Gruhn, G., Dumez, S., Moreau, P. - A., Roy, M., Morreale, O., Schimann, H., et al. (2017). The genus Resinicium in French Guiana and the West Indies: a morphological and molecular survey, revealing Resinicium grandisporum sp. nov. Cryptogamie, Mycologie, 38(4), 1–15.
Abstract: A revision of Resinicium collections (Basidiomycota, Hymenochaetales) from French Guiana and French West Indies is provided, and a new species, Resinicium grandisporum sp. nov., supported by morphological as well as phylogenetic analyses based on ITS DNA sequences, is described and illustrated. An updated key of the genus Resinicium is also provided, which includes species previously described from outside of the studied area.
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Leroy, C., Corbara, B., Dezerald, O., Trzcinski, M. K., Carrias, J. - F., Dejean, A., et al. (2017). What drives detrital decomposition in neotropical tank bromeliads? Hydrobiologia, 802(1), 85–95.
Abstract: Decomposition experiments that control leaf litter species across environments help to disentangle the roles of litter traits and consumer diversity, but once we account for leaf litter effects, they tell us little about the variance in decomposition explained by shifts in environmental conditions versus food-web structure. We evaluated how habitat, food-web structure, leaf litter species, and the interactions between these factors affect litter mass loss in a neotropical ecosystem. We used water-filled bromeliads to conduct a reciprocal transplant experiment of two litter species between an open and a forested habitat in French Guiana, and coarse- and fine-mesh enclosures embedded within bromeliads to exclude invertebrates or allow them to colonize leaf litter disks. Soft Melastomataceae leaves decomposed faster in their home habitat, whereas tough Eperua leaves decomposed equally in both habitats. Bacterial densities did not differ significantly between the two habitats. Significant shifts in the identity and biomass of invertebrate detritivores across habitats did not generate differences in leaf litter decomposition, which was essentially microbial. Despite the obvious effects of habitats on food-web structure, ecosystem processes are not necessarily affected. Our results pose the question of when does environmental determinism matter for ecosystem functions, and when does it not. © 2017, Springer International Publishing Switzerland.
Keywords: Context dependency; Ecosystem function; Food webs; Leaf litter; Phytotelmata; Rainforest
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Talaga, S., Dezerald, O., Carteron, A., Leroy, C., Carrias, J. - F., Céréghino, R., et al. (2017). Urbanization impacts the taxonomic and functional structure of aquatic macroinvertebrate communities in a small Neotropical city. Urban Ecosystems, 20(5), 1001–1009.
Abstract: Due to habitat fragmentation, resource disruption and pollution, urbanization is one of the most destructive forms of anthropization affecting ecosystems worldwide. Generally, human-mediated perturbations dramatically alter species diversity in urban sites compared to the surroundings, thus influencing the functioning of the entire ecosystem. We investigated the taxonomic and functional diversity patterns of the aquatic macroinvertebrate communities in tank bromeliads by comparing those found in a small Neotropical city with those from an adjacent rural site. Changes in the quality of detrital inputs in relation to lower tree diversity and the presence of synanthropic species are likely important driving forces behind the observed structural changes in the urban site. Leaf-litter processors (i.e., shredders, scrapers) were positively affected in the urban site, while filter-feeders that process smaller particles produced by the activity of the shredders were negatively affected. Because we cannot ascertain whether the decline in filter-feeders is related to food web-mediated effects or to competitive exclusion (Aedes aegypti mosquitoes were present in urban bromeliads only), further studies are necessary to account for the effects of intra-guild competition or inter-guild facilitation. © 2017, Springer Science+Business Media New York.
Keywords: Aedes aegypti; Bioindicator; Diversity; Functional traits; Tank bromeliads; Urban ecology
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Talaga, S., Petitclerc, F., Carrias, J. - F., Dezerald, O., Leroy, C., Céréghino, R., et al. (2017). Environmental drivers of community diversity in a neotropical urban landscape: a multi-scale analysis. Landscape Ecology, 32(9), 1805–1818.
