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Brown rot in stored stone fruits, caused by Monilinia spp., may be due to preharvest and storage factors, but the combined effect of these factors has yet to be investigated. We set up two experiments to monitor the progression of brown rot during the storage of nectarines subjected to various preharvest and storage conditions. We assessed the effects of different agricultural practices (irrigation regimen × fruit load) and harvest dates on brown rot progress during storage in 2018 and the effect of different storage temperatures in 2019. We found that the cumulative incidence of brown rot during storage increased with individual fruit mass, which was influenced by agricultural practices, and for later harvest dates. It also increased with storage temperature. We observed that during storage no secondary infections developed in nectarines not in direct contact with fruits infected with Monilinia laxa. These findings led to the identification of candidate variables describing the brown rot risk on nectarines during storage, such as individual fruit mass, meteorological conditions before fruit harvest, prevalence of brown rot at harvest, and storage temperature. We used these variables to build a mathematical model for estimating the time-to-appearance of brown rot symptoms in stored nectarines. This model fitted the experimental data well, highlighting the need to pay greater attention to the interaction between preharvest and storage conditions. This model could be used to evaluate management strategies for reducing the impact of brown rot in nectarines during storage.

International audience; Highlights: • We investigated multifunctionality and ecosystem services in agroecosystems. • 18 research questions, obstacles and solutions were identified. • Future research must integrate knowledge from different sectors and communities. • Biodiversity is a key factor to explore and incorporate into modelling approaches. • Promoting dialogue, standardization and data-sharing would enhance progress.Abstract:Agroecosystems are facing new challenges in the context of a growing and increasingly interconnected human population, and a paradigm shift is needed to successfully address the many complex questions that these challenges will generate. The transition to providing multiple services within an agroecosystem is a starting point for heightened multifunctionality, however, there is still hesitation among stakeholders about moving towards multi-service systems, largely because of the lack of knowledge linking productivity and multifunctionality. We reason that much of this reticence could be overcome through a better understanding of stakeholder requirements and innovative transdisciplinary research extended in the dimensions of time and space. We assembled experts in France to identify priority research questions for co-constructing projects with stakeholders. We identified 18 key questions, as well as the obstacles that hinder their resolution and propose potential solutions for tackling these obstacles. We illustrate that research into agroecosystem multifunctionality and service production must be a hugely collaborative effort and needs to integrate knowledge from different sectors and communities. Promoting dialogue, standardization and data-sharing would enhance transdisciplinary progress. Biodiversity is highlighted as a key factor to explore and incorporate into modelling approaches, but major advances must be made in the understanding of dynamic changes in the biodiversity-function-service nexus across landscapes. Resolving these research questions will allow us to translate knowledge into decision objectives, identify adaptation and tipping points in agroecosystems and develop social-ecological economic pathways that are adaptive over time.

The addition of flowering companion plants within or around crop fields is a promising strategy to strengthen pest regulation by their natural enemies. Aromatic plants are frequently used as companion plants, but their effects on natural enemies remain unclear under field conditions. Here, we evaluated the effects of two aromatic plant species on the parasitism of the codling moth (Cydia pomonella) and the recruitment of predatory arthropods (spiders, earwigs) in a factorial field experiment. Apple trees were intercropped with basil (Ocimum basilicum), French marigolds (Tagetes patula), or ryegrass (Lolium perenne). The association between apple trees and O. basilicum increases codling moth parasitism, but does not affect arthropod predator abundances. Furthermore, we find a general negative effect of T. patula on arthropod diversities and abundances, including the pest and its natural enemies. Finally, changes in the parasitism rate and arthropod community structure due to the aromatic plants do not reduce codling moth density or associated apple damage. Further experiments are needed to determine the mechanisms involved in aromatic plant effects on pest repellence and on natural enemy recruitment (volatile organic compound composition, floral resource supply, or pest density dependence).

A profound transformation of agricultural production methods has become unavoidable due to the increase in the world’s population, and environmental and climatic challenges. Agroecology is now recognized as a challenging model for agricultural systems, promoting their diversification and adaptation to environmental and socio-economic contexts, with consequences for the entire agri-food system and the development of rural and urban areas. Through a prospective exercise performed at a large interdisciplinary institute, INRAE, a research agenda for agroecology was built that filled a gap through its ambition and interdisciplinarity. It concerned six topics. For genetics, there is a need to study genetic aspects of complex systems (e.g., mixtures of genotypes) and to develop breeding methods for them. For landscapes, challenges lie in effects of heterogeneity at multiple scales, in multifunctionality and in the design of agroecological landscapes. Agricultural equipment and digital technologies show high potential for monitoring dynamics of agroecosystems. For modeling, challenges include approaches to complexity, consideration of spatial and temporal dimensions and representation of the cascade from cropping practices to ecosystem services. The agroecological transition of farms calls for modeling and observational approaches as well as for creating new design methods. Integration of agroecology into food systems raises the issues of product specificity, consumer behavior and organization of markets, standards and public policies. In addition, transversal priorities were identified: (i) generating sets of biological data, through research and participatory mechanisms, that are appropriate for designing agroecological systems and (ii) collecting and using coherent sets of data to enable assessment of vulnerability, resilience and risk in order to evaluate the performance of agroecological systems and to contribute to scaling up. The main lessons learned from this collective exercise can be useful for the entire scientific community engaged in research into agroecology.

