Defensive secretions of New Zealand tenebrionids V. Presence of methyl ketones inUloma tenebrionoides (Coleoptera: Tenebrionidae)

The defensive secretion ofUloma tenebrionoides (White, 1846) contains benzoquinone, 2-methylbenzoquinone (toluquinone), and 2-ethylben-zoquinone as in other tenebrionids, together with 2-methoxyphenol, pentadecene, heptadecene, 2-pentanone, 2-pentadecanone, 2-heptadecanone, heptadec-10-en-2-one and (Z)-nonadec-10-en-2-one. The latter four methyl ketones have not previously been identified in tenebrionid beetles, and the unsaturated ketones are novel arthropod chemicals.     

Inhibition of Fungal Spore Germination by Nasutitermes: Evidence for a Possible Antiseptic Role of Soldier Defensive Secretions

The antifungal property of two of the principal components of the terpenoid frontal gland secretions of nasute termite soldiers was studied by incubating spore suspensions of the fungus Metarhizium anisopliae with -pinene and limonene singly or in combination at different concentrations. In vitro assays showed that these substances reduced spore germination through direct and indirect (vapor) contact. To determine if the frontal gland secretions protected termites from fungal infection in vivo, the effect of M. anisopliae on the time course of survival of Nasutitermes costalis and N. nigriceps was studied by exposing termites to either a 4.3 × 10⁷ spores/ml or a control sporeless suspension. The caste composition of experimental groups was manipulated to create mixed-caste subcolonies and monocaste groups. Relative to Coptotermes formosanus, a species that relies on the mechanical defenses of soldiers, N. costalis and N. nigriceps were less susceptible to fungal infection. Spore-exposed N. costalis and N. nigriceps termites had 1.2 times the hazard ratio of death of controls, while the hazard ratio of death of spore-exposed C. formosanus was 11.4 times that of controls. Although the lower susceptibility to infection in Nasutitermes may be explained in part by the antifungal properties of -pinene and limonene, group composition also played a major role in the survival of spore-exposed termites. Mixed-caste and soldier monocaste groups had 3.4 and 4.7 times the hazard ratio of death, respectively, relative to the worker monocaste treatment. These results suggest that although Nasutitermes terpenoid secretions may have antifungal properties, the caste composition of groups and the social interactions of termites also play a role in determining susceptibility to fungal infection.     

Monoterpene oviposition stimulants ofDioryctria amatella in volatiles from fusiform rust galls and second-year loblolly pine cones

Volatiles collected on Poropak Q from fusiform rust galls (Cronartium quercuum F. sp.fusiforme) of loblolly pine for 3 hr were better ovi-position stimulants forDioryctria amatella (Hulst) females than extracts of 8-hr collections. GLC analysis of these extracts showed no major differences in relative monoterpene composition, although 8-hr collections contained an unidentified compound not detected in the 3-hr collections. Comparison of volatiles from second-year loblolly pine cones with those from fusiform galls showed that both containeddl--pinene, (–)--pinene, myrcene, and (+)-limonene. Camphene was found in galls only, and relatively large quantities of -phellandrene were identified only from cones. The five major monoterpenes found in the two host substrates were tested in an oviposition bioassay. Eighteen trials using different combinations of these terpenes showed that the combination of -pinene, myrcene, and limonene was as attractive toD. amatella females as all other terpene combinations, including turpentine.Lepidoptera: Pyralidae.     

Defensive secretion ofTenebrio molitor (Coleoptera: Tenebrionidae)

The defensive secretion ofTenebrio molitor contains a mixture of 2-methyl-1,4-benzoquinone andm-cresol. The phenol had not previously been detected in the secretion, although some investigators reported presence of 2-ethyl-1,4-benzoquinone as a second component. We failed to detect the latter quinone in secretion samples from three laboratory populations ofT. molitor.Paper No. 100 of the seriesDefense Mechanisms of Arthropods; No. 99 is Storey et al.,J. Chem. Ecol., 17, 687–693 (1991).     

Defensive sesquiterpenoids from a dipterocarp (Dipterocarpus kerrii)

Four sesquiterpenoids (2, 4, 7, and9) have been isolated and characterized from the termiticidal fraction ofDipterocarpus kerrii resin. The major constituent of this resin is -gurjunene (1).Presented at the Third Annual Meeting of the International Society of Chemical Ecology, June 21–24, 1986, University of California, Berkeley.     

