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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 burrowing nematode Radopholus similis and the lesion nematodes Pratylenchus spp. are considered as major constraints to banana cultivation worldwide. As an alternative to the use of chemical pesticides in commercial banana plantations, the possible role of the earthworm Pontoscolex corethrurus was studied regarding the reducing harmfulness of the main plant-feeding nematodes of banana. The interactions among banana plants, plant-feeding nematodes and earthworms have been tested in a controlled experiment combining treatments including or not earthworms and nematodes, over a complete vegetative banana development cycle. The aim of the work was to evaluate how earthworm activity can affect the pathogenicity of the three main plant-feeding nematodes associated with dessert banana (Musa spp. AAA group, cv. Cavendish) in Guadeloupe (French West Indies), R. similis, Pratylenchus coffeae and Helicotylenchus multicinctus. Results showed that damages caused by plant-feeding nematodes were lowered in the presence of the earthworm P. corethrurus; the population of plant-feeding nematodes did not decrease whereas root damage induced by nematodes was significantly reduced (50% reduction of root necrosis in the presence of earthworms). Moreover, in the presence of P. corethrurus, we observed a change of soil porosity. On the one hand, the burrowing activity of earthworms destroyed most of the initial structural porosity (mesobiotic pores, 3–300 _m) and on the other hand, they increased the volume of the finest structural pores diameter class (microbiotic pores, 0.3–3 _m). P. corethrurus also stimulated phosphorus mineralization. Soil bioturbation carried out by P. corethrurus could have enhanced the efficiency of microbial community that is involved in phosphorus bioavailability. This observation was corroborated by a higher phosphorus availability in earthworm casts (1386 ± 38 mg P kg−1 of dry matter in cast versus 778 ± 61 mg P kg−1 of dry matter in the soil compartment not influenced by earthworm activity), and a better plant phosphorus nutrition in the presence of earthworms. Phosphorus uptake resulted in a better plant nutrition and a better tolerance to plant-feeding nematodes. Besides, the reduction of the mesobiotic porosity by bioturbation could also have disturbed the nematodes activities during their soil phase and contributed to the reduction of their damage.

International audience; Bemisia tabaci populations belonging to Middle East-Asia Minor one (MEAM1) and Mediterranean (MED) groups (formerly biotype B and Q, respectively) have spread throughout the world. Although the introduction of MEAM1 is documented from several Caribbean islands, it is generally not known whether MED has also been introduced; whether indigenous populations have survived; and if in the affirmative, to which group (s) they belonged. Whiteflies were collected from seven islands on various plant species. The prevalence of MEAM1 and non-MEAM1 individuals was assessed using a microsatellite approach validated with sequences of the mitochondrial cytochrome oxidase I (mtCOI) gene. Of the 262 samples tested, 247 exhibited the MEAM1 pattern, whereas none showed the MED pattern. The mtCOI gene was partially sequenced from a sample of individuals exhibiting MEAM1 (n = 15) and non-MEAM1 patterns (n = 8) and compared with type sequences. The 15 individuals exhibiting the MEAM1 pattern were confirmed to belong to MEAM1. Of the eight individuals representative of the six non-MEAM1 patterns, two belonged to the indigenous New World (NW) group of B. tabaci (NW), one belonged to a distinct species of Bemisia, and five belonged to MEAM1. One individual belonging to NW exhibited 99.9% nucleotide identity with a NW individual from Puerto Rico. The other was identified as the most divergent individual of the North and Central American genetic cluster. We conclude that a highly homogenous MEAM1 population has extensively settled in the Caribbean and that heterogeneous NW populations were still detectable although severely displaced.

International audience; Chlordecone was applied between 1972 and 1993 in banana fields of the French West Indies. This resulted in long-term pollution of soils and contamination of waters, aquatic biota, and crops. To assess pollution level and duration according to soil type, WISORCH, a leaching model based on first-order desorption kinetics, was developed and run. Its input parameters are soil organic carbon content (SOC) and SOC/water partitioning coefficient (Koc). It accounts for current chlordecone soil contents and drainage water concentrations. The model was valid for andosol, which indicates that neither physicochemical nor microbial degradation occurred. Dilution by previous deep tillages makes soil scrapping unrealistic.Lixiviation appeared the main way to reduce pollution. Besides the SOC and rainfall increases, Koc increased from nitisol to ferralsol and then andosol while lixiviation efficiency decreased. Consequently, pollution is bound to last for several decades for nitisol, centuries for ferralsol, and half a millennium for andosol.

Correspondance: tixier@cirad.fr; International audience; Banana monocultures (Musa spp., AAA, Cavendish sub-group cv. Grande Naine) can have a detrimental impact on the environment. In these agro-systems, pesticide treatments can lead to surface and groundwater pollution, as is the case in the tropical insular conditions of the French West Indies. Using models to design alternative cropping systems is of growing interest but most of the research work has been concentrated on annual crops and most often in temperate climate. A specific model called SIMBA was built to assess environmental risks under a large range of cropping techniques and to help design more sustainable cropping systems. SIMBA simulates banana-cropping systems at field level over several cropping cycles. It includes sub-models that simulate soil structure, water balance, root nematode populations, yield, and economic outputs with a sound balance between representing the major phenomena well and keeping the model simple to reduce the parameterization costs in a large range of conditions. Agro-environmental indicators generated by the model make it possible to assess the major potential environmental impacts. The model has been developed and calibrated in Guadeloupe and Martinique and is used to draw up practical recommendations for farmers and for virtual experiments of agro-technological innovations or field management strategies. The structure of SIMBA is presented and a methodology is proposed for designing sustainable banana-based cropping systems using the model. SIMBA has been evaluated in a broad range of cropping systems in Guadeloupe by comparing model estimates to data collected in field experiments and surveys. Simulations lead to trends in rotation-based cropping systems characterized by systems that can be considered as intensive for profit evaluation, and combinations of frequent replanting, low nematicide application, no ploughing, and low fertilization level, for environmental evaluation. Simulations performed to optimize the replanting decision rule showed that relatively frequent replanting is good for profit while low frequency replantations (over four banana cycles) give a better environmental evaluation

