P É Lauri

B Pitchers

L Dufour

S Simon

Apple farming systems -Current initiatives and some prospective views on how to improve sustainability

Keywords: integrated fruit production, organic farming, agroecology, ecosystem services, agroforestry, climate change, socio-economics

Apple cultivation has evolved tremendously in past decades. Both apple productivity, and aesthetic and quality of the fruit, have been strongly improved resulting from genetic improvement, optimization of tree training and pruning, and orchard design and management. However, these improvements were also done at the expense of an increasing dependence on external inputs such as water, fertilizers and synthetic pesticides. This dependence is now questioned because of the generated environmental pollutions and health issues. In the last decades, an increasing amount of initiatives have been developed that open the way towards more sustainable apple production systems. Concepts as well as on-station and onfarm works are developed in various contexts such as 'Integrated Fruit Production', 'Organic Farming' and 'Agroecology' with the objectives to increase biological regulations of pests and diseases and/or to improve soil fertility. All together results point out the importance of diversifying resources and habitats for beneficial arthropods in the orchard and its vicinity to foster ecosystem services related to pest suppression and to adopt cultural practices enhancing soil fertility. They also indicate some practical guidelines consisting in a better management of grass alleys and lining hedgerows within and around the orchard, respectively. From a more prospective view and taking inspiration from tropical fruit-tree based agroforestry, these works suggest that combining apple trees with other herbaceous and woody plants with various uses (soft fruit, aromatic plants, etc.) opens to more resilient agroecosystems, possibly mitigating climate change. They also enlarge our vision of the current apple orchard towards a multiproduction system including apple among other productions. From the 'plant science' point of view this emerging paradigm challenges current knowledge of the plasticity of the apple tree physiology and architecture, and agronomic performance, in response to interactions with neighboring plants. It also stimulates necessary collaborations with other research fields such as socio-economics, for example on how the grower may handle those complex agroecosystems, optimize labor and valorize production.

INTRODUCTION

It is likely during the 1930s that apple was isolated from the traditional multispecies, often agrosilvopastoral, systems to be cultivated in monospecies fruit-tree orchards (e.g., in Europe; [START_REF] Herzog | Streuobst: a traditional agroforestry system as a model for agroforestry development in temperate Europe[END_REF]. Although statistics at the world scale need rigorous analyses and should be taken with caution, with for example a strong decrease of cultivation area from the middle on 1990's onwards (Figure 1a) that is not really consistent with changes in productivity (Figure 1b), some general statements can be made. In past decades, worldwide apple cultivation has undergone a tremendous increase in both cultivation area (from ca. 1.8 million ha in 1961 to ca. 7.7 million ha in 2016) and production (from ca. 17.2 million t in 1961 to ca. 133.8 million t in 2016) (Figure 1a). In the same time range mean productivity has increased from 5.9 t ha -1 to 15.2 t ha -1 (Figure 1b). These progresses are due to both the use of high performance plant material (e.g., breeding for new cultivars with high fruit aesthetic quality and long shelf life; Brown and Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16). [START_REF] Brown | Genetic Improvement of Apple: Breeding, Markers, Mapping and Biotechnology[END_REF] and cultivation techniques through the improvement of the planning, establishment and management of orchards [START_REF] Robinson | Apple-orchard Planting Systems[END_REF].

Figure 1. Progress in apple production (million ton) and cultivation area (million ha)(a), and apple productivity (t ha -1 )(b) in total world from 1961 to 2016 (FAO, http://www.fao.org/faostat/en/#data; for 'apple', 'all countries', 'all years', 'area harvested', 'production quantity ' and 'yield';accessed 29 March, 2018).

