ltd.
INSECT
Printed in Great Britain
PTERIDINES PIGMENTS-IV.* SOME HEMIPTERA L. MERLIN1
AND COLOUR
IN
and G. NASINI
Politecnico, Istituto di Chimica, Centro de1 C.N.R. per la chimica delle sostanze naturali, Milano, Italy (Received 23 June 1965)
Abstract-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.
INTRODUCTION
PTERIDINESare widespread in the animal kingdom, and particularly among insects (PFLEIDERER,1963). The order Hemiptera seems to be a good source of them. However, only three species, Oncopeltus fusciatus Dallas (BARTEL et al., 1958; HUDSON et al., 1959; FORREST, 1964), Pyrrhocoris apterus L. (MERLINI and MONDELLI, 1962), and Rhodnius prolixus Stal (VISCONTINI and SCHMID, 1963) Isoxanthopterin (I), xanthopterin, have been thus far thoroughly investigated. 7-methyl-xanthopterin (III), 2-amino-4_hydroxypteridine, biopterin, and erythropterin (IV) were found in the former, erythropterin and violapterin (II) in the second, erythropterin, lepidopterin, and isoxanthopterin in the third. BARTEL et al. (1958) reported the presence in ten members of Scutelleridae and one of Lygaeidae of the same pteridines as in Oncopeltw, and GOGALAand MICHIELI (1962a, b) published paper chromatograms of fluorescent pteridines from another six Hemiptera. 0
I.
II.
X = NH,. X = OH.
III. IV.
We report now the results of our investigation and
African
Hemiptera.
* Part III: MERLINI and CARDILLO(1963). 123
H
R = CH,. R = CH,CO COOH. on eleven
species
of European
124
L. hlERLrN1 AND G. NASINI AND
MATERIAL
METHODS
We had only two or three specimens of the first eight species (see Table 2). The insects were defatted with ether and methanol, then extracted with very dilute ammonia containing a trace of mercaptoethanol. Ammonia was immediately evaporated under reduced pressure and the solution subjected to thin-layer chromatography on cellulose Macherey and Nagel MN 300 G. This technique has the advantage over paper chromatography that smaller amounts may be used, spots appear smaller, and a better separation can be achieved. Eluents were those usually employed in paper chromatography of pteridines. Only some R, values are reported in Table 1. Mixtures with synthetic compounds were used for comparison. Of Graphosoma italicum we had enough material to employ preparative chromatography on Whatman 3 MM paper sheets, with eluent butanol-acetic acid-water (BAW), 20-3-7. The fluorescent strips were cut and extracted with water. Re-chromatography gave substances pure enough to measure their ultraviolet spectra. TABLE l--Rf
VALUESON THIN-LAYERPLATESOF CELLULOSEMN 300 G
(4 Erythropterin Isoxanthopterin Violapterin 7-Methylxanthopterin Eluents:
(a),
water;
(b),
0.32 0.36 0.50 0.42 butanol-acetic
(b) 0.08 0.25 0.22 0.36 acid-water,
(4 0.08 0.32 0.23 0.34 20-3-7
Fluorescence Orange Blue Blue Green
; (c), isopropanol-water,
2-l.
Mesocerus marginatus material (15 individuals) was ground, defatted, and chromatographed on Whatman cellulose columns, first with isopropanol-l”/o aq. ammonium acetate, 2-1, then with water. Here again U.V. spectra of the compounds corresponding to the fluorescent bands eluted could be measured. Pyrrhocoris apterus was reinvestigated in order to ascertain the structure of a green fluorescent substance, not previously identified. This substance, 7-methylxanthopterin (III), is easily located on the chromatograms. However, the U.V. spectra of samples obtained from a simple preparative paper or even column chromatography of the extracts exhibited surprisingly the absorption of uric acid peak at 375 mp. (&l&U 236, 289 rnp, pH 7) with an additional low-extinction The chromatographic behaviour of uric acid present (MERLINI and MONDELLI, 1962) in the insect is so similar that the following cumbersome procedure had to be applied before a sample free of uric acid and showing a reasonably clear U.V. spectrum of III (h,,, 268, 375 rnp, pH 7) could be obtained. The aqueous extract of 400 g of dry Pyrrhocoris material (previously defatted with ether) was concentrated under reduced pressure and subjected to chromatography on large Whatman cellulose columns, with O*3o/osodium citrate solution
INSECT PIGMENTS-IV.
