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Groc, S., Delabie, J. H. C., Fernández, F., Leponce, M., Orivel, J., Silvestre, R., et al. (2014). Leaf-litter ant communities (Hymenoptera: Formicidae) in a pristine Guianese rain-forest: Stable functional structure versus high species turnover. Myrmecological News, 19, 43–51.
Abstract: We compared the ant assemblages from four very heterogeneous habitats over a short-distance elevational gradient of vegetation (due to the presence of an inselberg) at the Nouragues Research Station, French Guiana. We focused on litter-dwelling ants, combining the use of pitfall traps and the Winkler method according to the Ants of the Leaf Litter Proto-col. This permitted us to note (1) a high leaf-litter ant diversity overall and a decreasing diversity gradient from the lowland rainforest to the top of the inselberg, and (2) differences in species density, composition and functional struc-ture. While the ant assemblages on the plateau and inselberg can be considered functionally similar and typical of an Amazonian rainforest, that of the transition forest, relatively homogenous, rather corresponded to an ant fauna typical of open areas. By contrast, the liana forest assemblage was unexpectedly richer and denser than the others, sheltering a litter-dwelling ant fauna dominated by numerous and abundant cryptic species. These taxonomical and functional dissi-milarities may reflect the influence of the environmental heterogeneity, which, through variable abiotic conditions, can contribute to maintaining a notably rich ant biodiversity in these Neotropical habitats.
Keywords: Diversity gradient; Functional groups; Habitat heterogeneity; Litter-dwelling ant communities; Local scale; Pristine Amazonian rainforest; Taxonomic and functional structure
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Dejean, A., Corbara, B., Roux, O., & Orivel, J. (2014). The antipredatory behaviours of neotropical ants towards army ant raids (Hymenoptera: Formicidae). Myrmecological News, 19, 17–24.
Abstract: Group hunting, nomadism, wingless queens and colony fission characterize army ants, allowing them to have become the main tropical arthropod predators, mostly of other social insects. We studied the reactions of different ant species to the New World army ants Eciton burchellii (WESTWOOD, 1842) and E. hamatum (FABRICIUS, 1782) (Ecitoninae). We compiled our results with those already known in a synthetic appendix. A wide range of ant species react to the ap-proach of army ant raids by evacuating their nests with several workers transporting brood. The Eciton plunder a large part of the brood but rarely kill workers or queens, so that the latter return to their nest and resume colony activity. One exception is Paratrechina longicornis (LATREILLE, 1802) colonies that quickly evacuate their nest, so that the entire col-ony can generally escape a raid. Another is Leptogenys mexicana (MAYR, 1870) that leave their nests in columns while some nestmates resist the attack; they therefore lose only a few larvae. We noted that colonies can avoid being raided if the army ants ignore them (Atta cephalotes (LINNAEUS, 1758)), or if the workers produce a repellent substance (Azteca associated with myrmecophytic Cecropia) or are repellent themselves (Pachycondyla villosa (FABRICIUS, 1804), Ec-tatomma spp.). In the other cases, a part of the brood is lost. When an Eciton raid approached the base of their host-tree trunk, Azteca andreae GUERRERO, DELABIE and DEJEAN, 2010 workers dropped a part of their brood on the ground. While numerous Eciton workers were gathering up this brood, the front of the column advanced, so that the Azteca andreae nests were not plundered. Pheidole megacephala (FABRICIUS, 1793) nests were partly plundered as the workers reacted aggressively, blocking the Eciton inside their nests during a long time. When the latter returned toward their bivouac, they were attacked and killed by their nestmates whether or not they had retrieved Pheidole brood. Consequently, the front of the column turned away from the Pheidole nest.
Keywords: Antipredatory behaviour; Army ants; Ecitoninae; Prey-ant species
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Brousseau, L., Tinaut, A., Duret, C., Lang, T., Garnier-Gere, P., & Scotti, I. (2014). High-throughput transcriptome sequencing and preliminary functional analysis in four Neotropical tree species. BMC Genomics, 15(238), 1–13.
