Species,individual and kin specific blends in Dufour's gland secretions of halictine bees

The compositions of Dufour's gland secretions of four sympatric halictine bee species were chemically studied by combined gas chromatography-mass spectrometry. The secretion is composed of C₁₆-C₂₄ macrocyclic lactones, isopentenyl esters, and hydrocarbons. Comparative analyses have revealed that the blends of compounds are species specific. Studies of individual glands belonging to bees of the speciesEvylaeus malachurum have demonstrated that each bee exhibits a specific blend in its Dufour's gland. Nestmate bees (considered as sister bees), however, are more similar to each other than nonrelated bees. The relative importance of species specificity, individual specificity, and similarities between kins are discussed.     

Identification and bioassay of macrocyclic lactone sex pheromone of the halictine beeLasioglossum zephyrum

The macrocyclic lactones found in the Dufour's gland of the halictine beeLasioglossum zephyrum are female sex pheromones. Octadecanolide, eicosanolide, docosanolide, and tetracosanolide, as well as monounsaturated homologs of each, are components of the Dufour's gland secretion of this species. Furthermore, a series of odd-carbon-numbered saturated and unsaturated hydrocarbons and isopentenyl docosanoate occur in extracts of the Dufour's gland and of whole females. Two different mixtures of all four synthetic lactones, and additionally a treatment consisting of the natural extract, elicit higher response levels than two of the lactones separately or either of the controls.     

Macrocyclic lactones and isopentenyl esters in the Dufour's gland secretion of halictine bees (Hymenoptera: Halictidae)

The volatile components of the Dufour's gland secretion of female halictid bees have been examined in 18 Nearctic species belonging toAgapostemon, Augochlora, Augochlorella, Augochloropsis, Dialictus, Evylaeus, Halictus, andLasioglossum. Nine saturated and unsaturated macrocyclic lactones ranging from C₁₈ to C₂₆ have been identified. Four of these compounds, the saturated C₂₆ and the unsaturated C₂₀, C₂₂, and C₂₄ lactones, are new natural products reported for halictine bees. A series of eight esters containing branched C₅-alkenols and fatty acids has been identified in several species. The cell linings and pollen ball inAugochlora pura pura contain the same major lactones as the Dufour's gland. A discussion of the significance of the Dufour's gland secretion for apoid systematics and its function in the Halictidae is presented.     

A comparative study of the exocrine products of cleptoparasitic bees (Holcopasites) and their hosts (Calliopsis) (Hymenoptera: Anthophoridae,Andrenidae)

The cephalic secretion of females of the cleptoparasitic beeHolcopasites calliopsidis contains two main volatiles, 6-methyl-5-hepten-2-one and geranyl acetone. The mandibular gland secretion of its host,Calliopsis andreniformis, on the other hand, contains the two isomeric forms of citral (neral and geranial). Neral and geranial are also produced by mandibular glands of two other species ofCalliopsis and one species in the related genusNomadopsis. The Dufour's gland ofC. andreniformis contains an oily secretion composed of hydrocarbons that are deposited on the brood cell walls and pollen balls providing a waterproof lining for both.     

Trail pheromone of ponerine ant Gnamptogenys striatula: 4-methylgeranyl esters from Dufour's gland

Dufour's gland is the origin of the trail pheromone of Gnamptogenys striatula. Chemical analysis of the glandular extracts revealed a series of new natural products, especially esters of (2E)-3,4,7-trimethyl-2,6-octadien-1-ol (4-methylgeraniol), and (2E)-3,4,7-trimethyl-2,6-nonadien-1-ol (a bishomogeraniol isomer) with medium-chain fatty acids. Bioassays with synthetic racemates of the esters revealed that the 4-methylgeranyl esters are highly active as trail pheromones, while the bishomogeranyl esters are either marginally active or not active at all. Assays with the individual 4-methylgeranyl esters showed each of them to be inferior to the glandular secretion in eliciting trail following. However, the mixture of racemic 4-methylgeranyl octanoate and the corresponding decanoate and dodecanoate, the main Dufour's volatile constituents, is as active as the natural secretion at similar concentration. We conclude that the trail pheromone constitutes a mixture of at least the 4-methylgeranyl esters identified in the gland. Since G. striatula generally preys on small arthropods rather than monopolizing large resources, we assume that trails are rarely used during foraging, but more often during nest migration. Production of new societies in this species is generally performed by budding, a period of considerable predation risk. Utilizing trails for efficient displacement in this context is, therefore, highly adaptive. This behavioral repertoire may also provide the ants with additional means of food resource exploitation.     

