Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
Natural disturbances are the dominant form of forest regeneration and dynamics in unmanaged tropical forests. Monitoring the size distribution of treefall gaps is important to better understand and predict the carbon budget in response to land use and other global changes. In this study, we model the size frequency distribution of natural canopy gaps with a discrete power law distribution. We use a Bayesian framework to introduce and test, using Monte Carlo Markov chain and Kuo–Mallick algorithms, the effect of local physical environment on gap size distribution. We apply our methodological framework to an original light detecting and ranging dataset in which natural forest gaps were delineated over 30 000 ha of unmanaged forest. We highlight strong links between gap size distribution and environment, primarily hydrological conditions and topography, with large gaps being more frequent on floodplains and in wind-exposed areas. In the future, we plan to apply our methodological framework on a larger scale using satellite data. Additionally , although gap size distribution variation is clearly under environmental control, variation in gap size distribution in time should be tested against climate variability.
ISSN: 1726-4170

hal-01590729
https://hal-univ-guyane.archives-ouvertes.fr/hal-01590729
https://hal-univ-guyane.archives-ouvertes.fr/hal-01590729/document
https://hal-univ-guyane.archives-ouvertes.fr/hal-01590729/file/bg-14-353-2017.pdf
DOI : 10.5194/bg-14-353-2017

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Here we show that Daceton armigerum, an arboreal myrmicine ant whose workers are equipped with hypertrophied trap-jaw mandibles, is characterized by a set of unexpected biological traits including colony size, aggressiveness, trophobiosis and hunting behavior. The size of one colony has been evaluated at ca. 952,000 individuals. Intra- and interspecific aggressiveness were tested and an equiprobable null model used to show how D. armigerum colonies react vis-à-vis other arboreal ant species with large colonies; it happens that D. armigerum can share trees with certain of these species. As they hunt by sight, workers occupy their hunting areas only during the daytime, but stay on chemical trails between nests at night so that the center of their home range is occupied 24 hours a day. Workers tend different Hemiptera taxa (i.e., Coccidae, Pseudococcidae, Membracidae and Aethalionidae). Through group-hunting, short-range recruitment and spread-eagling prey, workers can capture a wide range of prey (up to 94.12 times the mean weight of foraging workers).
ISSN: 1932-6203

hal-00825759
https://hal.archives-ouvertes.fr/hal-00825759
https://hal.archives-ouvertes.fr/hal-00825759/document
https://hal.archives-ouvertes.fr/hal-00825759/file/Dejean2012_TheEcology.pdf
DOI : 10.1371/journal.pone.0037683

Éditeur(s) : HAL CCSD springer Link
Résumé : International audience
Experimental Astronomy

hal-01094521
https://hal.archives-ouvertes.fr/hal-01094521
BIBCODE : 2014ExA...tmp...41R
DOI : 10.1007/s10686-014-9383-4
ARXIV : 1310.0696

Éditeur(s) : HAL CCSD Montpellier : CIRAD
Résumé :  
Cette étude a pour objet l'extraction d'information sur les pistes forestières en milieu tropical par l'utilisation de l'imagerie satellitaire. Un procédé simple a été mis au point afin d'analyser des images entières de façon aisée et rapide. Le résultat, qui se veut robuste, consiste en la réalisation d'un plan vecteur intégrable dans un système d'information géographique. L'actualisation régulière de ce vecteur permet alors de contrôler l'extension du réseau et de l'impact de l'exploitation sur le massif forestier.
ISSN: 0006-579X

hal-01032117
https://hal.archives-ouvertes.fr/hal-01032117

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : 1. This study focuses on the importance in hyperdiverse regions, such as the Amazonian forest, of accelerating and optimising the census of invertebrate communities.2. We carried out low-intensity sampling of tropical moth (Lepidoptera) assemblages in disturbed forest fragments in Brazil.3. We combined DNA barcoding and taxonomists' expertise to produce fast and accurate surveys of local diversity, including the recognition and census of undescribed and endemic species.4. Integrating expert knowledge of species distributions, we show that despite limited sampling effort, our approach revealed an unexpectedly high number of new and endemic species in severely threatened tropical forest fragments.5. These results highlight the risk of silent centinelan extinctions and emphasise the urgent need for accelerated invertebrate surveys in high-endemism and human-impacted tropical forests.
EISSN: 1752-458X

hal-01602363
https://hal.archives-ouvertes.fr/hal-01602363
DOI : 10.1111/icad.12187
PRODINRA : 389851

