The chemistry of the defensive secretion of the beetle, Drusilla canaliculata

J. Insect Physiol., 1973, Vol. 19, pp. 369 to 382. Pergamn

Press. Printed in Great Britain

THE CHEMISTRY OF THE DEFENSIVE SECRETION OF THE BEETLE, DRUSILLA CANALICULATA T. M. BRAND,l

M. S. BLUM,l

H. M. FALES,2 and J. M. PASTEELS

1 Department of Entomology,’ University of Georgia, Athens, Georgia 30601; ’ Laboratory of Chemistry, National Heart and Lung Institute, Bethesda, Maryland 20014; and 3 Laboratoire de Zoologie Get&ale, UniversitC Libre de Bruxelles, Belgium (Received 28 J&y 1972) Abstract-The tergal gland of the beetle, Drusilla canaliculata, contains defensive products which exhibit an extraordinary chemical diversity. This glandular exudate is fortified with alkanes, alkenes, saturated and unsaturated aliphatic aldehydes, 1,4-quinones, and hydroquinones. The aldehydes, 1zdodecanal, n-tetradecanal, n-tetradec-S-enal, and n-tetradeca-5,8-dienal, conIn addition, a new constituent in stitute a major group of components. arthropod defensive secretions, 2-hydroxy-3-methylhydroquinone, has been identified as a minor component in this exocrine exudate. INTRODUCTION

SINCE the various glands producing alarm pheromones in the social Hymenoptera are often not homologous, their function as liberators of alarm releasers must have developed polyphyletically (MASCHWITZ,1964). It now seems clear that this statement is also applicable to the defensive glands of many beetles. For example, many species of staphylinid beetles, such as those in the genus Stenus, in the subfamily Steninae, secrete defensive substances from their pygidial glands located near the tip of the abdomen (SCHILDKNECHT,1970). On the other hand, the staphylinid Lomechusa strumosa, a species in the large subfamily Aleocharinae, discharges its defensive exudate from the tergal gland, a dorsal structure which is located between the sixth and seventh abdominal tergites (PASTEELS,1968). The tergal gland, which in the family is limited to the Aleocharinae, is often highly developed in both myrmecophilous and free-living species. The tergal gland exudate of L. strumosa, which is reported to be an extremely effective defensive product (JORDAN,1913), is fortified with a series of 1,4-benzoquinones and aliphatic hydrocarbons (BLUM et al., 1971). We now report on the chemistry of the defensive secretion of a second aleocharine, Drudla ( = Astilbus) can&data, a free-living staphylinid that scavenges on dead ants. The secretion from its tergal gland is remarkably effective in repelling ants and was reported to react with Schiff reagent, thus presumably containing aldehydic constituents (PASTEELS,1968). The characterization of these aldehydes as part of a defensive secretion in which 15 compounds have been identified, demonstrates that this 369

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tergal gland exudate is one of the most complex yet analysed from any coleopterous species. MATERIALS

AND METHODS

Collection of secretion Adult beetles were laboratory reared at the Universite Libre de Bruxelles, Belgium. The tergal gland secretion was collected from beeties by inserting small filter-paper triangles, held with forceps, between the sixth and seventh abdominal tergites (counting system of BLACKWELDER, 1936). The impregnated triangles were extracted with n-hexane and the concentrated extract used for all subsequent analyses. Gas chromatographic and mass spectrometric analysis All gas chromatographic-mass spectrometric analyses were carried out on a LKB-9000 instrument at 70 eV, with a source temperature of 27O”C, separator temperature of 260°C and 60 PA ionizing current. Either one of two gas chromatographic stationary phases, 10% SP-1000 or 1% OV-17, were used in 2 m x 2.5 mm columns. Preparative gas chromatographic separations were carried out on a Tracer MT-220 gas chromatograph with 10% Carbowax 20 M as the stationary phase in a 2 m x 5 mm column. Oxonolysis Certain compounds in the extract known to contain double bonds were collected after elution from a 10 “//oCarbowax 20 M column and ozonized according to the procedure of BEROZAand BIERL (1966, 1967) or the modified procedure of BRADYet al. (1971). Gas chromatographic analyses of ozonolysis products were conducted either on 10% Carbowax 20 M (pentanal to dodecanal) or on Chromosorb 102 (acetaldehyde to butanal). Hydrogenation A small portion of the crude extract was hydrogenated, after the addition of PtO,, by passing hydrogen gas through it for approximately 15 min. The reaction mixture was analysed on the 10% SP-1000 column in the LKB-9000 mass spectrometer. Acetylution The crude extract was acetylated with acetic anhydride in pyridine reaction mixture analysed on either 10% SP-1000 or 1% OV-17.

and the

Sodium borohydride reduction The usual procedure for reduction with NaBH,, using ethanol as a solvent, was employed prior to acetylation and GC-MS analysis.