International audience; In this study, we analyzed the patterns of relationships between multiple ecosystem services in apple orchards by considering the cascade that links agricultural practices to ecosystem functions and then to ecosystem services. Five major ecosystem services were considered: fruit production, soil nitrogen availability, climate regulation, water cycle maintenance and regulation, including water quality, and pest and disease control. We derived indicators of ecosystem functions and of ecosystem services from model simulations of orchards driven by virtual cropping systems combining various modalities of nitrogen fertilization, irrigation, and pest control. We deciphered the links between practices and ecosystem functions and between those functions and ecosystem services and clustered cropping systems according to their ecosystem service supply. Noticeable synergies were found between yield, fruit mass and sequestrated carbon. The contribution of carbon allocation to fruit in sequestrated carbon was considerable. Nitrogen absorption, impacted by fertilization and irrigation, was a major driver of these relationships. The typology built from these virtual cropping systems clearly followed a gradient of provisioning and regulating ecosystem services. Five cropping systems optimized the compromise between provisioning and regulating services and were essentially characterized by organo-mineral fertilization, comfort irrigation, apple scab-resistant cultivars and exclusion nets against codling moth. Our approach could contribute to the design of cropping systems that would provide an acceptable compromise between multiple ecosystem services in orchards.

Integrated Pest Management (IPM) provides an illustration of how crop protection has (or has not) evolved over the past six decades. Throughout this period, IPM has endeavored to promote sustainable forms of agriculture, pursued sharp reductions in synthetic pesticide use, and thereby resolved myriad socio-economic, environmental, and human health challenges. Global pesticide use has, however, largely continued unabated, with negative implications for farmer livelihoods, biodiversity conservation, and the human right to food. In this review, we examine how IPM has developed over time and assess whether this concept remains suited to present-day challenges. We believe that despite many good intentions, hard realities need to be faced. 1) We identify the following major weaknesses: i) a multitude of IPM definitions that generate unnecessary confusion; ii) inconsistencies between IPM concepts, practice, and policies; iii) insufficient engagement of farmers in IPM technology development and frequent lack of basic understanding of its underlying ecological concepts. 2) By diverting from the fundamental IPM principles, integration of practices has proceeded along serendipitous routes, proven ineffective, and yielded unacceptable outcomes. 3) We show that in the majority of cases, chemical control still remains the basis of plant health programs. 4) Furthermore, IPM research is often lagging, tends to be misguided, and pays insufficient attention to ecology and to the ecological functioning of agroecosystems. 5) Since the 1960s, IPM rules have been twisted, its foundational concepts have degraded and its serious (farm-level) implementation has not advanced. To remedy this, we are proposing Agroecological Crop Protection as a concept that captures how agroecology can be optimally put to the service of crop protection. Agroecological Crop Protection constitutes an interdisciplinary scientific field that comprises an orderly strategy (and clear prioritization) of practices at the field, farm, and agricultural landscape level and a dimension of social and organizational ecology.

Productivity of fruit tree crops depends on the interaction between plant physiology, environmental conditions and agricultural practices. We develop a mechanistic model of fruit tree crops that reliable simulates the dynamics of variables of interest for growers and consequences of agricultural practices while relying on a minimal number of inputs and parameters. The temporal dynamics of carbon content in the different organs (i.e., shoots—S, roots—R and fruits—F) are the result of photosynthesis by S, nutrient supply by R, respiration by S, R and F, competition among different organs, photoperiod and initial system conditions partially controlled by cultural practices. We calibrate model parameters and evaluate model predictions using unpublished data from a peach (Prunus persica) experimental orchard with trees subjected to different levels of branch pruning and fruit thinning. Fiinally, we evaluate the consequences of different combinations of pruning and thinning intensities within a multi-criteria analysis. The predictions are in good agreement with the experimental measurements and for the different conditions (pruning and thinning). Our simulations indicate that thinning and pruning practices actually used by growers provide the best compromise between total shoot production, which impacts next year’s abundance of shoots and fruits, and current year’s fruit production in terms of quantity (yield) and quality (average fruit size). This suggests that growers are not only interested in maximizing current year’s yield but also in its quality and its durability. The present work provides for modelers a system of equations based on acknowledged principles of plant science easily modifiable for different purposes. For horticulturists, it gives insights on the potentialities of pruning and thinning. For ecologists, it provides a transparent quantitative framework that can be coupled with biotic and abiotic stressors.

Regulated deficit irrigation, which is a common practice to cope with water scarcity, can impact plant-aphid interactions, and possibly lead to a reduction in the use of pesticides. To test the possible effect of water restriction on the apple tree-rosy apple aphid (Malus domestica-Dysaphis plantaginea) system, we performed a factorial experiment with two levels of water supply and two genotypes on artificially infested trees. Plant growth and aphid abundance were characterised during the entire infestation period at two scales of analysis: the apical shoot scale and the tree scale, and additional measures were performed to evaluate plant water status. Aphid abundance increased with plant vegetative growth at both scales of analysis, which is consistent with the Plant Vigor Hypothesis (i.e. with the fact that most of the phloem feeders prefer fast growing plants). At the tree scale, aphid abundance was lower on trees that underwent water restriction, but at the shoot scale, aphid abundance responded differently to water restriction depending on the tree genotype. Water restriction modified the relationship between aphid abundance and growth, thus indicating that host suitability for aphids was affected by different plant variables susceptible to water stress, among which growth. The different response patterns at the two scales of analysis highlight the importance of scale choice in the study of plant-insect interactions.