Éditeur(s) : HAL CCSD Sociedade Entomológica do Brasil
Résumé : Variations in diel activity among hyperdiverse tropical communities of moths, despite representing a key component of niche partitioning between species, have barely been studied so far. Using light trapping from dawn to sunset over a 1-year period in French Guiana, we investigated these variations within and between two families of moths (Sphingidae and Saturniidae). Our results revealed contrasting patterns in flight activity at night between Sphingidae and Saturniidae. Sphingidae reached their peak in species richness and abundance between 7:00 and 8:00 p.m., followed by a decrease around 11:00 p.m. to midnight, whereas Saturniidae were continuously present throughout the night, with a peak around midnight. In addition, we found changes in diel activity among some of the most common genera in each family, highlighting distinct behavioral, physiological, and functional traits among taxa. Given differences in flight activity at different taxonomic levels, it is strongly recommended to monitor by light trapping throughout the night to effectively sample saturniid and sphingid assemblages, even though the activity of Sphingidae sharply declines after midnight. These results improve the general natural history information of tropical moths and reinforce the need of further research on the ecological and taxonomic consequences of differences in diel activity.
ISSN: 1519-566X

hal-01536447
https://hal.archives-ouvertes.fr/hal-01536447
DOI : 10.1007/s13744-014-0264-3
PRODINRA : 320714

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0378-8741

hal-01087030
https://hal-agroparistech.archives-ouvertes.fr/hal-01087030
DOI : 10.1016/j.jep.2009.07.037

Éditeur(s) : HAL CCSD Botanical Society of America
Résumé :  
To investigate the existence of coordinated sets of seedling traits adapted to contrasting establishment conditions, we examined evolutionary convergence in seedling traits for 299 French Guianan woody plant species and the stress response in a shadehouse of species representing seed size gradients within five major cotyledon morphology types. The French Guianan woody plant community has larger seeds than other tropical forest communities and the largest proportion of hypogeal cotyledon type (59.2%) reported for tropical forests. Yet the community includes many species with intermediate size seeds that produce seedlings with different cotyledonal morphologies. A split-plot factorial design with two light levels (0.8% and 16.1% PAR) and four damage treatments (control, seed damage, leaf damage, stem damage) was used in the shadehouse experiment. Although larger-seeded species had higher survival and slower growth, these patterns were better explained by cotyledon type than by seed mass. Even larger-seeded species with foliar cotyledons grew faster than species with reserve-type cotyledons, and survival after stem grazing was five times higher in seedlings with hypogeal cotyledons than with epigeal cotyledons. Thus, to predict seedling performance using seed size, seedling morphology must also be considered.
ISSN: 0002-9122

hal-01032177
https://hal.archives-ouvertes.fr/hal-01032177
DOI : 10.3732/ajb.94.6.901

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ETHNOPHARMACOLOGICAL RELEVANCE: Cutaneous leishmaniasis is a neglected disease with a high incidence in French Guiana, mainly in the middle and upper Oyapock basin, where Amerindian and some Brazilian people live. The main goals of this work were (i) to assess the knowledge about leishmaniasis in the different populations of the middle and upper Oyapock basin, (ii) to study the therapeutic strategies adopted by people affected by leishmaniasis and (iii) to document the use of phytotherapeutic remedies for leishmaniasis. Knowledge, attitudes and practices (K.A.P.) related to this disease and its treatments have been studied according to cultural group and geographical settlement. Within the Wayãpi group, the evolution of the knowledge of phytoremedies over the last 20 years has been characterised by literature-based comparisons. MATERIALS AND METHODS: A total of 144 questionnaires were administered in all the villages of the upper Oyapock and Camopi basins. Correspondence analyses were used for multivariate analysis. Plant species were identified at the Cayenne Herbarium (CAY). RESULTS: The biomedical concept of leishmaniasis correlates well with the Teko and Wayãpi concepts of kalasapa and kalasapau. Although the vector of this disease was not correctly identified, the most commonly cited aetiology (74.5%) was vector-borne, and related epidemiological schemes correlate well with the one encountered in French Guiana. Theoretically and practically, health centres were the most commonly used resource for diagnostic in instances of leishmaniasis infection (65.9%), independently of the patient's cultural group, along with the use of pharmaceutical drugs (85.3%). Pharmaceuticals were commonly utilised despite the frequent (51.5%) use of phytotherapeutic remedies, alone or in combination with drugs. The most cited medicinal plant species for the treatment of leishmaniasis included Eleutherine bulbosa (Mill.) Urb. (Iridaceae, cited 14 times), Euterpe oleracea Mart. (Arecaceae, 9), Cecropia obtusa Trecul (Cecropiaceae, 8), Jatropha curcas L. (Euphorbiaceae, 7), Ceiba pentandra (L.) Gaertn. (Bombacaceae, 6) and Carica papaya L. (Caricaceae, 6). Multiple correspondence analyses demonstrated that the species used in leishmaniasis remedies are more prone to vary by the user's place of residence than by their cultural origin, which indicates that exchange of knowledge about leishmaniasis remedies has occurred across different cultural groups. Literature-based comparisons between the remedies for leishmaniasis used by the Wayãpi during the 1980s showed a striking evolution, both in terms of diversity of species and number of plants used. The large number of species shared with other Guianese groups argues for intercultural exchange and may explain the majority (57.1%) of the newly used species highlighted in our study. CONCLUSIONS: Leishmaniasis is a well-known disease in the studied area. Phytotherapeutic treatments are still in use, although they are not the main source of remedies, and should undergo pharmacological studies to evaluate their potential therapeutic value.
ISSN: 0378-8741