The online version of this article (doi:10.1007/s11356-013-2095-x) contains supplementary material, which is available to authorized users.; International audience; When field pollution is heterogeneous due to localized pesticide application, as is the case of chlordecone (CLD), the mean level of pollution is difficult to assess. Our objective was to design a decision support tool to optimize soil sampling. We analyzed the CLD heterogeneity of soil content at 0-30- and 30-60-cm depth. This was done within and between nine plots (0.4 to 1.8 ha) on andosol and ferralsol. We determined that 20 pooled subsamples per plot were a satisfactory compromise with respect to both cost and accuracy. Globally, CLD content was greater for andosols and the upper soil horizon (0-30 cm). Soil organic carbon cannot account for CLD intra-field variability. Cropping systems and tillage practices influence the CLD content and distribution; that is CLD pollution was higher under intensive banana cropping systems and, while upper soil horizon was more polluted than the lower one with shallow tillage (< 40 cm), deeper tillage led to a homogenization and a dilution of the pollution in the soil profile. The decision tool we proposed compiles and organizes these results to better assess CLD soil pollution in terms of sampling depth, distance, and unit at field scale. It accounts for sampling objectives, farming practices (cropping system, tillage), type of soil, and topographical characteristics (slope) to design a relevant sampling plan. This decision support tool is also adaptable to other types of heterogeneous agricultural pollution at field level.

International audience; Bacterial wilt, a soilborne disease caused by Ralstonia solanacearum, one of the world's most important phytopathogenic bacteria, is responsible for high economic losses in horticultural crops, especially in tropical and sub-tropical areas. In Martinique (French West Indies), since 1999, a highly virulent population has been identified on solanaceous and cucurbitaceae crops (Wicker, 2007). Agronomic French research team (INRA and CIRAD) study different agroecological strategies to maintain health and productivity of tomato in the fields. However, tomato benefits from mycorrhization when challenged by root pathogens (Gianinazzi, 2010). Effect of previous mycorrhizal crop was assessed by sampling soils from neighbouring agricultural plots one cultivated with tomato, the other one with chive (Allium fistulosum) and compared to a sterilized control soil. Tomato, cv Heatmaster, was cultivated on these soils under greenhouse conditions. Tomatoes grown on Allium fistulosum previous crop showed significant higher rates of mycorrhization. Moreover, no disease incidence was observed on tomatoes grown after Allium fistulosum. On the contrary, the pourcentage of disease incidence reached 80 % on tomatoes grown after tomatoes. This experiment highlights the potential impact of AMF on tomato bacterial wilt bioprotection.

International 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; 1 Primary resources may affect the structure of species assemblages in upper trophic levels of food webs. These bottom-up effects may involve important ecological processes that affect pest control. For example, population densities of natural enemies may increase when alternative preys are favoured by a new resource. 2 Ants, particularly Solenopsis geminata Forel (Myrmicinae), are recognized as effective predators of herbivores eggs. In the present study, we tested the hypothesis that the addition of a primary resource in a banana agroecosystem will increase pest control of the banana weevil Cosmopolites sordidus Germar (Coleoptera, Curculionidae) by ants. 3 Using stable isotope analyses, we showed that S. geminata used the new resource pathway provided by the addition of a cover crop. This change was revealed by increased d13C values (13C/12C) in a cover crop treatment (C4 plant) compared with a banana (C3 plant) in bare soil treatment. 4 We also showed that the abundance of S. geminata, as measured with pitfall traps, was 4.85.4-fold higher in the cover crop treatment than in the bare soil treatment. Estimation of egg predation rates was in the range 7.870.3%, which occurred in plots with the lowest and highest S. geminata numbers, respectively. 5 The addition of a new primary resource in this system changed the origin of the carbon consumed by predators and increased their densities. The increased ant abundance resulted in increased predation of weevil eggs, which was consistent with our hypothesis. These results will be useful for the design of cropping systems that enhance the biological regulation of pests.

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; Chlordecone, one of the most persistent organochlorine pesticides, was applied between 1972 and 1993 in banana fields in the French West Indies, which results in long-term pollution of soils and contamination of waters, aquatic biota, and crops. As human exposure to chlordecone is mainly due to food contamination, early research was focused on chlordecone transfer to crops. Field trials were conducted to investigate chlordecone contamination of yam, sweet potato, turnip, and radish grown on a Ferralic Nitisol polluted by chlordecone. We also carried out trials on yam, courgette, and tomato under greenhouse conditions with homogenized Andosol and Nitisol, polluted by chlordecone to various extents. Our results indicated that i) all tubers were contaminated in accordance with the chlordecone content of the soils; ii) the plant contamination capacity of the Nitisol was greater than that of the Andosol; and iii) whatever the soil type, tuber contamination was related to the soil volumetric content of dissolved chlordecone. Nevertheless, no tubers showed sufficient chlordecone uptake for efficient soil decontamination by means of plant extraction. Soil contact accounted for most of the root crop contamination, which was inversely proportional to the tuber size. Internal transfer might also increase root crop contamination when the root central cylinder contained raw sap flow, as in the case of turnip or radish. Courgette fruits showed high contamination without soil contact. Thus, further research is needed to explore the pattern of both below- and aboveground plant chlordecone contamination and assess the hypothesis of its correlation with sap flow. Finally, we used our results to build a decision-making tool for farmers, relating soil pollution with the maximal contamination of the harvested organs to predict crop contamination and thus assisting farmers in making crop choices at planting in order to conform with the European Union's regulations.