Biochemical and behavioral evidence foe hybridization between fire ants,Solenopsis invicta andSolenopsis richteri (Hymenoptera: Formicidae)

Behavioral and biochemical evidence is presented for hybridization between the fire ants,Solenopsis richteri andS. invicta. The response of the two species to extracts of their trail pheromones presented as a point source is clearly species-specific; however, hybrid workers responded to parental Dufour's gland extracts and parental workers responded to Dufour's gland extracts of the hybrid. The behavioral evidence for hybridization was confirmed by gas Chromatograph comparison of the Dufour's gland extracts of the three fire ant forms, which showed a pattern for the hybrid that was intermediate to the two parental species.     

Exocrine secretions of bees

The volatile components of Dufour's gland extracts were analyzed in four species of NearcticNomia bees;Nomia (Dieunomia)heteropoda, N. (Tetrazonata)tetrazonata, N. (Epinomia)nevadensis, andN. (Epinomia)triangulifera. A homologous series of five saturated macrocyclic lactones ranging from C₁₈ to C₂₆ was identified. A series of esters (branched C₅-alkenols and fatty acids) was also identified in all species investigated. Two of these esters are new natural products reported for bees. A discussion of the significance of the Dufour's gland secretion for halictid systematics and its function in the Halictidae is also presented.Exocrine Secretions of Bees: I. Duffield et al. (1980), II. Fernandes et al. (1981), III. Duffieldetal (1981).     

Volatile communication substances in Dufour's gland of virgin females and old queens of the antFormica polyctena

Dufour's gland, which is present in worker ants ofFormica polyctena as a tiny gland emptying into the short duct from the poison reservoir, was found to be very enlarged in virgin females. In egg-laying queens the gland lobes were reduced in size to slender tubes. The glandular secretion was analyzed by capillary gas chromatography and mass spectrometry. Seventy-four percent of the gland secretion from virgin females consisted of undecane, but this compound was less than 1% in queens. Decane and nonane, making up 3.5% in virgin females, were not found in queens. About 74% of their secretion consisted of the lower hydrocarbons: tridecane, pentadecane, heptadecane, and a nonadecene with tridecane dominating to 50%. Apart from these characteristic differences, almost the same compounds were present in virgin females and queens. Thirty-three compounds were identified from the secretion of virgin females and 38 from queens. An additional compound present in trace amounts in the secretion from queens has not been identified. All the compounds were hydro-carbons with the exception of dodecanol, present in trace amounts in virgin females. The compounds are homologous series of saturated, aliphatic hydrocarbons from nonane to tricosane and corresponding series of monounsaturated and methyl-branched hydrocarbons. Geranylgeraniol and geranyl-geranyl acetate, present in worker ants together with some other alcohols and acetates, were absent in females.     

Volatile hydrocarbons in the dufour's gland of the parasiteNemeritis canescens (Grav.) (Hymenoptera; ichneumonidae)

The Dufour's gland of the parasitic waspNemeritis (= Venturia) canescens (Grav.) was shown by gas chromatography and mass spectrometry to contain a mixture of C₂₁, C₂₃, and C₂₅ saturated and monounsaturated hydrocarbons. The main component (62%) was (Z)-10-tricosene. The biological activity of the components is discussed.     

Exocrine glands ofPolyrhachis simplex: Chemistry and function

The mandibular glands of the Israeli weaver ant,Polyrhachis simplex, contain a mixture of 4-heptanone, 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol;its Dufour's gland secretion consists mainly ofn-tridecane. The significance of these glandular secretions in the biology of the weaver ant is discussed.     