However, this intensification of apple cultivation, often coupled with a 'weed-free' (or 'bare-soil') strategy eradicating all vegetation on the orchard floor, was done at the expense of an increasing reliance on pesticides, i.e., herbicides to limit competition for water and nutrients and phytosanitary treatments against pests and diseases, hereafter referred to as 'pests'. This reliance on chemicals with known adverse effects on the environment and human health is considered as the main obstacle to the sustainable intensification of agriculture in general (see for example in China; [START_REF] Lu | Sustainable intensification of China's agriculture: the key role of nutrient management and climate change mitigation and adaptation[END_REF]. Apple remains one of the most treated fruit crop (EWG, 2017). Indeed, in order to achieve high 1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 2011 2016 yields of high quality fruit apple, orchards require frequent pesticide applications, up to ca. 35 according to a survey made in France in 2012 [START_REF] Maaf | Enquête pratiques phytosanitaires en arboriculture 2012[END_REF] and more generally between 10 and 24 according to [START_REF] Granatstein | Assessing the environmental impact and sustainability of apple cultivation[END_REF]. Moreover, a strong reduction in the number of cultivars accompanied this intensification increasing the risk of narrowing the genetic ability to resist to or tolerate existing and new pests, and to adapt to climate change. For example, in Germany, it is estimated that the traditional multispecies 'streuobst' systems hosted a high apple genetic diversity with ca. 1400 cultivars which were robust and well adapted to the local pedoclimatic conditions [START_REF] Herzog | Streuobst: a traditional agroforestry system as a model for agroforestry development in temperate Europe[END_REF] whereas in the current monocropping system 52% of apple production is covered by only five cultivars [START_REF] Garming | Apple production in Germany[END_REF]. A main conclusion is that current high density monoclonal orchards are hardly appropriate to drastically reduce pesticide use [START_REF] Simon | Pesticide use in current and innovative apple orchard systems[END_REF] and that both the range of existing commercial apple cultivars and the design of the apple orchard system need to be reconsidered (Lauri and Simon, 2018).

P r o d u c t i v i t y ( t h a

In the following we review how initiatives such as 'Integrated Fruit Production', 'Organic Farming', and 'Agroecology' developed in past decades have renewed our way to establish and manage more sustainable systems of apple production. Secondly, taking inspiration from 'Agroforestry' we show that apple-based systems may also be designed including other crops and considering a range of 'ecosystem services'. The need to foster fundamental and applied researches on how the apple tree interacts with its environment will be emphasized.

IMPROVING THE SUSTAINABILITY OF CONVENTIONAL ORCHARDS

Integrated Fruit Production, Organic Farming and Agroecology

The idea to meet the global challenges of securing the food supply while reducing external inputs and minimizing negative impacts on the environment and human health were institutionalized in the 1980s [START_REF] Granatstein | Assessing the environmental impact and sustainability of apple cultivation[END_REF]. A common ground of the several initiatives developed in past decades is the concept of 'sustainability' which was defined as "the ability to make development sustainable to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs" [START_REF] Brundtland | Our Common Future. Report of the world commission on environment and development[END_REF]. In this general framework, three main apple farming systems have been developed in past decades that are still co-existing.

Integrated Production (IP) was officially initiated in 1977 under the umbrella of IOBC (International Organisation for Biological and integrated Control) to promote environmentally safe methods of pest control, and later to promote the development and adoption of IP methods [START_REF] Avilla | Integrated Fruit Production for Apples -Principles and Guidelines[END_REF]. Applied to fruit, Integrated Fruit Production (IFP) is defined as "the economical production of high quality fruit, giving priority to ecologically safer methods, minimizing the undesirable side effects and use of agrochemicals, to enhance the safeguards to the environment and human health" (Malavolta and Cross, 2009). Continuous studies have been developed to improve IFP implementation, mainly about Integrated Pest Management (IPM), including the use of biorational pesticides that express selectivity to specific developmental stages (e.g., biopesticides and insect growth regulators), semiochemicals (e.g., sex pheromones) and biological control (using natural enemies of pests) [START_REF] Damos | Integrated Fruit Production and Pest Management in Europe: The Apple Case Study and How Far We Are From the Original Concept?[END_REF]. In many countries, and also at the international scale through the impetus of institutions such as the 'Food and Agriculture Organization' (FAO), conventional apple orchards have been encouraged to move towards IFP with the objective to minimize synthetic pesticide use [START_REF] Damos | Integrated Fruit Production and Pest Management in Europe: The Apple Case Study and How Far We Are From the Original Concept?[END_REF]. IFP can then be considered as the standard conventional apple orchard, at least in Europe where IPM is compulsory since 2009 [START_REF] Damos | Integrated Fruit Production and Pest Management in Europe: The Apple Case Study and How Far We Are From the Original Concept?[END_REF].

