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Khia, A., Ghanmi, M., Satrani, B., Aafi, A., Aberchane, M., Quaboul, B., et al. (2014). Effect of provenance on the chemical and microbiological quality of essential oils of Rosmarinus officinalis L. in Morocco. Phytotherapie, 12(6), 341–347.
Abstract: This study is an assessment of the chemical quality and evaluation of antibacterial and antifungal activity of rosemary’s essential oils from three regions of Morocco (Rchida and Berkine/Eastern Morocco and Aknoul/North East of Morocco. The essential oils obtained by hydrodistillation of the leaves and young twigs of rosemary, were analyzed by GC / FID and GC/ MS. These essential oils are characterized by the presence of α and β-pinene, camphene, 1,8-cineole and camphor compounds. The quality of these essential oils met the AFNOR NF ISO 4730 rosemary Morocco kind (1,8-cineole). The evaluation of the antimicrobial activity of essential oils of Rosmarinus officinalis showed low efficacy against microorganisms tested which were all inhibited from 1/100 v/v except for Penicillium expansum whose growth was stopped at the concentration 1/250 v/v.
Keywords: Antibacterial; Antifungal activity; Chemical composition; Essential Oil; Provenance; Rosmarinus officinalis
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Biwolé, A. B., Dainou, K., Fayolle, A., Hardy, O. J., Brostaux, Y., Coste, S., et al. (2015). Light Response of Seedlings of a Central African Timber Tree Species, Lophira alata (Ochnaceae), and the Definition of Light Requirements. Biotropica, 47(6), 681–688.
Abstract: Light is of primary importance in structuring tropical tree communities. Light exposure at seedling and adult stages has been used to characterize the ecological profile of tropical trees, with many implications in forest management and restoration ecology. Most shade-tolerance classification systems have been proposed based on empirical observations in a specific area and thus result in contradictions among categories assigned to a given species. In this study, we aimed to quantify the light requirements for seedling growth of a Central African timber tree, Lophira alata (Ochnaceae), taking into account effects of population origin. In two controlled experiments: a light response experiment and a comparative population experiment, conducted in southwestern Cameroon, using seeds collected from four populations (three from Cameroon and one from Gabon), we examined the quantitative responses to irradiance of seedlings. After 2 years, mortality was very low (<3%), even in extremely low irradiance. Growth and biomass allocation patterns varied in response to light, with intermediate irradiance (24–43%) providing optimal conditions. Light response differed between populations. The Boumba population in the northeastern edge of the species' distribution exhibited the highest light requirements, suggesting a local adaptation. As a result of positive growth at low irradiance and maximum growth at intermediate irradiance, we concluded that L. alata exhibits characteristics of both non-pioneer and pioneer species. Implications of our results to propose an objective way to assign the light requirement for tropical tree species are discussed.
Keywords: biomass allocation; Central Africa; light requirement: Lophira alata; population; relative growth rate; seedling growth; timber species; Afrique centrale; allocation de biomasse; besoins en lumière; croissance des semis; bois d'œuvre; Lophira alata; population; taux de croissance relatif
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Vanbellingen, Q. P., Fu, T., Bich, C., Amusant, N., Stien, D., Della-Negra, S., et al. (2016). Mapping Dicorynia guianensis Amsh. wood constituents by submicron resolution cluster-TOF-SIMS imaging. Journal of Mass Spectrometry, 51(6), 412–423.
Abstract: The preparation of tropical wood surface sections for time-of-flight secondary ion mass spectrometry imaging is described, and the use of delayed extraction of secondary ions and its interest for the analysis of vegetal surface are shown. The method has been applied to the study by time-of-flight secondary ion mass spectrometry imaging with a resolution of less than one micron of a tropical wood species, Dicorynia guianensis, which is one of the most exploited wood in French Guiana for its durable heartwood. The heartwood of this species exhibits an economical importance, but its production is not controlled in forestry. Results show an increase of tryptamine from the transition zone and a concomitant decrease of inorganic ions and starch fragment ions. These experiments lead to a better understanding of the heartwood formation and the origin of the natural durability of D. guianensis. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
Keywords: Dicorynia guianensis; heartwood formation; mass spectrometry imaging; Tof-Sims; tropical wood; tryptamine
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Amusant, N., Beauchene, J., Digeon, A., & Chaix, G. (2016). Essential oil yield in rosewood (Aniba rosaeodora Ducke): Initial application of rapid prediction by near infrared spectroscopy based on wood spectra. Journal of Near Infrared Spectroscopy, 24(6), 507–515.
