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Plantes et invertébrés des systèmes agroforestiers tempérés : influence des linéaires sous-arborés

EABIOMEAGROSUP; De par leur structure tridimensionnelle, leur large gamme de porosité, la diversité de leurs caractéristiques physicochimiques et des conditions microclimatiques, les sols abritent un nombre considérable, parfois inestimable d'organismes. Au sein des agroécosystèmes, les enjeux sont de comprendre les relations entre la plante cultivée et son environnement biophysique incluant les interactions biologiques et les effets de la biodiversité des organismes des sols. L’impact de la faune du sol sur la production primaire peut être vu au travers de leur effet sur les fonctions de (i) recyclage des nutriments, (ii) entretien de la stabilité/structure du sol, (iii) contrôle des bioagresseurs et (iv) support de biodiversité. Ces fonctions écosystémiques sont respectivement associées du point de vue des plantes à (i) leur nutrition, (ii) le milieu physique dans lequel les plantes se développent, (iii) leur santé et (iv) les interactions entre plantes. L’effet de la faune du sol sur chaque fonction peut être expliqué par de nombreux processus et mécanismes qui impliquent l’ensemble des organismes des sols. Ces différents processus sont détaillés dans ce chapitre.

Laboratory microcosms were used to determine how leaf degradation processes (C–CO2 release and leaf mass loss) are affected by the diversity of soil macro-invertebrate assemblages (comprising earthworms, woodlice and millipedes). The relationships were tested using different measures of diversity (number of species and trait dissimilarities). Net diversity effects and transgressive overyielding were calculated to disentangle the relative impacts of negative, neutral and positive species interactions on the relationships observed. Minimum trait dissimilarities were found to be correlated with leaf mass loss and, to a lesser extent, with C–CO2 release. This suggests that process rates increase as trait similarity in species assemblage decreases. Conversely, increasing the number of species resulted in the saturation of process rates after 1–2 species had been added to a microcosm. The process rates observed could mainly be explained by positive species interactions (40–50% of microcosms being process-dependent), followed by neutral interactions (20–40%) and selection effects or negative interactions (less than 20%). These results thus suggest that the effects of a soil macro-invertebrate assemblage on soil processes are more likely to be driven by complementarity or facilitation than by competition., Es wurden Labormikrokosmen benutzt, um zu bestimmen, wie die Blattzersetzungsprozesse (C CO2-Freisetzung und Blattmassenverlust) durch die Diversität der Boden-Makroinvertebraten-Gemeinschaften (zusammengesetzt aus Würmern, Asseln und Tausendfüsslern) beeinflusst werden. Die Beziehungen wurden untersucht, indem verschiedene Maße der Diversität (Artenzahl und Dissimilarität der Eigenschaften) benutzt wurden. Die Netto-Diversitätseffekte und der transitive Überfluss wurden berechnet, um die relativen Auswirkungen der negativen, neutralen und positiven Interaktionen zwischen den Arten auf die beobachteten Beziehungen zu trennen. Die Dissimilarität sowohl in den Eigenschaften der Faezes als auch in den morphologischen Eigenschaften korrelierten mit dem Verlust der Blattmasse und in geringerem Maße mit der C CO2-Freisetzung und lässt vermuten, dass eine begrenzte Ähnlichkeit zwischen den koexistierenden Arten zu einer höheren Rate des Prozesses führt. Eine Erhöhung der Artenzahl resultierte in einer Sättigung des Prozesses wenn 1–2 Arten zu den Mikrokosmen hinzugefügt wurden. Die beobachteten Raten der Prozesse konnten vor allem mit positiven Interaktionen zwischen den Arten erklärt werden (40% bis 50% der Mikrokosmen waren prozessabhängig), gefolgt von neutralen Interaktionen (20% bis 40%) und Selektionseffekten bzw. negativen Interaktionen (weniger als 20%). Die Ergebnisse lassen daher vermuten, dass die Auswirkungen einer Boden-Makroinvertebraten-Gesellschaft mit größerer Wahrscheinlichkeit durch Komplementarität oder Begünstigung als durch Konkurrenz gesteuert werden.