Organic Farming (OF) is defined as a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than on the use of inputs with adverse effects. OF typically puts emphasis on maintenance of soil organic matter via the use of organic composts, mulches and green manures [START_REF] Neilsen | Nutritional Requirements of Apple[END_REF] and also makes use of nitrogen fixing plants [START_REF] Weibel | Organic Apple Production -with Emphasis on European Experiences[END_REF]. In Europe, OF conforms to strict regulations that define precise farming and processing techniques [START_REF] Migliorini | Converging and diverging principles and practices of organic agriculture regulations and agroecology[END_REF]. A main difference between IFP and OF is that OF aims to manage the orchard system as a whole insisting on the ban of synthetic inputs and their derivatives [START_REF] Weibel | Organic Apple Production -with Emphasis on European Experiences[END_REF]. Organic farming combines "tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved" (IFOAM, 2005;[START_REF] Niggli | A Global Vision and Strategy for Organic Farming Research[END_REF]. Although the area of apple production in OF is strongly increasing since the past recent years [START_REF] Granatstein | Global situation for organic tree fruits[END_REF], OF is still currently less developed than IFP with around 10% of the fruit-growing area in the main fruit production regions in Europe [START_REF] Kienzle | Growing organic apples in Europe[END_REF]. Agroecology (AE) combines knowledge in agronomy and ecology and has a defined set of principles for the ecological management of agrifood systems which extends what is developed in OF integrating the more general concept of 'ecosystem services' (see below) and especially socio-economic and political principles that are not or less explicitly managed in IFP and OF (Gomez et al., 2016;[START_REF] Migliorini | Converging and diverging principles and practices of organic agriculture regulations and agroecology[END_REF]. Agroecology meets an increasing interest in apple production since it opens routes to design novel apple-based systems optimizing interactions between the apple tree and the other plants of the system [START_REF] Simon | Methodology to design agroecological orchards: learnings from on-station and on-farm experiences[END_REF]. Although many cultivation practices are similar for IFP, OF and AE (e.g., choice of species and genotypes to optimize positive interactions and minimize negative interactions among them; management of soil structure and fertility; pest and weed management), the origin and quantity of products used and also often the design of the system, are different [START_REF] Migliorini | Converging and diverging principles and practices of organic agriculture regulations and agroecology[END_REF].

To summarize, if the use of synthetic products differentiates IFP and OF, without a clear position of AE on this aspect, these latter two farming systems share a common holistic view towards improving the sustainability of the apple systems based on more knowledge on, and a better use of, interactions among plants, and between plants and the environment. Using the grid established by [START_REF] Hill | Redesigning Agroecosystems for Environmental Sustainability: A Deep Systems Approach[END_REF] to compare the various degrees of sustainability of agroecosystems, IFP would conform essentially to the 'efficiency' (i.e., improving the use of a given chemical input) and 'substitution' (i.e., replacing one input by another one or by another technique that is less disruptive) strategies. On the other hand, OF and even more AE are more in the 'redesign' strategy (e.g., with various spatial and temporal combinations of plant species around the apple) and management of the whole system at both agricultural practices and socioeconomic levels. However, apart from the restriction on synthetic pesticides use specific to OF, practices (e.g., choice of associated plants, cultural operations) developed in IFP, OF and AE systems may have converged over time especially under the increasing constraints due to international or national regulations relative to the use of phytosanitary products. [START_REF] Simon | Pesticide use in current and innovative apple orchard systems[END_REF] compared the level of use of fongicides and insecticides, and agri-environmental performances of three farming systems, 'national IFP standards', in short 'IFP', 'low-input' (i.e., pesticide use as a last resort) and OF. The study also included the effect of the cultivar using three cultivars differing in scab susceptibility: 'Ariane' (Vf-resistant), 'Melrose' (low-susceptibility) and 'Golden Delicious' (susceptible). A significant farming system-cultivar interaction effect was found. Indeed, as hypothesized, the highest pesticide use was found for 'Golden Delicious' especially in IFP system. The least pesticide use (-43 to -56% compared to 'Golden Delicious') was found in 'Ariane' and 'Melrose' in both low-input and OF. However, considering yield and fruit damages, only 'low-input' 'Melrose' and 'low-input' 'Ariane' systems achieved similar results as the same cultivars in IFP. These results indicated that the choice of the cultivars according to their genetic resistance or tolerance to pests has a crucial role when implementing low pesticide systems. Within a given farming system, the system design also plays a significant role in pest dissemination. For example, working on the apple-scab pathosystem without fungicides, and mixing a susceptible cultivar and a resistant cultivar in equal proportions, [START_REF] Didelot | Effects of cultivar mixtures on scab control in apple orchards[END_REF] observed a significant reduction in disease incidence over both study years (-7.3 to -21.3%), and severity in the second year (-35.4%) in the within-row mixtures, compared to the monoculture of the susceptible cultivar. Moreover, combining within-row mixture and a moderate fungicide treatment, disease incidence was reduced by 75.1% on leaves and by 69.7% on fruits. Going further and although not really applicable in practice, the modeling work developed by Sapoukhina et al. (2007) showed that random patterning of susceptible and resistant apple cultivars can reduce pathogen infection.

