Chemical defense secretions of the termite soldiers ofAcorhinotermes andRhinotermes (Isoptera,Rhinotermitinae)

The defense secretions of advanced nasutoid rhinotermitine soldiers from the New World contain enolic -ketoaldehydes as the major components. The secretions of minor soldiers ofRhinotermes hispidus (Emerson) andR. marginalis (Emerson) consist primarily of 3-keto-13-tetradecenal and 3-ketotetradecanal, but possess in addition C₁₃, C₁₄, C₁₅, and C₁₇ saturated and unsaturated ketones. Major soldiers lacked these compounds and in fact had virtually no frontal gland secretion. The defense secretion of the monomorphic soldiers ofAcorhinotermes subfusciceps (Emerson) contains mostly 3-keto-(Z)-9-hexadecenal and (Z)-8-pentadecen-2-one. Biosynthetic origins and interrelationships are postulated for these compounds, and the concomitant evolution of chemical weaponry and the modified labral brush is discussed.Fellow of the Alfred P. Sloan Foundation (1981–1983).     

Odor correspondence betweenMelitta females and males of their nest parasiteNomada flavopicta K. (Hymenoptera: Apoidea)

Analyses have been performed with the help of combined capillary gas chromatography and mass spectrometry on volatile secretions emanating from the Dufour glands of femaleMelitta haemorrhoidalis andM. leporina and heads of maleNomada flavopicta, a nest parasite of theMelitta species. It was found that the cephalic secretions ofN. flavopicta males have definite similarities with the Dufour gland secretions of the two species ofMelitta. They all contain octadecyl butyrate as a major component. Monounsaturated alcohols of different chain lengths are also present in the secretions. Beside these compounds,Melitta has some other esters, notably C₁₂-, C₁₄-, C₁₆-, and C₂₀-butyrates as well as C₁₂- and C₁₆-acetates.     

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.     

Chemical ecology ofReticulitermes flavipes (Kollar) andR. virginicus (Banks) (Rhinotermitidae)

Reticulitermes flavipes andR. virginicus have been examined for the presence and possible defense functions of soldiers specific secretions. The cephalic extracts for soldiers of both species contained the identical two major sesquiterpenes which were absent from other castes. The sesquiterpenes have been identified as ₁-cadinene (I) and the corresponding aldehyde (II) by high-resolution nuclear magnetic resonance spectrometry using homonuclear proton decoupling and by high-resolution mass spectrometry. When groups of termite soldiers were exposed to foraging parties of the sympatric native fire ant,Solenopsis geminata, the termites utilized only mechanical defenses. No evidence was obtained to indicate that the ants had been sprayed or coated with either an irritant or toxicant, and there was no evidence that an alarm had been promulgated.     

Chemistry of metapleural gland secretions of three attine ants,Atta sexdens rubropilosa,Atta cephalotes,andAcromyrmex octospinosus (Hymenoptera: Formicidae)

The chemical composition of the secretions of the metapleural glands of workers and soldiers of twoAtta species,Atta sexdens rubropilosa andA. cephalotes, and workers ofAcromyrmex octospinosus, has been studied. As indicated by infrared spectrometry and confirmed by the ninhydrin test, the secretions contain chiefly proteins. Of the volatile acidic portion, which is present as ionized salts, phenylacetic acid is the major component in workers and soldiers ofA. s. rubropilosa andA. cephalotes. BothAtta species also contain 3-hydroxydecanoic acid and its homolog as minor components together with indoleacetic acid. While there are qualitative similarities in the acidic composition in the secretions ofA. s. rubropilosa andA. cephalotes, they differ quantitatively. The secretion ofAcromyrmex octospinosus contains 3-hydroxydecanoic and indoleacetic acids, but lacks phenylacetic acid. The bactericidal and fungicidal actions of the three major substances have been confirmed.     

