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Background and Aims Social, environmental and regulatory evolution encourages grapegrowers to reduce chemical use. Organic production is one possible answer, but controlling pests and diseases by products allowed in organic production is less easy than with chemicals. We integrated disease severity levels (Botrytis bunch rot, powdery and downy mildews) and pest incidence (grape berry moths) to develop an indicator of pests and disease damage in grape bunches, named assessment indicator of damage in grape bunches (AIDB), which can be used to assess pest incidence in networks of grower vineyards. Methods and Results In 2011 and 2012, we tested AIDB by monitoring damage at key phenological stages in 20 vineyards in the Bordeaux and Languedoc regions in the south of France, under three modes of production: conventional production, organic production and in conversion to organic production. The indicator proved accurate in describing the total damage on grape bunches under all conditions tested. Conclusions Irrespective of the mode of production, the AIDB value was negatively correlated with yield parameters and the technical expertise of the grower. This indicator proved to be an innovative tool to estimate the multipest damage on grapevines over a range of conditions. Significance of the Study The AIDB enables grapegrowers and advisors to assess the integrated impact of their treatment strategies on grape production, which is necessary when reducing pesticide use.

To improve its sustainability, viticulture should increase the provision of ecosystem services to decrease its use of inputs and the resulting environmental impact while maintaining high socioeconomic performance. Soil functions in relation with their physical, chemical and biological properties can be regulated by proper soil surface management. Cover crops deliver ecosystem services such as protection of soils, better water infiltration and nitrogen fixation. Yet to avoid tradeoff between provision of services and production of grapes, the management of cover crops should adapt to climate variations and to the yield objective. Pest and diseases can be regulated by various technical levers, including the control of the grape vegetative development. The assessment of damages due to pests and disease and of their consequences on yield losses is a key component of the design of alternative strategies of crop protection. This knowledge provides clues for designing management strategies with low pesticide use and high agro-ecological performance. A French national network of experiments has quantified the reduction of pesticide use with decision support systems, biocontrol or resistant varieties. To go further the challenge is now to design agroecological vineyards that combine innovations in management, and also in spatial organization at field, farm and landscape scales., Para mejorar su sostenibilidad, viticultura debería aumentar la prestación de servicios ecosistémicos para reducir su uso de insumos y el impacto ambiental resultante, manteniendo un alto desempeño socioeconómico. Las funciones del suelo en relación con sus propiedades físicas, químicas y biológicas pueden ser reguladas por un manejo adecuado del suelo. Cubiertas vegetales brindan servicios ecosistémicos tales como protección de suelos, mejor infiltración del agua y fijación de nitrógeno. Sin embargo, para combinar prestación de servicios y producción de uva, el manejo de cubiertas vegetales debe adaptarse a las variaciones climáticas y a los objetivos de producción. Las plagas y enfermedades pueden ser reguladas por varias técnicas, incluyendo el control del desarrollo vegetativo de la uva. La evaluación de los daños debidos a plagas y enfermedades y sus consecuencias sobre las pérdidas de rendimiento es un componente clave del diseño de estrategias alternativas de protección de cultivos. Este conocimiento proporciona pistas para diseñar estrategias de manejo con bajo uso de pesticidas y alto desempeño agroecológico. Una red nacional francesa de experimentos ha cuantificado la reducción del uso de pesticidas con sistemas de apoyo a la decisión, control biológico ovariedades resistentes. El desafío presente es diseñar viñedos agroecológicos que combinan innovaciones en manejo y organización espacial a los niveles del campo, de la granja y del paisaje.

After preliminary studies demonstrated that greenhouse air humidity increased considerably close to the lower leaf surface, particularly during daytime when crop transpiration is maximum, we have focused in this study on the consequences of greenhouse ventilation on the decoupling between outside and inside climate and between the latter and the climate in the neighbourhood of the leaves. The theory of moisture transfer within the leaf boundary-layer is first outlined and a model for the air temperature and humidity distribution reviewed. We have investigated also experimentally the ventilation dependence of inside air climate and of the climate in the leaf boundary-layer in two greenhouse tomato crop tunnels differing only in their ventilation conditions. We have demonstrated that wind speed and vent opening govern greenhouse ventilation flux and the resulting inside air speed, which determines inside air humidity, more particularly in the leaf boundary-layer and at leaf level. Inside air speed is also much higher in the area situated near the vent openings than in the centre of the tunnel and consequently inside climate and leaf boundary-layer climates near the vents or the open gable ends are more tightly coupled to outside conditions. Finally, implications of these findings are considered for biological control of whiteflies using myco-insecticides from the point of view of the tunnel ventilation, transpiration activity and crop growth systems.

