Contents of the poison apparatus of some species of Pheidole ants

Four Old World species of Pheidole ants contain different mixtures of farnesene-type hydrocarbons in their poison apparatus, and the mixture is different between the minor and major workers within a species. A bishomofarnesene (C₁₇H₂₈) provides approximately half of the secretion of the Dufour glands of minor workers of Pheidole pallidula. (Z,E)-α-Farnesene constituted 96% of the Dufour secretion of major workers of P. pallidula, but only 20% of that of minors. The Dufour glands of minor workers of Pheidole sinaitica contain a mixture of farnesene homologues with (Z,E)-α-farnesene and the bishomofarnesene also found in P. pallidula predominant. The mixture in major workers was similar but had, in addition, a small amount of (E)-β-farnesene. The Dufour glands of Pheidole teneriffana minors contain chiefly the same bishomofarnesene found in P. pallidula and P. sinaitica while major workers contain (Z,E)-α-farnesene. Pheidole megacephala minor workers contained small amounts of eight farnesenes, while major workers contained essentially no farnesenes. The poison glands of minor workers of P. pallidula contain 3-ethyl-2,5-dimethylpyrazine. No pyrazine compounds were found in the major workers of P. pallidula or the minor workers of P. sinaitica. The poison glands of the major workers of P. sinaitica contained larger amounts of tetra-substituted pyrazines. No pyrazines were found in the poison reservoirs of major or minor workers of P. teneriffana or P. megacephala.     

Comparative study of the dufour gland secretions of workers of four species of Myrmica ants

The Dufour gland secretions of myrmica rubra, M. ruginodis, M. sabuleti and M. scabrinodis have been studied. The most volatile portions of the secretion of workers of all four species were found to be similar, containing C₂C₄ oxygenated compounds. The less volatile portion consists of a mixture of hydrocarbons. In M. ruginodis this is chiefly a mixture of linear saturated and mono-unsaturated hydrocarbons, similar in composition to that of M. rubra, while in M. sabuleti it consists of (Z,E)-α-farnesene and its homologues, homofarnesene, bishomofarnesene and trishomofarnesene, similar in composition to that of M. scabrinodis. Workers of each species studied were attracted to the Dufour gland volatiles of all four species, these substances chiefly causing an increase in running speed, with the workers not distinguishing between conspecific and allospecific secretions, though small quantitative differences could be demonstrated between the speed and orientation reaction of workers of each species. The less volatile fraction of the Dufour gland secretion is used for territorial marking by foraging workers. This marking is specific for each species except between M. rubra and M. ruginodis.     

An unusual juxtaposition of polysaccharide components of Collema leptosporum

The lichenised ascomycete, Collema leptosporum Malme, was extracted with aqueous methanol to give traces of mannitol and 3-O-β- -glucopyranosyl- -mannitol (2.7% yield). The residue was consecutively extracted with hot water to give a complex uronic acid-containing polysaccharide, and then with hot aqueous alkali which provided a mixture of polysaccharides. This was fractionated with Cetavlon to give a branched galactomannan, which had the lowest content of galactose yet reported for such a lichen polysaccharide. It has a main chain of (1→6)-linked -Manp units partly substituted at O-2,4 by non-reducing end-units of Manp and Galp, shown by NMR spectroscopy to have - and β-configurations, respectively. The other polysaccharide component was unexpectedly a branched (1→3), (1→6)-linked β-glucan, which is typical of a basidiomycete, whereas those of ascomycetes contain similar linkages but in linear glucans.     

Unusual structural and chemical characteristics of the Dufour gland in the ant Meranoplus diversus

Abstract The Dufour gland of both queens and workers of Meranoplus diversus is very large. The reservoir is lined with flat epithelial cells, which usually contain smooth endoplasmic reticulum but also show the unusual accumulation of electron‐dense inclusions. Chemically, the gland contains an unusual mixture of long‐chain fatty acids and their derivatives, including hydrocarbons, ketones and amines with long‐chain substituents, hydroquinone, and sugars. Some of the substances identified are already known as insect defensive compounds against other arthropods.     