Abstract: Background: The Amazonian rainforest is predicted to suffer from ongoing environmental changes. Despite the need to evaluate the impact of such changes on tree genetic diversity, we almost entirely lack genomic resources. Results: In this study, we analysed the transcriptome of four tropical tree species (Carapa guianensis, Eperua falcata, Symphonia globulifera and Virola michelii) with contrasting ecological features, belonging to four widespread botanical families (respectively Meliaceae, Fabaceae, Clusiaceae and Myristicaceae). We sequenced cDNA libraries from three organs (leaves, stems, and roots) using 454 pyrosequencing. We have developed an R and bioperl-based bioinformatic procedure for de novo assembly, gene functional annotation and marker discovery. Mismatch identification takes into account single-base quality values as well as the likelihood of false variants as a function of contig depth and number of sequenced chromosomes. Between 17103 (for Symphonia globulifera) and 23390 (for Eperua falcata) contigs were assembled. Organs varied in the numbers of unigenes they apparently express, with higher number in roots. Patterns of gene expression were similar across species, with metabolism of aromatic compounds standing out as an overrepresented gene function. Transcripts corresponding to several gene functions were found to be over- or underrepresented in each organ. We identified between 4434 (for Symphonia globulifera) and 9076 (for Virola surinamensis) well-supported mismatches. The resulting overall mismatch density was comprised between 0.89 (S. globulifera) and 1.05 (V. surinamensis) mismatches/100 bp in variation-containing contigs.Conclusion: The relative representation of gene functions in the four transcriptomes suggests that secondary metabolism may be particularly important in tropical trees. The differential representation of transcripts among tissues suggests differential gene expression, which opens the way to functional studies in these non-model, ecologically important species. We found substantial amounts of mismatches in the four species. These newly identified putative variants are a first step towards acquiring much needed genomic resources for tropical tree species. © 2014 Brousseau et al.; licensee BioMed Central Ltd.
Keywords: 454-Pyrosequencing; Polymorphism discovery; Tropical rainforest tree species
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Marcon, E., Scotti, I., Herault, B., Rossi, V., & Lang, G. (2014). Generalization of the partitioning of Shannon diversity. PLoS ONE, 9(3), e90289.
Abstract: Traditional measures of diversity, namely the number of species as well as Simpson's and Shannon's indices, are particular cases of Tsallis entropy. Entropy decomposition, i.e. decomposing gamma entropy into alpha and beta components, has been previously derived in the literature. We propose a generalization of the additive decomposition of Shannon entropy applied to Tsallis entropy. We obtain a self-contained definition of beta entropy as the information gain brought by the knowledge of each community composition. We propose a correction of the estimation bias allowing to estimate alpha, beta and gamma entropy from the data and eventually convert them into true diversity. We advocate additive decomposition in complement of multiplicative partitioning to allow robust estimation of biodiversity. © 2014 Marcon et al.
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Dejean, A., Labrière, N., Touchard, A., Petitclerc, F., & Roux, O. (2014). Nesting habits shape feeding preferences and predatory behavior in an ant genus. Naturwissenschaften, 101(4), 323–330.
Abstract: We tested if nesting habits influence ant feeding preferences and predatory behavior in the monophyletic genus Pseudomyrmex (Pseudomyrmecinae) which comprises terrestrial and arboreal species, and, among the latter, plant-ants which are obligate inhabitants of myrmecophytes (i.e., plants sheltering so-called plant-ants in hollow structures). A cafeteria experiment revealed that the diet of ground-nesting Pseudomyrmex consists mostly of prey and that of arboreal species consists mostly of sugary substances, whereas the plant-ants discarded all the food we provided. Workers forage solitarily, detecting prey from a distance thanks to their hypertrophied eyes. Approach is followed by antennal contact, seizure, and the manipulation of the prey to sting it under its thorax (next to the ventral nerve cord). Arboreal species were not more efficient at capturing prey than were ground-nesting species. A large worker size favors prey capture. Workers from ground- and arboreal-nesting species show several uncommon behavioral traits, each known in different ant genera from different subfamilies: leaping abilities, the use of surface tension strengths to transport liquids, short-range recruitment followed by conflicts between nestmates, the consumption of the prey's hemolymph, and the retrieval of entire prey or pieces of prey after having cut it up. Yet, we never noted group ambushing. We also confirmed that Pseudomyrmex plant-ants live in a kind of food autarky as they feed only on rewards produced by their host myrmecophyte, or on honeydew produced by the hemipterans they attend and possibly on the fungi they cultivate. © 2014 Springer-Verlag Berlin Heidelberg.