Pentatomid natural products

In addition to the primarily defensive metathoracic glands, adult Pentatomoidea possess a pair of active exocrine glands that open between the III and IV abdominal tergites. In the southern green stink bug,Nezara viridula, and other phytophagous species examined, the glands are small (< 10 g secretion/individual) and of approximately equal size in both sexes. In some, but not all, of the predaceous pentatomids (Asopinae), the III-IV dorsal abdominal glands are small in females (< 10 g secretion/individual) and extremely large in males (>500 g secretion/individual). Using a GC-MS system, the secretion from both males and females ofN. viridula (Pentatominae) was found to contain (E)-2-hexenal, hexanal, 1-hexanol, andn-tridecane. Females contained about three times moren-tridecane than males. The capacious glands ofPodisus maculiventris (Asopinae) males produce (E)-2-hexenal, benzyl alcohol, -terpineol, linalool, terpinen-4-ol, andcis-piperitol. The composition of the previously unanalyzed secretions from the adult III-IV dorsal abdominal glands is compared and contrasted to that of secretions from the metathoricic gland, and the role of coexisting exocrine glands in adult Heteroptera is discussed.     

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.     

Caste-dependent reactions to soldier defensive secretion and chiral alarm/recruitment pheromone inNasutitermes princeps

The soldier frontal gland secretion ofNasutitermes princeps induces strong short-range caste-specific alarm and attraction in both soldiers and workers. Soldiers are excited and patrol the surroundings of the source. The secretion per se does not induce ejection of additional secretion. Large workers of the second stage or older are massively attracted when tested in homogeneous groups. They focus their activities much more accurately than the soldiers around the source. The workers' reaction is less intense in the presence of soldiers. Large and small workers of stage 1 scarcely react at all to the secretion, whether tested in homogeneous or mixed groups. These results suggest the following complementary roles of soldiers and workers in defense. The first line of defense is provided by soldiers, which immobilize and incapacitate mobile enemies with their sticky secretion. Defense then is completed by older large workers as they eliminate the source of disturbance. The absence of reaction of young workers, small or large, confirms previous reports on age polyethism inNasutitermes observed in other contexts: young workers tend to stay in the nest. Alarm reactions are elicited by a source of (+)--pinene, the major monoterpene in the secretion, while its enantiomer, almost absent from the secretion, induces a much weaker reaction.     

3-Methyl-α-himachalene: Proposed structure for novel homosesquiterpene sex pheromone ofLutzomyia longipalpis (diptera: Psychodidae) from Jacobina,Brazil

The principal behaviorally active volatile component (ca. 90% +) of the sex pheromone glands ofLutzomyia longipalpis from Jacobina. Brazil, has been isolated and characterized as a novel homosesquiterpene with the structure 3-methyl--himachalene (C₁₆H₂₆). A minor component (ca. 10%) of the gland extract has also been identified as the sesquiterpene-himachalene (C₁₅H₂₄). This work confirms that there are at least 3 members of theL. longipalpis species complex.     

The function of zeolite on Pt autoreduction and dispersion in Pt/L and Pt/β catalysts

TPR, CO-FTIR and¹²⁹Xe NMR spectroscopic techniques were used to measure the distribution of platinum species after the calcination of Pt/L and Pt/ zeolites. Autoreduction which occurred in Pt/ zeolite was avoided in the channel of L zeolite. Pt particles dispersed well and exhibited excellent reactivity for the aromatization ofn-hexane in L zeolite.     

Reduced offspring production in bark beetleTomicus piniperda in pine bolts baited with ethanol and α-pinene,which attract antagonistic insects