Description du sujet. L’article traite de la macrofaune du sol, composante clé du fonctionnement biologique du sol.Objectifs. Cette étude, réalisée en 2015, a eu pour objectif de tester l’effet de pratiques culturales et de systèmes de culture sur la macrofaune du sol dans une zone d’agriculture-élevage des Hautes-Terres de Madagascar. Cinq systèmes de culture ont été étudiés : cultures annuelles labourées annuellement avec apport de fumier modéré (LAMF) ou élevé (LAEF), cultures fourragères pérennes sans labour et avec apport de fumier élevé (CFEF), cultures annuelles en agriculture de conservation sans labour et apport de fumier modéré (ACMF) et pâturages permanents, non labourés et sans apport de fumier (PP0F).Méthode. Pour chaque système de culture, 12 parcelles d’expérimentation ou d’exploitation agricole ont fait l’objet d’un échantillonnage de la macrofaune du sol avec cinq monolithes de sol par parcelle, sur 30 cm de profondeur. Résultats. Cinquante-deux espèces d’invertébrés, classées en 15 ordres taxonomiques et 6 groupes fonctionnels, ont été identifiées. Pour les cultures annuelles sans labour, l’absence de travail du sol a favorisé la diversité taxonomique et la densité de la macrofaune, n’a pas réduit la densité des vers blancs (larves de Coléoptères Scarabeoideae) rhizophages mais a entrainé une diminution des densités de vers de terre par rapport au mode de culture fourragère. En systèmes labourés, l’intensité d’application du fumier n’a eu d’effet ni sur les vers blancs ni sur les vers de terre.Conclusions. Cette étude sur la macrofaune du sol dans cette région de Madagascar a permis de mieux percevoir les pratiques et les systèmes les plus favorables aux invertébrés utiles (comme les vers de terre) et plus défavorables aux invertébrés nuisibles (comme les vers blancs). Ceci permettra d’orienter les paysans dans la gestion de leurs terres., Crop management and soil macrofauna diversity in the Highlands of MadagascarDescription of the subject. This article deals with soil macrofauna as a key component of soil biological functioning.Objectives. This original study, performed in 2015, aimed to compare the effect of contrasted land uses and cultural practices on soil macrofauna in a crop-livestock area in the Madagascar Highlands. Five cropping systems were investigated: annual crops under tillage with low (LAMF) and high (LAEF) manure inputs, permanent tilled forage crops with high manure inputs (CFEF), crops under conservation agriculture without tillage or permanent mulch cover and with medium manure inputs (ACMF), and permanent pastures without tillage and without manure (PP0F).Method. In each of these five cropping systems, soil macrofauna was sampled in 12 plots from experimental trials and smallholder farms at the end of the rainy season. In each plot, soil macrofauna was hand-sorted from five soil monoliths at a 0-30 cm depth.Results. Fifty-two species were identified and organized into 15 orders and six functional groups. In the annual cropping systems (ACMF), the absence of tillage and the presence of a permanent soil cover increased soil macrofauna diversity and density without reducing harmful white grubs (Scarabeoid beetle larvae), while earthworm density was reduced in comparison with the CFEF system. In conventional tillage cropping systems, manure input intensity (LAMF versus LAEF) had no specific effects on white grubs or earthworms.Conclusions. This study on soil macrofauna in the Highlands of Madagascar helped to establish which agricultural practices and farming systems are favourable to beneficial soil invertebrates such as earthworms, and unfavourable to harmful insects such as white grubs. This will help farmers to achieve a more sustainable crop management.