PTERIDINES AND COLOUR IN
SOME
HEMIPTERA
125
as eluent. Three large bands, respectively with orange (erythropterin), blue (violapterin), and green fluorescence (7_methylxanthopterin), were eluted. The eluate corresponding to the latter (containing some violapterin) was similarly chromatographed three times: with water; BAW, 40-3-7; and isopropanol-water, 3-l. The residue from the last eluate was purified by suspending it in ethanol, adding ammonia until it was dissoIved, and concentrating. The compound had the chromatographic behaviour and U.V. spectra of 7-methylxanthopterin. Moreover, a nuclear magnetic resonance spectrum (in CF,COOH, methyl singlet at 2*786, NH, broad absorption at S-256), identical to that reported for synthetic III (VON PHILIPSBORN et al., 1963), could be measured. RESULTS The species investigated
and the pteridines
TABLE 2-PTERIDINE~ Family Pentatomidae Pentatomidae Pentatomidae Cercopidae Plataspidae Cicadidae Coreidae Coreidae Coreidae Pentatomidae Pyrrhocoridae
AND DISCUSSION
WUND IN
THE
Species
Tesseratoma aethiops Dist. Aspavia armigera F. Tantia gelei Locris sp. Milletia utveldeana Cicada,
gen. sp. not det.
Dilycochtha tenuicornis Karsch Leptocoris apicalis Westw. Mesocerus marginatus L. Graphosoma italicum Miill. Pyrrhocoris apte-rus L.
found
are reported
in Table
2.
HEMIPTERA INVESTIGATED Origin
I
II
III
IV
CAR C C CAR C CAR C C I I I
+ + + + + + + + + + +*
+ + +
? ? ? ? ? ? ? ? ? ? +
+ + + + + + + + + + +
Origin: CAR = Central African Republic; C = Congo; I = Italy. I = isoxanthopterin; II = violapterin; III = 7-methylxanthopterin; IV = erythropterin. The question mark means that lack of material and extraction method (presence of ammonia) did not allow an unambiguous identification. * Isoxanthopterin was clearly identified, together with II, only once in young Pywhocoris collected in spring.
According to PFLEIDERER (1963) the natural 7-methylxanthopterin (previously named chrysopterin: SCH~PF and BECKER, 1936; TSCHESCHE and KORTE, 1951) seems to be an artifact. Actually, erythropterin is extremely sensitive even to very dilute alkali in the cold and decomposes into 7-methylxanthopterin and oxalic acid (PFLEIDERER, 1962). However, we found the compound in aqueous and also butanolic extracts of Pyrrhocoris applied on chromatograms (developed with BAW) immediately after the death of the insects. In the same conditions, a sample of pure erythropterin gave no appreciable spot of 7-methylxanthopterin. Another report of the occurrence of 7-methylxanthopterin appeared recently (FORREST,
L. MERLINIANDG. NA.SINI
126
1964). Attention should be paid to the similarity of fluorescence, U.V. spectra, and chromatographic behaviour of xanthopterin and its 7-methyl derivative (PFLEIDERER,1962). Our identification is unambiguously substantiated by the NMR spectrum. Inspection in Table 2 shows that violapterin (II) appears alone* in Pyrrhocoris upterus and together with isoxanthopterin (I) in two other species. This result would suggest that some Hemiptera may have a deaminase enzyme?, able to convert these compounds one into the