Terpene variability of mainland Pinus radiata

GC-MS analysis and the effect of topical application of essential oils of Pinus canariensis C.Sm., Cupressus lusitanica Mill. and Cupressus arizonica Greene aerial parts in Imiquimod-Induced Psoriasis in Mice

ETHNOPHARMACOLOGICAL RELEVANCE

Traditionally, Coniferous plants, in particular Pinus and Cupressus species, have been used in the treatment of burns, skin infections, and immune-mediated inflammatory diseases such as psoriasis.

AIM OF THE STUDY

A comparative study between essential oils (EOs) extracted from aerial parts of three coniferous plants: Pinus canariensis C.Sm. (PC), Cupressus lusitanica Mill. (CL) and Cupressus arizonica Greene (CA), cultivated in Egypt, was designed to investigate their composition and their anti-psoriasis mechanism.

MATERIALS AND METHODS

The phytochemical profiles were confirmed using Gas Chromatography-Mass Spectrometry (GC-MS) method. In-vivo Imiquimod (IMQ)-induced psoriasis model was performed and EOs were applied topically and compared to mometasone cream as a standard subsequently histopathological analysis and inflammatory biomarkers were measured.

RESULTS

In GC-MS analysis, Monoterpene hydrocarbons, sesquiterpene hydrocarbons and oxygenated monoterpenes were the major detected classes in the three plants, except in Pinus canariensis essential oil, oxygenated monoterpenes were absent. A significant attenuation of imiquimod-induced psoriasis symptoms after topical application of P. canariensis C.Sm., and C. lusitanica Mill. essential oils were observed by reducing the psoriasis area severity index (PASI) score, alleviating histopathological alteration, restoring the spleen index, and decreasing serum levels of interleukins 23 and 17A. Indeed, the results of Pinus canariensis essential oil is comparable to mometasone and showed no significant difference from standard treatment. On the other hand, the topical application of C. arizonica essential oil failed to alleviate imiquimod-induced psoriasis symptoms as observed in the PSAI score, the histopathological investigation, and the spleen index.

CONCLUSION

The essential oils of P. canariensis C.Sm., and C. lusitanica Mill aerial parts could be promising candidates for psoriasis treatment and for further studies on inflammation-related skin diseases.

Effect of Host Volatile Release Rate and Racemic Fuscumol on Trap Catch of Hylurgus ligniperda, Hylastes ater (Coleoptera: Curculionidae), and Arhopalus ferus (Coleoptera: Cerambycidae)

Early detection of bark- and wood-boring beetles is critical to support the eradication of recently established populations in novel regions. Flight intercept traps baited with semiochemical lures are essential for surveillance and population monitoring of introduced insects. We present laboratory and field data to test potential improvements in trap sensitivity to detect Hylastes ater (Paykull), Hylurgus ligniperda (Fabricius) (Coleoptera:Scolytinae), and Arhopalus ferus (Mulsant) (Coleoptera:Cerambycidae). We evaluated the effects of type and permeability of plastic material on release rates of host-plant volatiles and the addition of the pheromone racemic E-fuscumol on beetle species catch within an exotic Pinus radiata (D. Don) plantation forest. We trapped 228,278 H. ligniperda, 91 H. ater, and 2,504 A. ferus over two experiments. Our results show strong attraction of H. ligniperda to host-plant volatiles with a positive relationship between increased release rates and trap catch. H. ater follows this trend, with attraction to ethanol and (-)-β-pinene. H. ligniperda was more strongly attracted to host volatiles than H. ater, the average ratio between baited and unbaited traps being 51.25:1 and 3.75:1, respectively for each species. There was no effect of host-plant volatiles or release rate on A. ferus catch, but a weak attraction by A. ferus to racemic E-fuscumol. Overall, we demonstrate species-specific differences in Coleoptera attraction to host-plant volatile release rates and semiochemical blends. Results demonstrate mechanisms to improve trap catch of H. ligniperda and H. ater. Racemic E-fuscumol shows some promise for A. ferus, but further investigation is required to determine whether chirality affects attraction.