List of contributors Foreword Introduction Serge Morand, Boris Krasnov and Tim Littlewood Part I. Evolutionary Ecology of Parasite Diversity: 1. Quantifying parasite diversity Robert Poulin 2. Relationships between parasite diversity and host diversity Boris Krasnov and Robert Poulin 3. Patterns of diversity and distribution of aquatic invertebrates and their parasites Tommy L. F. Leung, Camilo Mora and Klaus Rohde 4. Under the changing climate: how shifting geographic distributions and sexual selection shape parasite diversification Lajos Rozsa, Piotr Tryjanowski and Zoltan Vas 5. Impacts of parasite diversity on wild vertebrates: limited knowledge but important perspectives Frederic Bordes and Serge Morand Part II. The Evolutionary History of Parasite Diversity: 6. Revealing parasite diversity using brute force molecular techniques and gently persuasive microscopy Aurelie Chambouvet, Thomas A. Richards, David Bass and Sigrid Neuhauser 7. Evolution of simian retroviruses Ahidjo Ayouba and Martine Peeters 8. The diversity and phylogeny of Rickettsia Lucy A. Weinert 9. Advances in the classification of Acanthocephalans: evolutionary history and evolution of the parasitism Martin Garcia-Varela and Gerardo Perez-Ponce de Leon 10. The study of primate evolution from a lousy perspective David L. Reed, Julie M. Allen, Melissa A. Toups, Bret Boyd and Marina Ascunce 11. Host correlates of diversification in avian lice Lajos Rozsa and Zoltan Vas 12. Evolutionary history of Siphonaptera: fossils, origins, vectors Katharina Dittmar, Qiyun Zhu, Michael W. Hastriter and Michael F. Whiting 13. Bat fly evolution from the Eocene to the present (Hippoboscoidea, Streblidae and Nycteribiidae) Katharina Dittmar, Solon F. Morse, Carl W. Dick and Bruce D. Patterson 14. The evolution of parasitism and host associations in mites Ashley Dowling 15. Nematode life-traits diversity in the light of their phylogenetic diversification Serge Morand, Steve Nadler and Arne Skorping 16. Phylogenetic patterns of diversity in the cestodes and trematodes Timothy J. Littlewood, Rodney A. Bray and Andrea Waeschenbach 17. Patterns of diversification in the parasites of Caribbean Anolis lizards Bryan G. Falk and Susan L. Perkins Part III. Combining Ecology and Phylogenetics: 18. Comparative analysis - recent developments and uses with parasites Yves Desdevises, Serge Morand, Boris R. Krasnov and Julien Claude 19. Phylogenetic signals in ecological properties of parasites Boris R. Krasnov, Serge Morand and Robert Poulin 20. Parasite species coexistence and the evolution of the parasite niche Andrea Simkova and Serge Morand 21. A community perspective on the evolution of virulence Hadas Hawlena and Frida Ben-Ami 22. Host-specificity and species jumps in fish-parasite systems Maarten P. M. Vanhove and Tine Huyse 23. When is cophylogeny evidence of coevolution? Timothee Poisot 24. Bringing together phylogenies and behaviour in host-parasite interactions Tania Jenkins and Philippe Christe 25. The evolutionary epidemiology of the Hepatitis C virus Peter V. Markov, Rebecca R. Gray, James Iles and Oliver G. Pybus Conclusion and perspectives Armand Kuris Index.

Accepte le 19 novembre 2009 T Western Amazonian basin has long been recognized as supporting one of the highest levels of biological diversity in the world. Insects are particularly abundant and species rich in this region, yet the task of describing new species, discovering their range, understanding the factors that govern their distribution and the degree of alteration in their community structure as a result of habitat degradation is still in its early stages. Th e wide diversity of habitats that Ecuador possesses in a small area makes it an ideal location for biodiversity and ecological research. Although the diversity of many groups (e.g. plants, birds, and frogs) has been the focus of numerous publications data on the entomological fauna in Ecuador are scarce, mostly limited to the response of insect diversity to altitudinal gradients. During the past decades, the Ecuadorian research in Entomology has been dominated by taxonomic studies. Face to the acute environmental awareness and called attention to the pressing problem of biodiversity conservation, this taxonomic knowledge has recently been refocused in an ecological perspective. Th e nine contributions to this special issue aim to present some of the major lines of research developed in ecological entomology in Ecuador, mainly at the Museum of Zoology of the Catholic University of Quito (QCAZ), Invertebrate Section. Th e studies concern diff erent ecosystems of Ecuador such as lowland Amazonian rainforests (Carpio et al. 2009, Checa et al. 2009), Montane cloud forest (Donoso & Ramon 2009) and Andean paramos (Moret 2009). Most studies however cover a wide range of biogeographic regions (Badher et al. 2009, Barragan et al. 2009, Donoso et al. 2009, Dangles et al. 2009) including comparisons with other regions from Latin America (Cardenas et al. 2009). Th e coverage of taxa (e.g. Diptera, Isoptera, Hymenoptera, Lepidoptera, Coleoptera), thematic (e.g. taxonomy, biogeography, community ecology, conservation biology) and methodologies (e.g. multi-dimensional analysis, spatial statistics, niche modeling) was designed to highlight the diverse areas on which QCAZ entomologists have focused during the last years, giving a broad view of some of their scientifi c achievements. In spite of their large topical range, the contributions to this special issue are united by a common theme: a focus on how a good knowledge of species taxonomy plays a crucial role in fostering and underpinning ecological research in the fi eld of entomology. Th is is particularly important in tropical countries like Ecuador where the task of entomologists seems to have a time limit with a clock ticking faster and faster as human disturbance continues to increase. I hope that this special issue will not only provide a fresh view of entomological research performed in Ecuador but also foster interest from entomologists worldwide to come and perform research in this country which shelters one of the most species-rich but also most endangered insect fauna on Earth. Acknowledgements. I am grateful to Brigitte Frerot, Pierre Rasmont, and Yves Carton for their enthusiasm in this special issue project and their support for making it a reality. I also thank all the members of the QCAZ Museum, Invertebrates Section for their dedicated contribution to this issue. Special thanks to Raphael Cardenas, for his help in the coordination of the issue. Financial supports from the Pontifi cia Universidad Catolica del Ecuador (Donacion de Impuesto a la Renta), the IRD (UR-072) and the University of Delaware (Department of Entomology & Wildlife Ecology) for the publication of this special issue are greatly acknowledged.