International audience; Collaborative research was conducted at the INRA Research Centers to assess the microbial control potential of Beauveria bassiana- and Lecanicillium lecanii-based formulations against whiteflies in protected crops under Mediterranean conditions. Four series of small-scale glasshouse trials were performed in 1999 and 2000 in southern France. Two applications at 4-5 day intervals of Naturalis-L and Mycotal were conducted on young larvae of the greenhouse whitefly, Trialeurodes vaporariorum, at rate's recommended by the manufacturers. Because of the expectation that environmental conditions prevailing in Mediterranean greenhouse crops may lead to greater climatic constraints for mycoinsecticide efficacy than in more temperate areas, manipulation of the greenhouse climate has been used to aim at optimizing mycoinsecticide efficacy. The climatic management strategy was mainly based on closing the ridge vents 2 h more at night-time in so-called "humid" glasshouse compartment than in a "dry" one. Thus, the daily period at high humidity (>90% RH) was two or three times longer in the "humid" compartment than in the "dry" one. In spite of this differential, mycoinsecticide treatments reduced numbers of surviving whitefly larvae by >85% in the "humid" compartment as expected as favorable, as well as in the "dry" compartment, expected as unfavorable. The results indicated clearly that both B. bassiana- and L. lecanii-based mycoinsecticides have a strong potential for microbial control of whitefly larvae infesting tomato crops at moderate ambient humidity in Mediterranean glasshouses. Our investigations provided strong arguments for explaining these unexpected results. The RH conditions prevailing in the targeted insect habitat should be greatly disconnected from that of the ambient glasshouse air. We suggest that strategies of mycoinsecticide optimization against phyllophagous insects in protected crops have to take into account factors acting on the leaf transpiration activity. (C) 2003 Elsevier Science (USA). All rights reserved.

Two commercial mycoinsecticides, 'Mycotal', based on Verticillium lecanii and 'Naturalis-L', on Beauveria bassiana, were used at dosages recommended by manufacturers to examine effects of a range of medium and high humidities on infection towards Trialeurodes vaporariorum. Two series of bioassays were carried out using special devices. In one series, a non-excised bean leaf was sandwiched in order to create a chamber above the whitefly-infected area. In another series, three potted whole bean plants were maintained in an airtight plastic box. In both series, conducted at 25°C, relative humidity (RH) was controlled by injecting a circulating constant flow of humidity-regulated air which had passed over a salt solution used to maintain targeted air humidity levels (ranging from 53 to 98.5 and 75 to 98.5% RH, respectively). Microclimatic measurements demonstrated that non-excised leaves significantly increased the air humidity in the air circulating in the immediate environment of the leaf surface as well as...

National audience

Effects of temperature on growth on a semisynthetic medium of 65 isolates of Beauveria bassiana from different geoclimatic and host origins were determined. The isolates were grouped accord...

