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International audience; Banana crops in the Caribbean are characterized by the use of high rates of nitrogen (N) fertilization which causes severe environmental damages. The aim of this study was to assess the fertilizer N use efficiency (NUE) of banana crops in the field. To do so, a field trial was carried out during the first (GS1) and the fourth (GS4) growing seasons of banana crops, and the fate of a 15 N-labeled pulse applied late in the growing season (flowering stage) was determined. At harvest, NUE (average 24% 15 N applied) and the total recovery of fertilizer 15 N in the soil-plant system (i.e., 40% in GS1 and 62% in GS4) were low. Low NUE resulted mainly from the dilution in a large soil mineral N pool derived from earlier applications of the labeled-N fertilizer applied at flowering, combined with leaching caused by numerous high-intensity rainfall events (>20 mm d −1). Crop residues from previous cycles present at time of fertilizer application in the fourth growing season, promoted fertilizer N immobilization, which in turn favored fertilizer N recovery by decreasing N leaching. The results suggest that N fertilization after the first season could be reduced by 30% (i.e., −90 kg N ha −1) corresponding to the suppression of two applications from flowering to harvest with the current fertilizer management, as available N derived from earlier applications is sufficient to meet plant requirements.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; Nematodes are major pests for crops, including banana. Environmentally friendly methods for managing plant-parasitic nematodes have to be developed, such as organic material application. Our study focuses on the impacts of several organic amendments on banana plants, considering mainly their effect on soil nitrogen supply and soil microbial biomass, and the consequences on plant-parasitic nematode impacts on the plants. A microcosm experiment for 13 weeks was conducted to evaluate four organic materials: sugarcane bagasse, sugarcane sludge, plant residues, and sewage sludge, compared to a control without organic amendment. Input of organic materials led to an important change on nitrogen resource, and plants grew better when the N availability was the highest, but better growth conditions did not necessarily reduce parasitic nematodes impacts on the roots. Damage on the roots depended on plant-parasitic nematode abundance. Three of four tested amendments exhibited a regulator effect on plant-parasitic nematode populations (bagasse, sugarcane sludge, and plant residues). Root growth was not the explanatory factor for this regulation. Only sugarcane sludge led to an overall positive effect on the plant, increasing its growth and reducing its parasitism pressure. The other organic materials exhibited an antagonism between the promoted plant growth and the reduced nematode populations.

International audience; Farmers are inundated with advertisements about many innovations that are supposed to increase their yields or reduce environmental impact. However, the benefit of these innovations depends on the farming context. Here we present the ad hoc adaptation of the crop model SIMBA and a method to evaluate 16 innovations in six types of farms previously selected through a typology of the banana farming systems in Guadeloupe. The innovations include regulation of pesticide use, rotations and fallows, intercropping, conditional application of pesticides, resistant cultivars, and integrated systems. Our results show that, for a given innovation, the yield and pesticide reduction vary widely with different farm types. We show that environmentally friendly innovations often cause a greater decrease in yield in more productive farm types. Nevertheless, despite an apparent trade-off between yield and pesticide use, some innovations address both production and environmental issues, e.g., rotation with fallows improved with cover crops, regular fallows, and rotations with pineapples for the most intensive farm types. Our modelling study confirms the importance of innovation-farm type interactions and the usefulness of models for assessing large numbers of technological innovations among a wide range of biophysical and technical contexts.

International audience; A morphological phylogenetic hypothesis of the relationships among the species of Africana is provided. The phylogenetic analysis suggests that Squamata or Amphibia were ancestral hosts for species of Africana, with dispersal events to Testudinidae; a second transfer to amphibians is also suggested. On the basis of biological data for these parasites and the paleogeographic reconstructions, a South American origin for Africana spp. is indicated, with subsequent dispersal events to Africa. It is further proposed that Chamaleonidae acquired species of Africana after their 'out-of-Madagascar' dispersal events to Africa.

International audience; While pesticides help to effectively control crop pests, their collateral effects often harm the environment. On the French island of Reunion in the Indian Ocean, over 75% of the pesticides used are herbicides and they are regularly detected in water. Agri-environmental models and pesticide risk indicators can be used to predict and to help pesticide users to reduce environmental impacts. However, while the complexity of models often limits their use to the field of research, pesticide risk indicators, which are easier to implement, do not explicitly identify the technical levers that farmers can act upon to limit such transfers on their scale of action (the field). The aim of this article is to contribute to developing a decision support tool to guide farmers in implementing relevant practices regarding the reduction of pesticide transfers. In this article, we propose a methodology based on classification and regression trees. We applied our methodology to a pesticide risk indicator (I-PHY indicator) for identifying the importance of the variables, their interactions and relative weight in contributing to the score of the indicator. We applied our methodology to the assessment of transfer risks linked to the use of 20 herbicides applied to all soils in Reunion and according to different climate, plot management and product application scenarios (4096 scenarios tested). We constructed regression trees which identified, for each herbicide on each soil type, the contribution made by each input variable to the construction of the indicator score. The tree is represented graphically, and this aids exploration and understanding. The 20 herbicides were divided into 3 groups that differed through the main contributing variable to the indicator score. These variables were all technical levers available to farmers to limit transfer risks. These trees then become decision support tools specific to each pesticide user, enabling them to take appropriate decisions with a view to reducing pesticide environmental impacts.

The carbon status plays a key-role in flowering and fruiting of mango trees while influxes of carbohydrates seem to influence fruit size and taste. A model of carbon gain, losses and repartition between branch parts for mango is proposed. Photosynthesis represents the starting point of the modelling approach. The first step consisted of using 3D digitising to establish the relationship between the amount of leaf nitrogen per unit leaf area, N a and the gap fraction. The second step established the relationship between N a and the parameters of photosynthetic capacity derived from response curves of net photosynthesis to the intercellular CO 2 concentration (A-C i curves). Results are presented about this model. Its capacity for simulating leaf photosynthesis is also discussed.

The relative attractiveness of six commercially available protein hydrolysates and the influence of their concentration were evaluated in field cages by a release-capture method of lab-reared melon fly adults, #Bactrocera cucurbitae# (Coquillett). Buminal, Corn Steepwater, Hym-Lure, Pinnacle, Nulure, and SolBait were tested for both sexes of the melon fly. The tested products exhibited clear differences in attractiveness. SolBait was the most effective protein hydrolysate. Pinnacle and Corn Steepwater also gave promising results. A general tendency for an increase in effectiveness with increasing concentration within the range 0.5 to 10% was shown. This study will allow pest control practitioners to choose more effective attractants for use in bait sprays to control the melon fly thus reducing the intensive use of insecticides currently practiced in Reunion island and enabling the development of Integrated pest management (IPM) methods for cucurbit crops.

International audience

International audience; Black Leaf Streak Disease (BLSD), caused by the fungal pathogen Mycosphaerella fijiensis, is the most important foliar disease affecting banana production worldwide, reducing fruit weight and fruit aptitude for conservation. With growing concerns about environmental preservation and stricter legislation, alternatives to chemical control for BLSD are an important challenge, especially in the French West Indies. These new approaches include various agronomical practices that could help reducing disease development, and its impact on bunch weight and fruit conservation. Designing new cropping systems without fungicide control of BLSD implies an integrated strategy and a combination of these practices. To understand better the relationships between leaf spots diseases and fruit conservation, Cavendish bananas were grown in different situations in Cameroon, Guadeloupe and Brazil. These experiments showed that a signal from diseased leaves triggers a direct reduction in banana green life duration, and that this signal might be stopped through the elimination of diseased leaves. Lately, a new prototype of cropping system has been evaluated in ecological conditions unfavorable to BLSD (in Dominican Republic), combining practices that would control disease cycle and the reduction of crop losses. In such conditions, even if bananas were harvested with a very low leaf surface, green life of the fruit proved to be acceptable for export, thanks to an adequate and regular pruning of the infected leaves. This result questions the usual threshold of 4 to 5 leaves required at harvest time for bunches as acceptable for exportation. However, variable losses (10-15%) in fruit weight were observed. This prototype should be now evaluated in epidemiological situations more favorable to disease development. New practices might also be associated in these conditions, like the introduction of biodiversity (mixtures of species) or the use of plant defense stimulators. (Résumé d'auteur)

International audience; The association of N-2-fixing species (NFS) could be an attractive option for achieving a sustainable increase of Eucalyptus plantations (EP) productivity through a positive balance between facilitative effects and competition between species. A randomised block design was replicated at four sites (Cenibra, USP, Suzano and IP) in Southern Brazil and at one site in Congo. The development of mono-specific stands of Acacia mangium (100A) and Eucalyptus grandis or urophylla x grandis (100E), was compared with N fertilisation treatment (100E + N) and with mixed-species plantations in a 1:1 ratio (50A:50E), and in an additive series with varying densities of acacia for the same density of eucalypt (25A:100E, 50A:100E, 100A:100E). The objectives were to assess the effect of mixtures on tree growth and stand production, and the behaviour of the two species in contrasting soil and climatic conditions. Tree growth was monitored over stand rotation and the biomass of aboveground tree components estimated at mid-rotation and at harvesting age. Eucalyptus height was 13% higher in Brazil than in Congo. Favourable ecological conditions in Congo and Cenibra led to 50% higher Acacia tree height than at the other sites. A depressive effect of Eucalyptus neighbour trees on Acacia height and circumference growth, lower in Congo than in Brazil, was observed in the mixtures from age 1-2 years onwards. Depressive effects of acacia on eucalypt height and circumference growth were low in USP, Suzano and IP, high in Cenibra, and not observed in Congo, in 50A:50E and 25A:100E. A positive though insignificant response to N fertilisation was only found in USP and Congo. Complementarity for light and soil resource capture between Eucalyptus and Acacia trees resulted in mean annual increments in total stand stemwood biomass (MAI) that were 7-15%, 6-12%, and 40% higher in the additive series than for 100E in Cenibra, LISP and Congo, respectively at mid-rotation. Whilst lasting complementarity and facilitation in Congo led to 17-34% higher MAI in mixtures than for 100E at harvesting age, MAIs were not significantly higher in mixtures than for 100E in Brazil. Mixed-species plantations of Eucalyptus and A. mangium might enhance aboveground stand production on poor nutrient soils in warm and humid tropical climates with low water limitations