Abstract: Rosewood (Aniba rosaeodora) essential oil is a valuable ingredient that has long been used in the perfume and cosmetic industries. The main rosewood timber quality parameters are its essential oil yield and quality. A hydrodistillation method has been developed for yield determination, but it is time consuming. Here we tested the applicability of near infrared (NIR) spectroscopy for determining essential oil yield directly from wood powder. Essential oil from 139 wood powders was extracted via hydrodistillation. The measurements were based on the ratio between the extracted essential oil mass and the oven-dried wood mass and were correlated with the wood powder NIR spectra. The calibration model statistical findings demonstrated that NIR could be a fast and feasible alternative method for selecting trees with a high essential oil yield potential. NIR-based predictions obtained in an independent validation set indicated a high correlation (r2e = 0.92) with laboratory essential oil yield measurements. This NIR model could help wood managers in selecting trees with a high essential oil yield potential and in developing sustainable rosewood management strategies. © IM Publications LLP 2016. All rights reserved.
Keywords: Aniba rosaeodora; Calibration; Essential oil yield; Nir; Pls; Rosewood
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Talaga, S., Leroy, C., Céréghino, R., & Dejean, A. (2016). Convergent evolution of intraguild predation in phytotelm-inhabiting mosquitoes. Evol. Ecol., 30(6), 1133–1147.
Abstract: Intraguild predation (IGP) is a type of biological interaction involving the killing and consuming of competing species that exploit similar and often limited resources. This phenomenon is widespread among a great variety of taxonomic groups and has already been reported for mosquito (Diptera: Culicidae) larvae. Moreover, the larvae of certain mosquito species of the tribe Sabethini have evolved modified mouthparts ending in rigid apical structures signaling their capacity to be effective intraguild predators. We assumed that IGP confers a selective advantage under severe competitive conditions by both providing an immediate energetic gain and reducing potential competition. Because potential competition is likely to increase with decreasing habitat size, we hypothesized that the proportion of species with modified mouthparts would increase in smaller aquatic habitats. We tested this hypothesis by examining the mosquito species naturally associated with phytotelmata of decreasing sizes in French Guiana. We show that the degree of specialization in mosquito-phytotelm associations is high, suggesting a long coevolutive process. Indeed, short-term interaction experiments confirmed that species with modified mouthparts are able to prey upon similarly-sized intraguild prey and are, thus, effective intraguild predators. In addition, these species are larger and associated with smaller phytotelmata than those with typical mouthparts. Moreover, below a certain threshold of phytotelm size, only species with modified mouthparts were present. These results show that IGP confers a selective advantage under severe competitive conditions and results from the coadaptation of mosquito species to their specific phytotelm habitat. The presence of functionally analogous structures in different mosquito genera also implies that IGP has emerged from convergent evolution in small phytotelmata.
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Talaga, S., Leroy, C., Guidez, A., Dusfour, I., Girod, R., Dejean, A., et al. (2017). DNA reference libraries of French Guianese mosquitoes for barcoding and metabarcoding. PLoS ONE, 12(6), e0176993.
Abstract: The mosquito family (Diptera: Culicidae) constitutes the most medically important group of arthropods because certain species are vectors of human pathogens. In some parts of the world, the diversity is so high that the accurate delimitation and/or identification of species is challenging. A DNA-based identification system for all animals has been proposed, the socalled DNA barcoding approach. In this study, our objectives were (i) to establish DNA barcode libraries for the mosquitoes of French Guiana based on the COI and the 16S markers, (ii) to compare distance-based and tree-based methods of species delimitation to traditional taxonomy, and (iii) to evaluate the accuracy of each marker in identifying specimens. A total of 266 specimens belonging to 75 morphologically identified species or morphospecies were analyzed allowing us to delimit 86 DNA clusters with only 21 of them already present in the BOLD database. We thus provide a substantial contribution to the global mosquito barcoding initiative. Our results confirm that DNA barcodes can be successfully used to delimit and identify mosquito species with only a few cases where the marker could not distinguish closely related species. Our results also validate the presence of new species identified based on morphology, plus potential cases of cryptic species. We found that both COI and 16S markers performed very well, with successful identifications at the species level of up to 98% for COI and 97% for 16S when compared to traditional taxonomy. This shows great potential for the use of metabarcoding for vector monitoring and eco-epidemiological studies. © 2017 Talaga et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Birer, C., Tysklind, N., Zinger, L., & Duplais, C. (2017). Comparative analysis of DNA extraction methods to study the body surface microbiota of insects: A case study with ant cuticular bacteria. Mol Ecol Resour, 17(6), e34–e45.