Introduction : Eaux, végétaux et animaux sont contaminés par des polluants épandus dans l'environnement. Leurs degrés de contamination sont difficiles à déterminer car on ne peut tout analyser. De là, il est possible de considérer une approche globale et systémique de la contamination qui explicite les relations entre pollution des sols, des eaux et des organismes, éléments d'un même écosystème. Cette approche a été appliquée au cas de la Chlordécone (CLD). L'objectif a été ainsi de comprendre et caractériser les principaux mécanismes - physiques (transfert vers les rivières par ex.) et biologiques (capacité d'absorption par ex.) - régissant la dispersion de la molécule dans l'environnement jusqu'à son absorption par les plantes et animaux en vue d'expliquer leur niveau de contamination. Méthode : Différents dispositifs ont été mobilisés pour décrire le devenir de la CLD en partant de sa rétention dans le sol (instrumentation en colonne de sol), puis sa mobilisation et son transfert vers les nappes et les rivières (suivi hydrologique et de la qualité des masses d'eau sur un bassin versant guadeloupéen), jusqu'à son absorption par les végétaux (culture en milieu semi-contrôlé sur différents types de sol) et les animaux en rivière (impact chez le crustacé aquatique Macrobrachium faustinum). Résultats : Les résultats montrent que le principal réservoir de pollution est le sol. De 70 à 80% du stock de CLD du sol est potentiellement disponible à l'entraînement par lessivage, ce processus restant la voie majeure de décontamination des sols. De là, la rivière se contamine principalement du fait d'alimentations souterraines. Les concentrations moyennes dans les eaux restent faibles (moins de 1?g l-1) mais suffisantes pour observer une forte bioaccumulation de la CLD chez M. faustinum qui présente des anomalies de la croissance et de la physiologie. Chez les plantes, le degré de contamination des organes dépend de leur position dans le flux de sève brute qui transporte la CLD. A concentration en CLD équivalente, les nitisols apparaissent plus contaminants que les andosols. Conclusion et perspectives : Différents mécanismes à l'origine d'une contamination importante par la CLD des eaux, de certaines cultures ou animaux ont été identifiés. De plus, nos travaux ont permis de resituer la contamination dans le temps : le mode de dispersion de la CLD suggère une contamination quasi-permanente du milieu depuis les premiers épandages ; pour l'avenir, elle oblige à une surveillance des milieux à l'échelle du siècle ! Enfin, les résultats obtenus confirment l'intérêt de travailler à l'échelle englobante du bassin versant. Ils sont à l'origine d'un projet de mise en place de deux observatoires des pollutions agricoles, un en Martinique, l'autre en Guadeloupe, dédiés dans un premier temps à la CLD. Pour ces observatoires à vocation transdisciplinaire, le partenariat de recherche reste à construire. Ceci constitue un objectif majeur de la première année de projet.

National audience; Chlordecone is an organochlorine insecticide and it was used to fight against the banana black weevil (Cosmopolites sordidus) from 1971 to 1993 in the French West Indies. Chlordecone is not a mobile molecule and is very slowly or almost not degradable in aerobic soils. Its persistence is a long term one and technical remediation is not operational at this time, but soils stay fertile, even if they remain the main pollution source. Thus we have to face and manage this pollution. This leads to changes among agrosystems, whether on crop choice or on practices to reduce sanitary impact. Chlordecone crop uptake varies according to the type of plant and organ: roots and tubers are highly contaminated whether fruits (banana, pineapple, tomato, citrus, etc.) are chlordecone free. A management tool is now available for farmers to choose crops according to the field pollution level and to reduce the consumers’ exposure risk. Reciprocally, cropping systems have an influence on pollution dispersion at the field and watershed scales. Chlordecone pollutes water resources and aquatic organisms through leaching water from polluted fields. This article present the existing situation and sums up the knowledge available based on results from past and in progress projects on cropping systems management and transfer processes to the environment, as well as on their impacts on aquatic ecosystems.; La chlordécone, insecticide organochloré, était utilisée pour lutter contre le charançon du bananier (Cosmopolites sordidus) de 1971 à 1993. La chlordécone est peu mobile et se dégrade à une vitesse très lente, voire nulle dans les sols aérés. Sa persistance est donc longue, et la dépollution artificielle n'est pas opérationnelle actuellement. Cependant les sols restent fertiles même si ils constituent la principale réserve et source de pollution. Il faut donc gérer cette pollution. Cela implique des changements au sein des agrosystèmes, tant sur le choix des productions possibles que sur certaines pratiques agronomiques pour réduire les impacts sanitaires. Pour les espèces cultivées sur les parcelles polluées, certains organes sont très contaminés (tubercules), d'autres indemnes (fruits d'arbres, banane, ananas, tomate, etc.). Un outil de gestion est disponible pour les producteurs afin d'anticiper le choix des cultures et de réduire le risque d'exposition des consommateurs. Réciproquement, les systèmes de culture ont une incidence sur la dispersion de la molécule à l'échelle d'une parcelle et d'un bassin versant. La chlordécone contamine les ressources et les organismes aquatiques via les eaux de percolations issues des parcelles polluées. Cet article fait le point sur les principaux résultats disponibles et les projets en cours sur la gestion des agrosystèmes et les processus de transferts de la chlordécone vers l'environnement ainsi que leurs impacts sur les écosystèmes aquatiques.