Defensive secretions of three species ofAcilius (Coleoptera: Dytiscidae) and their seasonal variations as determined by high-pressure liquid chromatography

A rapid, sensitive, stable, and quantitative high-pressure liquid chromatographic technique was developed for the analysis of defensive secretions obtained from the pygidial and prothoracic glands of dytiscids. Methods were developed for both normal phase (Porasil) and reverse phase (Bondapak C₁₈) columns. The applicability of this technique was demonstrated when defensive compounds ofAcilius semiculcatus, A. sylvanus andA. mediatus were isolated, identified, and quantitated. No major differences were found in the composition of the defensive secretions between the three species. The seasonal defensive titer ofA. semisulcatus was determined from June through October 1977. The pygidial defensive agents (benzoic acid,p-hydroxybenzaldehyde, and methylp-hydroxybenzoate varied from 9.0 to 67.8 g and exhibited a maximum in July, and a steroid from the prothoracic gland varied from 7.1 to 33.2 g and was maximum in October.     

Defensive secretion of chrysomelid larvaeGastrophysa atrocyanea Motschulsky andPhaedon brassicae Baly

The active substance of the larval defensive secretion of the Japanese chrysomelid beetles,Gastrophysa atrocyanea Motschulsky andPhaedon brassicae Baly was identified as chrysomelidial.This is report No. 2 of the Defensive Secretion of Chrysomelid Beetles, Report No. 1 is Sugawara et al. (1978).     

Oxygenated monoterpenes produced by yeasts,isolated fromIps typographus (Coleoptera: Scolytidae) and grown in phloem medium

When yeasts associated withIps typographus beetles were grown in an aqueous phloem medium for two days, the main oxygenated monoterpenes produced were -terpineol and borneol. Terpinene-4-ol, myrtenol, andtrans-pinocarveol were also found but in lesser amounts. Of the six strains used in this study,Hansenula capsulata andCandida nitratophila produced the largest amounts of oxygenated monoterpenes. Addition of -pinene to the phloem medium generally reduced the amounts of oxygenated monoterpenes, probably because this substance is toxic to all tested yeast species. OurCandida diddensii strain seemed to be particularly sensitive to -pinene. None of the yeast strains producedcis-verbenol,trans-verbenol, or verbenone from the medium or from added -pinene.This study was made within the project Odour Signals for Control of Pest Insects.     

Asymmetric structure analysis of active surface-sites by in situ polarized total-reflection fluorescence EXAFS

An in situ polarization-dependent total reflection fluorescence yield EXAFS system has been developed to analyze the asymmetric structures of catalytically active metal sites on single crystal surfaces. This technique separately reveals the bonding feature parallel and perpendicular to the support surface. The systems of Cu ion on -quartz(0001), Co oxide on -alumina(0001), and Pt₄ on -alumina(0001) were investigated as model surfaces of supported catalytic systems. The location of Cu sites on -quartz(0001), the epitaxial growth mode of Co₃O₄ on -alumina(0001), and the Pt raft structure with metal-support interaction in Pt₄ / -alumina(0001) were observed.     

Chemistry and Defensive Efficacy of Secretion of Burrowing Bug (Sehirus cinctus cinctus)

Adult Sehirus cinctus cinctus emit a volatile secretion from their metathoracic scent glands when tactually stimulated. We identified the volatile components by gas chromatography, high-performance liquid chromatography, and mass spectrometry. The secretion of both sexes contained (1R)-(+)--pinene, (1S)-(–)--pinene, -myrcene, (R)-(+)-limonene, and -terpinolene. Two additional compounds were found in only female secretions: (E)-2-hexenyl acetate and (E)-2-octenal. We also tested the defensive capability of this insect by offering it to various predators. Anoles, starlings, and a killdeer rejected S. c. cinctus after an initial sampling. These findings suggest that the secretion plays a defensive role.     

Light-dependent toxicity of α-terthienyl and anthracene toward late embryonic stages ofRana pipiens

Alpha-terthienyl is toxic to late embryonic stages ofRana pipiens in the presence of sunlight. Neither -terthienyl alone in the dark nor a previously photolyzed solution of -terthienyl has comparable activity. The LC₅₀ was 0.11 ppm with 30 min of exposure and 0.018 ppm with 2 hr of exposure to sunlight. Anthracene, a representative example of polycyclic aromatic hydrocarbons widely distributed in the environment, also showed similar phototoxicity, with an LC₅₀ of 0.065 ppm after 30 min of exposure and 0.025 ppm after 5 hr.     