Keywords: Ant genus Pseudomyrmex; Arboreal and ground nesting; Feeding preferences; Myrmecophytism; Predation
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Zaremski, A., Gastonguay, L., Zaremski, C., Chaffanel, F., Le Floch, G., & Beauchene, J. (2013). Capacity of tropical forest soils of french guiana and réunion for depolluting the woods impregnated with biocides. Bois Forets Tropiques, 67(318), 51–58.
Abstract: Wood material for a long time was treated with fungicides or insecticides whose impact on the soil after leaching constitutes a real environmental problem. Nowadays, most of the studies on degradation of these toxic products was carried out with microorganisms which have been isolated in the laboratory. The present study sought to refine the knowledge vis-à-vis these microorganisms, especially wood-destroying fungi degrading pollutants in situ, from which few data are actually available. To decontaminate treated wood, the capacity of wooddestroying microorganisms from tropical forest soils of French Guiana and Reunion was evaluated to degrade toxic biocides. These are pentachlorophenol (PCP) and copper- chromium arsenic based compounds (CCA). Monitoring the degradation of samples of red pine, Pinus resinosa, shows that soils of French Guiana are more efficient than those of Reunion Island in terms of microbial activity vis-àvis these two biocides. A significant difference in loss of mass in specimens of red pine treated with CCA and PCP can range from single to double (respectively 18% and 30%). These findings confirm that CCA is less leacher and less degradable than the PCP by microorganisms in the soil. According to the scale of mass loss in laboratory tests, the wood so treated would be classified very not durable after three years of contact with soil, while the treatment is expected to be very durable.
Keywords: Bioremediation; Copper chromium arsenic(CCA) wood-destroying fungi; Depollution; Loss of mass; Pentachlorophenol(PCP); Treated timber; Tropical soil
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Niamké, F. B., Amusant, N., Kadio, A. A., Thevenon, M. - F., Nourissier, S., Adima, A. A., et al. (2014). Rapid prediction of phenolic compounds as chemical markers for the natural durability of teak (Tectona grandis Linn f.) heartwood by near infrared spectroscopy. J. Near Infrared Spectrosc., 22(1), 35–43.
Abstract: Near infrared (NIR) spectroscopy provides rapid and non-destructive analysis of wood properties and composition. In this study, we aimed to use NIR measurement for the prediction of teak phenolic compounds, which are chemical markers for natural durability of wood. Twenty-seven teak trees from two geographical zones (Malaysia and Ivory Coast) were used. On ground heartwood samples, the content of total phenolics and individual quinones (tectoquinone, 2-(hydroxymethyl)anthraquinone, 2-anthraquinone carboxylic acid, 1,4-naphthoquinoneand 4c,5c-dihydroxy-epiisocatalponol) were determined using high performance liquid chromatography (HPLC). Partial least squares (PLS) regression with NIR spectra on the same samples and phenolic data was used to build NIR models for phenolic contents. The PLS models for the total predicted phenolics and three quinone contents (tectoquinone, 2-(hydroxymethyl) anthraquinone, and 4¢,5¢-dihydroxy-epiisocatalponol) showed a good ratio of performance to deviation (RPD ≥ 2.5), strong coefficients of determination (r2 ≥ 0.8) and the prediction errors were consistent with the reference method. These results demonstrate that NIR spectroscopy can be reliable for the evaluation of total phenolics and individual quinones in teak heartwood wood meal. NIR spectroscopy is a promising technique for rapidly providing information on the quinone contents in teak wood and indirectly for knowing its natural durability. This finding leads to a precise, non-destructive tool for teak wood quality evaluation. © IM Publications LLP 2014.
Keywords: Heartwood; Hplc; Natural durability; NIR spectroscopy; Phenolic; Prediction; Quinone; Tectona grandis
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Wagner, F., Rossi, V., Aubry-Kientz, M., Bonal, D., Dalitz, H., Gliniars, R., et al. (2014). Pan-tropical analysis of climate effects on seasonal tree growth. PLoS ONE, 9(3), e92337.