National audience

Avec la collaboration de : Claridge Clermont-Dauphin, Guillaume Humbert, Antoine Lafont, Julie Sansoulet (INRA Antilles-Guyane UR ASTRO), François Laurent (INRA Toulouse UMR Xénobiotiques), Maurice Mahieu, Harry Archimède (INRA Antilles-Guyane UR Zootechniques), Philippe Cattan (Cirad Guadeloupe UR BPA), Raphael Achard, Audrey Caron, Christian Chabrier (Cirad Martinique PRAM); National audience; Chlordecone, an organochlorine insecticide, has been used in banana fields before 1993. Nowadays, it is still polluting water resources, food and aquatic biota. Agronomic research has been working very early to answer to how to manage this environmental and sanitary crisis: where are the polluted soils? Is the pollution a long term pollution? The molecule is not mobile. Risk maps, based on the past banana fields, resulted in the diffuse pollution of 1/5th of cultivated area in Guadeloupe and 2/5th in Martinique. Soils with a high content of organic matter are fixing chlordecone molecule. It has not been observed degradation in aerated soil conditions,thus natural soil leaching is the only way to decrease soil pollution which is highly persistent, from one to several centuries according to soil type. Efficient depollution is not operational at the moment. Thus, pollution has to be managed. To reduce population exposure and food contamination, producers need sustainable cropping systems because polluted soil stays productive and fertile. A decision tool is now available, it takes in account the soil pollution level of the field and potential crop contamination: some crops are highly contaminated (roots and tubers), others are chlordecone free (fruits, banana, pineapple, tomato).; La chlordécone, insecticide organochloré de synthèse, était utilisée dans les bananeraies antillaises avant 1993. Pourtant, elle contamine encore les ressources en eau, certaines denrées, et des organismes aquatiques. Très tôt, la recherche agronomique s’est mobilisée pour répondre aux questions posées pour la gestion de cette crise : Où sont les sols pollués? Est-ce une pollution durable ? La molécule est peu mobile. Des cartes de risques, fondées sur leur occupation rétrospective en bananeraies, aboutissent à 1/5e de la SAU polluée en Guadeloupe, 2/5e en Martinique. Les sols riches en matière organique retiennent fortement la chlordécone. Elle ne se dégrade pas dans les sols aérés, seules les eaux de percolation peuvent la dissiper. Sa persistance est donc longue, d’un à quelques siècles selon les sols. La dépollution artificielle n’est pas actuellement opérationnelle. Il faut donc gérer cette pollution. Pour réduire l’exposition de la population et la contamination des denrées, les agriculteurs doivent disposer de systèmes de culture et d’élevage compatibles avec les niveaux de chlordécone des sols, restés fertiles. Un outil est disponible, il prend en compte le niveau de pollution de la parcelle et la contamination des cultures: certaines sont très contaminées (tubercules), d’autres indemnes (fruits d’arbres, banane, ananas, tomate, …).

International audience; Conventional and agro industrial agriculture has reached its limits in fragile media like tropical islands where environmental and social constrains are among the highest in the world. New production modes have to be implemented to protect and rehab some polluted and degraded fields/agricultural areas. Agroecology could be a strategy to achieve ecological intensive agrosystems. In this paper we present some definitions of agroecology and its concepts applications in innovative cropping systems. Innovation is described through several steps and perspectives are given in the Caribbean in term of initiatives to spread knowledge, new cultural practices and production methods.

National audience; Dans la filière de production de banane aux Antilles, mieux conjuguer performances économiques et environnementales impose un changement de pratiques dans les systèmes de production. Pour contribuer à ce changement, la recherche agronomique développe des solutions techniques innovantes qui ne sont malheureusement pas toujours adoptées par les agriculteurs. Pour faire mieux converger les innovations agronomiques développées par la recherche avec les attentes et contraintes des producteurs, nous avons mis au point une méthode d’évaluation ex ante des conditions d’adoption. Quels systèmes innovants faut-il préconiser dans les différents types d’exploitations ? Quels impacts agro-environnementaux et économiques auront les innovations sur les exploitations et leur fonctionnement ? Quels seront les freins et les motivations à leur adoption ? Quelles politiques mettre en œuvre pour les favoriser ? L’objectif de la méthode que nous avons développée est de répondre à ces questions.La méthode d’évaluation que nous proposons est basée sur la combinaison de modèles agronomiques avec des modèles économiques. D’abord nous identifions par enquête la diversité régionale des exploitations, tant biophysique que socio-économique. Puis l’offre d’innovations agro-écologiques est recensée pour construire un pool de systèmes innovants plus ou moins complexes. Nous utilisons un modèle bio-économique pour prévoir quelles seront les conséquences de l’adoption des systèmes innovants dans les différents types d’exploitations. Les résultats de ces simulations sont alors utilisés pour questionner directement les agriculteurs sur leur consentement à adopter de tels systèmes, sous différents scénarios de prix et d’aides. La modélisation économétrique de ces choix permet enfin de révéler et quantifier les motivations et les freins à l’adoption, et de fonder une politique d’innovation adaptée aux diverses attentes des agriculteurs.En Guadeloupe et en Martinique, nous avons pu identifier une grande diversité de milieux physiques, de structures d’exploitations et de systèmes de culture. Pour renforcer la durabilité de ces divers modes de production, les solutions agro-écologiques candidates sont nombreuses. Celles-ci consistent en l’utilisation de plantes de services cultivées en association ou en rotation avec la banane, à l’intégration avec des systèmes d’élevage et au recours à de nouvelles variétés. Ces innovations ont été assemblées de manière cohérente en une vingtaine de prototypes de systèmes de production permettant de remplacer une gestion de la fertilité et des ravageurs qui est conventionnellement chimique, par une gestion plus durable, basée sur des régulations biologiques au sein de l’agro-écosystème. Nous avons ainsi identifié des options permettant de produire autant voire plus, tout en réduisant l’usage de pesticides de 25 à 50 % par rapport aux systèmes conventionnels. Ces systèmes sont néanmoins généralement plus consommateurs en main d’oeuvre et en savoirs. Notre méthode d’évaluation nous permet d’identifier trois types de recommandations pour concilier performances économiques, respect environnemental et fortes probabilités d’adoption par les agriculteurs : le ciblage des prototypes par type d’exploitation, le soutien à l’innovation via des subventions découplées et la poursuite de l’organisation de filière autour d’une production à haute valeur ajoutée.