Exocrine chemistry of the myrmicine ant Zacryptocerus pusillus (Hymenoptera: Formicidae)

Minor workers of the ant Zacryptocerus pusillus have unusual exocrine secretions in both their mandibular and Dufour glands. The mandibular glands contain a 3:1 mixture of 4-heptanone and 4-heptanol, a mixture found only in the related species Z. varians. The Dufour gland contains a mixture of 13 aldehydes from C9 to C18, not previously encountered in ant secretions. The venom glands gave variable results with only nonanal present consistently.     

Flavonoids of Helianthus series Microcephali

Ray flower and leaf flavonoids were investigated for the three species of Helianthus series Microcephali. Ray flowers of all species contain coreopsin, sulphurein, and quercetin 7-O-glucoside; those of H. microcephalus also contain quercetin 3-O-glucoside. A mixture of flavonoid aglycones, mostly methoxylated flavones, occurs in leaves of H. microcephalus, but not in H. glaucophyllus or H. laevigatus which also lack the glandular trichomes that in Helianthus are typically associated with flavonoid aglycones. The presence of compounds with the 6,8,4′ pattern of methoxylation in H. microcephalus suggests that the series is more similar in flavonoids to series Angustifolii than to series Corona-solis.     

Dufour gland secretions of Myrmica rugulosa and Myrmica schencki workers

The chemical composition and behavioural activities of the secretions of the Dufour glands of Myrmica rugulosa and M. schencki have been studied, as part of an extended study on Myrmica ants. Chemically, the Dufour gland of M. rugulosa is filled with a mixture of hydrocarbons dominated by straight chain alkanes and alkenes with 13 to 19 carbon atoms, as found in M. rubra. Significant quantities of (Z,E)-α-farnesene and its homologues, homofarnesene and bishomofarnesene, are also present. In M. schencki, the major compounds present are homofarnesene and bishomofarnesene. In both species, the very volatile portion of the Dufour gland secretion is identical to that analysed in M. rubra. From an ethological point of view, this very volatile part is efficient in attracting workers at a distance (6 to 8 cm) and in decreasing their wandering movements. No specificity was observed when performing cross-tests with Dufour glands freshly isolated from workers of other Myrmica species, but obvious specificities were detected when testing the less volatile part of the Dufour glands' contents, known to be used for marking newly discovered areas.     

Inhibitory effects of Hymenaea and Copaifera leaf resins on the leaf fungus, Pestalotia subcuticularis

Leaf resins in the leguminous genera Hymenaea and Copaifera may play a role in restricting infection by the associated leaf fungus, Pestalotia. We tested this hypothesis by assessing growth of the geographically widespread Pestalotia subcuticularis presented with different compositions of resins. Leaf resins of Hymenaea and Copaifera are composed of the same suite of sesquiterpene hydrocarbons, but these vary quantitatively to form discrete compositional patterns among individuals and populations. Leaf resins may also contain sesquiterpene oxides; caryophyllene oxide, which may have been formed from the caryophyllene precursor common in these resins, inhibited fungal growth in vitro.     

Ester production in E. coli and C. acetobutylicum

Genetic engineering has improved the product yield of a variety of compounds by overexpressing, inactivating, or introducing new genes in microbial systems. The production of flavor-enhancing ester compounds is an emerging area of heterologous gene expression for desired product yield in Escherichia coli. Isoamyl acetate, butyl acetate, ethyl acetate, and butyl butyrate are reported here to be produced by expressing Saccharomyces cerevisiae genes ATF1 or ATF2 and the strawberry gene SAAT in E. coli when the appropriate substrates are provided. Increasing the concentration of alcohol added to the reaction generally resulted in increased ester production. ATF1 expression was found to produce more isoamyl acetate and butyl acetate than ATF2 expression or SAAT expression in the strains and culture conditions examined. Additionally, SAAT expression resulted in greater isoamyl acetate and butyl acetate production than ATF2 expression. Butyl butyrate is produced by cell-free extracts of E. coli harboring SAAT but not ATF1 or ATF2.     

