Chemistry of mandibular and Dufour's gland secretions of ants in genusMyrmecocystus

Males of several species ofMyrmecocystus produce mandibular gland secretions that contain 2,4-dimethyl-2-hexenoic acid and a variety of monoterpenes that include neral, geranial, citronellol, limonene, and 2,6-dimethyl-5-hepten-1-ol. Other components identified include methyl anthranilate, octanal, octanol, octyl octanoate, and 2-hexyl-2-decenal. Methyl salicylate has been identified as a mandibular gland constituent of workers of several species in addition to mellein and monoterpenes such as cymene, limonene, and the isomers of citral. The Dufour's gland secretions of workers and females of 14 species contain typical formicine alkanes (e.g., undecane), 2-alkanols (e.g., 2-tridecanol), and 2-alkanones (e.g., 2-tridecanone). Two species in the subgenusEremnocystus produce secretions that are distinguished by the presence of significant quantities of tridecyl esters. The functions of these compounds as well as their possible chemosystematic significance in the genusMyrmecocystus are discussed.     

Linalool in mandibular gland secretion ofColletes bees (Hymenoptera: Apoidea)

Uinalool was identified as the main component of the mandibular gland secretion in females and males of four species ofColletes bees, viz.,C. cunicularius, C. daviesanus, C. impunctatus andC. succinctus. It was also shown to be the dominant volatile compound in the same gland in maleC. floralis (the female of this species has not yet been investigated). Further, in another species,C. similis, linalool is present in the mandibular gland secretions of females and males, but the dominant volatile component in these secretions is geranial, together with neral. Females of the speciesC. fodiens seem to lack monoterpenes altogether; nonadecane is the dominant volatile compound of the cephalic secretion (based on analysis of a single individual). When linalool is put out in the area of nest aggregation ofC. cunicularius, where the males are patrolling, a distinct increase in flight activity is noted. The function of linalool is discussed on the basis of field observations.This report forms part XXI in the series Studies on Natural Odoriferous Compounds.     

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.     

Volatiles from mandibular glands of male beewolves (Hymenoptera: Sphecidae,Philanthus) and their possible roles

Observations of wasp behavior indicate that male beewolves,Philanthus basilaris andP. bicinctus apply a marking pheromone to the leaves and stems of plants within their territories. We now provide direct evidence for the presence of volatile chemicals in the paired mandibular glands of the males, provide preliminary identification of these volatiles, and show that all of the volatile chemicals in the mandibular glands are present on freshly marked plant surfaces but are absent from unmarked plants. Pyrazines, which have been reported in other species of aculeate wasps including the EuropeanPhilanthus triangulum, were not found inP. basilaris orP. bicinctus.     

Chemistry of male mandibular gland secretions ofPhilanthus triangulum

Males of the European and African beewolf,Philanthus triangulum, possess a sex specific mandibular gland secretion that is used for marking plant stems in mating territories. The secretion is composed of 90% (Z)-11-eicosen-1-ol plus small amounts of 10-nonadecen-2-one, nonadecenal, octadecanoic and octadecenoic acids, and eicosenal. The chemistry of this secretion differs markedly from the secretions of North AmericanPhilanthus, which consist of a larger number of components that possess different chemical functionalities and are more volatile. We postulate that the chemical differences betweenP. triangulum and its New World relatives reflect phylogenetic differences plus a possible reduced necessity for species isolating mechanisms inP. triangulum.     

Morphology of the prothoracic defensive gland ofSchizura concinna (J.E. Smith) (Lepidoptera:Notodontidae) and the nature of its secretion

The larval defensive gland ofSchizura concinna (J.E. Smith) is situated in the thorax and consists of two sacs joined by an interglandular neck. Its orifice opens into a transverse invagination of the integument at the cervical margin of the prosternite. The major component of the defensive secretion, formic acid, was identified as itsp-bromophenacyl ester. Ancillary components decyl acetate, dodecyl acetate, and 2-tridecanone from the anterior portion of the gland were identified by GLC and GS-MS.     