Palm Protect is an EU-funded program (2012-14) entitled: “Strategies for eradication and containment of invasive palm borers, Rhynchophorus ferrugineus and Paysandisia archon. The project aims at throwing light on aspects of the pest biology in Europe, which are unknown and preclude efficient control, validating new and reliable methods for detection and control, and implementing them into strategies for eradication of the palm borers both at the points of entry in the EU and in the infested areas. The project also aims at providing with an economic analysis to value palm services and management options and to disseminate the findings to the stakeholders. Palm Protect associates 12 research organisations, 1 SME, UK, France, Greece, Italy, Slovenia, Spain, Israel and Egypt. It is based on 6 actions: Management, Biology, Detection, Control, Economics and Dissemination. France contributes by INRA (Versailles et Sophia Antipolis) and CIRAD, which are particularly involved to provide new fundamentals about adult mobility, semiochemicals and parasitoids. The results will make it possible to improve European regulation and its efficacy from a consolidated scientific background in compliance with the standards in force for pest control; Palm Protect est un programme financé par l’UE (2012-14) intitulé ‘Stratégies pour l'éradication et le confinement des ravageurs invasifs des palmiers P. archon et R. ferrugineus’. Il a pour objectifs d’éclairer les éléments inconnus de la biologie en Europe de ces espèces qui limitent l’efficacité de la lutte, de valider des méthodes et des stratégies fiables et nouvelles pour leur détection, leur gestion et leur éradication tant aux points d’entrée que dans les zones contaminées. Palm Protect diffusera le fruit de ces travaux à tous les acteurs de la filière ‘palmiers’. Le programme associe 12 organismes de recherche, une PME, le Royaume-Uni, l’Espagne, la France, la Grèce, l’Italie, la Slovénie, Israël et L’Egypte. Il comprend 6 actions : Coordination, Biologie, Détection et surveillance, Lutte, Economie et Diffusion des acquis. La France contribue par l'INRA (Versailles et Sophia Antipolis) et le CIRAD, et s’implique fortement dans l’acquisition de connaissances nouvelles sur le déplacement des adultes, les médiateurs chimiques et les parasitoïdes. Les résultats serviront de base pour améliorer la réglementation européenne et son efficacité à partir de données scientifiques en application des règles générales en vigueur pour le contrôle des bio-agresseurs

Chapter 7; The development of new methods and approaches for ensuring the sustainability of agriculture and ecosystem services is an important challenge that ecologists, agronomists, and theoreticians must address together. Enhancement of ecosystem services needs to be addressed at different scales and should include the interaction between farmland biodiversity and stakeholders (farmers, managers, policy makers, etc.) to optimize service delivery. Predictions require an understanding of the interactions between numerous management options and components of biodiversity. Here, we argue that interaction networks on a broad sense (from food webs to landscapes networks in which nodes could be species, trophic groups, fields or farms) can help address this high level of complexity. We examine how tools from mathematics and artificial intelligence, developed for network modelling and reasoning, could be useful for assessing and enhancing ecosystems services. In doing this we highlight the gaps that currently exist between our questions about ecosystem service provision and our ability to answer them with current modelling approaches. We illustrate the use of these tools with three case studies related to ‘pest regulation services’. These include food web approaches to assess animal pest regulation services and decisional models to address management strategies for diseases and weeds. Finally, we describe how different types of network models might operate at different scales of management. The future challenge for agroecologists will be to produce models of interactions and emergent ecosystem services, which are sufficiently quantified and validated. We suggest that network ecology is a nascent research topic that is developing a strong and unified empirical and theoretical foundation, which could serve as the central paradigm for a sustainable, intensive agriculture in the future.

National audience; no abstract

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; In the French West Indies, chlordecone (CLD), an organochlorine pesticide, was applied in banana plantations from 1972 to 1993. Our study was aimed at identifying the factors that determine soil CLD contamination and that thus can describe the spatial distribution of this contamination. For each of the 1045 plots analyzed for CLD, we collected spatial information on the physical environment and agricultural activities. Then, we searched for determinants of soil contamination and used a multiple regression model to predict the spatial distribution of CLD. First, the results showed that the soil type had a strong impact. Andosols, with a high organic carbon content (up to 100 g kg−1) and a high sorption capacity (Koc 20 000 L kg−1), had the highest CLD concentrations and stocks. Nitisols had 10-fold lower sorption capacities. Second, the results showed a "farm effect" on soil contamination, due to the more or less intensive application of inputs by farmers and to the shorter or longer application times, depending on the banana land-use frequency. However, despite these effects and given the weak accuracy of the usually available information on agricultural activities, it remained difficult to predict the spatial distribution of CLD contamination by a multiple regression model. In conclusion, this study highlighted the multifactorial nature of pollution. The main perspectives are related to better assessments of agricultural activities using remote sensing strategies and designing agricultural practices observatories focusing on pesticide use.

The "Use and Abuse of Crop Simulation Models" special issue of Agronomy Journal published in 1996 ended with the myth of the universal crop model. Sinclair and Seligman consequently recommended tailoring models to specific problems. This paper reviews the fate of the idea of such ad hoc approaches to crop simulation modeling during the past 15 yr. Most crop modelers have since adhered to the principles formulated by Sinclair and Seligman, but yet their practice faces two major issues: (i) how to define the structure of the model as depending on the question to be addressed (model conceptualization) and (ii) how to minimize efforts in software development (model computerization). Progress in model conceptualization as reported in the literature concerns (i) inferring a conceptual model from what is known of the problem to address, (ii) deriving summary models from comprehensive ones, and (iii) using multivariate methods to analyze the hierarchy of drivers of variability in the variable to be predicted. Considerable effort has been invested in the development of frameworks to facilitate model computerization, and the commercial modeling software is constantly improving. But there are limits in the flexibility permitted by these tools. Acquiring basic skills in coding a model using a scientific programming language is preferred by scientists wishing to keep the fullest understanding and control on their crop models. Connecting the model to commercial database software may facilitate this strategy. However, the computerization issue may still lead to tensions between modeling teams concerning the legitimacy to develop their own model. (Resume d'auteur)

Banana (Musa sp.) residues contain two thirds of the plant nitrogen (N) content at harvest which may represent a large N source for the daughter plant and contribute to reducing fertilizer rates. Our aim was to assess the decomposition kinetics of above- and below-ground banana residues, and to determine the uptake of the released N by the daughter plant. Residue decomposition was analyzed under laboratory and field conditions, and plant N uptake was evaluated in the field using 15N-labelled above-ground residues. The decomposition kinetics was interpreted with a simulation model. In the laboratory, residue decomposition showed an immobilization phase followed by remineralization. The immobilization phase was longer and remineralization was smaller for roots due to their higher C:N ratio and lignin content. The model satisfactorily described both phases and the effect of the residue C:N ratio. Experimental and model results indicated that root residues would be a minor N source for the daughter plant. In the field, above-ground residues decomposed according to first order kinetics. Residue half-life was 2 d in the laboratory and 32 d in the field, which was due to poorer soil–residue contact in the field. At the time of harvest of the daughter plant, 39% of residue N was recovered in the plant, 54% in the topsoil, and 3% in the remaining residues. About 4% of residue N was probably lost by leaching. Nitrogen derived from residues represented 19% (14 kg N ha−1) of N in bunches of the daughter plant and 18% (39 kg ha−1) of the whole plant N. Our study showed that above-ground residue N was an effective N source for the daughter plant, with a good overlap between the period of N release and that of greatest plant demand which reduced the risk of N leaching.

