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| Author |
Falkowski, M.; Jahn-Oyac, A.; Ferrero, E.; Issaly, J.; Eparvier, V.; Girod, R.; Rodrigues, A.M.S.; Stien, D.; Houel, E.; Dusfour, I. |
| Title |
Assessment of A Simple Compound-Saving Method to Study Insecticidal Activity of Natural Extracts and Pure Compounds Against Mosquito Larvae |
Type |
Journal Article |
| Year |
2016 |
Publication  |
Journal of the American Mosquito Control Association |
Abbreviated Journal |
Journal of the American Mosquito Control Association |
| Volume |
32 |
Issue |
4 |
Pages |
337-340 |
| Keywords |
Mosquitoes; natural insecticides; screening method |
| Abstract |
Research on natural insecticides has intensified with the spread of resistance to chemicals among insects, particularly disease vectors. To evaluate compounds, the World Health Organization (WHO) has published standardized procedures. However, those may be excessively compound-consuming when it comes to assessing the activity of natural extracts and pure compounds isolated in limited amount. As part of our work on the discovery of new mosquito larvicides from Amazonian plants, we developed a compound-saving assay in 5-ml glass tubes instead of WHO larval 100-ml cups. Comparing activity of synthetic and natural chemicals validated the glass tube assay. Raw data, lethal doses that kill 50% (LD50) and 90% (LD90) at 24 and 48 h, were highly correlated (0.68 < R2 < 0.96, P < 0.001, Pearson test) between cups and tubes. It was also established that 10 tubes (N = 50 larvae) provided the same level of sensitivity as 20 tubes (N = 100). This method proved suitable for rapid screening of natural extracts and molecules, identifying active compounds using 10 times less material than in the WHO protocol. © 2016 by The American Mosquito Control Association, Inc. |
| Address |
Sorbonne Universites, UPMC, Universite Paris 06, CNRS, Laboratoire de Biodiversite et Biotechnologies Microbiennes (USR 3579, LBBM), Observatoire Oceanologique, avenue de Fontaul e, Banyuls/Mer-sur-mer, France |
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Export Date: 3 March 2017 |
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EcoFoG @ webmaster @ |
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740 |
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| Author |
Alméras, T.; Clair, B. |
| Title |
Critical review on the mechanisms of maturation stress generation in trees |
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Journal Article |
| Year |
2016 |
Publication |
Journal of the Royal Society Interface |
Abbreviated Journal |
J R Soc Interface |
| Volume |
13 |
Issue |
122 |
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| Abstract |
Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering. |
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EcoFoG @ webmaster @ |
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719 |
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| Author |
Almeras, T.; Fournier, M. |
| Title |
Biomechanical design and long-term stability of trees: Morphological and wood traits involved in the balance between weight increase and the gravitropic reaction |
Type |
Journal Article |
| Year |
2009 |
Publication |
Journal of Theoretical Biology |
Abbreviated Journal |
J. Theor. Biol. |
| Volume |
256 |
Issue |
3 |
Pages |
370-381 |
| Keywords |
Mechanical design; Gravitropism; Bending stresses; Allometry; Reaction wood |
| Abstract |
Studies on tree biomechanical design usually focus on stem stiffness, resistance to breakage or uprooting, and elastic stability. Here we consider another biomechanical constraint related to the interaction between growth and gravity. Because stems are slender structures and are never perfectly symmetric, the increase in tree mass always causes bending movements. Given the current mechanical design of trees, integration of these movements over time would ultimately lead to a weeping habit unless some gravitropic correction occurs. This correction is achieved by asymmetric internal forces induced during the maturation of new wood. The long-term stability of a growing stem therefore depends on how the gravitropic correction that is generated by diameter growth balances the disturbance due to increasing self weight. General mechanical formulations based on beam theory are proposed to model these phenomena. The rates of disturbance and correction associated with a growth increment are deduced and expressed as a function of elementary traits of stem morphology, cross-section anatomy and wood properties. Evaluation of these traits using previously published data shows that the balance between the correction and the disturbance strongly depends on the efficiency of the gravitropic correction, which depends on the asymmetry of wood maturation strain, eccentric growth, and gradients in wood stiffness. By combining disturbance and correction rates, the gravitropic performance indicates the dynamics of stem bending during growth. It depends on stem biomechanical traits and dimensions. By analyzing dimensional effects, we show that the necessity for gravitropic correction might constrain stem allometric growth in the long-term. This constraint is compared to the requirement for elastic stability, showing that gravitropic performance limits the increase in height of tilted stem and branches. The performance of this function may thus limit the slenderness and lean of stems, and therefore the ability of the tree to capture light in a heterogeneous environment. (c) 2008 Elsevier Ltd. All rights reserved. |