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RESULTS

The defensive secretion from D. canalicukzta is distinctly yellow suggesting the possible presence of quinones, and the positive reaction obtained to Schiff’s reagent indicates that aldehydes probably are also present (PASTEELS, 1968). The temperature-programmed gas chromatographic separation of the crude extract on SP-1000 showed the presence of at least four major peaks and a number of minor peaks (see Fig. 1). On this phase, the mass spectrum of the peak eluting after the

Time,

min

FIG. 1. Gas chromatographic separation of the hydrocarbon and aldehydic fractions in the defensive secretion of D. canaliculata (10% SP-1000; temperature programmed from 100 to 200°C at 8”C/min).

solvent gave a molecular ion at m/e 156 and a fragmentation pattern characteristic of a normal hydrocarbon. A scan of a very minor peak on the tail of this first peak showed a similar fragmentation pattern with a molecular ion at m/e 154, contaminated by m/e 156. A comparison of the retention time and mass spectrum of the larger peak with that of n-undecane confirmed its identity as this hydrocarbon. The small amount of n-undecene present did not permit the position of the double bond to be determined by ozonolysis. The second major peak, together with its two associated minor peaks, gave mass spectra characteristic of normal hydrocarbons. The spectrum of the first peak gave a molecular ion at m/e 184 and a comparison of its retention time and fragmentation pattern with those of standard hydrocarbons established its identity as n-tridecane. The major peak of this group gave a molecular ion at m/e 182, corresponding to the formula C,,H,, and its mass spectrum indicated that it was a n-tridecene. This peak was collected after elution from a Carbowax 20 M column and ozonized. Analysis of the reaction mixture on both Chromosorb 102 and Carbowax 20 M established that nonanal was the main product, confirming that this component in the The stereochemistry of this alkene remains defensive secretion was n-tridec-4-ene.

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unknown. The third peak in this group gave a molecular ion at m/e 180 and a mass spectrum corresponding to a n-tridecadiene. Ozonolysis of the collected material produced both butyraldehyde and hexanal as major products, thereby establishing the structure of this component as a n-trideca-4,7-diene of unknown stereochemistry. The third major peak eluting at approximately 8.5 min in the chromatogram in Fig. 1 gave a mass spectrum corresponding to that of n-dodecanal. This identification was further confirmed by a comparison of the retention time of the authentic compound on the various stationary phases. The structure of the minor peak eluting immediately after the n-dodecanal was not determined. The final group of compounds eluting near 12 min in Fig. 1 gave mass spectra characteristic of aliphatic aldehydes. The minor first peak had a retention time and mass spectrum which was congruent with an authentic sample of n-tetradecanal. The major peak of this group gave a mass spectrum corresponding to a n-tetradecenal. Ozonolysis of this peak, collected after elution from Carbowax 20 M, gave nonanal as the major product thereby establishing its formula as n-tetradec-5enal of unknown stereochemistry. This identification was confirmed by the congruence of the mass spectrum of the reduced and acetylated n-tetradecJ-enyl acetate (see Fig. 2) with that of a synthetic sample of this compound. The third

Time,

min

FIG. 2. Gas chromatographic separation of the defensive secretion of D. canalidata after reduction and acetylation (1 o/0 OV-17; temperature programmed from 100 to 200°C at 8T/min).

peak of this group gave a mass spectrum corresponding to a n-tetradecadienal, and ozonolysis of collected material showed hexanal to be the main mono-aldehydic product. It is therefore evident that one point of unsaturation in the n-tetradecadienal is in position 8, and, by extrapolation from the n-tetradecJ-enal, n-tridec-4ene, and n-trideca-4,7-diene present in the extract, it would seem most probable that this compound is n-tetradeca-5,8-dienal of unknown stereochemistry.