Prod 2019-147 SPE BIOME INRA; National audience

A new mathematical modeling framework able to simulate the combined effect of fruit growth and post-harvest storage conditions (temperature and relative humidity) on nectarine quality is here proposed. The seasonal course of fruit surface conductance to water vapor, fruit mass loss during storage, and sugar concentration dynamics in fruit pulp were modeled. The three sub-models were integrated into a model capable of calculating a fruit sweetness index and relative water loss during storage, which were selected as nectarine quality criteria. Sub-models parameters were calibrated through results from experiments carried on during 2018 and 2019, where horticultural practices (irrigation and fruit load) and storage conditions were jointly varied. Irrigation level influenced fruit surface conductance to water vapor at harvest, but experimental results point out that this variable may have little influence on fruit mass loss during storage, which was mainly driven by relative humidity in the storage chamber. Irrigation intensity was also influential on sugar dynamics, along with storage temperature, with fruit stored at the higher temperature (25 °C) being sweeter than those stored at lower ones (2 and 15 °C). These experimental results were well replicated by the sub-model outputs. Model simulations during storage revealed a trade-off between the two selected quality criteria, which increased with increasing storage temperature and decreasing relative humidity. The best scenario in terms of acceptable fruit mass loss and sweetness index was for fruit from water-stressed and low crop-loaded trees, 15 °C and 70% relative humidity. Moreover, storage duration was shown to increase fruit mass loss and, to a lesser extent, the sweetness index, while fruit from late harvest dates had higher sweetness at the end of storage. The model can potentially be used to manage and optimize pre-harvest and storage practices that will maximize sweetness and minimize mass loss to meet fruit quality standards along supply chains.

QualiTree is a generic fruit tree object -based model in which the effects of management practices on the development of fruit quality are explicitly modelled. It considers a large range of fruit quality traits important for growers, retailers and consumers, including: fruit size, the proporti on of total mass consisting of fruit flesh, flesh dry matter content, flesh concentrations of various sugars, and sweetness, a linear combination of sugar concentrations. Though parsimonious in terms of 3D representation of the plant architecture, it is able to express a high degree of within- tree variability of fruit quality criteria. QualiTree has been successfully tested using several datasets. A range of peach cultivars – from very-early to late – has been parameterised into QualiTree. Simulation studies show the potential of QualiTree to predict how fruit quality profiles may change under various levels of biotic and abiotic stress, which will become common wi thin the context of global change. We simulated patterns of foliar attacks by parasites and showed that reductions in fruit quality were lower when attacks were late in the season. Other simulation studies indicated that severe water stress during stage III of fruit development decreased fruit size whereas it dramatically enhanced sugar accumulation in the fruit flesh, especially in the case of glucose and fructose. Hence, QualiTree might be useful in the design of innovative horticultural practices combining regulated deficit irrigation strategies and plant-mediated control of pests.

Aphids are commonly considered major agricultural pests because of their ability to alter host plant physiology and impair foliar growth. However, their effect on fruit production in perennial trees did not receive wide attention and few existing works have mainly focused on plant-aphid dynamics in a single growing season (i.e., few months). We modified an existing process based model for the peach tree Prunus persica - aphid Myzus persicae pathosystem, explicitly considering interactions between the two species under the influence of cultural practices (i.e., winter pruning and nitrogen fertilization), in order to consider multi-year dynamics. The new multi-year model suggests that consequences of aphid infestation, in terms of fruit production, become evident only when considering multi-year dynamics. (Resume d'auteur)

The green peach aphid, myzus persicae , is a major pest in peach orchards. In order to find alternatives to the use of chemicals for aphid control, it is crucial to better understand the interactions between aphid population dynamics and tree status, i.e. growth and nutrient composition of the plant tissues. M. persicae acts as a flush feeder on peach tree. Aphid abundance is expected to be maximized on vigorous non-stressed plants, in concordance with the plant vigour hypothesis. How far cultural practices could be used to control plant vigour and in turn aphid population was tested on potted trees submitted to 2 levels of nitrogen supply (N+/N-), and artificially infested. We described shoot growth, leaf nitrogen concentration and aphid population levels during the entire infestation period (two months). When separately considering shoot growth and nitrogen treatment, we evidenced a positive effect of both factors on aphid population dynamics. However, when testing for the concurrent effects of both shoot growth and nitrogen treatment, only shoot growth had significant positive effect over aphid population dynamics. These results suggest that the observed effect of nitrogen treatment on aphid population dynamics may be an indirect one, mediated by a modification of plant growth.