Comparison on Reduction of VOCs Emissions from Radiata Pine (Pinus Radiata D. Don) between Sodium Bicarbonate and Ozone Treatments

Volatile organic compounds (VOCs) in wood furniture are an important factor that affects indoor air quality. In this study, radiata pine (Pinus radiata D. Don) was treated with sodium bicarbonate and ozone aqueous solution to reduce the VOC contents without sacrificing mechanical properties. The VOCs of radiata pine were identified by gas chromatography-mass spectrometry (GC-MS), and the functional group changes of wood samples were characterized by Fourier-transform infrared spectroscopy (FTIR). The results showed that the main VOCs of radiata pine include alkenes, aldehydes, and esters. The sodium bicarbonate and ozone treatments almost eliminated the VOC contents of radiata pine. The two treatments mentioned above had little effect on compressive strength and surface color of radiata pine.

Follow your nose: leaf odour as an important foraging cue for mammalian herbivores

Studies of odour-driven foraging by mammals focus on attractant cues emitted by flowers, fruits, and fungi. Yet, the leaves of many plant species worldwide produce odour, which could act as a cue for foraging mammalian herbivores. Leaf odour may thus improve foraging efficiency for such herbivores in many ecosystems by reducing search time, particularly but not only, for plants that are visually obscured. We tested the use of leaf odour by a free-ranging mammalian browser, the swamp wallaby (Wallabia bicolor) to find and browse palatable tree seedlings (Eucalyptus pilularis). Wallabies visited patches non-randomly with respect to the presence of seedlings. In the absence of visual plant cues, they used leaf odour (cut seedlings in vials) to find patches earlier, and visited and investigated them more often than control patches (empty vials), supporting the hypothesis that wallabies used seedling odour to enhance search efficiency. In contrast, the grey kangaroo (Macropus giganteus), a grazer, showed no response to seedling odour. When the availability of seedling visual and olfactory cues was manipulated, wallabies browsed seedlings equally quickly in all treatments: upright (normal cues), pinned to the ground (reduced visual cues), and upright plus pinned seedlings (double olfactory cues). Odour cues play a critical role in food-finding by swamp wallabies, and these animals are finely tuned to detecting these cues with their threshold for detection reached by odours from only a single plant. The global significance of leaf odour in foraging by mammalian herbivores consuming conifers, eucalypts, and other odour-rich species requires greater attention.

Interruption of the semiochemical-based attraction of ambrosia beetles to ethanol-baited traps and ethanol-injected trap trees by verbenone

We examined the extent to which verbenone, a bark beetle antiaggregation pheromone, interrupted the semiochemical-based attraction of ambrosia beetles. Field trapping studies conducted in Ohio showed that a verbenone dispenser with a release rate of 50 mg/d at 25°C reduced the attraction of Anisandrus sayi Hopkins, Euwallacea validus (Eichhoff), Hypothenemus dissimilis (Zimmermann), Xylosandrus germanus (Blandford), and Xyleborinus saxesenii (Ratzeburg) to ethanol-baited traps. A verbenone dispenser attached to ethanol-injected Magnolia virginiana L. trap trees deployed in Ohio also reduced ambrosia beetle attacks compared to trap trees without a verbenone dispenser. Subsequent field trials demonstrated a direct relationship between distance from a verbenone dispenser and ambrosia beetle attacks on trap trees in Ohio in 2011 and 2012 and Tennessee in 2012, but not in Tennessee and Virginia in 2011. Assessment of the influence of verbenone on the probability of attacks above a density threshold found that although attacks occurred on trap trees regardless of their proximity to a verbenone dispenser, the higher density of attacks per tree occurred on trap trees farthest away from the verbenone source in Ohio and Tennessee. Verbenone alone could be somewhat useful for discouraging ambrosia beetle attacks on individual trees or on a small spatial scale, but deployment of verbenone might be most effective when integrated as part of a "push-pull" strategy.