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Additional support for the A6 position of the one double bond in the n-tetradecadienal was obtained from the following data. The methoxime of the ntetradec+enal from the extract had a base peak at m/e 73 (+H,C = CH-NH0-CH,) resulting from McLafferty rearrangement of a y-hydrogen, its intensity suggesting that the y-hydrogen is allylic. Direct allylic cleavage, without rearrangement of a hydrogen atom, furnishes an intense peak at m/e 86 (+CH,CH,CH = N-0-CH,). Both of these peaks were observed in the tetradecadienal methoxime spectrum strongly suggesting that there is a double bond in the A5 position in this case also. The only model compound available to us to confirm this latter point was synthetic tetradeca-3,5-dienyl acetate. Reduction and acetylation of the D. canaliculata extract provided a gas chromatographic peak whose mass spectrum was similar, but not identical, with that of the model dienyl acetate. Importantly, its retention time was much shorter than that of the conjugated model suggesting that the unknown was unlikely to be a conjugated diene. We therefore conclude that the last peak in the gas chromatogram in Fig. 1 is n-tetradeca-5,8-dienal. The crude extract, after hydrogenation and GC-MS analysis, contained only the expected saturated aldehydes and alkanes. The GC-MS analysis of the crude extract on OV-17 revealed the presence of two 1,4-benzoquinones which were not obtained on the more polar SP-1000 stationary phase. Their retention times and mass spectra were identical in all respects to those of authentic samples of p-toluquinone and 3-methoxy-p-toluquinone respectively. Due to difficulties encountered with their gas chromatographic detection, the presence of hydroquinones was established by acetylation of the crude extract with acetic anhydride in pyridine followed by GC-MS analysis on OV-17. Mass spectra corresponding to hydroquinone diacetate, 2-methylhydroquinone diacetate, 2methoxy-3-methylhydroquinone diacetate, and 2-hydroxy-3-methylhydroquinone triacetate were obtained from peaks observed in the gas chromatogram of the reaction mixture. Reduction of the crude extract from D. canaliculata with NaBH,, followed by direct acetylation with acetic anhydride in pyridine and GC-MS analysis, produced an increase in the relative amounts of 2-methylhydroquinone diacetate and 2methoxy-3-methylhydroquinone triacetate obtained (see Fig. 2). Other peaks in this chromatogram corresponded to dodecyl acetate and tetradecenyl acetate formed from the corresponding aldehydes. A standard sample of 2-hydroxy-3-methylhydroquinone triacetate was synthesized by treating 3-methoxy-p-toluquinone with HBr at 100°C for 10 min, evaporating the excess acid, followed by the addition of acetic anhydride and a little powdered zinc. After a few minutes the reaction mixture was cooled, diluted with water and the 2-hydroxy-3-methylhydroquinone triacetate extracted with CHCI,. The mass spectrum and retention time of this synthetic compound were identical to that obtained from the last peak in the chromatogram in Fig. 2. Thus, in addition to the hydrocarbons and aldehydes, the defensive secretion of D. canaliculata contains p-toluquinone, 3-methoxy-p-toluquinone, hydroquinone,

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2-methylhydroquinone, 2-methoxy-3-methylhydroquinone, methylhydroquinone (I).

and

2-hydroxy-3-

OH CHa (I)

‘I \ 0

OH OH

A comparison of Figs. 1 and 2, together with other chromatograms which were obtained, shows that the major components in the secretion are p-toluquinone The two hydrocarbons, n-undecane followed closely by 2-methylhydroquinone. and tl-tridec-4-ene, occur in amounts approximately equivalent to the aldehydes, n-dodecanal and n-tetradec5-enal. These six compounds, together with 3methoxy-p-toluquinone, account for more than 80 per cent of the volatiles oband 3-hydroxyserved in the secretion. The two quinones, p-benzoquinone p-toluquinone, were not shown to be present during any of the analyses but, nevertheless, are likely to be trace constituents of the secretion. DISCUSSION In general, the defensive secretions of staphylinid beetles originate from the so-called pygidial glands. However, as the morphology of these glands in Stems (Steninae), and, in particular, Stuphylinus (Staphylininae), is distinctly different from that of the analogous glands in Bledius (Oxytelinae) (PASTEELSand ARAUJO, unpublished), the pygidial glands of genera within the same family cannot necessarily be considered homologous. Rather, ‘pygidial gland’ is a term which more appropriately refers to the paired glands located near the tip of the abdomen. In contrast, the defensive substances of aleocharines are secreted by the tergal gland. This organ is not homologous with any of the known glands found in species in other staphylinid subfamilies. Although certain myrmecophilous species, e.g. L. strumosa, and non-myrmecophilous species, e.g. D. canuliculata, possess a particularly well-developed tergal gland, in termitophilous species it regresses. The degree of glandular regression appears to depend on the extent to which the species is integrated into the termite society in which it co-exists (PASTEELS,1968, 1969). One of us (PASTEELS,1968) has demonstrated that the tergal gland secretion of D. canaliculuta renders this aleocharine virtually immune to attack by ants. The defensive secretion of Drusilla is utilized only when this aleocharine is subjected to sustained molestation by ants, and this secretory frugality may represent an effective conservation mechanism. D. canaliculuta does not spray the products of its tergal gland; rather, the secretion oozes from the glandular orifice and is wiped on the assailant. When molested, a beetle will rotate its abdomen so as to bring the gland-bearing segments into proximity to the point of stimulation (Fig. 3) where the copious secretion can be smeared on the source of tactile irritation.