Contact: gary@supagro.inra.fr; En régions méditerranéennes, les fortes variations inter-annuelles de pluviométrie rendent difficile le maintien de performances agronomiques et environnementales stables dans les vignobles. Le modèle biodécisionnel Verdi permet de simuler les effets de différentes stratégies d’entretien du sol. On met en évidence que, sur des séries d’années climatiques contrastées, des statégies adaptatives (1) permettent de faire varier fortement la nature, le nombre et les dates des interventions techniques et (2) conduisent à des résultats agronomiques (développement végétatif, rendement, qualité des produits) et environnementaux (maîtrise du ruisselement) plus réguliers que des stratégies continues (sol nu permanent, enherbement permanent)

The banana weevil Cosmopolites sordidus (Germar) is an important pest of banana crops. Radio-tracking and capture-recapture studies at the scale of the field have revealed a limited capacity of dispersion of the banana weevil. However, for a better understanding of the epidemiological process more information on the movement at a finer scale is needed. To analyze the behavioral response of individuals, we use the Cosmodrome, an experimental design composed of two patches whose quality may vary (bare soil, Quels outils pour un changement d'échelle dans la gestion des insectes d?intérêt économique ? Montpellier, 4-5 Octobre 2011 9 banana rhizome). The patches are connected by a tunnel of one meter of length at the ends of which RFID tag readers are placed. We analyzed the behavioral response of individuals to variation in patch density. The statistical analysis of results using generalized linear model revealed that the individuals shows a non-linear response of movement to the density in patches. The banana weevil tends to move at a higher rate at intermediate density than at low and high density. The movement response to patch density differs also according to the sex, with a higher activity of females than males at low and intermediate patch density. These preliminary results on the effect of density may reflect the individual strategies of colonization of banana fields by Cosmopolites sordidus that maximize the individual fitness (mating, oviposition). The information on movement and behavior of the banana weevil at the plant level is of great importance for the understanding of the dynamic of the epidemiological front during the colonization process. (Texte intégral)

Farmers in the tropics are faced with crop protection issues such as adverse impacts of pesticides on human health and on the environment, particularly in intensive agrosystems in French overseas islands, or food insecurity and low income due to pest-induced crop losses, particularly in low-input traditional systems in Sub-Saharan Africa. A Cirad-funded " Omega3 " project tackles these problems by studying the effects of the planned introduction of plant species diversity (PSD) in tropical agrosystems, as a potential alternative to conventional practices based on pesticide use. One of the several study cases the project focused on is the use of sweet corn as a trap crop to control the populations and damages of Helicoverpa zea in tomato field in the French West Indies (Martinique). To understand system functioning and improve H. zea management, we are developing a spatially-explicit individual-based model at the field scale. The model comprises 3 interacting modules that describe (i) phenology of tomato and corn plants and dynamic of the attractive plant stages for H. zea (ii) H. zea development, both using thermal units, and (iii) H. zea movement and oviposition behavior. More widely, we aim to use this model as a generic tool to improve our understanding of what make the use of a trap crop successful in managing pests among the insect behavioural traits, the crop traits (e.g., relative attractiveness) and the spatio-temporal planting design of the trap and commercial crops. The modeling approach we are currently developing and further issues are presented. (Texte intégral)

1. The spatial distribution of populations is affected by the dispersal abilities of the species, interactions among individuals, or habitat selection. Linking these ecological processes to spatial patterns is of primary importance for understanding and prediction purposes. 2. We review both statistical and mechanistic methods for studying the spatial distribution of populations. Statistical methods, such as spatial indexes and nearest-neighbour analyses help characterizing the spatial pattern. They allow testing the effect of environmental variables on spatial patterns using regression analyses. 3. Mechanistic modelling can be used to analyse the effect of mechanisms underlying the spatial pattern. We review mechanistic models (e.g. metapopulation, individual-based and cellular automaton models) devoted to represent dispersal abilities, interactions among individuals and habitat selection. 4. We illustrate each method by works on insects, which cover a broad range of spatial patterns. Strengths and limitations of methods are discussed according to the process and type of data set. 5. Scientists can use statistical or mechanistic methods in an iterative manner to infer process from spatial pattern. New approaches such as "pattern-oriented modelling? or "space as a surrogate framework? determine whether alternative models reproduce an observed pattern. It allows selection of the process that best explain the observed pattern. (Texte intégral)

International audience; In viticulture as in other crop productions, adaptation to climate fluctuations is needed to mitigate their possible impacts on productivity and on the quality of products. The VERDI simulation model was developed to evaluate various adaptive strategies of intercrop management at field scale. Its main purposes were to design management strategies that are responsive to the state of the soil-crop system and to climate, and to reproduce realistically the dynamic interactions between the biophysical and decision systems in varying climate conditions. A simulation study involving various more or less adaptive strategies of soil surface management under different climate scenarios was carried out. The simulation outputs confirmed that in case of severe drought, the most flexible strategy yields the best agronomic and environmental results in the long term, in relation to its ability to trigger the removal of an intercrop according to the time-course of soil water availability

Action pilotée par le ministère chargé de l'agriculture, avec l‟appui financier de l‟Office national de l'eau et des milieux aquatiques, par les crédits issus de la redevance pour pollutions diffuses attribués au financement du plan Ecophyto 2018; L‟extrait suivant issu de la convention de l‟étude restitue son contexte : « Ecophyto 2018 est un Plan d‟Action National, tel que le prévoit la Directive européenne du 13 janvier 2009, pour parvenir à une utilisation des pesticides compatible avec le développement durable, dont la réduction de 50% est inscrite dans la loi Grenelle 1. Dans le cadre de ce plan, l'axe 6 porte sur la prise en compte des spécificités des départements d‟Outremer dans sa mise en œuvre. La présente étude a pour objectif de réunir un ensemble de données relatives aux expérimentations conduites dans les DOM sur la problématique de l‟usage des pesticides en agriculture et de la réduction de leur utilisation. Cette étude a été programmée pour appuyer le développement de plates-formes techniques DOM ». De façon plus spécifique, l‟étude a eu pour objectifs : - d‟identifier les critères permettant de caractériser et d‟évaluer les dispositifs expérimentaux ; - de réaliser un inventaire exhaustif des dispositifs expérimentaux en cours et passés portant sur la réduction de l‟utilisation de pesticides dans les DOM ; - de proposer des priorités en matière de développement de dispositifs expérimentaux relatifs à la réduction des pesticides dans les DOM-COM.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; Plant-parasitic nematodes are injurious crop pests that have been managed mainly by chemical nematicides. However, safe and alternative methods such as those based on organic materials need to be developed. Our study has evaluated (i) the effects of four organic amendments with different biochemical compositions that are abundantly produced in the study area (Guadeloupe, French West Indies) on soil nematode communities and (ii) some of the suppression mechanisms of banana parasitic nematodes, especially those involving the soil food web. This study is based on a microcosm experiment comparing sugarcane bagasse, sugarcane sludge, plant residues and sewage sludge. All amendments except sewage sludge decreased the root abundances of plant-parasitic nematodes, by 96% in the case of sugarcane bagasse. For this treatment, soil densities of carnivorous nematodes were six times higher than the treatments without organic amendment. Plant residues and bagasse were mainly composed of materials that are difficult to decompose, namely cellulose and lignins. These organic materials favored a fungal decomposition pathway and permitted development of carnivorous nematode populations and increased the Channel Index (CI). Pratylenchus coffeae control after sugarcane refinery sludge application remains unexplained. Lastly, sewage sludge, composed mainly of easily degradable compounds, did not permit nematode control, and only bacterivorous nematode populations were enhanced by this treatment. (C) 2011 Elsevier B.V. All rights reserved.

International audience; The analysis of animal movement within different landscapes may increase our understanding of how landscape features affect the perceptual range of animals. Perceptual range is linked to movement probability of an animal via a dispersal kernel, the latter being generally considered as spatially invariant but could be spatially affected. We hypothesize that spatial plasticity of an animal’s dispersal kernel could greatly modify its distribution in time and space. After radio tracking the movements of walking insects (Cosmopolites sordidus) in banana plantations, we considered the movements of individuals as states of a Markov chain whose transition probabilities depended on the habitat characteristics of current and target locations. Combining a likelihood procedure and pattern-oriented modelling, we tested the hypothesis that dispersal kernel depended on habitat features. Our results were consistent with the concept that animal dispersal kernel depends on habitat features. Recognizing the plasticity of animal movement probabilities will provide insight into landscape-level ecological processes.

Contact: jb.charlier@gmail.com; International audience; The aim of the study is to establish an hydrogeological scheme of the structure and the functioning of andesitic volcanic systems in the insular and humid tropical context. A watershed has been instrumented at Féfé in Guadeloupe (French West Indies) in the Lesser Antilles to measure rainfall, runoff and piezometric fluctuations between 2003 and 2006. Given the heterogeneity of the volcanic deposits, a multidisciplinary approach has been used: a geological and an hydrogeological survey, an hydrodynamic approach (hydraulic tests and signal processing of hydrological time series), and finally, an hydrogeochemical approach (major elements and some trace elements). Two main superposed aquifer respectively in aerial deposits, and in recent nuées ardentes (glowing ash) and lava flows, as well as the underlying aquiclude (the highly weathered older substratum) were identified. At a local scale, some hydrogeological heterogeneities internal to the aquifers were highlighted and related to a polyphased building-up of the geological formations. Hydraulic relationships between the multi-layered aquifers, such as the confinement of the deep aquifer upstream of the basin, were identified. Groundwater/stream exchanges were characterised, detailing various contributions of the shallow and the deep aquifers to stream and spring waters; significant river losses were also observed. At a global scale, within such relatively permeable volcanic formations, the aquifer recharge is about 85% of the annual effective rainfall for an average rainfall year. The hydrogeological scheme appears to be coherent with a geological structure of cut-and-fill paleovalleys frequently observed in andesitic areas. Consequently, groundwater drainage axis are mainly localised in recent nuées ardentes deposits, whereas the inversion of relief characteristic of volcanic areas explains the non-superposition of surface water and groundwater divides and both surface water losses and springs. Finally, this work shows the highly heterogeneous hydrogeological processes occurring in volcanic formations of andesitic-type. It also shows the relationships between the geological structure and the hydrogeological functioning of such basins, and proposes an affordable methodological approach to investigate such a hydrogeological context in depth.