pasteur-00634597
https://hal-riip.archives-ouvertes.fr/pasteur-00634597
DOI : 10.1016/j.jep.2011.07.044
PUBMED : 21816216

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Aim of the study: A knowledge attitude and practice study centred on leishmaniasis and its treatment was performed among the Chayahuita, an Amazonian Peruvian ethnic group living in an endemic area. This study documents traditional Chayahuita plant's use and disease concepts. Also, activty of some medicinal plants used by the Chayahuita is highlighted and discussed. Materials and methods: Ninety-three Chayahuita people were interviewed, following a semi-structured questionnaire focussed on disease knowledge and perception, personal attitude and healing practices. Simultaneously, a collection of plants was performed in different ecotopes, in order to make an extensive inventory of the pharmacopoeia. Results: For the Chayahuita, cutaneous (CL) and muco-cutaneous leishmaniasis (MCL) are considered as diseases of their own, with specific names, aetiologies, mode of transmission. Regarding CL, Chayahuita people consider that the humid characteristic of the skin ulcer is a discriminative fact orienting the diagnostic forTa'ta' (leishmaniasis). Forty-six different species were designated useful against LC and /or MCL (29 species by means of the questionnaire and 27 species when collecting in different ecotopes). Thirty-seven extracts corresponding to 31 species used medicinally were screened in vitro against Leishmania amnzonensis axenic amastigotes, assessing their viability by the reduction of tetrazolium salt (MTT). Six species displayed a good activity ( 10 μg/ml < IC50 < 20 μg/ml): an undetermined hemi-epiphytic Clusiaceae, Cyhianthus anthuriophyllus Pipoly (Myrsinaceae), two Piper, Piper sanguineispicum Trel., and Piper loretoanum Trel. (Piperaceae), Desmodium axillare Sw. DC. (Fabaceae), and Clibadium sylvestre (Aubl.) Baill. (Asteraceae). Conclusion: Perception of leishmaniasis, attitude, treatments and diet prohibitions still largely reflects traditional Chayahuita cosmovision, even if some tentative of bio-medical re-interpretation is arising.
ISSN: 0378-8741

hal-01087667
https://hal-agroparistech.archives-ouvertes.fr/hal-01087667
DOI : 10.1016/j.jep.2009.07.015

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0378-8741

hal-01082177
https://hal-agroparistech.archives-ouvertes.fr/hal-01082177
DOI : 10.1016/j.jep.2006.09.045

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
After noting the forecast of a La Niña episode, associated with heavy rainfall in French Guiana, we monitored the fate of wasp nests before and during the 2006 short rainy season. The population of the most abundant epiponine wasp species, Polybia bistriata, decreased dramatically during the short rainy season (60.6% of the nests disappeared) then remained low for at least 18 months. Colonies that survived moved from the shelter of large, low leaves (a situation well adapted to the previous dry season) of the most frequent substrate tree, Clusia grandiflora (Clusiaceae), to upper leaves, better ventilated and whose orientation provides good protection from the rain. Therefore, the possibility of moving the nest higher during the first rains following the dry season seems very adaptive as colonies that do not do so are eliminated during the La Niña years, whose frequency will increase with global climate change.
ISSN: 1631-0691

hal-00817397
https://hal.archives-ouvertes.fr/hal-00817397
DOI : 10.1016/j.crvi.2009.10.007
PUBMED : 20176334