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FIG. 3. D. canaliculata twisting the abdomen the tergal gland secretion

in response to pinching to the forceps.

and applying

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The gas chromatographic separations of the secretion of D. canaliculata presented in Figs. 1 and 2 illustrate the complexity of the secretion in terms of the number of components present. In addition, the variety of chemical types identified in this product comprises a combination which previously has not been associated in any insect defensive secretion. This study on the tergal gland secretion of D. canaliculata has shown the presence of alkanes, alkenes, aliphatic aldehydes, l,Cquinones, and hydroquinones. The chromatogram in Fig. 1 shows that n-undecane, n-tridecane, n-tridec4-ene, and n-trideca-4,7-diene constitute the major hydrocarbons present. A mass spectrum obtained from the tail of the n-undecane peak also showed the presence of n-undecene. The position of the double bond in n-tridec-4-ene is not that expected if it was derived from a common unsaturated fatty acid. A possible relationship between the hydrocarbons, undecane, tridecane, tridecene, and tridecadiene, and the aldehydes, dodecanal, tetradecanal, tetradecenal, and tetradecadienal offers some additional grounds for relating the biosynthetic origins of these compounds as the relative amounts of these two groups of compounds strongly indicate a quantitative relationship. For example, two of the most abundant compounds are n-undecane and n-dodecanal, each of which is present in approximately equivalent amounts. Indeed, the possible metabolic relationship between hydrocarbons and aldehydes becomes even more suggestive when one considers the C-13 hydrocarbons and C-14 aldehydes. The similarities in relative proportions of these two groups of compounds is strikingly evident from Fig. 1 and, significantly, the position of the double bonds in n-tridec-4-ene and n-tetradec-S-enal and the doubly unsaturated n-trideca-4,7-diene and n-tetradeca5,8-dienal correspond if the aldehydic group is removed. Thus, it would appear that the hydrocarbons may be formed from the corresponding aldehydes and that both the hydrocarbons and their corresponding aldehydes are related in terms of a common precursor. The quinoidal mixture present in the tergal gland exudate of D. canaliculata represents a qualitatively unique blend of quinones and hydroquinones among the characterized defensive secretions of arthropods. p-Toluquinone, which is the major component of this secretion, is a common quinone found in defensive secretions of insects. 3-Methoxy-p-toluquinone, however, is a characteristic component of millipede defensive glands (WEATHERSTON and PERCY,1970) and has not been encountered frequently as a defensive product of insects. This latter quinone is found in one species of scaratine carabid (SCHILDKNECHT et al., 1968) and has also been identified in members of the subgenus BZaphyZisof the tenebrionid genus Eleodes (TSCHINKEL, personal communication). Whether its occurrence in the exocrine secretion of D. canaliculata is typical of aleocharines cannot yet be ascertained. The fact that it is absent from the defensive exudate of another aleocharine, L. strumosa, raises the possibility that it may not be widespread in members of this subfamily. Thin-layer chromatography has been used to show that the quinone-rich secretions of some insects also contain the corresponding hydroquinones