| Address |
[Almeras, T.; Fournier, M.] INRA, UMR Ecol Forets Guyane, F-97310 Kourou, France, Email: t_almeras@hotmail.com |
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ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD |
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0022-5193 |
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ISI:000263077100008 |
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EcoFoG @ eric.marcon @ |
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123 |
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Stahl, C.; Burban, B.; Bompy, F.; Jolin, Z.B.; Sermage, J.; Bonal, D. |
| Title |
Seasonal variation in atmospheric relative humidity contributes to explaining seasonal variation in trunk circumference of tropical rain-forest trees in French Guiana |
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Journal Article |
| Year |
2010 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
| Volume |
26 |
Issue |
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Pages |
393-405 |
| Keywords |
bark; drought; secondary growth; seasonality; tropical rain forest; water |
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Large seasonal variation in the rate of change in girth of tropical rain-forest tree species has been described, but its origin is still under debate. We tested whether this variation might be related to variation in atmospheric relative humidity through its influence on bark water content and thickness. Variation in trunk circumference of 182 adult trees was measured about twice a month in an undisturbed tropical rain forest over 18 mo using dendrometers. Furthermore, a laboratory experiment was conducted to test the direct influence of relative air humidity on bark water content and thickness. in the field, most trees displayed highly positive rates of change in girth at the onset of the wet season, while a quarter of the trees displayed negative changes during long dry seasons, whatever their total annual growth. This variation was correlated with environmental conditions, particularly with atmospheric relative humidity. Trees with high bark water content and thickness displayed a stronger decrease in girth during the dry season. in the chamber experiment, desiccation induced a decrease in the diameter of the trunk sections in tandem with a decrease in bark water content. As a result, seasonal variation in the rate of change in girth of tropical rain-forest trees reflects variation in trunk biophysical properties, through the influence of relative humidity on bark properties. but not directly variation in secondary growth. |
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[Stahl, Clement; Burban, Benoit; Bompy, Felix; Jolin, Zachari B.; Sermage, Juliette; Bonal, Damien] INRA, UMR Ecol Forets Guyane 745, Kourou 97387, French Guiana, Email: bonal@nancy.inra.fr |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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| Notes |
ISI:000279100600005 |
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no |
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EcoFoG @ eric.marcon @ |
Serial |
57 |
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| Author |
Paine, C.E.T.; Harms, K.E.; Ramos, J. |
| Title |
Supplemental irrigation increases seedling performance and diversity in a tropical forest |
Type |
Journal Article |
| Year |
2009 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
| Volume |
25 |
Issue |
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Pages |
171-180 |
| Keywords |
diversity; Estacion Biologica Los Amigos; habitat filtering; palms; Peru; precipitation; seasonality; seedling recruitment |
| Abstract |
Diversity is positively correlated with water availability at global, continental and regional scales. With the objective of better understanding the mechanisms that drive these relationships. we investigated the degree to which variation in water availability affects the performance (recruitment, growth a rid survival) of juvenile trees. Precipitation was supplemented throughout two dry seasons in a seasonal moist forest in south-eastern Peru. Supplementing precipitation by 160 mm mo(-1), we increased soil moisture by 17%. To generate seedling communities or known species composition, we sowed 3840 seeds of 12 species. We monitored the fates of the 554 seedlings recruited from the sown seeds. as well as 1856 older non-sown seedlings (10 cm <= height < 50 cm), and 2353 saplings (> 1 m tall). Watering significantly enhanced young seedling growth and survival, increasing stern density and diversity. Watering diminished the recruitment of species associated with upland forests, but increased the survival of both upland- and lowland-associated species. Though supplemental watering increased the growth of older seedlings. their density and diversity were unaffected. Sapling performance was insensitive to watering. We infer that variation in dry-season water availability may affect seedling community structure by differentially affecting recruitment and increasing overall survival. These results suggest that differential seedling recruitment and survival may contribute to the observed relationships between water availability, habitat associations and patterns of tree species richness. |
| Address |
[Paine, C. E. Timothy; Harms, Kyle E.] Louisiana State Univ, Dept Biol Sci, Baton Rouge, LA 70803 USA, Email: timothy.paine@ecofog.gf |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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ISI:000264212400006 |