Setting innovative apple orchards. Example of initiatives reducing pesticide use

All together, these works indicate that, in a monospecies orchard, both the intrinsic tolerance or resistance of apple cultivars to pest and planting design can be combined to significantly reduce pest damages and/or at least permits reducing pesticide treatments. However, all these systems whether IFP, OF or AE are still dependent on regular and tightly adjusted inputs in terms of cultural operations and treatments. Improving apple cultivation sustainability needs revisiting actual concepts of apple cultivation, especially on two aspects that are developed in the following chapter, plant diversity 'around' the apple and plant arrangement.

REDESIGNING MORE DIVERSIFIED AND MULTIFUNCTIONAL APPLE-BASED SYSTEMS

The concept of ecosystem service

The Millennium Ecosystem Assessment (2005) and more recently the Common International Classification of 'ecosystem services' (CICES; Haines-Young and Potschin, 2018) consider that a natural ecosystem or an anthropized ecosystem, i.e., an agroecosystem, can provide various 'services' defined as ''the benefits people obtain from ecosystems'' (Millennium Ecosystem Assessment, 2005). Typically, a conventional apple farming system aims at providing quite only a 'provisioning service', namely apple production. However, considering more complex systems such as OF and AE, there is a shift from a monofunctionality to a multifunctionality of the orchard. This multifunctionality may be handled using the ecological concepts of 'ecosystem services' [START_REF] Barot | Designing mixtures of varieties for multifunctional agriculture with the help of ecology. A review[END_REF]. Other services may be considered beside production: 'regulation' (e.g., regulation of pests through the mixing of genotypes or nutrient cycling through the use of nitrogen-fixing grass in the alley) and/or 'cultural' (e.g., 'pick-your own' orchards). More precisely, [START_REF] Demestihas | Ecosystem services in orchards. A review[END_REF] identified five services that, apart from fruit production, can be provided to a satisfying level by an apple farming system: climate regulation, soil nitrogen availability, water regulation, pest and disease control, and pollination. These services can be optimized through the choice of plant material and agricultural practices. Both aspects can be optimized via the design of 'agroecological infrastructures' that include not only the management of the inter-row flower or grass strips but also the hedgerows composed of bushes and trees around the plot. The objective of these agroecological infrastructures is to host beneficial arthropods by providing food complements such as nectar, pollen and/or honeydew for optimal survival, fitness and fecundity [START_REF] Simon | Biodiversity and pest management in orchard systems. A review[END_REF][START_REF] Albert | Impact of Agroecological Infrastructures on the Dynamics of Dysaphis plantaginea (Hemiptera: Aphididae) and Its Natural Enemies in Apple Orchards in Northwestern France[END_REF][START_REF] Demestihas | Ecosystem services in orchards. A review[END_REF][START_REF] Simon | Methodology to design agroecological orchards: learnings from on-station and on-farm experiences[END_REF].

Scarce studies have been developed on ecosystem services in apple orchards and especially on interdependencies between them, and their relations with the environment and cultural operations. Recently, [START_REF] Demestihas | Analyzing ecosystem services in apple orchards using the STICS model[END_REF] modeled several ecosystem services (soil nitrogen availability, climate regulation, water cycle maintenance and regulation, and fruit production) at the annual scale and interactions between some of them. For example, considering apple production and denitrification, they showed that a weak crop reduces nitrogen needs and thus nitrogen absorption by the trees, therefore increasing nitrogen leaching.

Implementing ecosystem services in apple-based farming systems: combining plant diversity and plant arrangement 1. Increasing plant diversity.