The availabilities of water and nitrogen resources are among the main abiotic factors modifying plant physiology and growth. Consequently, via bottom-up processes, they also can have an impact on the performance of herbivorous insects. However, the extent to which the modification of plant growth is responsible for such an impact remains unclear. We conducted a factorial experiment quantifying Myzus persicae aphid abundance and the vegetative growth of Prunus persica peach tree shoots under contrasting levels of nitrogen and water supplies. We used a hierarchical analysis of multiple regression models to determine whether the consequences of the availability of nitrogen and water on aphid abundance could be the result of a modification of plant growth. Maximum aphid abundance was achieved under nitrogen and water comfort conditions. The best model explaining variance in aphid abundance took into account vegetative growth and water supply, as well as their interaction. The results of the present study suggest that a higher nitrogen supply increases aphid abundance by fostering plant growth. Additionally, the positive response of aphid abundance to vegetative growth is lower in the case of water restriction because, under such conditions, aphids cannot take full advantage of tree vigour. Such a result provides new insights into aphid control in agriculture, as well as on the possible effects of climate change.

PURE (Pesticide Use-and-risk Reduction in European farming systems with Integrated Pest Management), a large collaborative project funded by the EU, has designed and tested IPM solutions both on-station and on-farm. Ex-ante and ex-post assessment of such solutions – developed by combining tactical and strategic means of managing pests (animal pests, pathogens and weeds) – were performed for key European farming systems, spanning from annual arable to protected crops. Overall, the solutions showed good sustainability. PURE also developed models and methods to help predict pest damage or design pest management strategies. In addition, the project developed tactics to deal with pest evolution, agroecological engineering, and eventually bio- and technological products to be included into IPM toolbox in the near future. The societal dimension, the interdisciplinarity and a wide geographic coverage are key features of the project.

National audience; On a vu ces 20 dernières années une montée en puissance de la prise en compte de la biodiversité et de ses rôles en agriculture dans les recherches de l'lnra, avec des changements de paradigmes majeurs en réponse à la nécessité de considérer et de préserver la santé des écosystèmes et des hommes. Les études documentant le déclin de la biod1versité des milieux agricoles ont stimulé le développement d'outils de caractérisation de la biodiversité tandis que l'écologie fonctionnelle a alimenté la compréhension des liens entre biodiversité et fonctionnement des écosystèmes. L'expertise scientifique collective "Agriculture et biodiversité : valoriser les synergies" de 2008 marque un tournant ;on reconnaît que la biodiversité sauvage se déployant naturellement dans les milieux agricoles est aussi un atout pour l'agriculture. La valorisation de la biodiversité pour la fourniture de fonctions et de services devient un champ de recherche majeur au sein de l'institut. Le Chantier Agroécologie initié en 2011 a orienté les recherches sur l'identification d'options agronomiques intégrant le pilotage et la gestion de la biodiversité domestique, planifiée par le gestionnaire,mais aussi de ses interactions avec la biodiversité sauvage.

International audience; Fruit tree production faces the major challenge of ensuring maximal productivity with due consideration for the environment and human health. The increasingly recognized concept of ecosystem service could help to address this duality. In this paper, we propose an analytical framework based on a soil crop model to investigate how agricultural management and pedoclimatic conditions affect the joint production of marketed and non-marketed ecosystem services through underlying ecosystem functions in apple orchards. The ecosystem services considered on an annual scale were soil nitrogen availability, climate regulation, water regulation and fruit production. Ecosystem functions and services were described by specific indicators that were quantified using the STICS soil crop model. This model was parameterized using data collected on two experimental apple orchard sites under conventional and low-input or organic management in southeastern France. The interdependencies between environmental components, cultural operations and ecosystem functions were dynamically integrated by the model and highlighted significant interactions between the indicators of ecosystem services. Thus, the service indicators soil organic nitrogen variation and the prevention of nitrogen denitrification and of leaching were positively correlated and in conflict with soil mean nitrate concentration and mean soil humidity. They were also linked negatively to nitrogen mineralization enhanced by irrigation and positively to soil carbon sequestration impacted by fertilization; these two functions were impacted by soil conditions. Yield and carbon sequestration presented a strong synergy and were positively correlated to nitrogen absorption increased by mineral fertilization. Globally, nitrogen fertilization management and planting density were particularly important for the delivery of multiple ecosystem services, but soil and climate effects were far from negligible, especially for nitrogen and water-related services. The ecosystem service profiles of the studied cropping systems were diversified, with contrasted profiles showing high yield and carbon sequestration but low prevention of nitrogen denitrification and of nitrogen leaching, and more balanced profiles. The STICS crop model made it possible to quantify and analyze profiles of ecosystem services and should be helpful in instrumenting the dialogue between fruit growers and other stakeholders by simulating scenarios to optimize multiple services. However, it has to be improved to address the impact of grass cover on soil functions and the long-term functioning of apple orchards.

{debut du text] Phenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. Such an ability varies with genotypes (Pigliucci, 2005; El-Soda et al., 2014) and thus the environment and genotypes can interact to shape phenotypic traits (Via et al., 1995; Pigliucci and Hayden, 2001; Nussey et al., 2007). These interactions are at the basis of evolutionary processes that can, for example, drive natural populations to maladaptive evolution, when the environment is altered by anthropogenic pressures, or select for phenotypic plasticity, when the environment is unstable (Gotthard and Nylin, 1995; Pigliucci, 2005; Postma and van Noordwijk, 2005; Dunlop et al., 2009; Ingleby et al., 2010; Kuparinen and Hutchings, 2012). Genotype by environment interactions (GEI) can also alter community structures and dynamics (Miner et al., 2005). For instance, roots forming a symbiosis with different genotypes of arbuscular mycorrhizal fungi are not affected in the same way by phosphorus availability (Ehinger et al., 2009). On the other hand, the stability of ectomycorrhizal fungal communities can be altered as a consequence of the interactions of plant genotypes with drought conditions (Gehring et al., 2014).