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EcoFoG @ eric.marcon @ |
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118 |
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Gibernau, M.; Orivel, J.; Dejean, A.; Delabie, J.; Barabe, D. |
| Title |
Flowering as a key factor in ant-Philodendron interactions |
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Journal Article |
| Year |
2008 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
| Volume |
24 |
Issue |
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Pages |
689-692 |
| Keywords |
Araceae; domatia; habitat; nest site; non-specific association; Philodendron solimoesense; territoriality |
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[Gibernau, Marc; Orivel, Jerome] Univ Toulouse 3, Lab Evolut & Divers Biol, UMR CNRS 5174, F-31062 Toulouse 9, France, Email: gibernau@cict.fr |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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ISI:000261254400012 |
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no |
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EcoFoG @ eric.marcon @ |
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128 |
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Baraloto, C.; Bonal, D.; Goldberg, D.E. |
| Title |
Differential seedling growth response to soil resource availability among nine neotropical tree species |
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Journal Article |
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2006 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
| Volume |
22 |
Issue |
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Pages |
487-497 |
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biomass allocation; Dicorynia; drought stress; Eperua; French Guiana; Goupia; Jacaranda; plasticity; Qualea; Recordorylon; relative growth rate; Sextonia; soil phosphorus; specific leaf area; Virola |
| Abstract |
Although the potential contribution to tropical tree species coexistence of niche differentiation along light gradients has received much attention, the degree to which species perform differentially along soil resource gradients remains unclear. To examine differential growth response to soil resources, we grew seedlings of nine tropical tree species at 6.0% of full sun for 12 mo in a factorial design of two soil types (clay and white sand), two phosphate fertilization treatments (control and addition of 100 mg P kg(-1)) and two watering treatments (field capacity and water limitation to one-third field capacity). Species differed markedly in biomass growth rate, but this hierarchy was almost completely conserved across all eight treatments. All species grew more slowly in sand than clay soils. and no species grew faster with phosphate additions. Only Eperua grandiflora and E. falcata showed significant growth increases in the absence of water limitation. Faster-growing species were characterized by high specific leaf area, high leaf allocation and high net assimilation rate but not lower root allocation. Slower-growing species exhibited greater plasticity in net assimilation rate. suggesting that tolerance of edaphic stress in these species is related more to stomatal control than to whole-plant carbon allocation. Although relative growth rate for biomass was correlated with both its physiological and morphological components. interspecific differences were best explained by differences in net assimilation rate across six of the eight treatments. A suite of traits including high assimilation and high specific leaf area maintains rapid growth rate of faster-growing species across a wide gradient of soil resources, but the lack of plasticity they exhibit may compromise their survival in the poorest soil environments. |
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Univ Michigan, Dept Ecol & Evolutionary Biol, Ann Arbor, MI 48109 USA, Email: baraloto.c@kourou.cirad.fr |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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ISI:000239975200001 |
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EcoFoG @ eric.marcon @ |
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178 |
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Epron, D.; Bosc, A.; Bonal, D.; Freycon, V. |
| Title |
Spatial variation of soil respiration across a topographic gradient in a tropical rain forest in French Guiana |
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Journal Article |
| Year |
2006 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
| Volume |
22 |
Issue |
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Pages |
565-574 |
| Keywords |
acrisol; carbon balance; carbon flux; gleysol; root biomass |
| Abstract |
The objective of this study was to analyse the factors explaining spatial variation in soil respiration over topographic transects in a tropical rain forest of French Guiana. The soil of 30 plots along six transects was characterized. The appearance of the 'dry to the touch' character at a depth of less than 1.2 m was used to discriminate soils exhibiting vertical drainage from soils exhibiting superficial lateral drainage and along with colour and texture, to define five classes from well-drained to strongly hydromorphic soils. Spatial variation in soil respiration was closely related to topographic position and soil type. Increasing soil water content and bulk density and decreasing root biomass and soil carbon content explained most of the decrease in soil respiration from the plateaux (vertically drained hypoferralic acrisol) to the bottomlands (haplic gleysol). These results will help to stratify further field experiments and to identify the underlying determinants of spatial variation in soil respiration to develop mechanistic models of soil respiration. |