Abstract: Context: Many aquatic communities are linked by the aerial dispersal of multiple, interacting species and are thus structured by processes occurring in both the aquatic and terrestrial compartments of the ecosystem. Objectives: To evaluate the environmental factors shaping the aquatic macroinvertebrate communities associated with tank bromeliads in an urban landscape. Methods: Thirty-two bromeliads were georeferenced to assess the spatial distribution of the aquatic meta-habitat in one city. The relative influence of the aquatic and terrestrial habitats on the structure of macroinvertebrate communities was analyzed at four spatial scales (radius = 10, 30, 50, and 70 m) using redundancy analyses. Results: We sorted 18,352 aquatic macroinvertebrates into 29 taxa. Water volume and the amount of organic matter explained a significant part of the taxa variance, regardless of spatial scale. The remaining variance was explained by the meta-habitat size (i.e., the water volume for all of the bromeliads within a given surface area), the distance to the nearest building at small scales, and the surface area of buildings plus ground cover at larger scales. At small scales, the meta-habitat size influenced the two most frequent mosquito species in opposite ways, suggesting spatial competition and coexistence. Greater vegetation cover favored the presence of a top predator. Conclusions: The size of the meta-habitat and urban landscape characteristics influence the structure of aquatic communities in tank bromeliads, including mosquito larval abundance. Modifications to this landscape will affect both the terrestrial and aquatic compartments of the urban ecosystem, offering prospects for mosquito management during urban planning. © 2017, Springer Science+Business Media B.V.
Keywords: Aquatic metacommunity; Landscape ecology; Mosquitoes; Neotropics; Scale dependency; Tank bromeliads; Urban ecology
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Roux, O., Vantaux, A., Petitclerc, F., Orivel, J., Dejean, A., & Billen, J. (2017). Structural adaptations and mechanism of reflex bleeding in the larvae of the myrmecophilous ladybird Diomus thoracicus. Arthropod Structure and Development, 46(4), 529–536.
Abstract: Reflex bleeding is an effective defensive mechanism against predators. When attacked, some insects emit hemolymph, which coagulates, quickly entangling their aggressor. Bleeding occurs at weak intersegmental membranes or through dedicated organs, which can be associated or not with glandular cells. Here, we describe the behavior and morphological structures involved in reflex bleeding in the larvae of the ladybird, Diomus thoracicus, which are intranidal parasites of the ant Wasmannia auropunctata. The larvae are tolerated by the ants thanks to odor mimicry, but some rare aggressive ant behaviors were observed that trigger reflex bleeding both at a pair of thoracic tubercles and a pair of posterodorsal abdominal humps. No glandular structure was found in association with these emission points, which suggests that the material emitted was hemolymph only. A 3D reconstruction suggested that reflex bleeding seems to be controlled by muscles whose contraction increases the internal hydrostatic pressure and pushes the hemolymph into a funnel-like structure with an opening to the outside. In D. thoracicus, the morphological structures involved in reflex bleeding are among the most complex and prominent described to date. © 2017 Elsevier Ltd
Keywords: 3D reconstruction; Coccinellidae; Myrmecophagous insect; Reflex bleeding; Ultrastructure
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Morel, H., Nicolini, E., Bossu, J., Blanc, L., & Beauchene, J. (2017). Qualité et usages du bois de cinq espèces forestières adaptées à la plantation à vocation de bois d’oeuvre et testées en Guyane française. Bois & Forêts des Tropiques, 334, 61–74.
Abstract: Des essais de plantations forestières ont été menés en Guyane française depuis le début des années 1960 sur plus de 138 espèces (70 espèces natives et 68 espèces exotiques). Une étude récente sur la productivité de ces espèces en plantation (projet ForesTreeCulture, 2013-2015) a mis en avant le fort potentieldeproductiondetroisespècesnatives ( Simarouba amara Aubl., Vochysia tomentosa (G. Mey.) DC., Bagassa guianensis ( Aubl.)) et d’une espèce d’Afrique de l’Ouest ( Tarrietia utilis Sprague) avec des volumes de bois produits supérieurs à 20 m3/ha/an. Cependant, les propriétés du bois de ces espèces commerciales ne sont connues qu’au travers d’arbres issus de forêt naturelle. Nous présentons les propriétés du bois de ces espèces en conditions de plantation – densité, retrait, élasticité, angle du fil, durabilité – et discutons de leurs potentiels et de leurs usages respectifs futurs. Une autre espèce, Cordia alliodora ((Ruiz et Pavon) Oken), a également été retenue bien qu’elle n’ait pas encore été plantée en Guyane française. Cette espèce, native de Guyane, est bien connue en Amérique latine pour son bois et son fort potentiel de croissance en milieu anthropisé.
Keywords: propriétés technologiques; qualité du bois; plantation; Guyane française
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Lebrini, M., Suedile, F., & Roos, C. (2018). Corrosion inhibitory action of ethanol extract from Bagassa guianensis on the corrosion of zinc in ASTM medium. Journal of Materials and Environmental Sciences, 9(2), 414–423.