Abstract: High-throughput sequencing of the 16S rRNA gene has considerably helped revealing the essential role of bacteria living on insect cuticles in the ecophysiology and behaviour of their hosts. However, our understanding of host-cuticular microbiota feedbacks remains hampered by the difficulties of working with low bacterial DNA quantities as with individual insect cuticle samples, which are more prone to molecular biases and contaminations. Herein, we conducted a methodological benchmark on the cuticular bacterial loads retrieved from two Neotropical ant species of different body size and ecology: Atta cephalotes (~15 mm) and Pseudomyrmex penetrator (~5 mm). We evaluated the richness and composition of the cuticular microbiota, as well as the amount of biases and contamination produced by four DNA extraction protocols. We also addressed how bacterial community characteristics would be affected by the number of individuals or individual body size used for DNA extraction. Most extraction methods yielded similar results in terms of bacterial diversity and composition for A. cephalotes (~15 mm). In contrast, greater amounts of artefactual sequences and contaminations, as well as noticeable differences in bacterial community characteristics were observed between extraction methods for P. penetrator (~5 mm). We also found that large (~15 mm) and small (~5 mm) A. cephalotes individuals harbour different bacterial communities. Our benchmark suggests that cuticular microbiota of single individual insects can be reliably retrieved provided that blank controls, appropriate data cleaning, and individual body size and functional role within insect society are considered in the experiment.
Keywords: 16S rRNA; bacterial communities; cuticular microbiome; insect cuticle; metabarcoding
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Lambs, L., Bompy, F., & Dulormne, M. (2018). Using an “isotopic spike” from a tropical storm to understand water exchange on a large scale: Case study of Hurricane Rafael in the lesser antilles archipelago, October 2012. Rapid Communications in Mass Spectrometry, 32(6), 457–468.
Abstract: Rationale: Studies of wetland eco-hydrology in tropical coastal areas are scarce, and the use of water stable isotopes can be of great help. Key constraints for their analysis are (i) the small difference in delta18O values between seawater and old evaporated freshwater, and (ii) the fact that the presence of old brackish water limits the determination of the water origin and dynamic. Methods: The water from tropical storms displays distinctively depleted heavy stable isotopes, in comparison with usual tropical rainfall without strong convective thunderstorms. During tropical storms, such as Hurricane Rafael in mid-October 2012, the rainfall delta18O signal can be decreased by many units. This effect is called an “isotopic spike”, and it could be used as a temporal marker of the water fluxes. Results: Water samples, with delta18O values as low as −8.9/1000, were collected on the islands of Guadeloupe and Saint-Martin during Hurricane Rafael, whereas the usual range of groundwater or mean rainfall delta18O values is around −2.8 +/- 0.5 /1000, as measured from 2009 to 2012. These water “isotopic spikes” allow us to show a surface freshwater uptake by mangrove trees in Guadeloupe, and in Saint-Martin, to calculate the water renewal of the salt ponds and pools. Conclusions: The “isotopic spikes” generated by tropical storms are generally used to track back past storm events, as recorded in trees and stalagmites. Here, the propagation of isotopic spike is followed to improve the understanding of the freshwater circulation and the water dynamic within coastal ecosystems influenced by seawater.
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Bossu, J., Lehnebach, R., Corn, S., Regazzi, A., Beauchene, J., & Clair, B. (2018). Interlocked grain and density patterns in Bagassa guianensis: changes with ontogeny and mechanical consequences for trees. Trees, 32(6), 1643–1655.
Abstract: Interlocked grain and basic density increase from pith to bark in Bagassa guianensis and greatly improve trunk torsional stiffness and wood tenacity in the radial plane.
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Piponiot, C., Rödig, E., Putz, F. E., Rutishauser, E., Sist, P., Ascarrunz, N., et al. (2019). Can timber provision from Amazonian production forests be sustainable? Environmental Research Letters, 14(6), 064014.
Abstract: Around 30 Mm3 of sawlogs are extracted annually by selective logging of natural production forests in Amazonia, Earth’s most extensive tropical forest. Decisions concerning the management of these production forests will be of major importance for Amazonian forests’ fate. To date, no regional assessment of selective logging sustainability supports decision-making. Based on data from 3500 ha of forest inventory plots, our modelling results show that the average periodic harvests of 20 m3 ha−1 will not recover by the end of a standard 30 year cutting cycle. Timber recovery within a cutting cycle is enhanced by commercial acceptance of more species and with the adoption of longer cutting cycles and lower logging intensities. Recovery rates are faster in Western Amazonia than on the Guiana Shield. Our simulations suggest that regardless of cutting cycle duration and logging intensities, selectively logged forests are unlikely to meet timber demands over the long term as timber stocks are predicted to steadily decline. There is thus an urgent need to develop an integrated forest resource management policy that combines active management of production forests with the restoration of degraded and secondary forests for timber production. Without better management, reduced timber harvests and continued timber production declines are unavoidable.
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