other. Violapterin has been found since only in bee pupae (REMBOLDand BUSCHMANN,1963). We would like to remark that these two pteridines exhibit the same fluorescence, have very similar U.V. spectra, and show very near R, values with most solvents (REMBOLDand BUSCHMANN,1963), so that the identification could become difficult. We found that a very good separation is obtained with water as eluent for paper or cellulose thin-layer chromatography (Table 1). Erythropterin was found in all the species examined, and, as far as we know, in every species of Hemiptera so far investigated. This red pteridine should be considered to be very often responsible for the sometimes bright red colour of Hemiptera, together with carotenoids (GOGALA and MICHIELI, 1962a; PALMER and KNIGHT, 1924; MERLINI and MONDELLI, 1962). The so-called flavone-like pigments reported by PALMERand KNIGHT (1924) are almost certainly erythropterin. Their old suggestion, based only on the deepening with alkali of the colour of aqueous extracts (given by erythropterin solutions), has been often quoted as a statement of the presence of flavonoid pigments. The pigment extracted from Hemiptera by GOGALA and MICHIELI (1962a, b) is without any doubt rather pure erythropterin, as appears from the published U.V. spectrum (see VISCONTINIand STIERLIN, 1963). We believe that reports of the occurrence of flavonoids, which are not directly biosynthesized, in insects should be cautiously considered unless based on firm chemical grounds. The only unambiguous investigations in this respect are, to our knowledge, those by MORRIS and THOMSON (1963, 1964) on the butterflies Melanargia galatea (L.) and Coenonympha pamphilus (L.). Acknowledgements-We wish to thank Professor M. PAVAN(Pavia), who has kindly supplied or identified the material, and Mr. E. GAVEZZOTTI for his active participation in the experimental work. REFERENCES
BARTELA. H., HUDSONB. W., Oncopeltus fuscziztus Dallas-I. 348-354.
FORREST H. S. (1964) Pteridines
and CRAIG R. (1958) Identification and of the milkweed
Intern. Symp. Chem. natural Products, Kyoto,
Pteridines localization.
bug Oncopeltusfasciutus Dallas. Abstracts of papers, pp. 137-138.
GOGALA M. and MICHIELI s. (1962a) Beitrag zur Kenntnis Bull. Scient. Cons, Acads RPF
in the milkweed bug, J. Insect Physiol. 2,
der Farbstoffe
IUPAC
bei Heteropteren.
Yougosl. 7, 61-62.
* See footnote to Table 2. t Such an enzyme was found in the soil bacterium
Alcaligenes faecalis (MCNUTT,1964).
INSECTPIGMENTS-IV.
PTERIDINESANDCOLOURIN SOMEHEMIPTERA
127
GOGALA M. and MICHIELI S. (1962b) Sezonsko prebarvanje pri nekaterih vrstah stenic (Heteroptera). Biol. vestnik 10,33-44. HUDSON B. W., BARTEL A. H., and CRAIG R. (1959) Pteridines in the milkweed bug, Oncopeltus fasciutus Dallas-II. Quantitative determination of pteridine content of tissues during growth. J. Insect Physiol. 