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(SCHILDKNECHTand HOLOUBEK,1961; SCHILDKNECHT and KFLUXER,1962; IKAN et al., 1970). Due to difficulties encountered in the gas chromatographic separation of hydroquinones, together with the fact that the mass spectra of a quinone and its corresponding hydroquinone are similar, we undertook their analysis as the acetylated derivatives. Acetylation of the defensive exudate of D. canaliculata yielded products corresponding to hydroquinone diacetate, 2-methylhydroquinone diacetate, 2-methoxy-3-methylhydroquinone diacetate, and 2-hydroxy-3-methylhydroquinone triacetate. It may be concluded therefore that this secretion contains these four compounds in the hydroquinone form. The fact that hydroquinones have not been reported in most of the quinone-rich secretions analysed by gas chromatography probably indicates that they were not seen due to their gas chromatographic behaviour rather than that they were not present. Following the establishment of four hydroquinones in the secretion, we reinvestigated both the crude extract and its acetylated reaction mixture for the presence of 1,4-benzoquinone and either 3-hydroxy-p-toluquinone or 3-acetoxy-ptoluquinone. However, none of these compounds could be identified from the numerous mass spectra obtained. In any mixture of quinones, the proportions of the various compounds actually present will depend on their redox potentials (assuming the absence of a strong oxidant or reductant). As a result, it is to be expected that 1,4-benzoquinone, in the presence of large amounts of 2-methylhydroquinone, will be reduced to hydroquinone. In addition, both the hydroquinone and the 2-hydroxy-3-methylhydroquinone are present in the secretion as minor constituents. While we were unable to establish the presence of the two corresponding quinones, we consider it very likely that they nevertheless are present in trace amounts as the oxidized concomitants of their hydroquinones. This statement is supported by the fact that the analyses of all other hydroquinone-containing secretions have established the presence of the corresponding quinones. Since the tergal gland is not homologous with any other known gland, it is apparent that the glandular source of the quinoidal defensive secretion of many beetles has evolved independently on several occasions. As a number of unrelated glands apparently have the ability to synthesize certain quinones, the genetic information for the biosynthetic enzymatic systems must have been retained by various insects over a considerable period of time. Many members of the Coleoptera synthesize a number of 1,4-benzoquinones in spite of differences in both the location and morphology of the secretory areas of the defensive glands. The differences noticed between the secretions of the related beetles, Drusilla and Lomechusa, suggest that the genetic information required to make both p-ethylquinone (Lomechusa) and 3-methoxy-p-toluquinone (Drusilla) may be present in the same organism, but that if one metabolic route is expressed, the other will not be operational. Therefore, the inability to correlate the chemical nature of the various characterized defensive secretions with the taxonomic classification of the species which produce these secretions may not be too surprising. While a number of biosynthetic studies have been conducted on the formation of substituted quinones in fungi, only a few investigations have been carried out on

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arthropod quinones. MEINWALDet al. (1966), studying Eleodes longicollis, concluded that 1,4-benzoquinone arises from a preformed aromatic ring whereas p-toluquinone is formed from acetate and p-ethylquinone is formed from acetate and propionate. The substituted quinones, 6-hydroxy&methoxy-p-toluquinone, 3,6-dihydroxy-5-methoxy-p-toluquinone, 5,6-dihydroxy-p-toluquinone, and 6methoxy%hydroxy-p-toluquinone, found in Aspergillus fumigatus and Penicillium spinulosum also arise from acetate and malonate (PETTERSSON,1963, 1964). It appears that the O-methyl group of the various quinones is derived from either the CI-pool or the S-methyl group of L-methionine in both fungi (PETTERSSON,1963, 1964) and arthropods (WEATHERSTONand PERCY, 1970). The occurrence of 2hydroxy-3-methylhydroquinone in the secretion of D. canaliculata suggests that this compound is a likely precursor of the 3-methoxy-p-toluquinone and/or 2methoxy-3-methylhydroquinone found in this and other arthropod secretions. However, the opposite could be true as 0-methylquinones undergo hydrolysis fairly readily and biosynthetic demethylation is quite common. Like the defensive exudates of many other beetles, the tergal gland secretion of D. canalicutata has a yellow-orange colour. In this respect it is similar to the analogous secretion of the myrmecophilous beetle L. strumosa, the only other aleocharine species which, so far, has been chemically characterized (BLUM et al., 1971). However, while the odour of the secretion of L. strumosa is clearly dominated by that of quinones, the odour of the D. canaliculata secretion possesses a pleasantly fragrant aldehydic note. Since Drusilla and Lomechusa belong to the same tribe of the subfamily, one might anticipate definite similarities between their secretions. However, since the quinone-rich exudates of these two aleocharines are dissimilar in a very major qualitative sense, only p-toluquinone (and possibly 1,4-benzoquinone) being common to both, there are really no substantive grounds for concluding that the defensive secretions of members of this subfamily possess a characteristic composition. Conceivably, the complex defensive secretion of D. canaZicuZata may represent a qualitative extreme in the Aleocharinae, but until the secretions of other species in the taxon are chemically characterized, the full synthetic potential of these staphylinids cannot be ascertained. The diversity of aldehydes which accompanies the quinones in the defensive exudate of D. canaliculata demonstrates that this.glandular exudate is atypical of the exocrine secretions utilized by coleopterous species to repel predators. The aleocharine L. strumosa also produces quinones in its tergal gland but no aldehydic constituents are detectable (BLUM et aE., 1971). Similarly, species in the tenebrionid subfamily Tenebrioninae synthesize quinones in their pygidial glands, as do species in about five subfamilies in the Carabidae, but aldehydes are not reported to accompany the quinones in any of these defensive exudates. Indeed, the quinoidal secretions of carabids apparently do not contain additional constituents (MOORE and WALLBANK,1968), whereas the tenebrionid exudates may be fortified with the alkenes, 1-nonene, 1-undecene, 1-tridecene (HURST et al., 1964), 1-pentadecene (VON ENDT and WHEELER, 1971), or caprylic acid (MEINWAI,Dand