International audience; As primary forest is cleared, pastures and secondary forest occupy an increasing space in the Amazonian landscape. We evaluated the effect of forest clearing on a soil macrofauna (invertebrate) community in a smallbolder farming system of southeastern Amazonia. We sampled the soil macrofauna in 22 plots of forest, upland rice fields, pastures, and fallows of different ages. In total, we collected 10, 728 invertebrates. In cleared plots the species richness per plot of the soil macrofauna fell from 76 to 30 species per plot immediately after forest clearance, and the composition of the new community was different. Ants, termites, and spiders were most affected by the disturbance. In plots deforested several years before, the effect of forest clearance was highly dependent on the type of land use (pasture or fallow). In fallows, the community was similar to the initial state. The species richness per plot in old fallows rose to 66, and the composition was closer to the primary forests than to the other types of land use. On the contrary, in the pastures the species richness per plot remained low at 47. In fallows, all the groups showed a richness close to that in primary forest, whereas in the forest only the richness of earthworms and Coleoptera recovered. Our results show that forest clearing constitutes a major disturbance for the soil macrofauna and that the recovery potential of the soil macrofauna after 6 or 7 years is much higher in fallows than in pastures. Thus, fallows may play a crucial role in the conservation of soil macrofauna; A medida que el bosque es talado, los pastizales y la vegetación secundaria cada vez ocupan más espacio en el paisaje Amazónico. Evaluamos el efecto de la tala del bosque sobre una comunidad de macrofauna (invertebrados) del suelo en un sistema agrícola de pequeña propiedad en el sureste de la Amazonía. Muestreamos la macrofauna en 22 parcelas de bosque campos de arroz, pastizales y barbechos de diferentes edades. En total, recolectamos 10,728 invertebrados. En parcelas taladas, la riqueza de especies de macrofauna del suelo por parcela disminuyó de 76 a 30 especies por parcela inmediatamente después de que el bosque fue talado, y la composición de la comunidad nueva fue diferente. Las hormigas, termitas y arañas fueron las más afectadas por la perturbación. El efecto de la tala del bosque fue altamente dependiente del tipo de uso de suelo (pastizal o barbecho) en las parcelas deforestadas varios años antes. En los barbechos, la comunidad fue similar al estado inicial. La riqueza de especies por parcelas en los barbechos viejos se elevó a 66, y la composición fue más cercana a la de bosques primarios que a la de los otros tipos de uso de suelo. Por el contrario, la riqueza de especies por parcela en pastizales permaneció baja en 47. En los barbechos, todos los grupos mostraron una riqueza similar a la del bosque primario, mientras que en el bosque solo se recuperó la riqueza de lombrices y Coleópteros. Nuestros resultados sugieren que la tala de bosques constituye una perturbación mayor para la macrofauna del suelo y que el potencial de recuperación de la macrofauna del suelo después de 6 o 7 años es mucho mayor en los barbechos que en los pastizales. Por lo tanto, los barbechos pueden jugar un papel crucial en la conservación de la macrofauna del suelo