Bolts of Scots pine,Pinus sylvestris L., attacked by the bark beetleTomicus piniperda (L.) were baited with ethanol and -pinene to attract antagonistic insects and thereby enhance their detrimental effects on the production of bark beetle progeny. Unbaited and caged bolts were included in the experiments as controls. Attraction of beetles to the bolts and subsequent emergence were estimated using traps. Six phloem-feeding species (potential competitors ofT. piniperda) and four predatory species were caught in significantly higher numbers at the baited bolts than at the unbaited ones. The number of offspring and the productivity ofT. piniperda were four to seven times higher in unbaited bolts than in baited bolts. Exclusion of other insects, by using cages, resulted in a nine-fold increase in the number ofT. piniperda offspring per square meter and productivity (offspring per egg gallery) compared with unbaited, exposed bolts.Hylurgops palliatus (Gyll.) (Scolytidae) andRhagium inquisitor (L.) (Cerambycidae) attacked both the baited and unbaited bolts, whereasAcanthocinus aedilis (L.) (Cerambycidae) andPytho depressus (L.) (Pythidae) reproduced almost exclusively in the baited ones. Large numbers of larvae ofThanasimus (Cleridae) andRhizophagus (Rhizophagidae) emerged from both the baited and unbaited bolts. Adults ofPlegaderus vulneratus (Panzer) andCylister linearis (Er.) (Histeridae) emerged almost exclusively from the baited bolts. The low progeny production ofT. piniperda in the baited bolts was attributed largely to the influence of adults ofRhizophagus andEpuraea (Nitidulidae), and larvae ofThanasimus andA. aedilis.     

Allelopathic properties of α-terthienyl and phenylheptatriyne,naturally occurring compounds from species of asteraceae

Alpha-terthienyl (-T), a naturally occurring polyacetylene derivative from roots ofTagetes erecta L., and phenylheptatriyne (PHT), from leaves ofBidens pilosa L., were tested as possible allelopathic agents against four seedling species (Asclepias syriaca L.,Chenopodium album L.,Phleum pratense L.,Trifolium pratense L.).Asclepias was the most sensitive of the species. Allelopathic activity was enhanced in the presence of sunlight or sources of near-UV, with LC_50s forA. syriaca of 0.15 ppm and 0.66 ppm with -T and PHT, respectively; 0.27 and 0.85 forC. album; 0.79 and 1.43 forP. pratense, and 1.93 and 1.82 forT. pratense. Near-UV exposure was saturating but never more than found in summer sunlight at Ottawa, Canada. Growth inhibition was observed with seedlings treated with -T and PHT but without near-UV irradiation. Germination of seedlings was also sensitive to -T and PHT with or without near-UV treatment. -T was extracted from soil surrounding the roots ofTagetes. Concentrations calculated for the soil (0.4 ppm) indicate that seedling growth could be significantly hindered. The activity and specificity of -T was sufficiently high to warrant future field trials to assess its potential as a natural weed-control agent.     

Effects of biotic and abiotic stress on induced accumulation of terpenes and phenolics in red pines inoculated with bark beetle-vectored fungus

This study characterized the chemical response of healthy red pine to artificial inoculation with the bark beetle-vectored fungusLeptographium terebrantis. In addition, we sought to determine whether stress altered this induced response and to understand the implications of these interactions to the study of decline diseases. Twenty-five-year-old trees responded to mechanical wounding or inoculation withL. terebrantis by producing resinous reaction lesions in the phloem. Aseptically wounded and wound-inoculated phloem contained higher concentrations of phenolics than did constitutive tissue. Trees inoculated withL. terebrantis also contained higher concentrations of six monoterpenes,-pinene,-pinene, 3-carene, limonene, camphene, and myrcene, and higher total monoterpenes than did trees that were mechanically wounded or left unwounded. Concentrations of these monoterpenes increased with time after inoculation. Total phenolic concentrations in unwounded stem tissue did not differ between healthy and root-diseased trees. Likewise, constitutive monoterpene concentrations in stem phloem were similar between healthy and root-diseased trees. However, when stem phloem tissue was challenged with fungal inoculations, reaction tissue from root-diseased trees contained lower concentrations of-pinene, the predominant monoterpene in red pine, than did reaction tissue from healthy trees. Seedlings stressed by exposure to low light levels exhibited less extensive induced chemical changes when challenge inoculated withL. terebrantis than did seedlings growing under higher light. Stem phloem tissue in these seedlings contained lower concentrations of-pinene than did nonstressed seedlings also challenge inoculated withL. terebrantis. It is hypothesized that monoterpenes and phenolics play a role in the defensive response of red pine against insect-fungal attack, that stress may predispose red pine to attack by insect-fungal complexes, and that such interactions are involved in red pine decline disease. Implications to plant defense theory and interactions among multiple stress agents in forest decline are discussed.To whom correspondence should be addressed at USDA Forest Service, 2500 Shreveport Hwy., Pineville, Louisiana 71360.     