Abstract: Ethanol extract of Bagassa guianensis was tested as corrosion inhibitor for zinc in ASTM medium using polarization and electrochemical impedance spectroscopy (EIS). The results obtained show that this plant extract could serve as an effective inhibitor for the corrosion of zinc in sodium chloride media. The extract obtained give inhibition around 85%. Polarization curves show that Bagassa guianensis extract affects the anodic and cathodic reactions and the corrosion potential values were shifted to the positive potentials in the presence of the crude extract in the ASTM medium. The experimental data obtained from EIS method show a frequency distribution and therefore a modelling element with frequency dispersion behavior, a constant phase element (CPE alpha,Q ) has been used. Graphical methods are illustrated by synthetic data to determine the parameter of CPE (alpha, Q). Studies on the phytochemical constituents of thetotal extract were also established. Electrochemical studies, on the chemical families present in the crude extract, were also carried out to find the main constituents responsible for corrosion inhibition properties of the plant extract.
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Gourlet-Fleury, S., Gazull, L., Bigombe Logo, P., Billand, A., Bolaluembe, P. - C., Boyemba, F., et al. (2017). Are logging concessions a threat to the peatlands in DRC? Bois et Forets des Tropiques, (334), 3–6.
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Dézerald, O., Leroy, C., Corbara, B., Dejean, A., Talaga, S., & Céréghino, R. (2018). Tank bromeliads sustain high secondary production in neotropical forests. Aquatic Sciences, 80(14).
Abstract: In neotropical landscapes, a substantial fraction of the still waters available is found within tank bromeliads, plants which hold a few milliliters to several litres of rainwater within their leaf axils. The bromeliad ecosystem is integrated into the functioning of rainforest environments, but no study has ever estimated the secondary production, nor the biomass turnover rates of bromeliad macroinvertebrates in relation to other functional traits. We estimated secondary production at invertebrate population to metacommunity level in bromeliads of French Guiana. Coleoptera, Diptera and Crustacea with traits that confer resistance to drought had lower biomass turnover, longer generation times, and slower individual growth than species without particular resistance traits, suggesting convergent life history strategies in phylogenetically distant species. Detritivores and predators accounted for 87% and 13% of the overall annual production, respectively, but had similar production to biomass ratios. An average bromeliad sustained a production of 23.93 g dry mass m−2 year−1, a value which exceeds the medians of 5.0–14.8 g DM m−2 year−1 for lakes and rivers worldwide. Extrapolations to the total water volumes held by bromeliads at our field site yielded secondary production estimates of 226.8 ± 32.5 g DM ha−1 year−1. We conclude that the ecological role of tank bromeliads in neotropical rainforests may be as important as that of other freshwater ecosystems. © 2018, Springer International Publishing AG, part of Springer Nature.
Keywords: Biomass turnover; Epiphytes; Food webs; Functional traits; Invertebrates; Rainforests
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Anouhe, J. - B. S., Niamké, F. B., Faustin, M., Virieux, D., Pirat, J. - L., Adima, A. A., et al. (2018). The role of extractives in the natural durability of the heartwood of Dicorynia guianensis Amsh: new insights in antioxydant and antifungal properties. Annals of Forest Science, 75(1).
Abstract: Key message: The natural durability of Dicorynia guianensis Amsh’s Heartwood is conferred by the high content of antioxidant phenolic compounds, especially tannins and flavonoids combined with the presence of fungistatic alkaloids. The content of phenolic compounds increases according to the natural durability classes, from durable wood (class 2) to moderately durable wood (class 3) and correlated to the antioxidant capacity.
Context: The heartwood of Dicorynia guianensis Amsh is resistant to white rot fungi decay, but the mechanism of this natural durability is not fully elucidated.
Aims: Biochemical studies were carried out in order to better understand the role of extractives in natural durability of D. guianensis.
Methods: The powders from durable and moderately durable heartwood were extracted with methanol, ethanol, and hot water. The quantity of total phenols, tannins, and flavonoids as well as antioxidant activity, evaluated by 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) were determined using colorimetric methods. Antifungal activity was assessed by using two white rot fungi. The bioactive fractions and compounds were obtained using bio-guided fractionation, HPLC isolation, MS and RMN spectroscopic analyses.
Results: Durable woods contain higher amounts of heartwood extract and antioxidant activity. Antioxidant activity was highly correlated with the content of phenolics. The purification of the most antioxidant fraction FII affords the characterization of (+)-catechin (−)-epicatechin, neoastilbin, astilbin, and isoastilbin. Alkaloid fraction FIII exhibits dose-dependent fungistatic activity against Pycnoporus sanguineus Linnaeus and Trametes versicolor Quelet.
Conclusion: Phenolic antioxidants and fungistatic alkaloids positively impact the natural durability of D. guianensis.
Keywords: Alkaloid; Antifungal; Antioxidant; Dicorynia guianensis; Heartwood; Natural durability; Phenols
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