Apple and peach orchards are chemical-intensive systems, and aphids are one of their major pests. Aphids alter fruiting and shoot development, and they can spread viruses. Decades of insecticide use have developed aphid resistance, which calls on research to provide alternatives to chemicals for pest management. Here, we review the literature to identify, for each stage of the aphid life cycle, existing alternatives based on either top-down (i.e. aphid predation or parasitism) or bottom up (i.e. increase of host plant resistance) processes. Firstly, it was found that most studies focus on top-down processes, namely on conservation biological control aiming to preserve existing populations of natural enemies: predators, parasitoids and nematodes. This is achieved by (i) providing shelters (i.e. planting hedges, weed or flower strips) or alternative preys in periods of aphid scarcity or (ii) choosing chemicals with the lowest disruptive effects. Those methods prove more efficient when used early in the season, i.e. before the exponential increase of aphid populations. Fostering the complex of natural enemies is also preferable than just supporting one single enemy. Secondly, other techniques, like (i) releasing biological control agents (entomopathogenic fungi, nematodes) or (ii) using pheromone lures to prevent autumnal sexual reproduction, are currently adapted for their use in orchard conditions. Thirdly, bottom-up regulation has to be devised as a long-term strategy, which could start by choosing a cultivar enabling genetic avoidance or developing genetic resistance. Then, aphid development can be reduced by the control of shoot growth or nitrogen accumulation in response to pruning or moderate water and nutrient inputs. At last, autumnal return of aphids could be disrupted by techniques such as kaolin applications that impair aphid host plant location. It is concluded that these alternative methods have to be adapted to local conditions and combined in long-term strategies in order to decrease the infestation risks throughout the orchard lifespan.

Arboriculture must maintain acceptable fruit production levels while preserving natural resources. This duality can be analyzed with the concept of ecosystem service. We reviewed the literature on orchards to explain how ecological functions modified by agricultural practices provide six ecosystem services - fruit production, climate regulation, soil nitrogen availability, water regulation, pest and disease control, and pollination - and which indicators could describe them. The major points are, first, that orchards have a high potential of multiple services. They can sequester from 2.4 to 12.5 t C/ha/year. Their perennial character and multi-strata habitat, as well as the opportunity of creating diversified hedgerows and cover crops in alleys, may contribute to a high level of biodiversity and related services. Second, every service depends on many functions. Fruit yield, which could reach up to 140 t/ha in apple orchards, is increased by light interception, carbon allocation, and nitrogen and water uptake. Third, agricultural practices in orchards have a strong impact on ecosystem functions and, consequently, on ecosystem services. Overfertilization enhances nitrogen leaching, which reduces soil nitrogen availability for the plant and deteriorates the quality of drained water. Groundcover increases humification and reduces denitrification and runoff, thus enhancing soil nitrogen availability and water regulation. It also enhances biotic interactions responsible for pest control and pollination. Pruning may increase fruit quality trough a better carbon allocation but decreases pest control by fostering the dynamics of aphids. To study multiple ecosystem services in orchards, we suggest using models capable of simulating service profiles and their variation according to management scenarios. We then refer to the available literature to show that conflicts between provisioning and regulating services can be mitigated by agricultural practices. Improved knowledge of soil processes and carbon balance as well as new models that address multiple services are necessary to foster research on ecosystem service relationships in orchards.

10. International Symposium on Modelling in Fruit Research and Orchard Management Location: Montpellier, FRANCE Date: JUN 05, 2015; Orchards represent relevant study systems for investigating the functional role of insectivorous birds as regulators of pest insect populations. In this context, we used a bioenergetics model (Wiens and Innis, 1974) to estimate the seasonal variation in daily insect consumption by natural populations of the great tit (Parus major) in organic apple orchards. This model allowed us to estimate the changes in both adult densities and energy requirements in a P. major population, using field-measured parameters such as the brood size, and the length of incubation. The calculation of insect consumption rate by birds was based on both the existing literature on great tit diets and the simulated energy requirement of a great tit population. The effect of a temperature increase on energy requirement has been quantified. This study opens the way to consider the functional role of birds in agricultural landscapes and how this role may translate to ecosystem services.