Contents of the exocrine glands of the ant subfamily Cerapachyinae

The chemistry of the exocrine glands of three species of the small and little-known ant subfamily Cerapachyinae has been examined for the first time. The mandibular glands of Cerapachys jacobsoni contained acetophenone and skatole, but some individuals contained, in addition, 4-methyl-3-heptanone and 3-octanol. The mandibular glands of the new species, presently known as Cerapachys sp. 15 of FI contained 4-methyl-3-heptanone, as the major substance but also 4-methyl-3-heptanol, methyl 6-ethylsalicylate, and traces of 4,5-dimethyl-4-hexen-3-one and homomanicone. The Dufour glands of C. jacobsoni contained a mixture of higher aldehydes, acetates and other esters, with a small amount of hydrocarbons, all in the range C₁₁–C₂₀. The Dufour glands of Cylindromyrmex whymperi contained a mixture of long-chain epoxides, the second ant species to display them. The sternal glands of C. whymperi contain a recruitment pheromone, but only partial identification of the contents was possible. The venom glands of all three species were devoid of volatile material. The Dufour glands of Cerapachys sp. 15 of FI and the mandibular glands of C. whymperi had no detectable volatile contents.     

Pyranocoumarins as chemotaxonomic markers in Eriostemon coccineus and Philotheca citrina

Examination of the aerial parts of Eriostemon coccineus and Philotheca citrina has shown both to contain the unusual pyranocoumarins avicennol, avicennin and cis-avicennol. Three minor coumarins isolated from P. citrina have been identified as avicennol methyl ether, cis-avicennol methyl ether and avicennol ethyl ether. Philotheca citrina also yielded another pyranocoumarin, dipetalolactone, and the common lignan sesamin. Eriostemon coccineus, in addition to coumarins, gave the furoquinoline alkaloids maculosidine and γ-fagarine and two dihydrocinnanic acid derivatives, eriostoic acid and a new compound with a substitution pattern comparable to cis-avicennin and which has been assigned the trivial name cis-avicennic acid. The co-occurrence of these rare pyranocoumarins supports the contention that Philotheca is closely allied to certain taxa currently placed in Eriostemon sect. Nigrostipulae.     

Dufour gland secretion of Polistes wasp: Chemical composition and possible involvement in nestmate recognition (Hymenoptera: vespidae)

The Dufour gland secretion and cuticle lipids of foundresses of Polistes dominulus have been chemically analysed. The gland secretion (analysed for the first time in a polistine species) contains a complex mixture of hydrocarbons, which are the same as those found on the cuticle. The cuticular hydrocarbon mixture and gland secretion differ, however, in the proportions of components: in the first, linear hydrocarbons are more abundant, while in the second we found a higher quantity of dimethylalkanes. Multivariate statistical analysis has shown that foundresses belonging to different colonies are distinguished on the basis of both the composition of their Dufour gland secretion and cuticular hydrocarbon mixture. Branched hydrocarbons seem to be particularly important in distinguishing females according to their colony. We suggest that the Dufour gland may contribute substances to form the hydrocarbon layer on the cuticle.     

Morphology and chemistry of Dufour glands in four ectoparasitoids: Cephalonomia tarsalis,C. waterstoni (Hymenoptera: Bethylidae), Anisopteromalus calandrae,and Pteromalus cerealellae (Hymenoptera: Pteromalidae)