Sustainable development of agriculture in Europe relies on the design of innovative cropping systems able to achieve high productive performance (quantity and quality) with low use of pesticides, while remaining compatible with socio-economic (e.g. labour use) and other environmental objectives (e.g. energy use). Over the last decade, this has led to the emergence of inter-disciplinary research activities driven by system’s analysis and design methodologies. Designing such multifunctional cropping systems requires to develop new knowledge on the relationships between the structure of agroecosystems, the processes involved in plants and pest/disease interactions and how they influence the productive performances of the system and the trade-offs with the other agroecosystem’s services. Designing a “pest suppressive or less susceptible” agroecosystem with less chemical inputs generally leads to complexify its structure (e.g. more plants species in rotation and or association) and put emphasis on poorly known processes such as the interaction between plant vigor and the trade-off between pest/diseases susceptibility on one side and yield formation on the other side. Conceptual models have been developed to integrate existing knowledge from various disciplines, as well as expert knowledge, in order to analyze how the various cropping techniques, including pesticides and genotypes, can be combined in an operational Technical System (TS), in order to manipulate the process involved in plant productivity and pest/disease control to reach the set of objectives fixed for a given context (a farm in a soil/climate and a supply chain). Analysis and management indicators are essential tools to provide information, under field conditions, on the agroecosystem processes and properties in order to guide the design process and support decisions for the management of the TS. Prototyping methodologies have been developed to conceptualize these innovative TS, test them in system’s experiments, evaluate them with a set of assessment indicators and adjust them to reach a targeted compromise among agroecosystem’s services in a progress loop. In return this design oriented approach yields new knowledge on the emerging properties of the agroecosystem and new questions on poorly understood processes or components, which can be further used to prioritize research objectives and conduct analytical experiments. Simulation models can contribute to the approach at various steps and their role and nature will be discussed on the basis of processes to be simulated, affordable uncertainty and available data for their parameterization/evaluation. Specific questions arise from this field-based approach on how to integrate it at farm and landscape scales and how to ensure farmer’s and stakeholder’s involvement in the design/assessment process in order to increase the probability of adoption of these TS by farmers. We will illustrate these concepts, methods and new knowledge on the example of vineyards with results and research questions emerging from the EcoViti network in France

Un indicateur d’évaluation, l’IEDG (Indicateur d’Evaluation des Dégâts sur Grappes), a été mis au point pour quantifier les dégâts cumulés dus aux principaux bioagresseurs affectant les grappes de raisin : mildiou, oïdium, pourriture grise et tordeuses. Il permet d’estimer la perte de récolte imputable au cortège parasitaire et de faire le lien avec la stratégie phytosanitaire adoptée (caractérisée ici par l’IFT) et le mode de production (AB, conversion, conventionnel). Ainsi, les pertes sanitaires ont été supérieures en 2012 par rapport à 2011. La stratégie phytosanitaire des viticulteurs en conversion, basée sur des réductions de dose de cuivre de près de 80% et des passages plus nombreux dans les parcelles, n’a pas été efficiente en 2012 avec des sévérités proches de 20% sur grappe, essentiellement dues au mildiou. L’utilisation de doses d’applications supérieures et moins de passages dans les parcelles limite les dommages chez les autres viticulteurs. L’indicateur proposé permet d’évaluer les pertes quantitatives générées par les attaques de bioagresseurs et de les différencier des autres pertes non parasitaires. Une analyse plus fine incluant l’effet région et l’impact sur le rendement devra être réalisée., An original and integrative evaluation indicator has been developed to quantify the cumulated damage from major pests and diseases affecting grape bunches: downy mildew, powdery mildew, gray mould and tortricid moths. It made it possible to estimate the associated crop losses and to relate them to the plant protection strategy in different modes of production (organic farming, in-transition, conventional). Thus, overall plant losses were higher in 2012 than in 2011. The in-transition growers’ strategy, with reduced copper doses but increased numbers of sprays, led to a 20% increase in average severity on bunches (essentially due to Downy mildew). The more pragmatic approach of experienced organic growers and conventional ones (higher doses and fewer sprays) reduced the yield losses. The proposed indicator is used for two purposes, i) evaluating the quantitative losses due to pest attacksand ii) differentiating them from other non-pest ones. A more detailed analysis including the impact on performance will be achieved and published soon.