Chemistry of cephalic secretion of fire beeTrigona (Oxytrigona) tataira

Analysis of the volatile compounds derived from cephalic glands of the fire beeTrigona (Oxytrigona) tataira by GC-MS was undertaken. The following compounds were readily identified: hydrocarbons:n-C₁₁H₂₄,n-C₁₃H₂₈,n-C₁₄H₃₀,n-C₁₅H₃₂,n-C₁₇H₃₆,n-C₂₃H₄₈,_n-C₁₅H₃₀,n-C₁₇H₃₄,n-C₂₁ H₄₂, andn-C₂₃H₄₆; carboxylic acids: palmitic acid, linoleic acid, linolenic acid, stearic acid, and oleic acid; carboxylic esters: dodecyl acetate, tetradecyl acetate, hexadecyl acetate, octadecyl acetate, and dodecyl decanoate; monoketones: 5-hepten-2-one, 3-hepten-2-one, 2-heptanone, and 5-nonen-2-one. Two major components of the mixture were identified asE-hepten-2,5-dione andE-3-nonen-2,5-dione. Structures of these novel compounds were suggested by their GC-MS behavior and the GC-MS behavior of their dimethoximes and proved by comparison with authentic synthetic samples. Trace amounts of the corresponding Z isomers and the saturated analogs, heptan-2,5-dione and nonan-2,5-dione, were also found. The possible functions of these glandular constituents are discussed.In cooperation with the Louisiana State University Experiment Station, Baton Rouge, Louisiana 70803.Subspecies mellicolor.     

Chemistry of the defensive secretion of the caddisflyPycnopsyche scabripennis (Trichoptera: Limnephilidae)

From a pair of exocrine glands located on the fifth abdominal sternite, the caddisflyPycnopsyche scabripennis secretes a defensive exudate which containsp-cresol, indole, and skatole. This secretion effectively repels invertebrate predators such as ants. The probable significance of this secretion in the biology of these caddisflies is discussed.     

Constituents of mandibular and Dufour's glands of an australianPolyrhachis weaver ant

Worker ants ofPolyrhachis (Cyrtomyrma) ?doddi collectively discharge the secretions of their large mandibular glands when their nest is disturbed. The major glandular compounds of workers are 6-methylhept-5-en-2-one and phenylacetaldehyde oxime. Other components identified are mellein, 6-methylhept-5-en-2-one oxime, phenylacetonitrile, phenyiacetaldehyde, benzaldehyde, and several alkanes and alkenes. The mandibular gland secretions of queens differ from those of workers only quantitatively. Large queens have considerably more of most components, the small queens have much less of volatile components. There is a pronounced sexual difference: the major components of the male's secretions are octanoic acid and mellein, with geranic acid, 8-heptadecene, 2-methylbutanoic acid, and 9-nonadecene present in lesser amounts. Workers ofP. ?doddi also have unusually large Dufour's glands containing a large array of hydrocarbons, of which tridecane is the major component, but α-farnesene, pentadecane, and heptadecene are also present in large quantities.     

Chemical composition of the frontal gland secretion ofSyntermes soldiers (Isoptera,Termitidae)

The defensive secretions from the frontal glands of soldier termites of the genusSyntermes contain similar mixtures of mono- and sesquiterpene hydrocarbons. The major components inS. dirus, S. molestus, S. brevimalatus, S. peruanus, and a new species (Syntermes sp. n), iscis--ocimene. A substantial amount of aristolochene is found inSyntermes sp. n. and is present at lower levels in all the other species;S. brevimalatus contains onlycis--ocimene and aristolochene. The four other species also contain minor amounts of epi--selinene and germacrene A. The latter compound has been identified on the basis of its rearrangement product -elemene. The termiteS. grandis differed markedly from the otherSyntermes species in that no terpenoid components were found in the soldier extract. With the obvious exception ofS. grandis, the same soldier-specific mono- and sesquiterpenes occurred in all species. The total amount of secretion per unit weight of soldiers varies with the species and is inversely proportional to the development of the mandibular apparatus. InS. molestus smaller gland size is compensated for by a greater number of soldiers foraging trails.     

Synthesis of monoterpene esters by alcoholysis reaction with Mucor miehei lipase in a solvent-free system

The syntheses of geranyl acetate and citronellyl acetate by alcoholysis reaction catalyzed by immobilized lipase from Mucor miehei was studied for the first time in a solvent-free system. Reactions were carried out at a terpene alcohol/acyl donor molar ratio of 1:5 with Lipozyme at 10% of the total weight of the reactants in a solvent-free system. Incubations were carried out at 55 to 60°C for ethyl and butyl acetates as acyl donors, whereas for methyl acetate the incubation temperature was 40 to 45°C. Excess concentration of acyl donor increases the percentage of geranyl acetate and citronellyl acetate, while excess of terpene alcohol concentration decreases the same. Yields from 75 to 77% molar conversion (90 to 98% conversion, w/w) were obtained after 8 to 28 h of reaction time.     