Attraction of scolytids and associated beetles by different absolute amounts and proportions of α-pinene and ethanol

The attraction of bark and ambrosia beetles as well as associated beetles to -pinene and ethanol was studied in field experiments with flight barrier traps. -Pinene and ethanol were released individually and as combinations in approximately 11 or 110 ratios and at four different release rates. Ethanol attractedTomicus piniperda (L.),Hylurgops palliatus (Gyll.),Trypodendron lineatum (Oliv.),Hylastes cunicularius Er.,H. brunneus Er.,H. opacus Er., andAnisandrus dispar (F.) (Scolytidae);Glischrochilus quadripunctatus (L.) andEpuraea spp. (Nitidulidae);Thanasimus formicarius (L.) (Cleridae); andRhizophagus depressus (F.) (Rhizophagidae). -Pinene attracted all these species with the exception ofT. lineatum, H. cunicularius, andA. dispar. Combinations of a-pinene and ethanol resulted in synergistically increased attraction of all species with the exception ofH. opacus andA. dispar. A. dispar, the only hardwood-associated species in the study, was repelled by -pinene. Both the release rates and the ratio at which the two substances were released influenced the response of the beetles. The differences in response between the beetle species seem to reflect dissimilarities in the release of the two substances among the various types of breeding material to which the species are adapted.     

Contents of dufour glands of workers of three species ofTetramorium (Hymenoptera: Formicidae)

The Dufour glands of worker ants ofTetramorium caespitum, and the morphologically similarT. impurum are filled with similar, but species-specific mixtures of linear hydrocarbons and three homologous sesquiterpene corhpounds. Glands of workers ofT. caespitum contain, on average, 70 ng of oil containing C₁₃ to C₁₇ linear hydrocarbons withn-pentadecane (64%) and a mixture of pentadecenes (14%) as major components.T. impurum glands are smaller and contain an average of 40 ng of the same mixture but withn-pentadecane (49%) and a sesquiterpenoid compound (19%) the major components. Two isomeric pentadecenes, (Z)-6-pentadecene and (Z)-7-pentadecene are present in both species.T. semilaeve workers contain on average only 30 ng of a simple mixture of hydrocarbons with pentadecane contributing more than 90% of the total.     

Volatile secretions of old world army antAenictus rotundatus and chemotaxonomic implications of army ant dufour gland chemistry

The Dufour glands ofAenictus rotundatus contain a complex mixture of terpenoids with geranylgeraniol comprising over 50% of the secretion. Some novel compounds have been tentatively identified as higher homologs of 1,3,3-trimethyl-2,7-dioxabicyclo[2,2,1]heptane based on GC-MS data. The Dufour gland secretion ofA. rotundatus is more similar in composition to the secretions of members of the subfamily Ecitoninae than to its closer relatives from the tribe Dorylini, a result that further complicates studies on the phylogeny of army ants. The mandibular glands ofA. rotundatus contain a mixture of 4-methyl-3-heptanone and limonene in trace amounts, and the well-developed postpygidial glands contain methyl anthranilate only.     

Comparative survey of abdominal gland secretions of the ant subfamily Ponerinae

The chemical contents of three abdominal glands were investigated in representative species of the ponerine ants. The Dufour glands of 14 species show a wide variety of contents. In Mystrium camillae and Proceratium itoi, no volatile substances were found in either the Dufour or venom glands. In Ectatomma sp., Diacamma ceylonense, Diacamma indicum, Pachycondyla obscuricornis, and Pachycondyla striata, volatile chemicals were found in the venom glands as well as in the Dufour glands. Platythyrea punctata was examined, but unusually it does not have a Dufour gland and its venom gland contained no volatile substances. Epoxides were found in ants for the first time in the Dufour glands of Amblyopone reclinata. Venom glands of Pachycondyla tarsata were also found to contain volatile material, including bitter-tasting cyclic dipeptides. In all, 16 species have been added to the list of those examined. All of the 27 known analyses of Dufour glands, 21 analyses of venom glands, and 4 of pygidial glands of workers of ponerine ant species have been brought together in order to seek some pattern in the type of glandular contents. Although the great majority of species produce hydrocarbons in their worker Dufour glands, and some have terpenes, there is no observable pattern for this gland on a tribe or genus level. Volatile compounds have been found in the venom glands of some species of the tribe Ponerini only. The information on pygidial glands is still too fragmentary for any conclusions.     