Germacrene D, a common sesquiterpene in the genus Bursera (Burseraceae)

The volatile components of the leaves of five Bursera species, B. copallifera, B. exselsa, B. mirandae, B. ruticola and B. fagaroides var. purpusii were determined by gas chromatography–mass spectrometry (GC–MS). Germacrene D was one of the predominant components (15.1–56.2%) of all of these species. Germacrene D has also been found in other Bursera species and some species of Commiphora, the sister group of Bursera, suggesting that the production of germacrene D might be an ancient trait in the genus Bursera.

Role of plant enemies in the forestry of indigenous vs. nonindigenous pines

Plantations of rapidly growing trees are becoming increasingly common because the high productivity can enhance local economies, support improvements in educational systems, and generally improve the quality of life in rural communities. Landowners frequently choose to plant nonindigenous species; one rationalization has been that silvicultural productivity is enhanced when trees are separated from their native herbivores and pathogens. The expectation of enemy reduction in nonindigenous species has theoretical and empirical support from studies of the enemy release hypothesis (ERH) in the context of invasion ecology, but its relevance to forestry has not been evaluated. We evaluated ERH in the productive forests of Galicia, Spain, where there has been a profusion of pine plantations, some with the indigenous Pinus pinaster, but increasingly with the nonindigenous P. radiata. Here, one of the most important pests of pines is the indigenous bark beetle, Tomicus piniperda. In support of ERH, attacks by T. piniperda were more than twice as great in stands of P. pinaster compared to P. radiata. This differential held across a range of tree ages and beetle abundance. However, this extension of ERH to forestry failed in the broader sense because beetle attacks, although fewer on P. radiata, reduced productivity of P. radiata more than that of P. pinaster (probably because more photosynthetic tissue is lost per beetle attack in P. radiata). Productivity of the nonindigenous pine was further reduced by the pathogen, Sphaeropsis sapinea, which infected up to 28% of P. radiata but was absent in P. pinaster. This was consistent with the forestry axiom (antithetical to ERH) that trees planted "off-site" are more susceptible to pathogens. Fungal infections were positively correlated with beetle attacks; apparently T. piniperda facilitates S. sapinea infections by creating wounds and by carrying fungal propagules. A globally important component in the diminution of indigenous flora has been the deliberate large-scale propagation of nonnative trees for silviculture. At least for Pinus forestry in Spain, reduced losses to pests did not rationalize the planting of nonindigenous trees. There would be value in further exploration of relations between invasion ecology and the forestry of nonindigenous trees.

Trace level determination of enantiomeric monoterpenes in terrestrial plant emission and in the atmosphere using a β-cyclodextrin capillary column coupled with thermal desorption and mass spectrometry

For the first time, enrichment on solid sorbents followed by thermal desorption has been used for the determination of the enantiomeric signature of monoterpenes in the gaseous emission of terrestrial plants. A beta-cyclodextrin capillary column has been used for the separation of critical pairs. The temperature program and column loading were optimized for making the accurate quantification of individual enantiomers possible by mass spectrometry. The resolution achieved was sufficient for separating enantiomeric monoterpenes from other biogenic and anthropogenic volatile organic compounds present in air and vegetation emission samples. The method has been applied to the determination of the enantiomeric ratios of monoterpenes in the gaseous emissions of some evergreen plants and in the open atmosphere.

Inter-population differences in the essential oils of Pinus caribaea needles

Differences in volatile terpene content of Pinus caribaea needles and soil qualities between two pine plantations (Uverito and Sartenejas) in Venezuela were analyzed. Soils in the Uverito pine plantation were sandy, low in nutritional quality, and deficient in available nitrogen and phosphorus content. Pines grown on these soils presented in their needles higher concentrations of alpha-pinene, camphene, sabinene, myrcene+alpha-phellandrene mixture, beta-phellandrene, beta-caryophyllene, alpha-humulene, and a higher total monoterpene content than pines of the Sartenejas plantation, where soils were nutritionally richer and higher in nitrogen and phosphorus content. The hypothesis of the carbon/nutrient balance could explain these results. Alternatively, continuous stress on the pines of the Uverito plantation due to herbivory by the leafcutter ant Atta laevigata may induce, in part, the differences observed between these pines and those of the Sartenejas plantation.