Surface properties of ZSM-5 modified by phosphorus

Phosphorus modification of ZSM-5 leads to extra framework P⁵⁺ and probably incorporation of +3 valence state of P in the framework. The resulting system has increased Brønsted acidity. Theoretical calculations also favour the postulate that phosphorus in +3 valence state can be incorporated into the lattice.     

Allelochemical Potential of Callicarpa acuminata

The allelochemical potential of Callicarpa acuminata (Verbenaceae) was investigated by using a biodirected fractionation study as part of a long-term project to search for bioactive compounds among the rich biodiversity of plant communities in the Ecological Reserve El Eden, Quintana Roo, Mexico. Aqueous leachate, chloroform-methanol extract, and chromatographic fractions of the leaves of C. acuminata inhibited the root growth of test plants (23-70%). Some of these treatments caused a moderate inhibition of the radial growth of two phytopathogenic fungi, Helminthosporium longirostratum and Alternaria solani (18-31%). The chloroform-methanol (1:1) extract prepared from the leaves rendered five compounds: isopimaric acid (1), a mixture of two diterpenols [sandaracopimaradien-19-ol (3) and akhdarenol (4)], alpha-amyrin (5), and the flavone salvigenin (6)]. The phytotoxicity exhibited by several fractions and the full extract almost disappeared when pure compounds were evaluated on the test plants, suggesting a synergistic or additive effect. Compounds (4), (5), and the semisynthetic derivative isopimaric acid methyl ether (2) had antifeedant effects on Leptinotarsa decemlineata. Compound 5 was most toxic to this insect, followed by (2), (4), and (6) with moderate to low toxicity. No correlation was found between antifeedant and toxic effects on this insect, suggesting that different modes of action were involved. All the test compounds were cytotoxic to insect Sf9 cells while (6), (4), and (1) also affected mammalian Chinese Hamster Ovary (CHO) cells. Compound 5 showed the strongest selectivity against insect cells. This study contributes to the knowledge of the defensive chemistry and added value of C. acuminata.     

Limonene inhibits attraction to α-pinene in the pine weevilsHylobius abietis andH. pinastri

The field responses ofHylobius abietis (L.) andH. pinastri (Gyllenhal) (Coleoptera: Curculionidae) to various combinations of two host monoterpenes and ethanol were studied using baited pitfall traps. Both species were attracted to -pinene, and when ethanol was added the attraction increased by 5–16 times. Limonene completely inhibited the attraction to -pinene, even when the release rate of limonene was only about 1/50 that of -pinene. The catches in traps with -pinene and limonene as well as with limonene alone were similar in size to catches in empty control traps, i.e., no true repellent effect was demonstrated. When limonene was added to the combination of -pinene and ethanol on old clear-cuttings, the catch ofH. pinastri was completely inhibited while that ofH. abietis was reduced by two thirds. On fresh clear-cuttings the inhibitory effect of limonene on the attraction to the -pinene-ethanol combination was small or absent. Some aspects of host interactions are discussed as are practical implications regarding the choice of seedling material for planting and prospects of finding deterrents for protecting seedlings from pine weevil damage.     

Volatile glandular secretions of three species of new world army ants,Eciton burchelli,Labidus coecus,andLabidus praedator

The Dufour glands of workers ofEciton burchelli contain a mixture of small quantities of oxygenated compounds, some of which are derived from terpenes, and C₁₇-C₂₅ hydrocarbons. The secretion of the Dufour glands of soldiers was either similar to that of workers, with geranylacetone a significant component, or they contained geranyllinalool in large amounts. The glands of workers and soldiers ofLabidus praedator andLabidus coecus contained (E)--ocimene, a new substance for the Dufour glands of ants. 4-Methyl-3-heptanone was the dominant compound in the mandibular glands ofE. burchelli andL. coecus. Skatole and indole were found in the gasters ofL. praedator, and skatole was present in the venom glands of some soldiers ofE. burchelli.     

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.     