International audience; In order to reduce pesticide use in vineyards, we propose a bioeconomic model to evaluate different fungicide treatment strategies. This model estimates the development of the downy mildew Plasmopara viticola for a given year’s weather on a grapevine plot, and predicts the damage done, the yield loss, and the resulting partial gross margin, depending on the chosen protection strategy. Grapevine growth and phenology are simulated with the STICS grapevine crop model according to the year’s weather; fungal components quantify downy mildew development; damage onto leaves and fruits is characterized as a percent reduction of potential leaf area and yield; the effect of fungicide treatments is simulated as a partial protection against infection; the economic result is calculated at plot level, taking into account simulated yield, local economic conditions and costs of observations and sprayings. The model parameters were estimated using three sets of experimental data from vineyards in the French wine-growing region of Bordeaux. Using these parameter values, the model was used to evaluate the following five protection strategies: 3 systematic fungicide spraying strategies with 2-, 3- or 4-week intervals, the “Mildium” adaptive strategy, which includes field observations and decision rules, and a control untreated strategy. Yield losses and the resulting partial gross margins were calculated for 23 annual weather examples for each strategy and the statistics of these strategies were compared. The adaptive strategy was found to be slightly less protective on average against downy mildew than the 2- week systematic spray strategy. However its low variability ensures sustainability in terms of grower’s income, while reducing by one third the number of sprayings. The model hypotheses and simulation results are discussed, in relation to the particular economic context of the “Bordeaux” protected designation of origin with the objective of reducing pesticide use in vineyards.

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International audience

International audience; Trees at low density and cereals may be combined in silvoarable agroforestry systems: tree rows and their companion vegetation introduce an heterogeneity in the cropped field that may modify the dynamics of insects crop pests and their predators. This hypothesis was tested in tree-wheat systems by monitoring aphids and their predators for two years in southern France, in two fields in 2006 and one in 2007. Tree row vegetation diversity was either suppressed by weeding or stimulated by seeding flowering species that could attract adult predators of aphids. The dynamics of aphids and predators were recorded by tiller sampling and yellow trap monitoring. Between 3500 and 5000 aphids were collected from each studied field. Surprisingly, no differences could be evidenced on the dynamics of both aphids and their predators between agroforestry and monocropping plots, nor between weeded and flowered plots. The heterogeneity induced by the tree row in the cropped field was probably not strong enough to alter the populations dynamics. A high landscape diversity in the area due to nearby forest patches and fallows may have blurred the impact of the tree lines. Different results may be expected in areas with lower biodiversity like cereal monocropping zones.

Collaborative research was conducted in the south of France to assess constraints related to both climate heterogeneity and ventilation systems on the control potential of a Lecanicillium muscarium-based formulation against whiteflies in Mediterranean greenhouses. Four series of small-scale greenhouse trials were performed in 2001 and 2002. Two applications at 4–5 day intervals of Mycotal were conducted on young larvae of the greenhouse whitefly, Trialeurodes vaporariorum, at the rate recommended by the manufacturer (ca. 1010 viable spores per liter of water suspension). The climatic heterogeneity was taken into account by comparing the fungus-induced mortality of nymphs located on lateral row plants to that of nymphs on center row plants. In spite of significant differences in air flows (0.7–1.2 and 0.3 ms−1, respectively) there was no effect on fungus efficacy (53–76% mortality). When comparing the influence of greenhouse equipment (sophisticated glasshouse vs. polyethylene-covered greenhouse), the fungus was not affected (89–96% mortality) in spite of significant differences in ventilation rates. The results confirmed that entomopathogenic Hyphomycetes have a strong potential for microbial control of whitefly larvae infesting tomato crops at moderate ambient humidity in Mediterranean greenhouses in spite of windy periods. These investigations confirmed that microclimatic conditions prevailing in the targeted insect habitat (under-leaf surface boundary layer) are greatly disconnected from that of both outside and inside the greenhouse. In northern Mediterranean greenhouses, non-stressed tomato crops provide unexpected favorable conditions for mycoinsecticide use against a phyllophagous insect.

Five non-linear models with three to five parameters, built to quantify the effect of temperature on insect development and microbial growth, were tested to describe the influence of temperature on in vitro-measured growth rates of entomopathogenic hyphomycetes. Data from two isolates of each of the four fungal species, Paecilomyces fumosoroseus, Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, were used to assess the features of each model. Criteria for model evaluation included the statistical quality of parameters estimates, the goodness of fit to data, as well as the ability to provide estimates of several key parameters: the upper and lower development thresholds, the thermal optimum and the maximal growth rate at thermal optimum. The second model proposed by Briere et al. (1999) was found to be the best, and Ratkowsky's model (1983) also exhibited good features.