The venom apparatus of four hymenopterous parasitoids, including two bethylids, C. tarsalis (Ashmead) and C. waterstoni (Gahan), and two pteromalids, A. calandrae (Howard) and P. cerealellae (Ashmead), were removed and the associated Dufour glands characterized with respect to their external morphology and chemistry. Dufour glands in all four species have a characteristic translucent appearance that apparently results from their lipid content. The stalked Dufour glands of C. tarsalis and C. waterstoni are pear-shaped and have overall lengths of approximately 0.2 and 0.15 mm, respectively. The thin venom glands are bifurcate and insert through a fine duct into the transparent ovoid- to pear-shaped venom reservoir in these bethylids. In A. calandrae and P. cerealellae the Dufour glands are elongated, tubular structures of ca. 0.35 and 0.8 mm in length, respectively, that constrict to a short stalk that empties into the common oviduct. The venom glands in these pteromalids are simple elongated structures that insert into the sac-like venom reservoir through a fine duct. The chemistry of the volatile contents of the Dufour gland in these four species differs considerably. C. tarsalis Dufour glands contain the same hydrocarbon components as found on the cuticle of this species (Ann. Entomol. Soc. Am. 91:101-112 (1998)), and no other chemicals. The Dufour glands of C. waterstoni also contain only hydrocarbons, most of which are the same as the cuticular hydrocarbons (Ann. Entomol. Soc. Am. 85:317-325 (1992)), but in addition the Dufour gland contains ca. 3% of a mixture of 2,17- and 2,19-dimethyl C(23). A. calandrae Dufour gland chemistry is somewhat more complex than that of either of the two bethylids, but like the bethylids, only hydrocarbons are present. The carbon number range is from C(30) to C(39) and consists of a mixture of n-alkanes (C(30)-C(38)); 3-, 5-, 7-, 9-, 11-, 12-, 13-, 14-, 15- and 17-methyl alkanes; 3,7- and 3,11-dimethyl alkanes; 5,9- and 5,17-dimethyl alkanes; 7,11-, 9,13-, 13,17-, 14,18- and 15,19-dimethyl alkanes; 3,7,11- and 3, 9,15-trimethyl alkanes; and 3,7,11,15-tetramethyl alkanes. The cuticular hydrocarbons of this species have not been previously reported, but they are the same as the Dufour gland hydrocarbons. The Dufour glands of P. cerealellae contain both hydrocarbons and two long-chain aldehydes. Most of the hydrocarbons are identical to those found on the cuticle of this species (Ann. Entomol. Soc. Am. 94:152-158 (2001)), but in addition, 5,9-dimethyl C(27), 5,13-, 5,17- and 5,19-dimethyl C(35), 12- and 14-methyl C(36), 12,16- and 13,17-dimethyl C(36), 13-methyl C(37) and 13,17-dimethyl C(37) are present. The two aldehydes detected in glands from P. cerealellae are n-tetracosanal (C(23)CHO) and n-hexacosanal (C(25)CHO).     

Contents of Dufour glands in some formicine ants: queens and workers of Camponotus aethiops and a re-examination of Lasius fuliginosus

The Dufour gland secretions of both virgin queens and workers of Camponotus aethiops are similar and consist of straight chain hydrocarbons ranging from C₁₀–C₁₅ with C₁₁ the major compound. The difference between the two castes is that C₁₅ appears only as a trace in queens, and the total amount of secretion is smaller in queens than in workers.In Lasius fuliginosus, the Dufour gland secretion contains a series of straight chain hydrocarbons (C₁₀–C₁₇) with undecane the major compound, and a series of 2-alkanones ranging from C₁₃ to C₁₉.

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Résumé Les sécrétions des glandes de Dufour sont toutes semblables et comprennent, chez les reines et les ouvrières de C. aethiops, une chaîne linéaire d'hydrocarbures de C₁₀ à C₁₅, avec C₁₁ comme constituant principal. Les différences entre les castes se traduisent chez la reine, par une teneur totale en sécrétions plus faible et l'existence de C₁₅ uniquement sous forme de traces.Chez L. fuliginosus, la sécrétion de la glande de Dufour comprend une série de chaînes linéaires d'hydrocarbures (C₁₀–C₁₇) avec l'undécane comme constituant principal, et une série de 2-alkanones allant de C₁₃ à C₁₉.

     

Differential inhibition of fungal oxidosqualene cyclase by 6E and 6Z isomers of 2,3-epoxy-10-aza-10,11-dihydrosqualene

Inhibitory properties of 6E (compound 1) and 6Z (compound 2) isomers of 2,3-epoxy-10-aza-10,11-dihydrosqualene against oxidosqualene-lanosterol cyclase were assayed on microsomes and whole cells of Saccharomyces cerevisiae and Candida albicans. Only the 6E isomer (compound 1), bearing a correct substrate-like configuration, strongly inhibited the enzyme both in microsomes and cell cultures. The difference between compounds 1 and 2 (which had an unfavorable geometry) was especially evident when measuring [¹⁴C]acetate incorporation into non-saponifiable lipids extracted from treated cells. While isomer Z was totally ineffective at up to 30 μM, in cells treated with 5 μM isomer E, labelled oxidosqualene, the level of which was negligible in the control, rose to over 60% of the non-saponifiable lipids.     