Éditeur(s) : HAL CCSD
Résumé : The aim of this work was to search for new bioactive compounds, displaying either antiplasmodial or antifungal activity. Two strategies were developed here: the evaluation of traditional remedies identified as antimalarial through ethnopharmacological study, and the search for antifungal essential oils, the criterium being here a bioinspired approach. Our work led to the discovery that the antimalarial activity of Quassia amara L. (Simaroubaceae) fresh young leaves was due to the presence of a known quassinoid, simalikalactone D. In the case of Psidium acutangulum DC. (Myrtaceae), a flavonol glycosides mixture explained the activity observed for the decoction. The search for antifungal essential oils from the Amazonian flora lead to the identification of several interesting species, thus validating our bioinspired strategy. The essential oil of Otacanthus azureus (Linden) Ronse was among the most active ones, either alone or in combination with azole drugs. Eventually, a metabolomic study of the GC/MS composition of these oils allowed us to develop a statistical tool which could help to select interesting antifungal products. This work thus demonstrate the major interest of the two strategies - ethnopharmacology and bioinspiration - for the search of new bioactive compounds.
L'objectif du travail effectué était la recherche de nouvelles substances actives d'origine végétale, présentant soit une activité antiplasmodiale soit une activité antifongique. Cette étude a été menée suivant deux stratégies différentes: l'étude de remèdes traditionnels antipaludiques identifiés suite à des enquêtes ethnopharmacologiques, et la mise en évidence des propriétés antifongiques d'huiles essentielles grâce à une stratégie bioinspirée. La première partie du travail a permis de mettre en évidence le rôle d'un quassinoïde connu, la simalikalactone D, dans l'activité antipaludique d'une tisane de jeunes feuilles fraîches de Quassia amara L. (Simaroubaceae). Dans le cas de la décoction de rameaux de Psidium acutangulum DC. (Myrtaceae), c'est cette fois un mélange de flavonoïdes glycosylés qui est responsable de l'activité du remède. Dans le cadre de la recherche de nouvelles substances antifongiques, le criblage effectué a permis d'identifier de nombreuses huiles essentielles présentant des activités intéressantes, validant ainsi la démarche bioinspirée retenue dans ce cas. L'huile essentielle d'Otacanthus azureus (Linden) Ronse a en particulier démontré une activité remarquable, à la fois seule et en combinaison avec des antifongiques azolés. Enfin, l'étude métabolomique de la composition des huiles essentielles a permis de mettre au point un outil pouvant orienter la sélection des huiles en fonction des données obtenues en GC/MS dans l'optique de la recherche de nouvelles substances antifongiques. Ce travail démontre donc la validité des stratégies retenues - ethnopharmacologie et bioinspiration - dans la recherche de nouvelles substances bioactives.
https://tel.archives-ouvertes.fr/tel-00718910

tel-00718910
https://tel.archives-ouvertes.fr/tel-00718910
https://tel.archives-ouvertes.fr/tel-00718910/document
https://tel.archives-ouvertes.fr/tel-00718910/file/TheseEH2011_SUBST_BIOACTIVES.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
French Guiana (North-East Amazonia) records high malaria incidence rates. The traditional antimalarial remedy most widespread there is a simple tea made out from Quassia amara L. leaves (Simaroubaceae). This herbal tea displays an excellent antimalarial activity both in vitro and in vivo. A known quassinoid, simalikalactone D (SkD), was identified as the active compound, with an IC50 value of 10nM against FcB1 Plasmodium falciparum chloroquine resistant strain in vitro. Lastly, it inhibits 50% of Plasmodium yoelii yoelii rodent malaria parasite at 3.7 mg/kg/day in vivo by oral route. These findings confirm the traditional use of this herbal tea.
ISSN: 0378-8741

hal-00384337
https://hal.archives-ouvertes.fr/hal-00384337
DOI : 10.1016/j.jep.2006.04.017

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
ISSN: 2041-210X

hal-01504648
https://hal-agroparistech.archives-ouvertes.fr/hal-01504648
DOI : 10.1111/2041-210X.12591