As seen above plant diversity is a main issue in OF and AE because it is the combination of the various plant species, whether annuals or perennials, grass, bush or even trees, that is the basis of ecosystem services provided by the system. Indeed, plant diversity is at the core of the three main classes of ecosystem services identified in all OF and AE systems [START_REF] Migliorini | Converging and diverging principles and practices of organic agriculture regulations and agroecology[END_REF] and especially in apple-based OF and AE systems [START_REF] Demestihas | Ecosystem services in orchards. A review[END_REF][START_REF] Demestihas | Analyzing ecosystem services in apple orchards using the STICS model[END_REF][START_REF] Simon | Methodology to design agroecological orchards: learnings from on-station and on-farm experiences[END_REF], namely, provisioning, regulation and cultural.

There is a consensus that functional differences among species are more important for biodiversity effects than species richness per se. This means that it is important to identify precisely the traits of the species (their 'functional characteristics') one wants to introduce in the system and the way they can be managed, e.g., soil cover, nitrogen fixing, host for natural enemies [START_REF] Bakker | Can root trait diversity explain complementarity effects in a grassland biodiversity experiment[END_REF]. Several species can share a given functional trait and in this case the choice of only one of these species may be sufficient. For example, considering soil nitrogen availability, biological nitrogen fixation can be provided using various legumes such as white clover (Trifolium repens) but also alfalfa (Medicago sativa) or sainfoin (Onobrychis viciifolia) and the choice of one of those species depends more on the will to grow an annual or a perennial grass cover in relation to technical and economic considerations, and pedoclimatic conditions. However, some redundancy may be useful to face disruptions caused by climatic events [START_REF] Duru | How to implement biodiversity-based agriculture to enhance ecosystem services: a review[END_REF]. For example, pest control often relies on a range of resources in the agroecosystem, e.g., plant assemblages providing natural enemies with resources and habitat all year long [START_REF] Simon | Biodiversity and pest management in orchard systems. A review[END_REF] or 'banker plants' that serve as alternative hosts for a parasitoid or predator of the target crop pest [START_REF] Demestihas | Ecosystem services in orchards. A review[END_REF]. Plant diversity also needs to be considered in interaction with management even though a given practice can have various effects on pest dissemination depending on the period of the year, and above all the presence of alternative resources. For example, codling moth sentinel egg predation in apple canopy mainly due to the earwig Forficula pubescens is significantly higher in alleys with tall grass than in frequently mowed alleys maintaining short grass in June, but the opposite was observed in July when alternative food was available in the tall grass [START_REF] Marliac | Increased grass cover height in the alleys of apple orchards does not promote Cydia pomonella biocontrol[END_REF].

Apart from the provisioning and the regulation services, plant diversity in the apple-based system also provides cultural services, consisting for example in the heritage value of some endemic or cultivated plants grown in the orchard and its surroundings, or from another point of view the enjoyment of 'pick your own' activities for families, not only of apple but also of other fruits or aromatic plants, especially around large cities.

Plant arrangement: insights into the structural and temporal dimensions.

Plant diversity needs to be considered along with the spatial arrangement, and the within-time and within-space interactions have to be considered in the design and the decisional system [START_REF] Simon | Methodology to design agroecological orchards: learnings from on-station and on-farm experiences[END_REF]. In typical OF and AE where apple production is the main production, apple trees are planted in rows and the agroecological infrastructures and agricultural practices are mainly devoted to pest regulation (e.g., [START_REF] Albert | Impact of Agroecological Infrastructures on the Dynamics of Dysaphis plantaginea (Hemiptera: Aphididae) and Its Natural Enemies in Apple Orchards in Northwestern France[END_REF] and soil nitrogen availability [START_REF] Demestihas | Ecosystem services in orchards. A review[END_REF]. However, apple trees can also be grown with plants providing other production such as soft-fruits, vegetables and aromatic plants that can be combined with plants providing pest control and/or soil nitrogen availability services (e.g., 'verger maraîcher' in France, GRAB, 2017; 'silvoarable agroforestry' in UK, [START_REF] Smith | Silvoarable agroforestry: an alternative approach to apple production?[END_REF]. Moreover, such diversity also enables to design 'pest suppressive' agroecosystems (i.e., highly unfavourable to pests and highly favourable to their natural enemies) through barrier-dilution effects, push-pull processes with trap and repulsive plants, and avoidance strategies beside conservation biocontrol.