3, 63-73. MCNUTT W. S. (1964) The enzymatic conversion of pteridines into xanthine-%carboxylic acid. In P&dine Chemistry, pp, 427-441. Pergamon Press, Oxford. MERLINI L. and CARDILLO G. (1963) Sui carotenoidi di Leptinotarsa decemlineata Say. Gaze. chim. ital. 93, 949-952. MERLINI L. and MONDELLI R. (1962) Sui pigmenti di Pyrrhocoris apterus L. Gazz. chim. itaE. 92, 1251-1261. MORRIS S. J. and THOMSON R. H. (1963) The flavonoid pigments of the marbled white butterfly Melanargia galatea Seltz. J. Insect Physiol. 9, 391-399. MORRIS S. J. and THOMSON R. H. (1964) The flavonoid pigments of the small heath butterfly, Coenonympha pamphilus L. J. Insect Physiol. 10,377-383. PALMER L. S. and KNIGHT H. H. (1924) Anthocyanin and flavone-like pigments as cause of red colorations in the hemipterous families Aphididae, Coreidae, Lygaeidae, Miridae and Reduviidae. J. biol. Chem. 59, 451-455. PFLEIDERERW. (1962) Uber die Isolierung und Struktur des orangeroten Schmetterlingspigmentes Erythropterin. Cha. Ber. 95, 2195-2204. PFLEIDERERW. (1963) Neuere Entwicklungen in der Pteridin-Chemie. Angew. Chem. 75, 993-1011. VON PHILIPSBORN W., STIERLIN H., and TRABER W. (1963) Uber ProtonenresonanzSpektren von Pteridinen-III. Zur Struktur von 9-Acetonylxanthopterin und Erythropterin. Helv. chins. Acta 46, 2592-2596. REMBOLDH. and BUSCHMANN L. (1963) Untersuchungen iiber die Pteridine der Bienenpuppe (Apis mellifica). Justus Liebigs An&z Chem. 662, 72-82. SCH~PF C. and BECKER E. (1936) fllb er neue Pterine. Justus Liebigs Annln Chem. 524, 49-123. TSCHESCHE R. and KORTE F. (1951) uber Pteridine-IV. Zur Konstitution des Chrysopterins und Mesopterins. Chem. Ber. 84, 641-648. VISCONTINI M. and SCHMID H. (1963) Fluoreszierende Stoffe aus Rhodnius prolixus Stal. Helv. chim. Acta 46, 2509-2516. VISCONTINI M. and STIERLIN H. (1963). Fluoreszierende Stoffe aus Ephestia hiihniella Zeller-4. Synthese von Erythropterin, Ekapterin und Lepidopterin. Helv. chim. Acta 46, 51-56.
INSECT
Printed in Great Britain
PTERIDINES PIGMENTS-IV.* SOME HEMIPTERA L. MERLIN1
AND COLOUR
IN
and G. NASINI
Politecnico, Istituto di Chimica, Centro de1 C.N.R. per la chimica delle sostanze naturali, Milano, Italy (Received 23 June 1965)
Abstract-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.
INTRODUCTION
PTERIDINESare widespread in the animal kingdom, and particularly among insects (PFLEIDERER,1963). The order Hemiptera seems to be a good source of them. However, only three species, Oncopeltus fusciatus Dallas (BARTEL et al., 1958; HUDSON et al., 1959; FORREST, 1964), Pyrrhocoris apterus L. (MERLINI and MONDELLI, 1962), and Rhodnius prolixus Stal (VISCONTINI and SCHMID, 1963) Isoxanthopterin (I), xanthopterin, have been thus far thoroughly investigated. 7-methyl-xanthopterin (III), 2-amino-4_hydroxypteridine, biopterin, and erythropterin (IV) were found in the former, erythropterin and violapterin (II) in the second, erythropterin, lepidopterin, and isoxanthopterin in the third. BARTEL et al. (1958) reported the presence in ten members of Scutelleridae and one of Lygaeidae of the same pteridines as in Oncopeltw, and GOGALAand MICHIELI (1962a, b) published paper chromatograms of fluorescent pteridines from another six Hemiptera. 0
I.
II.
X = NH,. X = OH.
III. IV.
We report now the results of our investigation and
African
Hemiptera.