National audience; La chlordécone, molécule organochlorée de synthèse, était utilisée aux Antilles comme insecticide contre le charançon du bananier de 1972 à 1993. Depuis 2000, des contrôles ont montré que cette molécule contaminait encore les eaux de rivière et de source, certaines denrées alimentaires, et des organismes aquatiques, y compris marins. Des mesures ont alors été prises pour limiter l’exposition des consommateurs, en particulier, l’épuration des eaux distribuées, l’interdiction ou l’encadrement des cultures et des pêches, la fixation d’une limite maximale de résidu pour tous les aliments, à 20 μg/kg de poids frais.La recherche agronomique s’est mobilisée de façon concertée pour fournir rapidement des connaissances en réponses aux questions posées par la gestion de cette crise.Où les sols sont-ils pollués? Des cartes de risques de pollution des sols, fondées sur leur occupation rétrospective en bananeraies, ont été établies. C’est ainsi que les parts de surface agricole utile polluées sont 1/5e pour la Guadeloupe et 2/5e pour la Martinique.Combien de temps va durer la pollution? La chlordécone était épandue sur des sols volcaniques, riches en argiles et en matière organique, sur laquelle elle s’est fortement fixée. Seul son lessivage par les eaux percolant dans les sols assure sa lente dissipation, elle ne se dégrade pas dans les sols aérés. Sa persistance est donc longue, de quelques décennies à quelques siècles selon l’affinité des sols pour la molécule. Ainsi, pour des épandages passés identiques, les sols les moins pollués, qui seront assainis le plus tôt, ont aujourd'hui la plus forte capacité de contaminer les cultures et les eaux. Les sols restent la principale source de pollution du milieu.Comment se fait la contamination des cultures? Les organes souterrains sont les plus contaminés car ils sont en contact avec la solution du sol. Cependant les parties aériennes sont aussi contaminées par la chlordécone entraînée dans le flux de sève brute, des racines aux feuilles. La contamination des organes récoltés dépend alors de leur position dans ce flux et des tissus « filtres » traversés. Ces connaissances permettent de suggérer les cultures possibles selon le niveau de pollution d’un sol. Certains produits agricoles restent indemnes malgré la pollution (fruits d’arbres, banane, ananas, tomate, piment…).Comment remédier à la pollution des sols? Même pollués, ils conservent leur potentiel de fertilité, il convient alors de définir les cultures, les systèmes d’élevage et les pratiques compatibles avec les niveaux de chlordécone biodisponible des sols et limitant les transferts. Les solutions de dépollution ne sont ni simples ni rapides, un effort collectif de recherche est engagé sur des voies peu explorées : dégradation par des consortiums microbiens, conditions écologiques de la dégradation, couplages de méthodes. En aval, tant que la dépollution des sols ne sera pas effective, leur lessivage contaminera les eaux souterraines et de surface, et les écosystèmes côtiers.Que les surfaces agricoles soient polluées ou indemnes, la mise au point de pratiques économes en intrants, minimisant leurs pertes, permettant de maintenir, voire de restaurer, la qualité environnementale exceptionnelle de ces îles sera au coeur de nos enjeux scientifiques.

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.

International audience; Banana producers have been using persistent organochlorine pesticides for 1970 to 1993 in French West Indies. Chlordecone molecule is now polluting soils, water and food chains. Then, farmers have to manage the molecule transfer to food crops when fields are polluted. In our work, we first assessed the transfer sensitivity for food crops, we mainly focused on horticultural crops. We established the transfer relationship between soil pollution level and crop contamination. It differed according to the soil type, the crop and the harvested organ. The more sensitive crops are root vegetables and the very less sensitive are banana, pineapple and solanaceae. Then, we built a decision tool that integrated these results and the UE sanitary regulation (Maximum Residue Limit, MRL). We used the maximum transfer curve, an envelop curve, to assess the risk of contamination for each crop and we translated the MRL value into a chlordecone maximum soil level. Our tool would help the farmers to anticipate the contamination risk for food products at the planting stage using a soil analysis. In the case of relevant farming system evolution or conversion, it would help them to choose adapted crops according to the field pollution context and the farmers’ objectives. Our tool would help too the decision makers to propose pollution management measures and new cropping system practices and orientations.

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.