Integrated Pest Management (IPM) aims to promote physical and biological regulation strategies that help farmers contain populations of pests (pathogens, animal pests and weeds) and to finally reduce the reliance on pesticides. It is based on the holistic combination of multiple management measures rather than on the sum of single methods, each of them having only small effects on pests reduction. Thus, to analyse the interactions between IPM measures and to evaluate the sustainability of their implementation, we require an approach considering the whole cropping system (CS), i.e. a functional entity whose complexity is more than the sum of its parts. A network of European experiments at the CS level was set up recently, and aimed at sharing data and expertise to enhance knowledge of IPM. Comparison of existing methodologies highlighted a diversity of CS designs and experimental layouts. We deduced that the concept of CS itself was viewed differently among scientists, and this affected experimental protocols. Other differences were related to the research context and objectives. Some experiments aimed to explore very innovative strategies and generated knowledge on both their effects on the agroecosystem and their ability to satisfy a set of performance targets, while others aimed to provide quickly adoptable solutions for local farmers in line with the current socio-economic constraints. In some research programmes, the experiment was part of the CS design process — and tested CS were regularly revised based on an continuous improvement loop — while in other cases CS were kept stable across years so as to enable the evaluation of their long-term cumulative effects. A critical aspect contributing to the diversity among CS experiments was the distinction between a factorial design of experimental CS and systemic approaches: factorial experiments allowed quantification of the effects of each IPM component regardless of the consistency between components defining the CS. In contrast, systemic approaches focused on the overall evaluation of CS designed with consideration of their consistency, hence maximising their ability to meet the objectives. Because CS experiments represent a huge investment in terms of economics and time, preliminary reflections of the relevance of the experimental strategy is of critical importance.

A major difficulty in the use of metaheuristics (i.e. evolutionary and particle swarm algorithms) to deal with multi-objective optimization problems is the choice of a convenient point at which to stop computation. Indeed, it is difficult to find the best compromise between the stopping criterion and the algorithm performance. This paper addresses this issue using the Non-dominated Sorting Genetic Algorithm (NSGA-II) and the Multi-Objective Particle Swarm Optimization with Crowding Distance (MOPSO-CD) for the model-based design of sustainable peach fruits. The optimization problem of interest contains three objectives: maximize fruit fresh mass, maximize fruit sugar content, and minimize the crack density on the fruit skin. This last objective targets a reduction in the use of fungicides and can thus enhance preservation of the environment and human health. Two versions of the NSGA-II and two of the MOPSO-CD were applied to tackle this difficult optimization problem: the original versions with a maximum number of generations used as stopping criterion and modified versions using the stopping criterion proposed by the authors of (Roudenko & Schoenauer, 2004). This second stopping criterion is based on the stabilization of the maximal crowding distance and aims to stop computation when many generations are performed without further improvement in the quality of the solutions. A benchmark consisting of four plant management scenarios has been used to compare the performances of the original versions (OV) and the modified versions (MV) of the NSGA-II and the MOPSO-CD. Twelve independent simulations were performed for each version and for each scenario, and a high number of generations were generated for the OV (e.g., 1500 for the NSGA-II and 200 for the MOPSO-CD). This paper compares the performances of the two versions of both algorithms using four standard metrics and statistical tests. For both algorithms, the MV obtained solutions similar in quality to those of the OV but after significantly fewer generations. The resulting reduction in computational time for the optimization step will provide opportunities for further studies on the sustainability of peach ideotypes.

International audience; Agricultural intensification has increased crop productivity but decreased agroecosystem services. Agricultural intensification is occurring notably for horticultural crops such as lettuce. In conventional agriculture, lettuce protection is achieved mostly by preventive applications of pesticides with about eight treatments for a 60–90-day-long cycle in the Mediterranean region. However, new sustainable control strategies are needed due to pesticide impact on environment and human health, emerging pesticide resistance, and stricter policies on levels of pesticide residues in food. Here, we review knowledge and methods allowing to grow lettuce with less pesticides. Advances shown are based on pest ecology and pathogen control by the agroecosystem. The major points are as follows: (1) pest and pathogen community composition depends partly on climatic conditions. The identification of pests and pathogens that can threaten the crop is the first step to design innovative lettuce cropping systems less dependent on pesticides. (2) The numerous alternative techniques currently available should be combined to control lettuce pests and pathogens. The effects of alternative techniques on non-target organisms including non-target pests are poorly known so far. (3) Designing sustainable systems requires taking into account ecological interactions and suitability of different management techniques of low impact.

International audience; The soluble sugar concentration of fleshy fruit is a key determinant of fleshy fruit quality. It affects directly the sweetness of fresh fruits and indirectly the properties of processed products (e.g., alcohol content in wine). Despite considerable divergence among species, soluble sugar accumulation in a fruit results from the complex interplay of three main processes, namely sugar import, sugar metabolism, and water dilution. Therefore, inter-species comparison would help to identify common and/or species-specific modes of regulation in sugar accumulation. For this purpose, a process-based mathematical framework was used to compare soluble sugar accumulation in three fruits: grape, tomato, and peach. Representative datasets covering the time course of sugar accumulation during fruit development were collected. They encompassed 104 combinations of species (3), genotypes (30), and growing conditions (19 years and 16 nutrient and environmental treatments). At maturity, grape showed the highest soluble sugar concentrations (16.5–26.3 g/100 g FW), followed by peach (2.2 to 20 g/100 g FW) and tomato (1.4 to 5 g/100 g FW). Main processes determining soluble sugar concentration were decomposed into sugar importation, metabolism, and water dilution with the process-based analysis. Different regulation modes of soluble sugar concentration were then identified, showing either import-based, dilution-based, or import and dilution dual-based. Firstly, the higher soluble sugar concentration in grape than in tomato is a result of higher sugar importation. Secondly, the higher soluble sugar concentration in grape than in peach is due to a lower water dilution. The third mode of regulation is more complicated than the first two, with differences both in sugar importation and water dilution (grape vs. cherry tomato; cherry tomato vs. peach; peach vs. tomato). On the other hand, carbon utilization for synthesis of non-soluble sugar compounds (namely metabolism) was conserved among the three fruit species. These distinct modes appear to be quite species-specific, but the intensity of the effect may significantly vary depending on the genotype and management practices. These results provide novel insights into the drivers of differences in soluble sugar concentration among fleshy fruits.