Chemical Characters of Two Related Species of Giant Honeybees (Apis dorsata and A. laboriosa): Possible Ecological Significance

The Himalyan honeybee, Apis laboriosa, is sometimes considered to be a form of the rock honeybee, A. dorsata, rather than a separate species. Analyses of potential exocrine compounds produced by both forms revealed that the cephalic and abdominal natural products of these two honeybees shared no common denominators. The sting shaft of workers of A. dorsata is the source of a large series of esters dominated by 1-acetoxy-2-decene. Other major constituents include isopentyl acetate, accompanied by isopentyl propionate, farnesyl acetate, and several other esters. On the other hand, nothing but presumed structural lipids (e.g., ethyl palmitoleate) were identified from sting shafts of workers of A. laboriosa. By contrast, cephalic (including mandibular glands) extracts from workers of A. laboriosa contained -octanoic lactone, whereas comparable extracts of A. dorsata workers contained only structural lipids. The major qualitative differences in the chemical characters between A. laboriosa and A. dorsata are consistent with the designation of these two forms as distinct species.     

Semiochemicals from the Predatory Stink Bug Eocanthecona furcellata (Wolff): Components of Metathoracic Gland, Dorsal Abdominal Gland, and Sternal Gland Secretions

Volatile compounds from the metathoracic glands (MTG), dorsal abdominal glands (DAG), and sternal setae of the generalist predatory stink bug Eocanthecona furcellata (Wolff) were studied by gas chromatography–mass spectrometry. MTGs of both male and female bugs contained (E)-2-decenal as the major component, with lesser amounts of (E,E)-2,4-decadienal, (E,Z)-2,4-decadienal, and (E)-2,9-decadienal. The relative amount of (E)-2,9-decadienal in the MTGs of female bugs was higher than in male bugs. There was no dimorphism in the morphology of the DAGs of adults. However, the DAG contents of adult bugs were different between the sexes. Geraniol was found only in the DAGs of males, and limonene and -terpineol were found only in the DAGs of females, whereas linalool oxide isomers, linalool, neral, and geranial were found in DAGs of both sexes. The DAG contents of nymphs were also analyzed, with 4-oxo-(E)-2-hexenal, 4-oxo-(E)-2-octenal, tridecane, and tetradecanal being major components. Male bugs but not females possess sternal setae, and 6,10,13-trimethyltetradecyl isovalerate was detected from extracts of the sternal setae of males. The possible biological significance of dimorphism in the contents of the glands in adults is discussed.     

Sticky secretion from two pairs of defensive glands of rove beetleDeleaster dichrous (Grav.) (Coleoptera: Staphylinidae)

The phylogenetically primitive rove beetleDeleaster dichrous (Grav.) (Oxytelinae) has been shown for the first time to possess two pairs of neighboring abdominal glands which are depleted simultaneously on molestation. The morphology of these glands is described. The defensive constituents of theDeleaster glands were elucidated directly from the mixtures by gas chromatographic-mass spectroscopic methods and microchemical reactions. The paired whitish glands secrete iridodial, which polymerizes on exposure to air to form an adhesive that probably deters small predatory arthropods. The red gland system ofD. dichrous contains the toxicp-toluquinone and a variety of isopropyl andsec-butyl esters. Artificial quinoid ester mixtures simulating the secretion ofD. dichrous showed only weak effects on mortality ofLucilia larvae in comparison with more effective secretions of phyiogenetically derived Oxytelinae. The secretion of the primitive genusDeleaster is characterized chemotaxonomically by , -unsaturated C₁₂ acids and esters, which are postulated as precursors for the characteristic defensive compounds of the derived species, thus indicating a clear evolutionary trend at the micromolecular level.