Fabrice Vinatier (fabrice.vinatier@supagro.inra.fr); International audience; 1. The spatial distribution of populations is affected by the dispersal abilities of the species, interactions among individuals, or habitat selection. Linking these ecological processes to spatial patterns is of primary importance for understanding and prediction purposes. 2. We review both statistical and mechanistic methods for studying the spatial distribution of populations. Statistical methods, such as spatial indexes and nearest-neighbour analyses help characterizing the spatial pattern. They allow testing the effect of environmental variables on spatial patterns using regression analyses. 3. Mechanistic modelling can be used to analyse the effect of mechanisms underlying the spatial pattern. We review mechanistic models (e.g. metapopulation, individual-based and cellular automaton models) devoted to represent dispersal abilities, interactions among individuals and habitat selection. 4. We illustrate each method by works on insects, which cover a broad range of spatial patterns. Strengths and limitations of methods are discussed according to the process and type of data set. 5. Scientists can use statistical or mechanistic methods in an iterative manner to infer process from spatial pattern. New approaches such as 'pattern-oriented modelling' or 'space as a surrogate framework' determine whether alternative models reproduce an observed pattern. It allows selection of the process that best explain the observed pattern.

The PhD work aims at detecting and understanding factors and mechanisms explaining the spatial heterogeneity of banana black weevils' (Cosmopolites sordidus) populations in order to control them. Two approaches are commonly considered to understand the spatial heterogeneity of populations: statistics applied to spatial data and mechanistic modelling. My PhD work considers the interest of combining those approaches to understand the movement processes of insect adults and the interaction between life traits and spatial dynamics of a population. Understanding movement processes requires collecting spatial data at the individual level. By combining a statistical approach by maximum likelihood estimation and a mechanistic individual-based model, I showed a high dependence of movement versus habitat matrix. I showed also that perception of space is less important for a weevil located on a banana plant or on crop residues than for a weevil located on bare soil or ditch. An individual-based model (COSMOS) was developed to simulate the spatial dispersion and infestation of C. sordidus in interaction with different elements of the cropping system. The model was successfully tested at the plot scale, by comparing infestation statistics between observed and simulated values. The emerging properties of the model were tested by simulating different spatial arrangements of banana plants. For instance, the model showed that the time to colonize a plot is longer when the plot is planted regularly than when it is planted in patches. The model revealed the importance of the interface between banana area and fallow for locating weevils' trap.; L'objectif de cette thèse est d'identifier et de comprendre les processus liant un ravageur à son habitat afin de limiter la population de ce ravageur. Deux approches peuvent permettre d'étudier l'hétérogénéité spatiale des populations d'une espèce: les statistiques appliquées à des données spatialisées et la modélisation mécaniste. Mon travail de thèse montre l'intérêt de combiner ces deux approches afin de comprendre l'interaction entre traits de vie et dynamique spatiale d'une population. Comprendre les comportements de dispersion nécessite de collecter des données spatiales à l'échelle de l'individu. En combinant une approche statistique par maximum de vraisemblance et un modèle mécaniste sur des données spatialisées que j'ai récoltées sur l'insecte par télémétrie RFID (Radio Frequency IDentification), j'ai montré une forte dépendance du déplacement vis-à-vis des éléments du paysage. Un modèle stochastique individu-centré (COSMOS) a été développé afin de simuler la propagation spatiale et les attaques du charançon en interaction avec les différents éléments du système de culture. Le modèle a été confronté avec succès à des données d'infestation réelles à l'échelle d'une parcelle de bananiers, en comparant les données d'infestation observées aux données simulées. Les propriétés émergentes du modèle ont été explorées en simulant des assemblages spatiaux de bananiers. Par exemple, le modèle a montré que la vitesse de colonisation d'une parcelle est plus importante lorsqu'elle est plantée de manière régulière plutôt qu'en groupes de bananiers. Le modèle a révélé l'importance de la zone de transition entre la bananeraie et la jachère pour l'optimisation du piégeage.

International audience; Agri-food supply chains are at the heart of sustainable development concerns. In order to comprehend whole complex parameters and their global impacts, it appeared necessary to adopt a systemic approach, justifying a Life Cycle Assessment (LCA), not only from an environmental point of view but from a social and economic one too. Taking into account specificities and stakes of fruits and vegetables (F&V) supply chains in developing countries this paper focus on absences, deficiencies and methodological limits that LCA meets integrating social and economic aspects. The elements presented lead to an in-depth conceptual and theoretical discussion and suggest placing LCA in the perspective of development theory. The proposition is to endow LCA with an approach by capitals, which seems particularly adapted to express sustainable development and well-being.

The PhD work aims at detecting and understanding factors and mechanisms explaining the spatial heterogeneity of banana black weevils' (Cosmopolites sordidus) populations in order to control them. Two approaches are commonly considered to understand the spatial heterogeneity of populations: statistics applied to spatial data and mechanistic modelling. My PhD work considers the interest of combining those approaches to understand the movement processes of insect adults and the interaction between life traits and spatial dynamics of a population. Understanding movement processes requires collecting spatial data at the individual level. By combining a statistical approach by maximum likelihood estimation and a mechanistic individual-based model, I showed a high dependence of movement versus habitat matrix. I showed also that perception of space is less important for a weevil located on a banana plant or on crop residues than for a weevil located on bare soil or ditch. An individual-based model (COSMOS) was developed to simulate the spatial dispersion and infestation of C. sordidus in interaction with different elements of the cropping system. The model was successfully tested at the plot scale, by comparing infestation statistics between observed and simulated values. The emerging properties of the model were tested by simulating different spatial arrangements of banana plants. For instance, the model showed that the time to colonize a plot is longer when the plot is planted regularly than when it is planted in patches. The model revealed the importance of the interface between banana area and fallow for locating weevils' trap., L'objectif de cette thèse est d'identifier et de comprendre les processus liant un ravageur à son habitat afin de limiter la population de ce ravageur. Deux approches peuvent permettre d'étudier l'hétérogénéité spatiale des populations d'une espèce: les statistiques appliquées à des données spatialisées et la modélisation mécaniste. Mon travail de thèse montre l'intérêt de combiner ces deux approches afin de comprendre l'interaction entre traits de vie et dynamique spatiale d'une population. Comprendre les comportements de dispersion nécessite de collecter des données spatiales à l'échelle de l'individu. En combinant une approche statistique par maximum de vraisemblance et un modèle mécaniste sur des données spatialisées que j'ai récoltées sur l'insecte par télémétrie RFID (Radio Frequency IDentification), j'ai montré une forte dépendance du déplacement vis-à-vis des éléments du paysage. Un modèle stochastique individu-centré (COSMOS) a été développé afin de simuler la propagation spatiale et les attaques du charançon en interaction avec les différents éléments du système de culture. Le modèle a été confronté avec succès à des données d'infestation réelles à l'échelle d'une parcelle de bananiers, en comparant les données d'infestation observées aux données simulées. Les propriétés émergentes du modèle ont été explorées en simulant des assemblages spatiaux de bananiers. Par exemple, le modèle a montré que la vitesse de colonisation d'une parcelle est plus importante lorsqu'elle est plantée de manière régulière plutôt qu'en groupes de bananiers. Le modèle a révélé l'importance de la zone de transition entre la bananeraie et la jachère pour l'optimisation du piégeage.

National audience

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The ex ante assessment of innovative agro-ecological innovations is a key step in the development of more sustainable crop management systems. To this end, models are useful tools because they make it possible to rapidly assess numerous innovations in different contexts. Whereas many farm optimisation models focusing on the farmer’s strategic decision to adopt new crop management systems have been published, little attention has been given to the ex ante modelling of the dynamic operational impacts of innovation adoption at the farm level. BANAD, a mechanistic model for such applications,is proposed. It allows the ex ante assessment of innovative management systems including new agroecological techniques, while taking into account different farming contexts and policy and market conditions. It includes three components: (i) a crop management system model, (ii) a crop model (SIMBA) and (iii) a farming system model. Our results applied to the ex ante assessment of six innovative banana management systems for three contrasted farm types in Guadeloupe showed that the impacts of agroecological innovations, which include rotations, improved fallow, intercropping, pest-resistant cultivar, and an integrated organic system, can vary considerably according to (i) the farm type in which the innovation is integrated, (ii) the nature of the agro-ecological innovations, and (iii) the criteria considered and the temporal horizon of the assessment. Innovative intercropping systems that were effective at the field level in terms of the yield improvement and decreased pesticide use could be problematic at the farm level because they increased the workload and decreased income. The adoption of rotations or improved fallow seemed to be relevant for smallholders but could induce a critical period of 1.5–2.5 years during which income decreased drastically. Under certain conditions of markets and subsidies, very environmentally friendly innovations that are less productive can however be economically effective.