* Part III: MERLINI and CARDILLO(1963). 123
H
R = CH,. R = CH,CO COOH. on eleven
species
of European
124
L. hlERLrN1 AND G. NASINI AND
MATERIAL
METHODS
We had only two or three specimens of the first eight species (see Table 2). The insects were defatted with ether and methanol, then extracted with very dilute ammonia containing a trace of mercaptoethanol. Ammonia was immediately evaporated under reduced pressure and the solution subjected to thin-layer chromatography on cellulose Macherey and Nagel MN 300 G. This technique has the advantage over paper chromatography that smaller amounts may be used, spots appear smaller, and a better separation can be achieved. Eluents were those usually employed in paper chromatography of pteridines. Only some R, values are reported in Table 1. Mixtures with synthetic compounds were used for comparison. Of Graphosoma italicum we had enough material to employ preparative chromatography on Whatman 3 MM paper sheets, with eluent butanol-acetic acid-water (BAW), 20-3-7. The fluorescent strips were cut and extracted with water. Re-chromatography gave substances pure enough to measure their ultraviolet spectra. TABLE l--Rf
VALUESON THIN-LAYERPLATESOF CELLULOSEMN 300 G
(4 Erythropterin Isoxanthopterin Violapterin 7-Methylxanthopterin Eluents:
(a),
water;
(b),
0.32 0.36 0.50 0.42 butanol-acetic
(b) 0.08 0.25 0.22 0.36 acid-water,
(4 0.08 0.32 0.23 0.34 20-3-7
Fluorescence Orange Blue Blue Green
; (c), isopropanol-water,
2-l.
Mesocerus marginatus material (15 individuals) was ground, defatted, and chromatographed on Whatman cellulose columns, first with isopropanol-l”/o aq. ammonium acetate, 2-1, then with water. Here again U.V. spectra of the compounds corresponding to the fluorescent bands eluted could be measured. Pyrrhocoris apterus was reinvestigated in order to ascertain the structure of a green fluorescent substance, not previously identified. This substance, 7-methylxanthopterin (III), is easily located on the chromatograms. However, the U.V. spectra of samples obtained from a simple preparative paper or even column chromatography of the extracts exhibited surprisingly the absorption of uric acid peak at 375 mp. (&l&U 236, 289 rnp, pH 7) with an additional low-extinction The chromatographic behaviour of uric acid present (MERLINI and MONDELLI, 1962) in the insect is so similar that the following cumbersome procedure had to be applied before a sample free of uric acid and showing a reasonably clear U.V. spectrum of III (h,,, 268, 375 rnp, pH 7) could be obtained. The aqueous extract of 400 g of dry Pyrrhocoris material (previously defatted with ether) was concentrated under reduced pressure and subjected to chromatography on large Whatman cellulose columns, with O*3o/osodium citrate solution
INSECT PIGMENTS-IV.
PTERIDINES AND COLOUR IN
SOME
HEMIPTERA
125
as eluent. Three large bands, respectively with orange (erythropterin), blue (violapterin), and green fluorescence (7_methylxanthopterin), were eluted. The eluate corresponding to the latter (containing some violapterin) was similarly chromatographed three times: with water; BAW, 40-3-7; and isopropanol-water, 3-l. The residue from the last eluate was purified by suspending it in ethanol, adding ammonia until it was dissoIved, and concentrating. The compound had the chromatographic behaviour and U.V. spectra of 7-methylxanthopterin. Moreover, a nuclear magnetic resonance spectrum (in CF,COOH, methyl singlet at 2*786, NH, broad absorption at S-256), identical to that reported for synthetic III (VON PHILIPSBORN et al., 1963), could be measured. RESULTS The species investigated
and the pteridines
TABLE 2-PTERIDINE~ Family Pentatomidae Pentatomidae Pentatomidae Cercopidae Plataspidae Cicadidae Coreidae Coreidae Coreidae Pentatomidae Pyrrhocoridae
AND DISCUSSION
WUND IN
THE
Species
Tesseratoma aethiops Dist. Aspavia armigera F. Tantia gelei Locris sp. Milletia utveldeana Cicada,
gen. sp. not det.
Dilycochtha tenuicornis Karsch Leptocoris apicalis Westw. Mesocerus marginatus L. Graphosoma italicum Miill. Pyrrhocoris apte-rus L.
found
are reported
in Table
2.