Egg marking in the facultatively queenless ant Gnamptogenys striatula: the source and mechanism

Conflicts over reproductive division of labour are common in social insects. These conflicts are often resolved via antagonistic actions that are mediated by chemical cues. Dominant egg layers and their eggs can be recognized by a specific yet similar cuticular hydrocarbon profile. In the facultatively queenless ant Gnamptogenys striatula, a worker's cuticular hydrocarbon profile signals its fertility and this determines its position in the reproductive division of labour. How eggs acquire the same hydrocarbon profile is as yet unclear. Here, we search for glandular sources of egg hydrocarbons and identify the putative mechanism of egg marking. We found that eggs carry the same hydrocarbons as the cuticle of fertile workers, and that these hydrocarbons also occur in the ovaries and the haemolymph. None of the studied glands (Dufour, venom, labial and mandibular gland) contained these hydrocarbons. Our results indicate that hydrocarbons are deposited on eggs while still in the ovaries. The low hydrocarbon concentration in the ovaries, however, suggests they are produced elsewhere and transported through the haemolymph. We also found that fertile workers regularly deposit new hydrocarbons on eggs by rubbing laid eggs with a hairy structure on the abdominal tip from which a non-polar substance is secreted.     

Identification of the components of Dufour gland secretion of the ant Myrmica rubra and responses to them

The Dufour gland secretion consists of a solution of volatile oxygenated compounds in a mixture of higher hydrocarbons and sesquiterpenoid alkenes. Methanol, butenone, 2-methylpropanal, and 1-butanol have now been identified as the remaining major volatile components. These substances have no strong behavioural effect upon ants, nor do they induce trail following behaviour. The principal activity of the Dufour gland can be traced to the three more abundant volatile components, ethanal, acetone, and butanone, together with the minor component ethanol.     

Do social parasitic bumblebees use chemical weapons? (Hymenoptera,Apidae)

The bumblebee Bombus (Psithyrus) norvegicus Sp.-Schn. is an obligate social parasite of B. (Pyrobombus) hypnorum L. Behavioural observations indicated that nest-invading B. norvegicus females may use allomones to defend themselves against attacking host workers. However, so far no defensive chemicals used by social parasitic bumblebee females have been identified. We analysed volatile constituents of the cuticular lipid profile of B. norvegicus females. Furthermore, we performed electrophysiological studies and behavioural experiments in order to identify possible chemical weapons. Coupled gas chromatography-electroantennography showed 15 compounds to trigger responses in antennae of the host workers. Using gas chromatography–mass spectrometry, the main compound among the cuticular volatiles of B. norvegicus females was found to be dodecyl acetate. A corresponding mixture of synthetic volatiles as well as pure dodecyl acetate showed a strong repellent effect on starved host workers. B. norvegicus females use dodecyl acetate to repel attacking B. hypnorum workers during nest usurpation and subsequently during colony development. Dodecyl acetate is the first repellent allomone identified in bumblebees.     

On the similarity of the Dufour gland secretion and the cuticular hydrocarbons of some bumblebees

Abstract. There is a close correspondence in composition between the hydrocarbons of the Dufour gland and the cuticular hydrocarbons of workers of some bumblebee species. This correspondence is characteristic of the species, and independent of the place and time of collection.     

Change in the chemical signature of the ant leptothorax lichtensteini bondroit with time

The cuticular hydrocarbons of foraging workers of the ant Leptothorax lichtensteini have been identified by gas chromatography-mass spectrometry. Characterization of these compounds at regular intervals, by gas chromatography, has shown a change with time in the relative proportions of some of the hydrocarbons: n-hexacosane, 4-methylhexacosane, 4-methyloctacosane, 3-methylnoncosane. Some of which constitute a part of the colony signature. These changes occur in a synchronous manner, and in the same way for all the individuals of a colony tested at the same time. The changes also appear in queenless colonies; nevertheless, the presence of a queen seems to accelerate the change over the course of 1 yr. Certain hypotheses are formulated as to the mode of regulation of the synthesis of cuticular hydrocarbons responsible for these changes with time and as to the role played by the queen in this regulation. The implications of such a dynamic system for the process of nestmate recognition are discussed.