| Address |
Univ Nancy 1, UMR 1137, INRA, UHP Ecol & Ecophysiol Forestieres,Fac Sci, F-54506 Vandoeuvre Les Nancy, France, Email: Daniel.Epron@scbiol.uhp-nancy.fr |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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ISI:000239975200008 |
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EcoFoG @ eric.marcon @ |
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179 |
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Bereau, M.; Bonal, D.; Louisanna, E.; Garbaye, J. |
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Do mycorrhizas improve tropical tree seedling performance under water stress and low light conditions? A case study with Dicorynia guianensis (Caesalpiniaceae) |
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Journal Article |
| Year |
2005 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
| Volume |
21 |
Issue |
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Pages |
375-381 |
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French Guiana; leaf gas exchange; mycorrhizal symbiosis; tropical forest; water limitation |
| Abstract |
We tested the response of seedlings of Diconyina guianensis, a major timber tree species of French Guiana, to mycorrhizal symbiosis and water limitation in a semi-con trolled experiment under natural light conditions. Under well-watered conditions, mycorrhizal colonization resulted in an increase of net photosynthesis, growth and phosphorus uptake. When submitted to water stress, no growth reduction of mycorrhizal seedlings was observed. Mycorrhizal seedlings were more sensitive to drought than non-mycorrhizal ones in terms of carbon assimilation, but not with regard to stomatal closure. In contrast to previous studies on temperate tree seedlings, this result precludes a mycorrhizal effect on the hydraulic properties of this species. Furthermore, our results suggest that below a specific threshold of soil moisture, carbon assimilation of D. guianensis seedlings was decreased by the mycorrhizal symbiosis. This is probably related to the competition between the plant and its host fungus for carbon allocation under low light intensity, even though it did not seem to have a significant effect on mortality in our experiment. |
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UMR Ecofog, Kourou 97387, French Guiana, Email: bercau.m@kourou.cirad.fr |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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ISI:000231009300003 |
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EcoFoG @ eric.marcon @ |
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232 |
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Koponen, P.; Nygren, P.; Domenach, A.M.; Le Roux, C.; Saur, E.; Roggy, J.C. |
| Title |
Nodulation and dinitrogen fixation of legume trees in a tropical freshwater swamp forest in French Guiana |
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Journal Article |
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2003 |
Publication |
Journal of Tropical Ecology |
Abbreviated Journal |
J. Trop. Ecol. |
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19 |
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655-666 |
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acetylene reduction assay; Bradyrhizobium; flooding; microtopography; N-15 natural abundance method; 16S rDNA sequencing |
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Nodulated legume trees comprised 43% of the stand basal area in the low, most frequently flooded microsites, and 23% in higher, drier microsites in a tropical freshwater swamp forest in French Guiana. Dinitrogen fixation in Pterocarpus officinalis, Hydrochorea corymbosa and Inga pilosula was confirmed by acetylene reduction assay (ARA), presence of leghaemoglobin in nodules and the N-15 natural abundance method. The results for Zygia cataractae were inconclusive but suggested N-2 fixation in drier microsites. Nodulated Inga disticha had a N-15-to-N-14 ratio similar to non-N-2-fixing trees, but ARA indicated nitrogenase activity and leghaemoglobin was present in nodules. All bacterial strains were identified as Bradyrhizobium spp. according to the partial 16S rDNA sequences, and they were infective in vitro in the model species Macroptilium atropurpuretan. About 35-50% of N in the leaves of P. officinalis, H. corymbosa and I. pilosula was fixed from the atmosphere. Dinitrogen fixation was estimated to contribute at least 8-13% and 1728% to whole-canopy N in high and low microsites, respectively. Symbiotic N, fixation appears to provide both a competitive advantage to legume trees under N-limited, flooded conditions and an important N input to neotropical freshwater swamp forests. |
| Address |
Univ Helsinki, Dept Forest Ecol, FIN-00014 Helsinki, Finland |
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CAMBRIDGE UNIV PRESS |
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0266-4674 |
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ISI:000186710800005 |
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EcoFoG @ eric.marcon @ |
Serial |
242 |
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