Mandibular Gland Secretion of <Emphasis Type="Italic">Melipona beecheii</Emphasis>: Chemistry and Behavior

The mandibular gland secretion of Melipona beecheii contains a rich mixture of terpenoid and oxygenated compounds and unsaturated and saturated hydrocarbons. However, it differs markedly from the 11 other Brazilian species examined in previous studies, both by the absence of 2-heptanol and the presence of rose oxides. The most abundant compound was geranyl hexanoate, whereas the most volatile compounds were cis- and trans-rose oxide and geraniol. The complete blend and five individual components found in the gland secretion were tested by electroantennography (EAG) and behavioral assays. The complete mandibular gland extract and geraniol elicited the strongest EAG responses, whereas these and farnesyl acetate induced the strongest attack response from workers. The role of the rose oxides remains to be elucidated, as they do not appear to play a major role as an alarm pheromone of this species.     

Chemistry of the Dufour's gland secretions of North American andrenid bees (Hymenoptera: Andrenidae)

The volatile components of the Dufour's gland secretions were examined in 22 Nearctic species of andrenid bees representing 10 subgenera. Farnesyl hexanoate was the dominant component in the secretion of 17 species. In others, various terpenoid esters such as geranyl octanoate, farnesyl octanoate and geranylgeranyl octanoate were the major components. Approximately 30 compounds have been identified in the secretions; many are newly identified in andrenid bees. Three different groups of secretions are discerned with exceptions. A discussion of the possible function of the Dufour's gland secretion in the biology of, and its use in, the systematics of these bees is presented.     

Chemistry of the Cephalic Labial Gland Secretions of Male Bombus morrisoni and B. rufocinctus, Two North American Bumblebee Males with Perching Behavior

The labial gland secretions from males of the North American bumblebees Bombus morrisoni Cresson and B. rufocinctus Cresson were analyzed by gas chromatography/mass spectrometry. In both species, 3,7,11,15-tetramethyl-2,6,10,14-hexadecatetraenyl acetate was found as the major compound of a complex mixture of alkenols, acetates, hydrocarbons, and wax-type esters. In addition to a mixture of saturated and mono-unsaturated straight chain hydrocarbons, the labial gland of both species contained the isoprenoid hydrocarbons (6E, 10E)-3,7,15-trimethyl-3-methylene-hexadeca-1,6,10,14-tetraene [β-springene], three isomers of 3,7,11,15-tetramethyl-hexadeca-1,3,6,10,14-pentaene [α-springene], and two further unidentified cyclic diterpenes. In B. morrisoni, 3,7,11-trimethyl-2,6,10-dodecatrien-1-ol and 3,7,11,15-tetramethyl-6,10,14-hexadecatrien-1-ol were detected as characteristic alcohols, as well as small amounts of 9-hexadecenol and hexadecanol. Furthermore, a large peak of hexadecyl dodecanoate and minor amounts of 9-hexadecenyl, 9-octadecenyl, and eicosenyl 9-tetradecenoate were found as typical esters in this species. In B. rufocinctus, 9-hexadecenol, hexadecanol, and 9-octadecenol were present in considerable amounts, with their acetates and 9-tetradecenoic, tetradecanoic, hexadecanoic, and 11-octadecenoic acids. The chemical composition of cephalic labial glands in male bumblebees with perching behavior is discussed.     

Isolation of the trail recruitment pheromone ofSolenopsis invicta

TheSolenopsis invicta trail pheromone is synthesized by the Dufour's gland and is released through the sting apparatus. The recruitment subcategory of theS. invicta trail pheromone was shown to be composed of a mixture of the orientation pheromone, (Z,E)--farnesene and an unidentified homosesquiterpene consisting of three rings and one double bond (C-1). C-1 is present in worker Dufour's glands at only 75 pg per worker equivalent. This is the first report that demonstrates that different exocrine products from the same gland control different subcategories of behavior related to mass recruitment.     

Chemistry and functions of exocrine secretions of the antsTapinoma melanocephalum and T. erraticum

Volatile constituents produced by ant workers belonging to the speciesTapinoma melanocephalum andT. erraticum have been analyzed by gas chromatography-mass spectrometry. The pygidial (=anal) gland secretion ofT. melanocephalum is fortified with 6-methyl-5-hepten-2-one and actinidine (the mass spectrum of which is corrected in this paper). An unidentified compound was detected in cephalic extracts. The pygidial gland secretion ofT. erraticum was also dominated by 6-methyl-5-hepten-2-one, in addition to two isomers of iridodial, and iridomyrmecin. The sternal glands contained iridodial and C₁₅-C₂₀ hydrocarbons. Workers ofT. melanocephalum effectively utilize their pygidial gland secretions as an alarm-defense system during aggressive encounters with workers ofSolenopsis geminata. 6-Methyl-5-hepten-2-one is active as a releaser of alarm behavior, and actinidine is repellent to workers ofT. melanocephalum. Cephalic extracts possessed attractant and arrestant properties for workers of this species.     