Oral communication; International audience; Assessment of water-pollution risks in agricultural regions requires studying pesticide transport processes in soil and water compartments at the catchment scale. In tropical regions, banana (Musa spp.) plantations are located in zones with abundant rainfalls and soils with high infiltration rates, which lead to washout and leaching of soilapplied pesticides, causing severe diffuse pollution of water resources. The aim of this paper is to determine how the nematicide cadusafos [S,S-di-sec-butyl O-ethyl phosphorodithioate], used in banana plantations, contaminates water and soils at the two scales of subcatchment and catchment. The study site was a small banana-growing catchment on the tropical volcanic island of Guadeloupe in the Caribbean (FWI). The catchment is located in pedoclimatic conditions where rainfall is abundant (> 4000 mm/year), and soil permeable (saturated hydraulic conductivity of Andosol Ks > 30 mm/h). Two campaigns of nematicide application were conducted, one in 2003 over 40% of the catchment and one in 2006 over 12%. For 100 days after application, we monitored the surface water and groundwater flows and the cadusafos concentrations in the soil and in surface and ground waters in a 2400 m2 subcatchment and a 17.8 ha catchment. The results show that at the subcatchment scale the high retention in the A horizon of the soil limited the transport of cadusafos by runoff, whereas the lower retention of the molecule in the B horizon favoured percolation towards the shallow groundwater. The contamination levels of surface water, as well as shallow and deep groundwaters, reflected the geological structure of the Féfé catchment: i.e. a shallow aquifer in the most recent volcanic deposits that is rapidly exposed to pollution and a deeper aquifer that is relatively protected from the pollution coming from the treated fields. Comparing the losses of cadusafos at the subcatchment and at the catchment scales revealed that the nematicide re-infiltrated in the hydrographic network. Two successive phases of stream water contamination were observed, corresponding to two distinct contamination mechanisms: an event-dominated contamination phase (of less than 30 days) when transport was linked to overland flow during precipitation shortly after application, and a stabilized contamination phase when transport originated mainly from the drainage of the shallow aquifer. Lastly, comparing the losses of the two phases during 2003 and 2006 showed that shallow groundwater, which is promoted in such permeable soils under abundant tropical rainfalls, seems to be the main contributor to stream contamination.

[Departement_IRSTEA]Territoires [TR1_IRSTEA]DTAM; Pesticides used for intensive agricultural production threaten the water resources of the French West Indies. For example, the pesticide chlordecone was used until the nineties in banana fields. Operational and simple tools are needed to assess the potential risk of pollution by pesticides. Here, we propose a method to assess the spatial variability of pollution risk on a watershed scale. This method proceeds in four steps: (1) surveying practices; (2) determining the pesticide load for each field in the watershed; (3) establishing an indicator of pollution contribution for each field based on the load of pesticide per year weighted by the toxicity and solubility of each molecule; and (4) spatializing the indicator. We applied this method to an agricultural watershed in the north of Martinique, French West Indies. The results showed detailed information of pesticide dose spread and the distribution of the pollution risk, highlighting risk areas. Specifically designed for the volcanic and tropical areas of the French West Indies, our method could be adapted by integrating other data on soil-climate conditions and the topography.

Correspondance auteur: Jean-Baptiste Charlier jb.charlier@gmail.com; International audience; The aim of this article is to determine how the nematicide cadusafos [S,S-di-sec-butyl O-ethyl phosphorodithioate] contaminates water and soils at two scales, subcatchment and catchment. The study site was a small banana (Musa spp.)-growing catchment on the tropical volcanic island of Guadeloupe in the Caribbean. Two application campaigns were conducted, one in 2003 on 40% of the catchment and one in 2006 on 12%. The study involved monitoring for 100 d the surface water and groundwater flows and the cadusafos concentrations in the soil and in surface and groundwaters in a 2400 m2 subcatchment and a 17.8 ha catchment. The results show that at the subcatchment scale the high retention in the A horizon of the soil limits the transport of cadusafos by runoff, whereas the lower retention of the molecule in the B horizon favors percolation toward the shallow groundwater. Comparing the losses of cadusafos at the subcatchment and at the catchment scales revealed that the nematicide re-infiltrated in the hydrographic network. Two successive phases of stream water contamination were observed, corresponding to two distinct contamination mechanisms: an event-dominated contamination phase (of

Rainfall partitioning by vegetation modifies the intensity of rainwater reaching the ground, which affects runoff generation. Incident rainfall is intercepted by the plant canopy and then redistributed into throughfall and stemflow. Rainfall intensities at the soil surface are therefore not spatially uniform, generating local variations of runoff production that are disregarded in runoff models. The aim of this paper was to model runoff at the plot scale, accounting for rainfall partitioning by vegetation in the case of plants concentrating rainwater at the plant foot and promoting stemflow. We developed a lumped modelling approach, including a stemflow function that divided the plot into two compartments: one compartment including stemflow and the related water pathways and one compartment for the rest of the plot. This stemflow function was coupled with a production function and a transfer function to simulate a flood hydrograph using the MHYDAS model. Calibrated parameters were a "stemflow coefficient", which compartmented the plot; the saturated hydraulic conductivity (Ks), which controls infiltration and runoff; and the two parameters of the diffusive wave equation. We tested our model on a banana plot of 3000m2 on permeable Andosol (mean Ks=75mmh?1) under tropical rainfalls, in Guadeloupe (FWI). Runoff simulations without and with the stemflow function were performed and compared to 18 flood events from 10 to 140 rainfall mm depth. Modelling results showed that the stemflow function improved the calibration of hydrographs according to the er- Correspondence to: J.-B. Charlier (jb.charlier@gmail.com) ror criteria on volume and on peakflow, to the Nash and Sutcliffe coefficient, and to the root mean square error. This was particularly the case for low flows observed during residual rainfall, for which the stemflow function allowed runoff to be simulated for rainfall intensities lower than the Ks measured at the soil surface. This approach also allowed us to take into account the experimental data, without needing to calibrate the runoff volume on Ks parameter. Finally, the results suggest a rainwater redistribution module should be included in distributed runoff models at a larger scale of the catchment.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Rainfall redistribution by plant canopy, notably the water flow down the plant stem (stemflow), modifies the incident rainfall rate at the soil surface and may affect runoff generation. To test this hypothesis, we observed and measured runoff at the plant scale with banana cultivated on tropical Andosol. Observation of runoff by video and matrix potential monitoring showed that, during a runoff event, the matrix potential increased mainly downstream from the pseudostem in line with the slope, delimiting a saturated zone of runoff propagation that appeared on video monitoring. The results indicate that rainfall redistribution by plant canopy, i.e. stemflow and dripping areas, enhances runoff even on soil with a high infiltration rate (mean hydraulic conductivity at saturation Ks of 67 mm h−1). Data analysis of 40 runoff events showed that events were composed of at least two runoff phases characterized by an abrupt increase in runoff coefficient (RC) from 0.16 to 0.65 between the first and the second phase. The change in RC was related to rainfall rate. Also, between the first and the second runoff phase, the apparent infiltration rate at the plot scale decreased from 30 to 10 mm h−1. This was related to an increase in runoff contributing areas (RCA), from an estimated 18% to 93% of the plot surface. However, data analysis and model simulations showed that the increase in mean rainfall rate in RCA due to stemflow was not sufficient to account for large runoff volumes. Hence, one must also take into account the spatial variation of hydraulic conductivity at saturation with low values relative to RCA (estimation for the second runoff phase was 7.6 mm h−1). Moreover, simulation results implied Ks decreases with time. Finally, rainfall redistribution may have an impact at a larger scale. In banana plantations, the hydraulic connectivity of runoff areas can enhance the stemflow effect up to the plot scale. From this point of view, the two-compartment scheme we chose for modeling could be applied at a larger scale: one compartment including stemflow and the relative water pathways and one compartment for the rest of the plot.

Rainfall partitioning by vegetation modifies the intensity of rainwater reaching the ground, which affects runoff generation. Incident rainfall is intercepted by the plant canopy and then redistributed into throughfall and stemflow. Rainfall intensities at the soil surface are therefore not spatially uniform, generating local variations of runoff production that are disregarded in runoff models. The aim of this paper was to model runoff at the plot scale, accounting for rainfall partitioning by vegetation in the case of plants concentrating rainwater at the plant foot and promoting stemflow. We developed a lumped modelling approach, including a stemflow function that divided the plot into two compartments: one compartment including stemflow and the related water pathways and one compartment for the rest of the plot. This stemflow function was coupled with a production function and a transfer function to simulate a flood hydrograph using the MHYDAS model. Calibrated parameters were a "stemflow coefficient", which compartmented the plot; the saturated hydraulic conductivity (Ks), which controls infiltration and runoff; and the two parameters of the diffusive wave equation. We tested our model on a banana plot of 3000 m2 on permeable Andosol (mean Ks=75 mm h−1) under tropical rainfalls, in Guadeloupe (FWI). Runoff simulations without and with the stemflow function were performed and compared to 18 flood events from 10 to 140 rainfall mm depth. Modelling results showed that the stemflow function improved the calibration of hydrographs according to the error criteria on volume and on peakflow, to the Nash and Sutcliffe coefficient, and to the root mean square error. This was particularly the case for low flows observed during residual rainfall, for which the stemflow function allowed runoff to be simulated for rainfall intensities lower than the Ks measured at the soil surface. This approach also allowed us to take into account the experimental data, without needing to calibrate the runoff volume on Ks parameter. Finally, the results suggest a rainwater redistribution module should be included in distributed runoff models at a larger scale of the catchment.