Dermal gland secretions of tropical bont tick,Amblyomma variegatum (Acarina: Ixodidae): Biological activity on predators and pathogens

When they are mechanically disturbed, all instars of the tropical bont tickAmblyomma variegatum exude droplets of a liquid on the dorsal, lateral, and ventral cuticle. These spread out and quickly evaporate. In this study, the possible role of these secretions was investigated in relation to predators and pathogens. In laboratory bioassays, it was demonstrated that the secretions from engorged larvae, nymphs, and females have an antibiotic activity against the bacteria speciesBacillus thuringiensis andSerratia marcescens, combined with a repellent effect on a potential predator, the fire-antSolenopsis geminata.     

Chrysomelidial in the defensive secretion of the leaf beetleGastrophysa cyanea Melsheimer

Larvae of the chrysomelid beetleGastrophysa cyanea produce a defensive secretion in their eversible thoracic and abdominal glands that is an effective repellent for small predators such as fire ants. This secretion is composed primarily of chrysomelidial, 2-(2-formyl-3-methyl-2-cyclopentenyl)propanal, and a compound tentatively identified as its enol lactone. Adaptations that optimize the effectiveness of the larval defensive exudate are discussed.     

Variation with caste of the mandibular gland secretion in the leaf-cutting antAtta sexdens rubropilosa

InAtta sexdens rubropilosa, a strongly polyethic and polymorphic species of myrmicine ant, the contents of the mandibular gland vary with caste. Small workers of head width 0.5–1.8 mm, those generally engaged in duties inside the nest, contain chiefly 4-methyl-3-heptanone. Larger workers, those chiefly engaged in foraging, and the soldier caste contain a mixture dominated by neral and geranial, with very little of the ketone of the smaller workers. The soldiers have massive glands containing milligram amounts of neral and geranial. Virgin and mated females contain essentially only 4-methyl-3-heptanone, the amount increasing after mating, while virgin males have 4-methyl-3-heptanone and 4-methyl-3-heptanol in approximately equal proportions. Mated males have less secretion and lose the 4-methyl-3-heptanol.     

Chemistry of male mandibular gland secretions ofPhilanthus basilaris cresson andPhilanthus bicinctus (Mickel) (Hymenoptera: Sphecidae)

Detailed chemical characterizations are provided for the species-specific mixtures of marking pheromones utilized by the male beewolvesPhilanthus basilaris andP. bicinctus. Successful analysis of these complex mixtures of 2-ketones, fatty acids, ethyl esters, and aldehydes was facilitated by the treatment of the crude extracts with 1,1-dimethylhydrazine and direct analysis of the resulting hydrazones, methyl esters, and starting ethyl esters by GC-MS.     

Task-related chemical analysis of labial gland volatile secretion in worker honeybees (Apis mellifera ligustica)

Chemical analyses revealed that the labial gland complex of worker honeybees possesses a series of hydrocarbons dominated by odd-numbered carbon chain alkanes along with minor amounts of alkenes and branched alkanes. Foragers contained significantly more secretion than nurse bees. Experiments with bees from colonies induced to have a division of labor independent of age revealed that the differences in the amount of secretion were task, but not age dependent.     

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.     

Defensive secretion of a carabid beetle,Helluomorphoides clairvillei

The defensive spray of a single female of the rare carabid beetle,Helluomorphoides clairvillei (subfamily Carabinae, supertribe Lebiitae, tribe Helluonini). was found to contain a mixture of compounds, including carboxylic acids (formic, acetic), aliphatic esters (principally nonyl acetate), and hydrocarbons (principally decane). In a single series of discharges, the beetle ejected a total of about 1% of its body weight as formic acid (1.1 mg). Our findings demonstrate that characterization of secretory components from even minimal samples of secretion should be possible in many cases.Report no. 108 of the seriesDefense Mechanisms of Arthropods; no. 107 is Dussourd, D.E. et al.,Proc. Natl. Acad. Sci. USA, 88:9224, (1991).     

Volatile secretion of dufour gland of workers of an army ant,Dorylus (Anomma) molestus

The Dufour glands of workers ofDorylus (Anomma) molestus contain chiefly linear alkenes and alkanes, with (Z)-9-tricosene and tricosane representing over 70%. The glands are relatively small with some indication of very small (nanogram or less) amounts of dihydrofarnesol. Minima, medium, and major workers ofDorylus (Anomma) nigricans contain a similar spectrum of compounds.Dedicated to Professor J.K.A. van Boven on his seventy-sixth birthday.     

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.