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EISNER, 1964). The terminally unsaturated alkenes in tenebrionid defensive secretions contrast markedly with those in the secretion of D. canalicutata in which the double bonds are internal. None of the aldehydes fortifying the defensive secretion of D. canaliculata have been isolated previously from coleopterous exocrine secretions and the significance of this class of compounds as a concomitant of the 1,4-quinones is not readily apparent. Indeed, the only example reported of a fairly long-chain aldehyde accompanying a quinone in an arthropod defensive secretion is the case of the julid millipede, Rhinocricus insulatus, which produces a defensive secretion containing a mixture of trans-2-dodecenal and p-toluquinone (WHEELERet al., 1964). Of the four aldehydes produced in the tergai gland of D. canahculata, only ra-tetradecanal has previously been identified in insects. This compound, along with n-hexadecanal, is utilized by several species of Bombus as one of the components in the territorial-marking pheromones which are evacuated from the mandibular glands of male bees (KULLENBERGet al., 1970). Although the chemistry of the defensive secretions of only six species of staphylinids have been examined, it is nevertheless quite obvious that the members of this family possess a remarkable repertoire of natural products. The tergal gland products of two members of the Aleocharinae are identified with five of the six 1,4-benzoquinones that do occur (or are likely to occur e.g. 3-hydroxy-ptoluquinone) in insect exocrine secretions (WEATHERSTON and PERCY, 1970), and, in addition, one of these species synthesizes a novel series of aliphatic aldehydes and hydrocarbons. In contrast, the pygidial gland defensive products of beetles in three other staphylinid subfamilies reflect a strong terpene emphasis. Thus, Stews bipunctatus (Steninae) synthesizes 1,8-cineole, &so-piperitenol, and 6methyl-S-hepten-2-one in its pygidial glands (SCHILDKNECHT, 1970), whereas Staphylinus olens (Staphylininae) utilizes a defensive exudate which is dominated by iridodial (ABou-DONIA et al., 1971), a monterpene aldehyde which is also produced by several species of dolichoderine ants. Monoterpene aldehydes are also present in the pygidial gland secretion of Bledius mandibularis and B. spectabilis (Oxytelinae), but these compounds do not constitute the major products in the exocrine exudate (WHEELER et ai., personal communication). Like the aleocharines, the Rledius species also produce 1,Cbenzoquinone and, in addition, 1-undecene is present. However, the main defensive compound produced by these Bkdius spp. is y-dodecalactone, a compound not previously isolated from arthropod defensive secretions (WHEELERet al., personal communication). These facts strongly indicate that the members of the Staphylinidae probably possess as versatile a natural products chemistry as any coleopterous family which has been investigated. Acknowledgements-We thank Mr. FRANCISCORASQHINOfor technical assistance. We are grateful to Professor R. M. SILVERSTEIN and Mr. M. JACOBSONfor providing us with chemical standards.

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