Identification and source of a queen-specific chemical in the pharaoh's ant,Monomorium pharaonis (L.)

Fertile queens of the antMonomorium pharaonis produce a chemical substance which is not present in worker ants or in young, alate (virgin) queens. The material has been identified as (E,E,E)-1-isopropenyl-4,8,12-trimethylcyclotetradeca-3,7,11-triene (neocembrene). This chemical is produced in the Dufour's gland of fertile queens and may serve as a queen-recognition pheromone.     

Identification of new homoterpene esters from Dufour's gland of the ponerine ant Gnamptogenys striatula

Extracts of Dufour's gland of the ponerine ant, Gnamptogenys striatula, were analyzed by using the combination of gas chromatography and mass spectrometry. Series of esters of the new homoterpenoids (2E,6)-3,4,7-trimethyl-2,6-octadiene-1-ol (4-methylgeraniol) and (2E,6)-3,4,7-trimethyl-2, 6-nonadiene-1-ol (bishomogeraniol) with unbranched medium-chain fatty acids were identified. Transformation of the chiral natural products into 1,4-di(trifluoroacetoxy)-3-methylpentane and comparison of its gas chromatographic retention time on a modified cyclodextrin phase with that of synthetic optically active reference samples proved the stereogenic center to keep (S)-configuration. (2E,4S,6)-3,4,7-Trimethyl-2,6-octadien-1-yl decanoate and the corresponding dodecanoate are the main volatiles in the extracts.     

Dufour's gland and its role in secretion of nest cell lining in bees of the genusColletes (Hymenoptera: Colletidae)

The liquid secretion of the Dufour's gland in mated females comprises a mixture of macrocyclic lactones, straight chain mono- and dicarboxylic acids, together with trace amounts of di- and trihydroxy monocarboxylic acids and a series ofn-alkanes. Polymerization of the liquid to form the membranous nest cell lining, which also contains alanine and glutamic acid as major constituents, may be mediated by an enzyme from the thoracic salivary gland and voided via the mouth. The composition and structure of the cell linings are similar to those of Wigglesworth's cuticulin.     

Propaganda substances in the cuckoo antLeptothorax kutteri and the slave-makerHarpagoxenus sublaevis

This paper reports the first discovery of propaganda substances in a workerless inquiline ant, the European myrmicineLeptothorax kutteri Buschinger. These substances are used by the parasite queen as a chemical weapon for defense against hostile workers of the host speciesL. acervorum. The substances also have an unusual behavioral effect: they cause host workers to attack each other, and they therefore appear to override nestmate recognition in host colonies. Laboratory experiments show that the source of these substances is the Dufour's gland of theL. kutteri queen. Our experiments also confirm the hypothesis that the closely related slave-making antHarpagoxenus sublaevis uses its Dufour's gland secretions as a chemical weapon during slave raids and colony foundation. The behavioral effect of these slave-maker secretions is identical to that ofL. kutteri queens.     

Change in mandibular and mesosomal gland contents of maleXylocopa micans (Hymenoptera: Anthophoridae) associated with mating system

Males ofXylocopa micans employ two mating systems in south-central Texas. They defend territories around flowering wisteria and redbud in March and April, and they maintain nonresource-based or landmark territories in July and August. Mandibular and mesosomal gland contents (analyzed by GC-MS) are different in bees employing the two mating systems. Mandibular glands contain only straight-chain hydrocarbons in bees defending floral resources, but include ethyl oleate in bees defending landmark territories. Mesosomal glands contain saturated, mono- and diunsaturated straight-chain hydrocarbons and methyl and ethyl esters of long-chain fatty acids. The major ethyl ester, ethyl oleate, comprises only 1.1% of mesosomal gland contents in bees defending floral resources but comprises 39.7% of gland content of bees defending landmark territories. These findings are discussed relative to the proposed sex pheromone function ofXylocopa gland secretions.Approved as TA 24821 by the Director of the Texas Agriculture Experiment Station.