HEMIPTERA INVESTIGATED Origin
I
II
III
IV
CAR C C CAR C CAR C C I I I
+ + + + + + + + + + +*
+ + +
? ? ? ? ? ? ? ? ? ? +
+ + + + + + + + + + +
Origin: CAR = Central African Republic; C = Congo; I = Italy. I = isoxanthopterin; II = violapterin; III = 7-methylxanthopterin; IV = erythropterin. The question mark means that lack of material and extraction method (presence of ammonia) did not allow an unambiguous identification. * Isoxanthopterin was clearly identified, together with II, only once in young Pywhocoris collected in spring.
According to PFLEIDERER (1963) the natural 7-methylxanthopterin (previously named chrysopterin: SCH~PF and BECKER, 1936; TSCHESCHE and KORTE, 1951) seems to be an artifact. Actually, erythropterin is extremely sensitive even to very dilute alkali in the cold and decomposes into 7-methylxanthopterin and oxalic acid (PFLEIDERER, 1962). However, we found the compound in aqueous and also butanolic extracts of Pyrrhocoris applied on chromatograms (developed with BAW) immediately after the death of the insects. In the same conditions, a sample of pure erythropterin gave no appreciable spot of 7-methylxanthopterin. Another report of the occurrence of 7-methylxanthopterin appeared recently (FORREST,
L. MERLINIANDG. NA.SINI
126
1964). Attention should be paid to the similarity of fluorescence, U.V. spectra, and chromatographic behaviour of xanthopterin and its 7-methyl derivative (PFLEIDERER,1962). Our identification is unambiguously substantiated by the NMR spectrum. Inspection in Table 2 shows that violapterin (II) appears alone* in Pyrrhocoris upterus and together with isoxanthopterin (I) in two other species. This result would suggest that some Hemiptera may have a deaminase enzyme?, able to convert these compounds one into the other. Violapterin has been found since only in bee pupae (REMBOLDand BUSCHMANN,1963). We would like to remark that these two pteridines exhibit the same fluorescence, have very similar U.V. spectra, and show very near R, values with most solvents (REMBOLDand BUSCHMANN,1963), so that the identification could become difficult. We found that a very good separation is obtained with water as eluent for paper or cellulose thin-layer chromatography (Table 1). Erythropterin was found in all the species examined, and, as far as we know, in every species of Hemiptera so far investigated. This red pteridine should be considered to be very often responsible for the sometimes bright red colour of Hemiptera, together with carotenoids (GOGALA and MICHIELI, 1962a; PALMER and KNIGHT, 1924; MERLINI and MONDELLI, 1962). The so-called flavone-like pigments reported by PALMERand KNIGHT (1924) are almost certainly erythropterin. Their old suggestion, based only on the deepening with alkali of the colour of aqueous extracts (given by erythropterin solutions), has been often quoted as a statement of the presence of flavonoid pigments. The pigment extracted from Hemiptera by GOGALA and MICHIELI (1962a, b) is without any doubt rather pure erythropterin, as appears from the published U.V. spectrum (see VISCONTINIand STIERLIN, 1963). We believe that reports of the occurrence of flavonoids, which are not directly biosynthesized, in insects should be cautiously considered unless based on firm chemical grounds. The only unambiguous investigations in this respect are, to our knowledge, those by MORRIS and THOMSON (1963, 1964) on the butterflies Melanargia galatea (L.) and Coenonympha pamphilus (L.). Acknowledgements-We wish to thank Professor M. PAVAN(Pavia), who has kindly supplied or identified the material, and Mr. E. GAVEZZOTTI for his active participation in the experimental work. REFERENCES
BARTELA. H., HUDSONB. W., Oncopeltus fuscziztus Dallas-I. 348-354.