Earth has recently entered the new era of the Anthropocene, during which the rise of human activities are impacting for the first time ecosystems and climate on the global scale. Since the 1960s the green revolution has improved food production in quantity using industrially-designed agriculture, which has led to global pollution by pesticides and losses of food quality, biodiversity and soil carbon. As a consequence there is a need to implement agroecological practices in order to produce food safely and in a sustainable way. This virtual issue presents principles and applications of agroecological engineering, exemplified in 19 selected review articles from the journal Agronomy for Sustainable Development, one of the most recognized journals in Agronomy. Practical examples of agroecological engineering include ecological pest control, intercropping, multiple cropping systems, biofertilisation, or the management of important components of agroecosystems such as ditches in landscapes, weeds and bees, and soil biodiversity. On the whole, this virtual issue covers a large range of topics and systems in temperate and tropical environments.

Aphids are commonly considered major agricultural pests because of their ability to severely alter host plant physiology. However, their effects on fruit tree yield have not received wide attention and few existing works considering plant-aphid interaction and its consequences have only been conducted over a single year. We modified an existing process based model for the peach tree Prunus persica − green aphid Myzus persicae pathosystem, explicitly considering interactions between the two species under the influence of cultural practices (i.e. winter pruning and nitrogen fertilization), in order to simulate multi-year dynamics. The new model indicates that fertilization affects plant growth more than aphid infestation and the consequences of aphid infestation over fruit yield only emerge when considering the entire tree life span (ca. 10 yr). In fact, in a given year, aphid infestation mainly impairs shoot growth and, as fruits are borne on 1-yr old wood, its effects on fruit production are delayed in time. Our results are in accordance with the few existing experimental studies and highlight the need of considering multi-year dynamics, both via modelling and field observations, when dealing with perennial crops as fruit trees.

In horticulture, stringent market requirements regarding the visual quality of products have led to the intensive use of pesticides worldwide. The immediate need for environmentally-friendly pest control, already embodied in the development of IPM, is exacerbated by pressing social demands and policy contexts. At the same time, the scientific community is increasingly interested in new disciplinary branches and concepts such as agroecology, ecosystem services and ecological intensification that create an opportunity to develop new approaches to pest control research. A conceptual framework is presented that addresses the issue of the ecological control of pests in horticulture. It is based on key ecological concepts- trophic network, biotic interactions, niche and dispersal. This framework stresses the trophic and nontrophic interactions that occur between the components of three trophic levels plants, pests and natural enemies. It highlights the effect of agroecosystem management on these components, namely on the niche dimensions and dispersal of pests and enemies, and its consequences on pest control. This management includes the addition of plant or animal biodiversity, as well as practices to control the functioning of this planned biodiversity. Examples taken from greenhouse and orchard studies illustrate the salient points of the conceptual framework. This approach has a high potential in horticultural systems where there is the possibility to combine various sources of biodiversity and various technical levers. However, more knowledge about the functioning of target ecological networks is required to improve its robustness. In addition, a major current challenge that makes this approach more difficult is the necessity to consider the ecological control of pests within a set of multiple agroecosystem services to be managed.

Process-based simulation models (PBSMs) combine, in various mathematical frameworks, many biological functional hypotheses on responses of plant processes to environmental fluctuations. Model simulated responses can be analysed in the context of adapting the current agricultural systems to the changing environment. From loads of simulations made with various cultural practices, these models allow the virtual profiling of plants and a mere analysis of how processes interact when crops are perturbed by one or several changes. They allow also describing the development of plant traits as a consequence of environmental and genetic conditions. Such knowledge is required to decipher the genotype × environment × management (G × E × M) interactions so as to build genotypes adapted to particular conditions, i.e., plant ideotypes. Two PBSMs dealing with (1) fruit quality and sensitivity to diseases and (2) root system architecture, respectively, are shortly described in this chapter. These models have been used to analyse various fruit and root properties, to deconvolute G × E × M interactions and to identify ecophysiological traits related to crop yield improvement, root foraging performance and fruit quality. PBSMs appear to be powerful tools to phenotype plants at the process level in a comprehensive and “costless” way.