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : International audience
The pollination of the genus Arum (Araceae) is mainly achieved by deception, the floral odour mimicking the pollinator ovipositing site. In order to discover the sensory organs involved in this attraction, we have studied the antennae of five species of psychodine moth-flies (former Psychoda sensu lato=Psychodini), pollinators of Arum spp. The antennae of the five Psychodini reveal seven types of sensilla: multiporous tribranched sensilla basiconica (sensilla ascoidea), multiporous sensilla basiconica, multiporous sensilla coeloconica, multiporous sensilla auricillica, uniporous sensilla basiconica, aporous sensilla chaetica, aporous Böhm’s sensilla. Each species possesses three, five or six of these sensillum types. All the multiporous sensilla are probably olfactory receptors while the uniporous sensilla basiconica must possess a contact chemoreceptive function. The multiporous tribranched sensilla basiconica (s. ascoidea), present in all the species, are the best candidates for the reception of the odours given off by the ovipositing sites and the inflorescences of Arum. The multiporous sensilla basiconica and the multiporous sensilla coeloconica may be involved respectively as CO2 receptors or thermoreceptors. Psychoda phalaenoides, which is the main pollinator of A. maculatum, is the species which possesses the largest number of antennal sensilla. The sexual dimorphism, studied only in Psycha grisescens, as concerns the number of sensilla and the absence of a sensillum type which differ according to sex, is difficult to interpret.
ISSN: 0037-9271

hal-01096881
https://hal-agroparistech.archives-ouvertes.fr/hal-01096881

Éditeur(s) : HAL CCSD Ecological Society of America
Résumé : CABI:20153174020
Understanding how plants are constructed - i.e., how key size dimensions and the amount of mass invested in different tissues varies among individuals - is essential for modeling plant growth, carbon stocks, and energy fluxes in the terrestrial biosphere. Allocation patterns can differ through ontogeny, but also among coexisting species and among species adapted to different environments. While a variety of models dealing with biomass allocation exist, we lack a synthetic understanding of the underlying processes. This is partly due to the lack of suitable data sets for validating and parameterizing models. To that end, we present the Biomass And Allometry Database (BAAD) for woody plants. The BAAD contains 259634 measurements collected in 176 different studies, from 21084 individuals across 678 species. Most of these data come from existing publications. However, raw data were rarely made public at the time of publication. Thus, the BAAD contains data from different studies, transformed into standard units and variable names. The transformations were achieved using a common workflow for all raw data files. Other features that distinguish the BAAD are: (i) measurements were for individual plants rather than stand averages; (ii) individuals spanning a range of sizes were measured; (iii) plants from 0.01-100 m in height were included; and (iv) biomass was estimated directly, i.e., not indirectly via allometric equations (except in very large trees where biomass was estimated from detailed sub-sampling). We included both wild and artificially grown plants. The data set contains the following size metrics: total leaf area; area of stem cross-section including sapwood, heartwood, and bark; height of plant and crown base, crown area, and surface area; and the dry mass of leaf, stem, branches, sapwood, heartwood, bark, coarse roots, and fine root tissues. We also report other properties of individuals (age, leaf size, leaf mass per area, wood density, nitrogen content of leaves and wood), as well as information about the growing environment (location, light, experimental treatment, vegetation type) where available. It is our hope that making these data available will improve our ability to understand plant growth, ecosystem dynamics, and carbon cycling in the world's vegetation.
ISSN: 0012-9658

hal-01535227
https://hal.archives-ouvertes.fr/hal-01535227
DOI : 10.1890/14-1889.1
PRODINRA : 306122

Éditeur(s) : HAL CCSD IM Publications
Résumé : 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.
ISSN: 1469-0667

hal-01532634
https://hal.archives-ouvertes.fr/hal-01532634
DOI : 10.1002/jms.3762
PRODINRA : 383376

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
ISSN: 0378-8741

hal-01152706
https://hal.archives-ouvertes.fr/hal-01152706
DOI : 10.1016/j.jep.2015.03.015

Éditeur(s) : HAL CCSD American Chemical Society
Résumé : Four new sesquiterpene alkaloids (1-4) with a β-dihydroagrofuran skeleton and a new triterpenoid (5) were isolated from an ethyl acetate extract of Maytenus oblongata stems. Their structures were elucidated using 1D and 2D NMR spectroscopy as well as MS and ECD experiments. The M. oblongata stem EtOAc extract and the pure compounds isolated were tested for larvicidal activity against Aedes aegypti under laboratory conditions, and compounds 2 and 3 were found to be active.
ISSN: 0163-3864

hal-01603411
https://hal.archives-ouvertes.fr/hal-01603411
DOI : 10.1021/acs.jnatprod.6b00850
PUBMED : 28186749
PRODINRA : 406747