The growth of the urban market in Africa leads to a multi-functional outer-urban agriculture and to a specialization on the fresh and perishable products. From the analysis chart which proposes the localized production systems, we try to understand how the structural characteristics and the functioning of the slums agriculture create opportunities and activate strategic resources. The results show how the geographical proximity bound to the city can facilitate the organizational and technical innovation., La croissance des marchés urbains en Afrique conduit à une multifonctionnalité de l'agriculture périurbaine et à une spécialisation sur les produits frais et périssables. En mobilisant le concept de système de production localisé, nous analysons en quoi les caractéristiques structurelles et le fonctionnement de l'agriculture de bas-fonds créent des opportunités et activent des ressources stratégiques. Les résultats montrent comment la proximité géographique liée à la ville peut favoriser l'innovation organisationnelle et technique.

L'épuisement annoncé des ressources naturelles non renouvelables et les externalités environnementales liées à la consommation d'énergies fossiles pose la question énergétique au centre de l'évolution du paradigme technologique de l'agriculture et de l'agro-alimentaire. Quel est le caractère durable de l'agriculture en abordant l'équité ntergénérationnelle, l'efficacité économique et l'impact environnemental ? Cette communication étudie l'impact du coût énergétique dans les choix technologiques à privilégier et les dynamiques de localisation des productions horticoles : comment choisir entre une production de proximité (chauffage et protection sous abris des cultures), et une délocalisation dans des zones pédoclimatiquement plus avantagées (prise en compte du transport induit). Pour y répondre, l'analyse aborde les limites des différentes approches conventionnelles mobilisables depuis les années 70. A partir de ces limites elle propose une méthode d'évaluation des écobilans énergétiques dans les filières fruits et légumes. Cette démarche est élaborée à partir de tests sur les productions de melon et de salade. Elle propose de distinguer les phases de production, de conditionnement et de transport ainsi que trois niveaux d'analyse énergétique (énergie directe, indirecte et énergie issue du capital). A partir d'une matrice de coefficients énergétiques, les flux sont convertis en unité commune, le MJ puis le Tep, unité qui permet aisément d'obtenir le coût financier de l'écobilan énergétique. L'évaluation économique a pour objectif d'évaluer symétriquement les coûts réels et les coûts cachés. Il est de ce fait proposé de prendre en considération le coût énergétique du traitement des déchets. Ce travail permet de simuler l'impact d'une hausse des prix de l'énergie sur les filières horticoles et de faire des comparaisons intra et inter-filière pour proposer une méthode de localisation des lieux d'innovations en anticipant les trajectoires techniques d'évolution des systèmes de production.

The burrowing nematode Radopholus similis is a major pest of bananas and plantains all over the world. Introduced from the XVIth century in Africa and America, this nematode causes important losses in the traditional banana plantations. Recent development of new cropping systems reduced its impact; but additional knowledge is required to understand its persistence in soil and to prevent its dispersal. Usually considered as marginal, the soil phase of Radopholus similis has not been extensively studied because the concentrations of R. similis are not very important in the soil (almost 1/1,000 of the concentration in roots). While taking into account both soil volume and nematode numbers, the soil phase contains 30 to 50 % of R. similis individuals. After considering the characteristics of the West Indian volcanic soils, especially classes of capillaries which are likely to contain R. similis (capillaries from 20 to 300 µm in diameter), we evaluated the various methods of extraction of nematodes: Baermann filtration, elutriation, centrifugation-flotation, aspersion, maceration in hydrogen peroxide. The extraction efficiency of each method, their advantages and disadvantages were discussed. This work was completed by the evaluation of a method of vital coloration to differentiate the dead nematodes from the living ones. Then, the capacity of survival of R. similis in soils was evaluated. We placed a R. similis suspension in 30 mL containers filled up with soils of different types at different water potential, but always without food source. These containers were stored for up to 180 days in conditions of optimal temperature for R. similis. The observed survival durations were slightly higher than those usually found in the bibliography: water saturated soils set apart, we recovered after six months from 1.7 to 9.3 % of the initial population in the nitisol and from 9.5 to 11.9 % in the andosol. Considering the adults, the decreasing curves of R. similis populations could generally be adjusted either with an exponential model or with a Teissier's model. These curves depended on the soil nature, the water potential and the nematode sex. We thus observed that males had a remarkable survival capacity; in the nitisol, their average survival rates were close to twice those of females. This survival capacity is likely to be linked with a lesser daily energy expense in males than in females: it would seem that males, whose digestive system is atrophied, did not forage and did not use reserves for the development of eggs. Apart from this, in the sterilized soil, survival was optimal when soils were close to the field capacity; in the natural soils, survival was optimal in the driest conditions. These contradictory results may be explained by the interactions with other soil organisms which, by decreasing the capacity of survival, may have an antagonistic effect. A complementary study was carried out in tubes filled with water or with soil solutions, extracted from a nitisol by centrifugation. After 35 days, 7 to 8 % of the initial populations of R. similis of each sex remained alive. This species can thereby remain long enough in running waters to be dissipated by runoff. We thus studied the dispersion of R. similis by water flows; on soil surface with rainfall simulators and along soil depth with soil cylinders on which we sprinkled simulated rainfalls which totalized up to 3.7 times the pore volume of the cylinder (total of 540 mm rainfall). These studies were completed by a field trial which led to successive maps of nematode recontaminations in subplots isolated or not from upstream water by ditches. The passive dissemination seems very weak inside the soil and affects only a marginal fraction of the populations. It seems that R. similis resorts to a behaviour of fleeing from leaching (plasticity reflex?) to resist water flows. On soil surface, rainfall simulation showed that dissemination by surface waters required very particular conditions: soils close to water saturation, unearthed roots or toppled-over plants on soil surface. Nevertheless, passive water dissemination occurs mostly on soil surface, but this phenomenon is restricted to "disaster" events at the scale of the nematode: destruction of its environment by tropical showers with heavy runoff. Actually, R. similis leaching by runoff water is sufficient to contaminate a banana plot in less than two years. All these studies showed that the behaviour of R. similis is an essential knowledge to understand its survival and dispersal. Its biology allows good adaptation to the long-lasting cultures with vegetative reproduction, such as banana plants. When these are cultivated in monoculture, R. similis damages can be considerable., Le nématode phytoparasite Radopholus similis est un ravageur majeur des bananiers et plantains dans le monde. Introduit à partir du XVIe siècle en Afrique et Amérique, ce nématode occasionne des pertes importantes dans les bananeraies traditionnelles. La mise au point de nouvelles méthodes culturales a permis de réduire son impact ; mais des connaissances supplémentaires sont requises pour comprendre sa persistance et prévenir sa dispersion. Considérée jusqu'alors comme marginale, la phase sol de R. similis avait été peu étudiée car les populations de R. similis sont faiblement concentrées dans le sol (environ 1/1 000e de celle des racines). Pourtant, le volume du sol exploré par les racines de bananier représente 100 à 300 fois le volume de ces racines ; la phase sol concerne 30 à 50 % des effectifs de R. similis. Après avoir considéré les caractéristiques des sols volcaniques antillais, et notamment les classes de capillaires susceptibles d'héberger R. similis (capillaires de 20 à 300 µm de diamètre), nous avons évalué les différentes méthodes d'extraction des nématodes : filtration Baermann, élutriation, centrifugation-flottaison, aspersion, macération dans l'eau oxygénée. Les rendements à l'extraction de chaque méthode, leurs avantages et inconvénients ont été discutés. Ce travail a été complété par l'évaluation d'une méthode de coloration vitale qui permet de discriminer les nématodes morts et vivants. L'aptitude à la survie de R. similis dans le sol a ensuite été évaluée. Pour cela, nous avons déposé des suspensions de nématodes dans des piluliers remplis de sol de natures et de potentiels matriciels variables, mais toujours sans ressource alimentaire. Ces piluliers ont ensuite été conservés jusqu'à 180 jours dans des conditions de température optimale pour R. similis. Les durées de survie mesurées ont ainsi été légèrement supérieures à celles que l'on trouve habituellement dans la bibliographie : si on exclut les sols saturés en eau, il restait au bout de six mois de 1,7 à 9,3 % de la population apportée dans le nitisol et de 9,5 à 11,9 % dans l'andosol. Pour les adultes, les courbes de décroissances de population de R. similis pouvaient généralement être ajustées à l'aide des modèles de décroissance exponentielle ou de Teissier. Ces courbes dépendaient de la nature du sol, du potentiel hydrique et du sexe. Nous avons ainsi observé que les mâles avaient une capacité de résistance surprenante ; dans le nitisol, les taux de survie ont été en moyenne proches du double de ceux des femelles. Cette capacité de survie des mâles serait liée à une moindre dépense énergétique journalière que chez les femelles : les mâles, dont le système digestif est atrophié, ne chercheraient pas activement leur nourriture et ne perdraient pas de réserves lors du développement des œufs. Par ailleurs, dans les sols stérilisés, la survie était optimale quand les sols étaient proches de la capacité au champ ; dans les sols non perturbés, elle était optimale dans les sols les plus secs. Ces résultats contradictoires pourraient s'expliquer par les interactions avec les autres organismes du sol qui, en diminuant la capacité de survie, pourraient avoir un rôle antagoniste. Une étude complémentaire a été réalisée dans des tubes remplis d'eau ou de solutions de sol, extraites d'un nitisol par centrifugation. Au bout de 35 jours, il restait 7 à 8 % des populations initiales de R. similis, et ce, pour les deux sexes. Cette espèce peut donc subsister assez longtemps dans des eaux qui circulent pour être disséminée par ruissellement. Nous avons donc étudié la dissémination de R. similis par les flux d'eau ; en surface à l'aide de simulateur de pluie, en profondeur à l'aide de cylindres de sol sur lesquels nous avons simulé des pluies allant jusqu'à 3,7 fois le volume poral du cylindre (pluie de 540 mm). Ces études ont été complétées par un dispositif au champ qui a permis de cartographier les recontaminations dans des parcelles isolées ou non hydrologiquement par des fossés. La dissémination passive a été très faible dans le sol et n'a concerné qu'une fraction marginale des populations. Il semble que R. similis ait adapté ses comportements pour résister à l'entraînement par les eaux (plasticité réflexe ?). En surface, les simulations de pluie ont montré que la dissémination par les eaux nécessitait des conditions bien particulières : sols proches de la saturation en eau, racines ou bulbes arrachés à la surface du sol. Néanmoins, la dissémination passive existe, essentiellement en surface ; elle s'apparente à un phénomène restreint aux évènements "catastrophe" à l'échelle du nématode : destruction de son milieu de vie par les intempéries accompagnées d'épisodes de ruissellement important. Elle est suffisante pour entraîner la recontamination d'une parcelle en moins de deux ans. L'ensemble de ces travaux a montré que le comportement de R. similis est un facteur essentiel pour comprendre sa survie et sa dispersion. Sa biologie lui permet de bien s'adapter aux cultures pérennes à multiplication végétative, comme le bananier. Lorsque ces dernières sont cultivées en monoculture, les dégâts peuvent être considérables.