International audience

To minimize application of nematicides in banana fields, crop systems have been developed in the French West Indies that combine fallow or rotation crops and nematode-free in vitro plants. After two to four years, populations of the burrowing nematode Radopholus similis have developed enough to cause economic losses, leading banana growers to use nematicides. To understand how banana fields are recontaminated, we studied the dissemination of R. similis by water flow. At a 1-m scale, we analyzed the dispersion of R. similis under a rainfall simulator: we isolated a 1-m 2 study plot, placed a R. similis suspension on the upstream soil surface, and simulated a 60 mm/h rainfall for 72 min. We collected soil samples every 10 cm downstream after 12 min of rainfall, and subsequently at 20-min intervals, and extracted the nematodes using a Seinhorst elutriator and then a Baermann funnel. Our results showed that the nematode dissemination follows an inverse exponential law, and depends more on soil moisture at the beginning of rainfall than on the length of rainfall: in fresh soil, 69–80% of the R. similis recovered were found less than 10 cm downstream from the nematode inoculation line, whereas in wetted soil, 76–85% of the recovered individuals were collected in the outlet tub located downstream from the apparatus. This passive dissemination model partially explains the distance covered by individual nematodes but not the low percentage of motile nematodes recovered in the outlet tub (10% and 36% in fresh and wet soils) compared to the percentage of motile nematodes found in the soil (80% and 84% in fresh and wet soils). Indeed, water runoff is likely to disseminate R. similis over long distances only when soil moisture is close to field capacity.

International audience

International audience; Chlordecone is an organochlorine pesticide whose use is now forbidden but which persists in soils. It was used as an insecticide against the banana weevil from the 1970s to the early 1990s in the French West Indies. Late contamination of root vegetables (RVs) was revealed in 2002. In our work, we studied the mode of transfer of chlordecone from different types of tropical soil (Andosol, Ferralsol and Nitisol) to different RVs (dasheen, yam, sweet potato, turnip and radish) to explore plant sensitivity to contamination. We conducted complementary experiments: surveys, field trials, and mesocosm trials to link soil chlordecone content with plant chlordecone contamination. In all those experiments, RVs contamination was heterogeneous as soil pollution was heterogeneous, but dispersion of the chlordecone molecule was the same for each crop. Due to this dispersion, the soil type did not significantly affect contamination. Average contamination values measured in harvested organs were positively correlated to chlordecone soil content. Belowground organs themselves were contaminated heterogeneously depending on where there was direct contact between the organ and contaminated soil. The cortex was more highly contaminated than the pulp (up to ten times more). These two results thus support the hypothesis that contamination by direct contact between the chlordecone molecule and the plant organ is the most important mode of transfer in RVs. This has already been demonstrated in the yam Discorea cayenensis, whose tubers were chlordecone free even when the root system explored contaminated soil. Chlordecone diffusion into the plant was very weak suggesting that it is a passive process in RVs. A common model, based on morphology and duration of the soil/organ contact, accounted for the RVs contamination. We calculated an envelope curve of the relationship between soil chlordecone content and RVs contamination and the maximum transfer ratio observed was 1/5. This envelope curve which represents zero risk of contamination was calculated for crops on both Andosol and Ferralsol. This relationship is thus a decision tool to determine whether or not there is a risk involved in cultivating roots and tubers based on the result of soil analysis. With this tool, the risk of contamination can be foreseen at planting which is preferable to analyzing the product at the harvest stage. Further studies are in progress to determine the sensitivity of other mainly horticultural crops and fruits, and to analyze the contamination of aboveground organs. Factors that govern the bioavailability of the chlordecone molecule in the soil for the plants, like water, organic matter content, type of clay, need to be analyzed in more detail to better understand chlordecone transfer to plants and thus improve pollution management

International audience; To be successful, initiatives to improve farmer’s goat production should directly address the needs and objectives of the keepers while promoting rational use of local genetic resources. A survey was carried out to implement a genetic policy governing meat goat farming in Martinique (11400 heads and 33400 ha arable land). The questionnaire comprised a total of 27 items with 306 modalities, and included questions on farm structure, crop and animal productions, management of feeding, reproduction and health control. The sample consisted of 33 farmers with 644 ha and 2680 goats (1286 does and 52 bucks), 97% of does in the studied sample were crossbred, 56% of bucks were” imported” breeds (Boer or Anglo-Nubian). The number of goats per farm varied from 16 to 582. The feeding system was predominantly grazing, according to a rotation (55% of cases) or continuous grazing system (42%). On 62% of farms, the males remained with the females permanently, also 83% of farmers did not resort to methods of controlled-mating. The first criteria used for choosing animals (80 to 90% of answers) of both sex, were development and conformation. Assuming that adaptive together with productive traits are important in tropical zones, it is advisable to better define the maternal lineage of the local livestock (presently very sparse records), to improve reproduction management and culling strategies (poor and inadequate management practices do not support any genetic improvement programme), and to guide the farmers in their decisions by employing concerted interprofessional actions (choice of meat breed, market studies).

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; New crop systems have been developed in the French West Indies that combine fallow or rotation crops with nematode-free vitro-plants to avoid the massive application of nematicides in banana fields. In these new banana fields, recontamination by the burrowing nematode Radopholus similis can then happen either by run-off or irrigation water. To understand these phenomena, we studied the vertical dissemination of R. similis by water leaching using soil cylinders and rainfall simulations. Steel drums were used to collect cylinders of soil (around 14.3 dm3) with a backhoe. The soil cylinders were placed in an aspersion chamber, saturated with water, and a R. similis suspension was placed on the soil surface. Afterwards, rainfalls ranging from 12 to 540 mm were simulated. Nematodes were then extracted from different soil layers (0–5 to 20–25 cm depth) using either (i) a Seinhorst elutriator followed by a Baermann funnel or (ii) centrifugation–flotation combined with Meldola blue staining. Results showed that dissemination of R. similis at the scale of the decimetre in nitisoil is limited: less than 8% of the applied nematodes reached layers deeper than 10 cm after exceptional rainfalls that represent several times the poral volume of the soil. Dissemination below 25 cm depth seemed to be limited to very few individuals, from 0.1 to 0.2%. Among leached nematodes, the percentage of non-active and dead nematodes increased significantly with depth. It seems that R. similis have developed a behaviour to escape leaching. These findings question the generally accepted idea that water dissemination of plant-parasitic nematodes is mainly a passive phenomenon.