Factors governing the electrochemical synthesis of α-nickel (ii) hydroxide

The electrodeposition of -nickel hydroxide is promoted by the simultaneous chemical corrosion of the electrode by an acidic nitrate bath. Chemical corrosion results in the formation of a poorly ordered layered phase which is structurally similar to -nickel hydroxide and provides nucleation sites for the deposition of the latter. Therefore under conditions which enhance corrosion rates such as low current density (<1.3 mA cm–2), high temperature (60 C), high nickel nitrate concentration ( 1M) and the resultant low pH (1.7), -nickel hydroxide electrodeposition is observed, while -nickel hydroxide forms under other conditions. Further, -nickel hydroxide deposition is more facile on an iron electrode compared to nickel or platinum.     

Hydroformylation of olefins with water-soluble rhodium catalysts in the presence ofα-cyclodextrin

Hydroformylation of hex-1-ene using a water soluble rhodium catalyst HRh(CO)[PPh₂(m-C₆H₄SO₃Na)]₃ (HRh(CO)(TPPMS)₃) (I), gives lower yields when-cyclodextrin is added to the biphasic reaction system implying an interaction between the cyclodextrin and rhodium catalyst.     

Corn volatiles as attractants for northern and western corn rootworm beetles (Coleoptera: Chrysomelidae:Diabrotica spp.)

Synthetic corn volatiles and selected analogs were tested in commercial corn fields for attractiveness to feral northern (NCR,Diabrotica barberi) and western corn rootworm beetles (WCR,D. virgifera virgifera). Two new attractants, geranylacetone and -terpineol, were identified among corn terpenes and compared at four stages in crop development with the phenylpropanoid standards cinnamyl alcohol and 4-methoxy-cinnamaldehyde, with each component at 30 mg/trap. Dose-response relationships (0.1–100 mg/trap) and efficacy of two-component blends (30 mg/component) were also examined. More beetles were captured on traps baited with (+)- than (–)--terpineol, but the difference was statistically significant only for WCR. Captures with geranylacetone or (+)--terpineol were directly proportional to the logarithm of the attractant dose. WCR females were attracted to as little as 0.1 mg of either compound. WCR males required 1.0 mg of (+)--terpineol and were not attracted to geranylacetone at any dose. NCR required 0.3 mg of either attractant and showed less marked response differences between the sexes than did WCR. Geranylacetone and cinnamyl alcohol were equally effective attractants, whereas (+)--terpineol was significantly less attractive to WCR but more attractive to NCR than was 4-methoxycinnamaldehyde. Corn terpenes and phenylpropanoid standards produced similar seasonal response patterns in that captures tended to rise in each case as the season progressed, except during silking when no compound was attractive. Mixing corn terpenes or phenylpropanoid standards synergized responses of WCR females, but (+)--terpineol suppressed attraction of NCR females to geranylacetone.Mention of a proprietary product or company name does not imply endorsement by the U.S. Department of Agriculture.     

Sex attractant pheromone of the red-shouldered stink bug Thyanta pallidovirens: a pheromone blend with multiple redundant components

The male-produced sex pheromone of the red-shouldered stink bug, Thyanta pallidovirens (Stål) (Hemiptera: Pentatomidae) consists of a blend of methyl (E2,Z4,Z6)-decatrienoate (E2,Z4,Z6–10:COOMe), and the sesquiterpenes (+)-curcumene, (–)-zingiberene, and (–) --sesquiphellandrene. In laboratory bioassays, sexually mature males attracted sexually mature females but not males, and females did not attract either sex. Extracts of volatiles collected from sexually mature males contained compounds not present in extracts from females or sexually immature males, and male-produced extract was attractive to females. Biological activity was lost when the extract was fractionated, indicating that the pheromone consisted of at least two components having different chemical properties. Individually, pheromone components were not attractive to females, but E2,Z4,Z6–10:COOMe in combination with at least one of the three male-produced sesquiterpenes was attractive. The presence of more than one sesquiterpene in the blend did not increase attraction, indicating redundancy in the pheromone signal. Male extract was as attractive as a blend reconstructed from synthesized compounds, indicating all biologically active components had been identified. In bioassays conducted at dusk in a 1- × 1- × 1-m screen field cage, females were attracted to synthetic pheromone lures. In field trials, adult female T. pallidovirens were attracted to pheromone-baited traps in relatively low numbers. The profile of volatiles released by sexually mature males of a congeneric species, Thyanta accerra custator McAtee, was remarkably similar to that of male T. pallidovirens, with the exception that the former species produced (E)-2-decenal, a compound that was not found in T. pallidovirens extracts.