Les sols abritent une faune très diverse par le nombre des espèces recensées (plusieurs centaines dans un site naturel donné) et par les fonctions accomplies. Les conditions particulières du milieu, la compacité et la faible qualité des ressources organiques disponibles favorisent de nombreuses interactions entre ces organismes. Les plus gros invertébrés de la macrofaune capables de creuser et de mélanger la terre affectent de façon significative les conditions de vie des organismes plus petits, la mésofaune qui colonise la porosité remplie d'air, la microfaune et la microflore qui mènent une vie aquatique dans les micropores et les capillaires remplis d'eau. On décrit ainsi dans cet article un effet dépresseur des vers de terre sur les populations de nématodes du riz, dans des dispositifs de laboratoire. Une expérience montre que le ver de terre géophage africain Millsolnia anomala limite la multiplication du nématode phytoparasite Heterodera sacchari dans la rhizosphère du riz, tout en stimulant directement l'aptitude de la plante à se défendre. D'autres expériences montrent que la diversité des pathogènes eux-mêmes peut atténuer leur effet; c'est le cas des nématodes phytoparasites du mil qui, bien que plus nombreux à la sortie d'une jachère, n'exercent pas d'effet pathogène, en liaison possible avec un effet de compétition entre ces espèces. L'emploi systématique des pesticides, s'il semble régler le problème posé par les parasites à court terme, a le plus souvent des effets très négatifs à long terme, avec de sérieux effets sur la santé des écosystèmes et la santé publique. Dans des rizières de Java, on a montré que les prédateurs généralistes qui contrôlent les herbivores du riz se nourrissent d'invertébrés détritivores et planctonivores, avant de s'attaquer, plus tard dans la saison, aux ennemis des cultures, lorsque ceux-ci commencent à se multiplier. L'application systématique de pesticides en début de culture, en diminuant les populations de détritivores, limite la capacité des prédateurs généralistes à contrôler les parasites dont le nombre augmente fortement; à l'inverse, l'apport de matière organique, qui augmente les populations de détritivores, augmente le nombre des prédateurs généralistes et leur capacité à contrôler les herbivores qui attaquent le riz, notamment l'homoptère Nilaparvata ligens. Les pratiques de gestion intégrée des ennemis des cultures doivent tenir compte de ces effets et intégrer leur prise en compte dans les approches de recherche participative avec les agriculteurs et les actions de formation qui permettent leur diffusion. Pour citer cet article: P. Lavelle et aL, C. R. Biologies 327 (2004). © 2004 Académie des sciences. Published by Elsevier SAS. All rights reserved.

A bibliographic review of the impacts of herbicides on microbial and invertebrate populations and activities in wetland ricefields.110 references are analyzed. This review summarises the information on relationships between herbicides and non-target microorganisms and invertebrates that was obtained from experiments in ricefields, with ricefield soil or with organisms isolated from ricefields. It considers successively (i) the microbial degradation of herbicides, (ii) their impact on algae and cyanobacteria, non photodependant microorganisms, and non-target invertebrates, and (iii) the possible detrimetal long-term effects. Current knowledge is biaised, very fragmentary, and partly outdated. Available data show that herbicides applied on soil at recommended levels rarely had a detrimental effect on microbial populations or their activities. Herbicides, applied in combination with insecticides, affected invertebrate populations more than the microorganisms, inducing the blooming of individual species of floodwater zooplankton and reducing populations of aquatic oligochaetes in soil. Available information raises concerns regarding the scarcity of data on long-term effects of herbicides on (i) microorganisms, primary producers, and invertebrates of importance to soil fertility, (ii) soil microbial biomass, (iii) predators of rice pests and vectors, and (iv) microbial metabolism of herbicides.(Résumé d'auteur)

International audience; This study highlights the effects of interaction between microbial, macro- and meiofauna on NO3−-N and DOC reduction in macroporous stream sediment. The tested hypotheses are: the transformation of nutrients and dissolved organic matter (1) is influenced by the presence of invertebrates, (2) is more effective when the diversity of the vertical benthic community increases. These hypotheses were tested using microcosms reproducing a portion of a river bed water-sediment interface that was colonized with different levels of invertebrate biodiversity. Experimental treatments were abiotic sediment (AS); sediment and biofilm (SB); sediment, biofilm and meiofauna (SBM); and sediment, biofilm, meiofauna and macrofauna community assemblage, which corresponds to the total benthic community of a river bed (SBMM). Reduction rates of nitrates (NO3−-N) and dissolved organic carbon (DOC) in the microcosms were measured and considered as a function of the different levels of biodiversity. Nutrient reduction rates were monitored by their decrease from the aqueous phase. Nitrate reduction rates increased significantly with increasing the vertical biodiversity level. After 56 days of biofilm development, NO3−-N reduction rates ranged from 3.76 ± 0.35 in SB treatment to 8.92 ± 0.69 mg N d−1 kg−1sediment Fresh Weight (sed FW) in the treatment with the maximum biodiversity (SBMM). Denitrification rates increased by a factor of 6 in presence of meiofauna and macrofauna compared to that measured in sediment without invertebrates. DOC reduction rates also varied significantly with biodiversity levels but in a lesser extent than nitrate reduction rates (41.89 ± 2.24 mg C d−1 kg−1sed FW with biofilm alone (SB) to 51.00 ± 1.39 mg C d−1 kg−1sed FW with the addition of meiofauna community) (SBM).