Confrontée à la croissance urbaine, l'agriculture proche des villes revêt diverses formes. Elle peut être urbaine et périurbaine, structurée ou informelle. Ces agricultures créent des emplois et fournissent des produits alimentaires pour une population urbaine qui vit souvent dans des conditions précaires. Elles contribuent à la création de villes durables par la réalisation d'espaces verts, tels que des parcs, des jardins, des espaces horticoles et des aires de drainage. Mais ces agricultures sont aussi une source de nuisances et de risques pour l'environnement ou la santé humaine. Au-delà de la question de la place de l'agriculture dans la ville, d'autres questions se posent : la pollution de l'eau, l'alimentation ou le recyclage des déchets domestiques ou industriels, et la qualité sanitaire des produits.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The vitamin C content and the colour of orange juice made from concentrate were measured during 9 months of storage at 20 degrees C either under artificial light or in darkness. The packaging materials used were glass, standard monolayer polyethylene terephthalate (PET) and multilayer PET (PET/nylon and oxygen scavenger/PET) containers. In this experiment, all bottles were sealed with aluminium foil in order to avoid any cap effect. The results showed that in plastic packaging materials, the loss of vitamin C was related to the oxygen permeability, and that glass provided the best preservation of ascorbic acid. No statistical difference (p < 0.05) was revealed between the vitamin C content in the juice stored under artificial light or in darkness, whatever the packaging used. The modification Of colour was studied with the L, a* and b* values during storage at 20 degrees C under artificial light. L and b* decreased, revealing a reduction of lightness and yellow colour of the juice, whereas a* increased, due to the formation of brown pigments. This change in colour was partly related to the oxygen permeability of the packaging used. The losses of aroma compounds by permeation through the bottle (PET) and the cap (high-density polyethylene, HDPE) have also been investigated. The results showed that permeation mainly took place through the cap. The use of a multilayer cap [HDPE with internal barrier layer of low-density polyethylene (LDPE)/EvOH/ LDPE] considerably limited the permeation of the aroma compounds studied, whatever the PET bottle used

We aimed to define a more robust indicator for banana harvest date that ensures an optimal fruit green life (GL). Our hypothesis was that development rather than growth would account for GL more accurately. To this end, five indicators were compared: one related to fruit size (i.e., growth, expressed as the diameter of fruit); two related to fruit age [i.e., development, expressed as the age of fruit measured in the number of days or in degree days (°Cd) from inflorescence emergence]; and two related to metabolism during maturation (i.e., the concentrations of malate and citrate in the pulp). Different treatments (e.g., fruit removal, leaf shading, bunch bagging, defoliation, water deficit, and flooding) were applied to modify the fruit growth rate. On different dates between the emergence of the inflorescence and harvest, fruit GL and the five indicators were measured. The results showed that there was a decreasing exponential relationship between GL and accumulated °Cd from inflorescence emergence (r2 = 0.77). This was more reliable than the relationships between GL and fruit diameter (r2 = 0.39), or between GL and fruit age, expressed in days (r2 = 0.39). Relationships were also established between GL and malate or citrate concentrations, but they were not sufficiently reliable to estimate GL. The results illustrate that GL is related to fruit development, and that °Cd is a more reliable criterion for harvest date than the number of days, or fruit diameter, because it is less sensitive to different fruit growth rates. Banana growers in the French West Indies usually use fruit diameter and age in days to determine harvest date. However, they face problems of fruit ripening during transportation. The use of °Cd as an indicator may help to determine the optimum harvest date more accurately.

email: Jean-Baptiste Charlier (jb.charlier@gmail.com) Correspondence to Jean-Baptiste Charlier, CIRAD, UPR Systèmes bananes et ananas, Capesterre-Belle-Eau, Guadeloupe, F-97130, France.; International audience; The hydrological behaviour of the cultivated Féfé catchment (17.8 ha) on the tropical volcanic island of Guadeloupe was studied to identify flow paths, to quantify water fluxes, and finally, to build a lumped model to simulate discharge and piezometer levels. The approach combined two steps, an experimental step and a modelling step, which covered two time scales, the annual and the storm event scale. The hydrological measurements were conducted over 2 years. The Féfé catchment is characterized by heavy rainfall (4229 mm/year) on permeable Andosols; the results showed that underground flow paths involved two overlapping aquifers, and that the annual water balance in 2003 was shared among outflows of the deep aquifer (42%), evapotranspiration (31%), and streamflow (27%). On the event scale, the surface runoff coefficient ranges between 6.2% and 24.4% depending on antecedent dry or wet moisture conditions. Hortonian overland flow predominated over subsurface and saturation overland flow processes. Recharge of the shallow aquifer is mainly governed by a constant infiltration capacity of the Andosols with depth in the vadose zone. Outflows of this shallow aquifer were the baseflow of the main stream and the recharge of the deep aquifer. Volcanic deposits at Féfé promoted the underground flow path, and cultivated areas seemed to explain the high stormflow values relative to other tropical small catchments under rain forest. A conceptual lumped model integrating runoff, infiltration, evapotranspiration, and fluctuations of the two overlapping aquifers was developed. The model has six parameters and was calibrated and validated on the hydrograph at the outlet and on the two piezometers of the shallow and the deep aquifers. The results show fair to good agreement between measured and simulated variables, and consequently, the model was consistent with the main hydrological processes observed from experimental results in wet conditions.

La réforme de l'Organisation commune du marché de la banane interpelle sur l'avenir de la banane des Antilles françaises. Cet article par une analyse de filière caractérise les déterminants de la compétitivité (Martinique, Guadeloupe) au niveau de ses coûts et impacts territoriaux. Il en déduit deux axes d'amélioration de la compétitivité : l'accélération de l'innovation, la réalisation d'économies d'échelle et une différenciation qualitative portant sur l'origine., The reorganization of the banana european market is a challenge for the French West Indies banana commodity chain. This paper presents the competitiveness determinants of the banana production in Guadeloupe and Martinique for its costs and its territorial impacts. Three main propositions are exposed to improve the French banana chain: investments in innovation, economies of scale at farm and grower’s association levels and a promotion of the fruits related to its geographical origin.