Une synthèse des connaissances sur la pollution par les organochlorés aux Antilles a été réalisée dans le cadre du Groupe d'étude et de prospective de juin 2005 à mars 2006. La connaissance acquise à ce jour sur le vo-let agronomique et sur la contamination des sols et des cultures est intégrée. Les contaminations par la dieldrine et le BHCH étant sporadiques et peu durables, cet article est focalisé sur la chlordécone utilisée contre le charançon (Cosmopolites sordidus) en bananeraies de 1971 à 1993. Cette molécule est très stable, la pollution des sols est durable et hétérogène dans les parcelles. Le transfert vers les plantes est lié à la teneur dans le sol, au type de sol et au type de culture. La voie de contact est la voie privilégiée de contamination des organes souterrains (racine, tubercule). Un transfert par diffusion vers les organes aériens (tige, feuille, fruit) existe, mais ces derniers sont bien plus faiblement contaminés. Peu de données sont disponibles pour les productions animales. On doit porter une attention particulière aux productions informelles. À partir de limites maximales dans les denrées, un outil de gestion du risque est proposé. Des référentiels de contamination utilisant les relations existant entre teneur du sol et teneur de la plante permettent d'anticiper le risque à partir de l'analyse de sol. Cet outil implique un dispositif analytique local et des connaissances sur la sensibilité des cultures à la contamination. Les traitements physiques, la phyto-extraction et la dégradation biologique ne sont pas envisageables à court terme. Les filières de reconversion possibles (productions non alimentaires) ne seront valides qu'après évaluation technico-économique.

Between the 60’ and the 90’, organochlorides, i.e. dieldrin, HCH and chlordécone have been applied as insecticides on banana crops in the F.W.I.. The firsts are rarely detected in water resources. Since 1999, chlordecone has been largely detected in sparkling waters, and then in harvested roots (yam, sweet potato, dasheen…). Soil analysis of a “space for time” parcel network, where different chlordecone input schedules have been established, allowed validating a model of chlordecone dissipation by drainage water. This process appeared to be the only one capable of reducing the soil contamination. The bulk partition coefficients between the sorbed fraction on the soil organic matter and the soluble fraction (Koc) decreased according to the nature of the mineral fraction: allophane, halloysite +oxi-hydroxides, halloysite. The drainage water concentrations corroborated this gradation. Field and green-house experiments showed that the contamination of below ground plant organs results mainly from a contact with the surrounding soil, which was difficult to highlight because of the chip distribution of chlordécone. Where chlordecone has not been deeply incorporated by previous tillage, local scrapings allow to harvest few contaminated “roots”. No biodegradation index or bio- remediation plant has been identified.; Des insecticides organochlorés (dieldrine, HCH, chlordécone) ont été appliqués dans les bananeraies des Antilles françaises des années 60 à 90. Les deux premiers sont rarement détectés dans les sols et les eaux. La chlordécone, très stable et hydrophobe, a été largement détectée depuis 1999 dans les eaux de source, puis dans les «racines» récoltées. L’analyse des sols de parcelles agricoles renseignées par des chroniques rétrospectives d’apports a permis de valider un modèle de dissipation de la chlordécone par les eaux de drainage, seul processus permettant la très lente décontamination des sols. Les coefficients de partage apparents, élevés, entre la fraction sorbée sur la matière organique des sols et la fraction en solution (Koc), décroissent selon la nature minéralogique des sols : allophane, halloysite + oxyhydroxides, halloysite. Les concentrations des eaux de drainage confirment la réalité des différents Koc. Des expérimentations au champ et en conditions contrôlées ont montré la prédominance d’une contamination des organes végétaux souterrains par contact, compliquée par une distribution de la chlordécone en «copeaux» dans les sols. Là où la chlordécone n’a pas été profondément incorporée par des labours, des décapages superficiels localisés en créneaux permettent d’obtenir des «racines» peu contaminées. Aucun indice de biodégradation ni solution de bio-remédiation n’ont été identifiés.

National audience

Between the 60’ and the 90’, organochlorides, i.e. dieldrin, HCH and chlordécone have been applied as insecticides on banana crops in the F.W.I.. The firsts are rarely detected in water resources. Since 1999, chlordecone has been largely detected in sparkling waters, and then in harvested roots (yam, sweet potato, dasheen…). Soil analysis of a “space for time” parcel network, where different chlordecone input schedules have been established, allowed validating a model of chlordecone dissipation by drainage water. This process appeared to be the only one capable of reducing the soil contamination. The bulk partition coefficients between the sorbed fraction on the soil organic matter and the soluble fraction (Koc) decreased according to the nature of the mineral fraction: allophane, halloysite +oxi-hydroxides, halloysite. The drainage water concentrations corroborated this gradation. Field and green-house experiments showed that the contamination of below ground plant organs results mainly from a contact with the surrounding soil, which was difficult to highlight because of the chip distribution of chlordécone. Where chlordecone has not been deeply incorporated by previous tillage, local scrapings allow to harvest few contaminated “roots”. No biodegradation index or bio- remediation plant has been identified.; Des insecticides organochlorés (dieldrine, HCH, chlordécone) ont été appliqués dans les bananeraies des Antilles françaises des années 60 à 90. Les deux premiers sont rarement détectés dans les sols et les eaux. La chlordécone, très stable et hydrophobe, a été largement détectée depuis 1999 dans les eaux de source, puis dans les «racines» récoltées. L’analyse des sols de parcelles agricoles renseignées par des chroniques rétrospectives d’apports a permis de valider un modèle de dissipation de la chlordécone par les eaux de drainage, seul processus permettant la très lente décontamination des sols. Les coefficients de partage apparents, élevés, entre la fraction sorbée sur la matière organique des sols et la fraction en solution (Koc), décroissent selon la nature minéralogique des sols : allophane, halloysite + oxyhydroxides, halloysite. Les concentrations des eaux de drainage confirment la réalité des différents Koc. Des expérimentations au champ et en conditions contrôlées ont montré la prédominance d’une contamination des organes végétaux souterrains par contact, compliquée par une distribution de la chlordécone en «copeaux» dans les sols. Là où la chlordécone n’a pas été profondément incorporée par des labours, des décapages superficiels localisés en créneaux permettent d’obtenir des «racines» peu contaminées. Aucun indice de biodégradation ni solution de bio-remédiation n’ont été identifiés.