Abstract: Climate models predict a range of changes in tropical forest regions, including increased average temperatures, decreased total precipitation, reduced soil moisture and alterations in seasonal climate variations. These changes are directly related to the increase in anthropogenic greenhouse gas concentrations, primarily CO2. Assessing seasonal forest growth responses to climate is of utmost importance because woody tissues, produced by photosynthesis from atmospheric CO2, water and light, constitute the main component of carbon sequestration in the forest ecosystem. In this paper, we combine intra-annual tree growth measurements from published tree growth data and the corresponding monthly climate data for 25 pan-tropical forest sites. This meta-analysis is designed to find the shared climate drivers of tree growth and their relative importance across pan-tropical forests in order to improve carbon uptake models in a global change context. Tree growth reveals significant intra-annual seasonality at seasonally dry sites or in wet tropical forests. Of the overall variation in tree growth, 28.7% was explained by the site effect, i.e. the tree growth average per site. The best predictive model included four climate variables: precipitation, solar radiation (estimated with extrasolar radiation reaching the atmosphere), temperature amplitude and relative soil water content. This model explained more than 50% of the tree growth variations across tropical forests. Precipitation and solar radiation are the main seasonal drivers of tree growth, causing 19.8% and 16.3% of the tree growth variations. Both have a significant positive association with tree growth. These findings suggest that forest productivity due to tropical tree growth will be reduced in the future if climate extremes, such as droughts, become more frequent. © 2014 Wagner et al.
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Chartier, M., Gibernau, M., & Renner, S. S. (2014). The evolution of pollinator-plant interaction types in the araceae. Evolution, 68(5), 1533–1543.
Abstract: Most plant-pollinator interactions are mutualistic, involving rewards provided by flowers or inflorescences to pollinators. Antagonistic plant-pollinator interactions, in which flowers offer no rewards, are rare and concentrated in a few families including Araceae. In the latter, they involve trapping of pollinators, which are released loaded with pollen but unrewarded. To understand the evolution of such systems, we compiled data on the pollinators and types of interactions, and coded 21 characters, including interaction type, pollinator order, and 19 floral traits. A phylogenetic framework comes from a matrix of plastid and new nuclear DNA sequences for 135 species from 119 genera (5342 nucleotides). The ancestral pollination interaction in Araceae was reconstructed as probably rewarding albeit with low confidence because information is available for only 56 of the 120-130 genera. Bayesian stochastic trait mapping showed that spadix zonation, presence of an appendix, and flower sexuality were correlated with pollination interaction type. In the Araceae, having unisexual flowers appears to have provided the morphological precondition for the evolution of traps. Compared with the frequency of shifts between deceptive and rewarding pollination systems in orchids, our results indicate less lability in the Araceae, probably because of morphologically and sexually more specialized inflorescences. © 2013 The Society for the Study of Evolution.
Keywords: Ancestral state reconstruction; Inflorescence traits; Phylogeny; Pollination syndromes; Trap flowers
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Chevalier, M., Robert, F., Amusant, N., Traisnel, M., Roos, C., & Lebrini, M. (2014). Enhanced corrosion resistance of mild steel in 1 M hydrochloric acid solution by alkaloids extract from Aniba rosaeodora plant: Electrochemical, phytochemical and XPS studies. Electrochim Acta, 131, 96–105.
Abstract: The present report continues to focus on the broadening application of plant extracts for metallic corrosion control and reports on the inhibiting effect of the Aniba rosaeodora alkaloidic extract on the corrosion of C38 steel in 1 M hydrochloric acid. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of inhibitor. Studies on the phytochemical constituents were established to determine the active(s) molecule(s). XPS was also carried out to establish the mechanism of corrosion inhibition of the active molecule of C38 steel in acid solution. The inhibitor extract acted as an efficient corrosion inhibitor in 1 M HCl. The experimental data obtained from EIS method show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPEα, Q) has been used. Graphical methods are illustrated by synthetic data to determine the parameter of CPE (α, Q). Polarization studies showed that the Aniba rosaeodora alkaloidic extract was a mixed-type inhibitor and its inhibition efficiency increased with the inhibitor concentration. Studies on the phytochemical constituents of the total alkaloids extract shows that it contains the anibine as the major alkaloid. The results obtained from the electrochemical study have clearly showed that the inhibition efficiency of the total extract was due to the presence of anibine. The XPS studies showed the formation of inhibitor layer containing the Aniba rosaeodora alkaloidic extract and the anibine molecules. © 2014 Elsevier Ltd. All rights reserved.
Keywords: Acidic media; Adsorption-XPS; Aniba rosaeodora extract; Anibine; C38 steel; Corrosion inhibitor
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