The efficiency of mycoinsecticides as a means of whitefly control was examined under greenhouse conditions, focusing in particular on the high humidity levels favouring infection of the whitefly larvae infesting the under leaf surface. The theory of the moisture transfers occurring within the leaf boundary layer under laminar conditions is outlined and a model for the air temperature and humidity distribution is developed. Measurements were made of the humidity of the air in the boundary layer on the underside of leaves of a tomato crop grown in a full scale greenhouse. A considerable increase in relative humidity was detected 5 mm from the underside of the leaves, particularly during day-time when crop transpiration reached its maximum. These measurements were compared with the results of the model based on boundary layer theory and it was established that the data recorded were accurately predicted by the model during day-time from both the qualitative and quantitative points of view, but they were underestimated at night. The implications of these findings were examined and discussed in the context of the microbiological control of whiteflies under the conditions of confinement pertaining in various greenhouses and similar cultural systems. It is suggested that the concept of the microclimate pertaining in the leaf boundary layer developed here could be applied to the biological control of insects and microbial pathogens, in both protected and open crop growth systems.

The detrimental effects of solar radiation, especially the ultraviolet waveband, on quiescent conidia of Paecilomyces fumosoroseus were investigated. Conidia were irradiated by a high-intensity source, which emitted a continuous spectrum from 270 to 1100 nm and which was equipped with long-pass filters to block short wavelengths below 280, 295, 320, or 400 nm. After irradiation, conidia were tested for germinability, survival, and infectivity toward Spodoptera frugiperda larvae. It was demonstrated that the detrimental effects of light depended on irradiance in the shortest wavelengths. The UVB (280-320 and 295-320 nm) appeared to be the most detrimental part of natural radiation, although UVA (320-400 nm) was also harmful. Visible and near infrared radiations were less harmful than UV. Our results demonstrate that the irradiance of the UVB waveband should be considered as the pertinent factor for the detrimental effects of sunlight on the persistence of conidia of entomopathogenic fungi in insolated environments.

Persistence of conidia of the entomopathogenic fungus Paecilomyces fumosoroseus exposed to artificial and solar radiation at a constant temperature was studied by monitoring the ability to germinate and to form colonies (colony - forming units , CFUs) . The photic effect of radiation on each of these variables was modelled by a decreasing function of UVB irradiation ( in J m 2) . Germination ability was represented by a logistic function and viability (log CFU) by an infinitely decreasing function . Experiments carried out under artificial conditions , at three different UVB irradiances ( from 0 . 3 to 1 . 6 W m 2) , similar to those observed in nature , confirmed the adequacy of the predictor variable and of the functions chosen for describing these data . The proposed models appeared to be irradiance independent . Under solar radiation , the models were able to describe data collected on three different summer days in France (48 o 51 N , 2 o 06 E) . However , it took a greater amount of solar UVB radiat...

The detrimental effect of solar radiation on the survival of conidia of the entomopathogenic fungusPaecilomyces fumoroseus was studied by monitoring germinability and ability to form colonies (CFU) of conidia irradiated at two temperatures, 25 and 35 °C, harmless to shaded conidia. There was no apparent effect when spores were exposed to a high level of artificial radiation (0.66 W m(-2) UVB). However, at a lower level of irradiance (0.33 W m(-2)), effects of radiation occurred more quickly at 35 °C than at 25 °C. Under natural solar radiation, the rate of decrease in germinability or viability was doubled at 35 °C as compared to 25 °C, indicating an interaction between temperature and radiation effects under natural conditions. This interaction was not detected in indoor experiments, indicating that the spectral distribution of UV radiation has to be taken in account as well as its irradiance when studying its effects.

The detrimental photic effects of natural solar radiation on the conidial persistence of the entomopathogenic hyphomycete Paecilomyces fumosoroseus were investigated by exposing quiescent conidia either to total solar radiation or to its diffuse component. A given amount of UVB diffuse radiation was found to be as detrimental, and sometimes twice as detrimental, as the same amount of total solar radiation. The variability in quantity and spectral distribution of the diffuse component of UVB solar radiation reaching the earth's surface, observed through spectral measurements, may be responsible for the difference in biological effects.