In typical OF and AE, apple-trees are in most cases at the higher stratum, i.e., in full sun whereas all the other plants, as bush or grass, occupy the lower strata below apple trees. However, more complex systems may combine plants in various strata: large trees (e.g., nut and timber trees) over-topping the apple, with shrubs (e.g., black currant) and possibly annuals (e.g., corn-soybean rotation) in the understory. These systems are identified as 'multifunctional woody polycultures' [START_REF] Lovell | Temperate agroforestry research: considering multifunctional woody polycultures and the design of long-term field trials[END_REF]. They resemble traditional 'agrisylvicultural systems', and also 'agrosilvopastoral systems' [START_REF] Parrotta | The Historical, Environmental and Socio-Economic Context of Forests and Tree-Based Systems for Food Security and Nutrition[END_REF] when they combine grazing sheeps or chickens that can eat fallen leaves possibly infected by scab and pest arthropod larvae on the ground [START_REF] Burgess | Lessons learnt -Grazed orchards in England and Wales[END_REF][START_REF] Corroyer | Research and Development protocol for Grazed Orchards in France[END_REF][START_REF] Mcadam | System report: Grazed Orchards in Northern Ireland[END_REF]. These systems belong to 'agroforestry' that is a contraction of the terms "agriculture and forestry and designates land use that combines aspects of both, including the agricultural use of trees" [START_REF] Van Noordwijk | Central hypotheses for the third agroforestry paradigm within a common definition, Working paper 233[END_REF]. Fruit trees are the primary driver of agroforestry adoption worldwide especially in the tropics [START_REF] Wolz | Alley cropping: Global patterns of species composition and function[END_REF] and are considered as high value for agroforestry [START_REF] Den Herder | Current extent and stratification of agroforestry in the European Union[END_REF][START_REF] Pantera | Agroforestry for high value tree systems in Europe[END_REF][START_REF] Lauri | Agroforestry for fruit trees in the temperate Europe and dry Mediterranean[END_REF].

Agroforestry and agroecology are two approaches of complex multifunctional systems, with agroforestry including explicitly woody plants. It is worth noticing that agroforestry is not mentioned in the European regulations and IFOAM (2005) norms concerning crop production practices in OF and AE [START_REF] Migliorini | Converging and diverging principles and practices of organic agriculture regulations and agroecology[END_REF]. However, it is considered that agroforestry offers a relevant framework for agroecological practices [START_REF] Wezel | Agroecological practices for sustainable agriculture[END_REF]. Although agroforestry considers mainly the structural and temporal arrangement of the system associated to different uses (e.g., in the USA: alley cropping, silvopasture, riparian buffers, windbreaks and forest farming; [START_REF] Wilson | Agroforestry-The Next Step in Sustainable and Resilient Agriculture[END_REF], agroecology clearly addresses the ecological-driven functioning of the system [START_REF] Wezel | Agroecological practices for sustainable agriculture[END_REF]. It should also be mentioned that agroforestry systems have no guidelines about pesticide use even though those systems are "less reliant… on the use of synthetic pesticides" compared to simplified and specialized cropping systems (UCDAVIS Agricultural Sustainability Institute, 2018) (Figure 2). Designing 'Apple-Tree based AgroForestry Systems' (AT-AFS) that would include the apple in a multistrata system complementing apple production with other productions (other fruits, vegetables, aromatic plants; animals) and providing other services such as those already included in OF and AE, is challenging. Some indications on the spatial arrangement of such complex systems already exist in literature. For example, although OF and AE may keep on planting distances usual for IFP, i.e., 3.5 m to 6 m between tree rows and 1 to 4 m between trees within the row, depending on the cultivar-rootstock combination [START_REF] Smith | Silvoarable agroforestry: an alternative approach to apple production?[END_REF], 'multifunctional woody polycultures' have larger distances with ca. 9 m and ca. 4 m between rows and within the row, respectively [START_REF] Lovell | Temperate agroforestry research: considering multifunctional woody polycultures and the design of long-term field trials[END_REF].

Potential advantages of Apple-Tree based AgroForestry Systems.

A main economic interest of OF, AE and further AT-AFS would be to optimize the global productivity per land area but it has to consider the fact that not all productions are at the same pace. For example in an AT-AFS that would combine apple and timber trees, apple production is at the annual pace whereas timber is only valorized after 20 to 50 years. Such improvement in area productivity is all the more true if there is deep and rich soil and complementarity in vegetation cycle. This is typically the case for an agroforestry system combining winter wheat harvested at the end of spring and walnut with late budburst thus with a little overlapping in the growing cycles. Various metrics exist to evaluate the performance of multiproduction systems, among which the Land Equivalent Ratio (LER) is the most known [START_REF] Lovell | Temperate agroforestry research: considering multifunctional woody polycultures and the design of long-term field trials[END_REF]. LER compares yields of crops grown together to crops grown as pure stands. For example for a system with two species: LER = (mixed yield A/pure yield A) + (mixed yield B/pure yield B). There are no guidelines about inputs in agroforestry systems (AFS).