Brown rot can lead to considerable fruit losses in peach orchards and cultural practices likely to contend this major disease have to be promoted. In order to limit peach brown rot incidence in a three-year-old mid-season maturing peach orchard of the cultivar ’Ruby Bright’, four combinations of irrigation and soil management treatments were assessed: conventional (Conv) irrigation (I) and soil management (S) (ConvI+ConvS); modified (Mod) irrigation and soil management (ModI+ConvS); conventional irrigation and modified soil management (ConvI+ModS); and modified irrigation and soil management (ModI+ModS). Conventional irrigation and soil management in the tree row consisted of irrigation scheduling using tensiometer readings and herbicide use, respectively. Modified irrigation and soil management in the tree row consisted of water deprivation during stage III of fruit development and ground cover with white clover, respectively. For four consecutive years (2010–2013), in the conditions of the Middle Rhone Valley in France, the lowest and highest brown rot incidence were detected under (ModI+ModS) and (ConvI+ConvS), respectively, whereas brown rot incidence under (ModI+ConvS) and (ConvI+ModS) was intermediate. This lower brown rot incidence under the modified treatments occurred from one to two weeks before fruit maturity and was still observed for several days in post-harvest storage. Ground cover with white clover was shown to limit water availability in the soil after heavy rainfall compared to bare soil, probably limiting peach growth variations, well-known as a possible source of detrimental microcracks at the fruit surface. This suggests that under our conditions appropriate cultural practices, water deprivation and a clover crop cover in the tree row possibly decrease peach disease sensitivity, which might lead to the reduced use of pesticide sprays to control brown rot in the orchard.

UMR AGAP - équipe AFEF - Architecture et fonctionnement des espèces fruitières; International audience; Ideotypes are a popular concept for plant breeders, who designate as such the ideal combinations of traits in a particular genotype to reach a pre-set production objective within a given socio-economic context. The historical, ‘genetic’ view of ideotypes has been more recently extended to cover the design of plant genotypes for specific cropping systems (the ‘agronomic’ view), or even the ideal combination of parameters, identified from formal or simulation modeling, to a specific agronomic problem (the ‘modelling’ view). These different forms of ideotypes in turn lead to different strategies for breeding plants. This paper will briefly describe, analyse and discuss some applications of these ideotype views, using the specific case of architectural traits of plant and crop canopies to limit the epidemic development of pests and diseases in crops. It is not intended to be an exhaustive and objective review of the existing literature on plant ideotypes, but rather to express as an ‘opinion’ paper the views discussed and elaborated among participants to the EpiArch network.

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; Watersprout occurrence and growth were investigated over a two-year period in an early maturing peach cultivar (Alexandra) under different intensities of dormant pruning for fruited and defruited trees. A preliminary study focused on identifying the laws that determine the probability of presence and occurrence of watersprouts in relation to watersprout-bearing shoot (WBS) length. The increase in watersprout probability of presence and occurrence resulting from greater WBS length illustrated the high capacity of peach for sprouting. Watersprout lengths were measured, as well as the lengths of young shoots, one-year-old fruit-bearing shoots (FBSs) and older branches considered as WBS in order to evaluate total shoot growth within the tree. Watersprout number and total length tended to be higher under severe dormant pruning and in fruited trees than under light dormant pruning and in defruited trees. This stimulation of watersprout length appeared to compensate for the concomitant lower total length of young shoots, resulting in a constant overall vegetative growth rate for the whole tree. In the second year of the experiment, watersprouts were either removed by summer pruning or not in order to evaluate watersprout incidence on the rest of the tree. After light and severe watersprout removal (WSR), the annual diametrical growth of FBS tended to be higher and lower, respectively, compared to trees not submitted to summer pruning. Light WSR might favour light interception in the centre of the canopy, thus improving assimilate production and allocation to FBS, whereas severe WSR could prevent carbohydrate export from watersprouts to FBS. Under our conditions, the limit at which WSR intensity became detrimental for FBS diametrical growth appeared to be after approximately 75% of the watersprouts were removed. Severe WSR appeared likely to improve fruit diameter, whereas it had no significant impact on the percentage of soluble solids

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; In this paper, QualiTree, a fruit tree model designed to study the management of fruit quality, and developed and described in a companion paper (Lescourret et al. in Trees Struct Funct, 2010), was combined with a simple light-interception sub-model, and then parameterised and tested on peach in different situations. Simulation outputs displayed fairly good agreement with the observed data concerning mean fruit and vegetative growth. The variability over time of fruit and vegetative growth was well predicted. QualiTree was able to reproduce the observed response of trees to heterogeneous thinning treatments in terms of fruit growth. A sensitivity analysis showed that the average seasonal growth rates of the different organs were sensitive to changes to the values of their respective initial relative growth rates and that stem wood was the tree organ the most affected by a change in the initial relative growth rates of other organs. QualiTree was able to react to simulated scenarios that combined thinning and pest attacks. As expected, thinning intensity and the percentage damage caused by pests significantly affected fruit yield and quality traits at harvest. These simulations showed that QualiTree could be a useful tool to design innovative horticultural practices

Summary 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.

International audience; Innovative cropping systems leading to high quality production and limiting chemical input are required to meet agriculture challenges. However designing cropping systems with reference to the cultivated plot constitutes an obstacle to innovation. We illustrate this viewpoint using fruit tree cropping systems as a case study. The following points will be developed: (1) plot definition depends on the point of view adopted; (2) product quality requires whole field consideration implying multi-level modelling of crop production; (3) farmers often break down or group together plots when managing crops; (4) pest species dynamics involve landscape patterns. In conclusion, the plot may be considered as a multilevel management entity, embedded in a more general context. This stresses the need for infra- and supra-plot studies