FORREST H. S. (1964) Pteridines
and CRAIG R. (1958) Identification and of the milkweed
Intern. Symp. Chem. natural Products, Kyoto,
Pteridines localization.
bug Oncopeltusfasciutus Dallas. Abstracts of papers, pp. 137-138.
GOGALA M. and MICHIELI s. (1962a) Beitrag zur Kenntnis Bull. Scient. Cons, Acads RPF
in the milkweed bug, J. Insect Physiol. 2,
der Farbstoffe
IUPAC
bei Heteropteren.
Yougosl. 7, 61-62.
* See footnote to Table 2. t Such an enzyme was found in the soil bacterium
Alcaligenes faecalis (MCNUTT,1964).
INSECTPIGMENTS-IV.
PTERIDINESANDCOLOURIN SOMEHEMIPTERA
127
GOGALA M. and MICHIELI S. (1962b) Sezonsko prebarvanje pri nekaterih vrstah stenic (Heteroptera). Biol. vestnik 10,33-44. HUDSON B. W., BARTEL A. H., and CRAIG R. (1959) Pteridines in the milkweed bug, Oncopeltus fasciutus Dallas-II. Quantitative determination of pteridine content of tissues during growth. J. Insect Physiol. 3, 63-73. MCNUTT W. S. (1964) The enzymatic conversion of pteridines into xanthine-%carboxylic acid. In P&dine Chemistry, pp, 427-441. Pergamon Press, Oxford. MERLINI L. and CARDILLO G. (1963) Sui carotenoidi di Leptinotarsa decemlineata Say. Gaze. chim. ital. 93, 949-952. MERLINI L. and MONDELLI R. (1962) Sui pigmenti di Pyrrhocoris apterus L. Gazz. chim. itaE. 92, 1251-1261. MORRIS S. J. and THOMSON R. H. (1963) The flavonoid pigments of the marbled white butterfly Melanargia galatea Seltz. J. Insect Physiol. 9, 391-399. MORRIS S. J. and THOMSON R. H. (1964) The flavonoid pigments of the small heath butterfly, Coenonympha pamphilus L. J. Insect Physiol. 10,377-383. PALMER L. S. and KNIGHT H. H. (1924) Anthocyanin and flavone-like pigments as cause of red colorations in the hemipterous families Aphididae, Coreidae, Lygaeidae, Miridae and Reduviidae. J. biol. Chem. 59, 451-455. PFLEIDERERW. (1962) Uber die Isolierung und Struktur des orangeroten Schmetterlingspigmentes Erythropterin. Cha. Ber. 95, 2195-2204. PFLEIDERERW. (1963) Neuere Entwicklungen in der Pteridin-Chemie. Angew. Chem. 75, 993-1011. VON PHILIPSBORN W., STIERLIN H., and TRABER W. (1963) Uber ProtonenresonanzSpektren von Pteridinen-III. Zur Struktur von 9-Acetonylxanthopterin und Erythropterin. Helv. chins. Acta 46, 2592-2596. REMBOLDH. and BUSCHMANN L. (1963) Untersuchungen iiber die Pteridine der Bienenpuppe (Apis mellifica). Justus Liebigs An&z Chem. 662, 72-82. SCH~PF C. and BECKER E. (1936) fllb er neue Pterine. Justus Liebigs Annln Chem. 524, 49-123. TSCHESCHE R. and KORTE F. (1951) uber Pteridine-IV. Zur Konstitution des Chrysopterins und Mesopterins. Chem. Ber. 84, 641-648. VISCONTINI M. and SCHMID H. (1963) Fluoreszierende Stoffe aus Rhodnius prolixus Stal. Helv. chim. Acta 46, 2509-2516. VISCONTINI M. and STIERLIN H. (1963). Fluoreszierende Stoffe aus Ephestia hiihniella Zeller-4. Synthese von Erythropterin, Ekapterin und Lepidopterin. Helv. chim. Acta 46, 51-56.