The management and protection of water resources require a good knowledge of hydrological processes at the catchment scale. This issue is crucial in the Antilles where agricultural practices have caused water and soil resources chronic pollutions.This thesis aims to characterize the hydrological behaviour of a small catchment situated in a volcanic tropical region mainly planted with banana. The study site is the Féfé catchment (17.8 ha), located on the Basse-Terre island in Guadeloupe (FWI), which has been monitored between 2003 and 2006. Two complementary approaches were used.First of all, the experimental approach, combining geology, hydrology, hydrogeology and pesticide tracer, was used to characterize the structure, the water balance and the hydrological processes of a small catchment. A global behaviour scheme has been established, and the main characteristics are: high water fluxes (annual rainfall > 4 000 mm), an important recharge of groundwater (60% of the annual effective rainfall), and a predominance of Hortonian overland flow. A lumped model based on this scheme allowed to correctly simulate surface and groundwater flows. These studies have led to identify the main mechanisms of contamination of soils and waters by a nematicide used in banana plantations (cadusafos).Then, the modelling approach using the distributed model MHYDAS highlighted the impact of land use and ditch network on flood generation. This approach has taken into account the specificities of the cultivated tropical environment that is the rainfall partitioning by vegetation (stemflow of banana plant) and aquifer/ditch exchanges. The application of the model at the three scales of the plot, the sub-catchment and the catchment, has led to better characterize the spatial and temporal variability of hydrological processes.Both approaches are an appropriate way to measure the environmental impact of pesticide applications on the field, to characterize up-scaling, and to test the impact of land use.; La gestion et la protection des ressources en eau nécessitent une bonne connaissance des processus hydrologiques à l'échelle du bassin versant. Le problème se pose en particulier aux Antilles où l'activité agricole est à l'origine de pollutions chroniques des ressources en eau et des sols.L'objectif de cette thèse est de caractériser le fonctionnement hydrologique d'un petit bassin versant volcanique en climat tropical, dans un contexte cultivé principalement en banane. Le site d'étude est le bassin de Féfé (17,8 ha), sur l'île de la Basse-Terre en Guadeloupe, qui a été instrumenté entre 2003 et 2006. Deux approches complémentaires ont été utilisées.Premièrement, l'approche expérimentale combinant géologie, hydrologie, hydrogéologie et traçage (pesticide) a permis de caractériser la structure, le bilan et les processus hydrologiques d'un petit bassin versant. Un schéma de fonctionnement global a été établi avec comme caractéristiques principales des flux hydriques élevés (pluie annuelle > 4 000 mm), une importante recharge des nappes (60 % de la pluie efficace annuelle), et une prédominance du ruissellement hortonien. Un modèle global à réservoirs basé sur ce schéma conceptuel a permis de reproduire correctement les flux de surface et souterrains. Ces études nous ont permis d'identifier les principaux mécanismes de contamination des sols et des eaux de surface et de nappes par un nématicide utilisé en bananeraies (le cadusafos).Deuxièmement, l'approche de modélisation à l'aide du modèle distribué MHYDAS, a permis de rendre compte de l'incidence de l'occupation du sol et du réseau de fossés sur la genèse des crues. Cette approche intègre les spécificités du milieu cultivé tropical que sont la redistribution de la pluie par la plante (stemflow du bananier) et les échanges nappe-fossé. L'application du modèle aux échelles de la parcelle, du sous-bassin et du bassin versant, a permis de mieux caractériser les variabilités spatiale et temporelle des processus hydrologiques.Ces deux approches constituent une voie pertinente pour évaluer l'impact environnemental des épandages agricoles, caractériser les changements d'échelle, et tester l'impact de l'occupation du sol.

The management and protection of water resources require a good knowledge of hydrological processes at the catchment scale. This issue is crucial in the Antilles where agricultural practices have caused water and soil resources chronic pollutions.This thesis aims to characterize the hydrological behaviour of a small catchment situated in a volcanic tropical region mainly planted with banana. The study site is the Féfé catchment (17.8 ha), located on the Basse-Terre island in Guadeloupe (FWI), which has been monitored between 2003 and 2006. Two complementary approaches were used.First of all, the experimental approach, combining geology, hydrology, hydrogeology and pesticide tracer, was used to characterize the structure, the water balance and the hydrological processes of a small catchment. A global behaviour scheme has been established, and the main characteristics are: high water fluxes (annual rainfall > 4 000 mm), an important recharge of groundwater (60% of the annual effective rainfall), and a predominance of Hortonian overland flow. A lumped model based on this scheme allowed to correctly simulate surface and groundwater flows. These studies have led to identify the main mechanisms of contamination of soils and waters by a nematicide used in banana plantations (cadusafos).Then, the modelling approach using the distributed model MHYDAS highlighted the impact of land use and ditch network on flood generation. This approach has taken into account the specificities of the cultivated tropical environment that is the rainfall partitioning by vegetation (stemflow of banana plant) and aquifer/ditch exchanges. The application of the model at the three scales of the plot, the sub-catchment and the catchment, has led to better characterize the spatial and temporal variability of hydrological processes.Both approaches are an appropriate way to measure the environmental impact of pesticide applications on the field, to characterize up-scaling, and to test the impact of land use.; La gestion et la protection des ressources en eau nécessitent une bonne connaissance des processus hydrologiques à l'échelle du bassin versant. Le problème se pose en particulier aux Antilles où l'activité agricole est à l'origine de pollutions chroniques des ressources en eau et des sols.L'objectif de cette thèse est de caractériser le fonctionnement hydrologique d'un petit bassin versant volcanique en climat tropical, dans un contexte cultivé principalement en banane. Le site d'étude est le bassin de Féfé (17,8 ha), sur l'île de la Basse-Terre en Guadeloupe, qui a été instrumenté entre 2003 et 2006. Deux approches complémentaires ont été utilisées.Premièrement, l'approche expérimentale combinant géologie, hydrologie, hydrogéologie et traçage (pesticide) a permis de caractériser la structure, le bilan et les processus hydrologiques d'un petit bassin versant. Un schéma de fonctionnement global a été établi avec comme caractéristiques principales des flux hydriques élevés (pluie annuelle > 4 000 mm), une importante recharge des nappes (60 % de la pluie efficace annuelle), et une prédominance du ruissellement hortonien. Un modèle global à réservoirs basé sur ce schéma conceptuel a permis de reproduire correctement les flux de surface et souterrains. Ces études nous ont permis d'identifier les principaux mécanismes de contamination des sols et des eaux de surface et de nappes par un nématicide utilisé en bananeraies (le cadusafos).Deuxièmement, l'approche de modélisation à l'aide du modèle distribué MHYDAS, a permis de rendre compte de l'incidence de l'occupation du sol et du réseau de fossés sur la genèse des crues. Cette approche intègre les spécificités du milieu cultivé tropical que sont la redistribution de la pluie par la plante (stemflow du bananier) et les échanges nappe-fossé. L'application du modèle aux échelles de la parcelle, du sous-bassin et du bassin versant, a permis de mieux caractériser les variabilités spatiale et temporelle des processus hydrologiques.Ces deux approches constituent une voie pertinente pour évaluer l'impact environnemental des épandages agricoles, caractériser les changements d'échelle, et tester l'impact de l'occupation du sol.

Oral communication; International audience; An important issue in spatially distributed modelling is parameterisation and calibration strategies from the local measure to the plot and the catchment scales. In cultivated areas, hydrological processes are mainly controlled by the geometry of surface flow pathways (ditches, tracks, etc.), the tillage practices and the vegetation pattern which modify rainfall interception. Soil properties are measured at the local scale and then extrapolated to the basin scale. However, few studies take into account the role of tropical vegetation on rainfall/runoff processes across scales. This paper aims to characterize the role of banana (Musa spp.) cover in tropical region on runoff processes across scales and to assess at the catchment scale the runoff contributing areas. Three sites, located in Guadeloupe (FWI), Lesser Antilles are planted with banana and monitored for runoff and piezometric measurements since year 2001: plot A (3 000 m2), plot B (2 400 m2) which is included in the C catchment (17.8 ha; 55% banana, 40% fallow land, and 5% tracks and sheds). The experimental sites are characterized by abundant rainfall (4230 mm/year) and a high water infiltration capacity on andisols (saturated hydraulic conductivity, Ks of 30 to 75 mm h). The spatially distributed model MHYDAS, which considers a catchment as a series of interconnected fields units linked to the ditch network, was used at the storm event timescale. At the banana tree scale, since rainfall is intercepted and concentrated at its base via stemflow, we developed a rainfall redistribution function which takes into account the increase of rainfall intensity on the furrow. First, MHYDAS parameters were calibrated at the A plot scale on 20 events. Then, the calibrated parameters were spatially distributed at the catchment scale. Finally, for validation, MHYDAS was used to simulate runoff and piezometric levels at the B plot and the C catchment scales on 30 events with different spatial partitioning of landscape, e.g. from a global approach (one unit) to a distributed approach (n units). The results show, at the plot scale, a high vegetation influence on surface runoff simulation generated by stemflow processes and a production of runoff for smaller rainfall intensities than the Ks measured on the field. At the catchment scale, the influence of vegetation pattern is globally lower and decreases with an increase of the variability of fields units used in the spatially distributed model. In fact, spatially distributed model allows re-infiltration and drainage in fields and ditches and generates a smoothed response of the basin. Globally, results highlight the cropping influence on runoff coefficient across scales and allow progress in identifying modelling strategies for cultivated areas.

International audience

African consumers' expectations concerning quality of food products are great. In spite ofconstrained budgets, we showed that market retailed prices revealed quality preferences of theconsumers and not only production costs. In very poor countries like Mali, food innovation islimited by the very low purchasing power of the population. However, technological food productor process innovations are possible and sometimes valuable. Demand driven innovation may lead toopen new markets, opportunities for small and medium scale enterprises and to improve consumers'welfare. Based on this assumption, technical research was done to provide new food products. Inthis paper, using both sensory test and a hedonic price approach, we estimated consumer demandfor different characteristics of fonio, a West African cereal, and showed that poor consumers dohave quality requirements and actually pay for it. We showed that the shadow or hedonic price paidfor quality characteristics is small but significant. A comparison of sensory test and market studyshowed a convergence between what people say they prefer and what they really pay for. Resultswere consistent and showed directions for technological improvement of the product and itsproduction process. The Partial Least Square method was used to estimate hedonic prices of thedifferent modalities of fonio quality traits. This method was interesting since it solved the OrdinaryLeast Square method's colinearity problems.