National audience

National audience; Cinq réseaux de recherche font actuellement l'objet de projets de constitution d'un réseau associatif de chercheurs caraïbéens dans le domaine de la sécurité sanitaire et des maladies émergentes et en progression dans la Caraïbe : la maladie à bégomovirus de la tomate, le jaunissement mortel du cocotier, les maladies des agrumes (tristeza, chancre citrique, CVC et greening), les maladies de la canne à sucre et les cercos- porioses et de BSV du bananier. Les premières missions de prises de contact et de finalisation de rédaction des projets de réseaux des partenaires débuteront en mai 2005 dans le cadre d'un projet global financé par l'Etat français et le Conseil Régional de Guadeloupe. Des analyses de risques phytosanitaires ont été réalisées en 2003 et 2004 par le Cirad en relation avec la Mission de Coopération Phytosanitaire du Ministère de l'Agriculture, de l'alimentation, de la Pêche et de la Ruralité. Un sixième réseau fonctionne depuis 1999, il inclut les services vétérinaires, les laboratoires de diagnostic, les universités, les partenaires nationaux et internationaux de la surveillance de la santé animale. Dans le cadre des activités de ce réseau, des missions d'appui technique et de diagnostic auprès des Etats de l'OECS ont débuté en 2004 et se poursuivront en 2005 principalement sur financement de l'ambassade de France.

Titre du périodique-hôte : Les stocks de carbone dans les sols des Antilles. Importance agronomique et environnementale; International audience

In tropical agro-ecosystems, nematodes Radopholus similis, Pratylenchus spp. and Helicotylenchus spp. are considered as the worst constraints to banana (Musa acuminata group Cavendish) production. These pests attack primary and lateral roots, causing necrosis, affecting plant nutrition and reducing the root anchorage, shortening plantations’ lifespan and reducing yields. Since the use of chemical nematicides has been regimented, new ecological alternatives have been prospected. Among them, the use of earthworms as control agents of nematodes patogenicity was tested. Lafont et al. (2007) shown that the pathogenicity of nematode Radopholus similis was significantly reduced in the presence of earthworm Pontoscolex corethrurus. While a positive effect on the growth of banana was found, the processes involved were not clearly identified. The objective of this work is to understand how earthworm Pontoscolex corethrurus activity affects the pathogenicity of the main parasitic nematodes of banana. Indirect effects of earthworm activity via physical, chemical and biological modifications of the soil biotic and abiotic components are hypothesized as the main factor contributing to the decrease of nematodes pathogenicity by reducing root necrosis and increasing nutrient availability. This hypothesis was tested in controlled conditions in a greenhouse of the INRA research station in Guadeloupe (FWI). Four treatments : N-E- (absence of fauna); N-E+ (P. corethrurus alone); N+E- (phytoparasitic nematodes alone); N+E+ (earthworms plus nematodes) were setted-up and replicated five times. Each replication was composed by a banana plant cultivated in a pot containing 20 kg of soil. 337 days after the experiment set-up, shoot and root weight, shoot chemical contents, root necrosis extent and the populations of nematodes were determined. Soil samples were analysed for determination of total C and N and for nutrient contents (P2O5, NO3- and NH4+). Shrinkage curves of centimetric aggregates and casts were also calculated. Results showed that: i) root necrosis induced by nematodes was significantly reduced (50%) in the presence of the earthworm P. corethrurus, whereas the population of nematodes did not decrease ii) the burrowing activity destroyed most of the initial structural pores (3-300μm) and increased the volume of finest structural pores diameter class (0.3-3μm). Earthworm aggregates could then shelter high microbial activity in the increased 0.3-3 μm pore class and probably became unfavourable to nematodes activity due to the decrease of larger pores of 3-300μm in diameter. This observation was corroborated by a greater phosphorus availability in earthworm casts, and a better plant phosphorus nutrition in the presence of earthworms that induced a better growth of banana plants. These results confirm the indirect and positive effects enhanced by earthworm activity and mainly the availibilty of phosphorus via soil porosity transfer. The reduction of nematodes pathogenicity without a significant reduction of nematodes abundance, however, could not be clearly explained. Blouin et al. (2005) attested of similar effects in a rice experiment and hypothesized a systemic action of earthworm on plant growth driven by a modification of the expression of genes that code for tissue reparation. Complex interactions occurring in the soil biota-soil-plant continuum still remain a great challenge in the field of ecological engineering dedicated to the improvement agro-ecosystems performances.