Although, to the best of our knowledge no statistics exist for AT-AFS, the LER of a cherry-walnut-annual intercrop (sunflower, durum wheat, barley, oilseed rape) agroforestry system is close to 1.3, i.e., 1 ha of cherry-walnut-annual intercrop agroforestry may produce as much 1.3 ha of cherry, walnut and annual intercrop in separated stands due to fact that cherry and annual intercrop grow in the inter-row of walnut that is otherwise not used, even if in the combined system the inter-row of walnut is a little larger than in pure walnut stand [START_REF] Dupraz | Synthesis of the Sylvoarable Agroforestry for Europe (SAFE) project[END_REF]. Beyond this global economic interest that can be valorized only in the long term, depending on the species production, AT-AFS should also ensure more stable economic returns over the years because it is based on various plant productions (e.g., vegetables; GRAB, 2017) and possibly animals such as poultry or sheep (see above) provided the apple tree shape is redesigned or the presence of sheep in the orchard is restricted from fall to spring before trees begin to grow [START_REF] Lauri | Agroforestry for fruit trees in the temperate Europe and dry Mediterranean[END_REF].

GOING FORWARD: RESEARCH ROUTES FOR THE FUTURE

Most of our knowledge in apple tree architecture and physiology has been developed removing as much as possible influences of the global biotic and abiotic environment. When external variables (temperature, irrigation, nutrition…) are considered in these studies they are generally well focused and research seldom considers combination of variables for obvious reasons of complexity. These research works are well adapted to the setting of conventional apple orchards whose performance is tightly related to the good integration of all the components of the 'orchard system puzzle', namely the plant material (rootstock, tree quality), the system design (tree arrangement and density, support system) and cultural operations (tree training and pruning, irrigation, fertilization) [START_REF] Barritt | Intensive orchard management. Good Fruit Grower[END_REF].

Designing apple OF, AE or AT-AFS, needs more research on both plant-plant and plant-environment (biotic and abiotic) interactions. The ecological science already provides some main concepts, such as the 'competition-facilitation' framework (e.g., interactions between trees or shrubs and grass; [START_REF] Scholes | Tree-grass interactions in savannas[END_REF]) that now need to be better applied in the field of apple diversified systems. From the 'plant science' point of view we need more knowledge on the plasticity of plant architecture and ecophysiology in response to the more complex biotic and abiotic environment.

Belowground niche partitioning.

The interest of multispecies systems was already promoted by [START_REF] Gliessman | Chapter 5 -Multiple Cropping Systems: A Basis for Developing an Alternative Agriculture[END_REF] considering that although multiple cropping systems "use more water, they are able to obtain water not available to monoculture", and therefore "they use the water more efficiently, and contribute significantly to soil conservation". These multispecies systems therefore demonstrate the further potential for their more widespread use. More generally, interactions at the belowground level need more detailed studies. The positive effects of legumes as groundcover in the inter-row alleys (e.g., white and red clover, Trifolium repens L. and Trifolium pratense L., respectively, or alfalfa, Medicago sativa L.) are well known for their contribution to soil nitrogen [START_REF] Merwin | Orchard-floor Management Systems[END_REF]. This typically illustrates the facilitation process where the root systems of the various species explore a same soil layer. However, several lines of evidence would show that an aboveground multistrata system is also mirrored, even to a lesser extent, by multilayer root systems with annuals being mostly in the top soil and trees having deeper rooting. For example, in an experiment on walnut-winter cereals, [START_REF] Cardinael | Competition with winter crops induces deeper rooting of walnut trees in aMediterranean alley cropping agroforestry system[END_REF] show that competition induces deeper rooting of the trees keeping the perennial grass or annuals in the top soil horizon. Nevertheless, most of these studies are realized without irrigation supply in either wetlands or drylands. In these conditions, hydraulic redistribution (HR) has been measured from moist to drier portions of the soil [START_REF] Domec | Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange[END_REF] but also from soil to roots and from roots to soil and among overstory trees and understory shrubs and grasses [START_REF] Barron-Gafford | Impacts of hydraulic redistribution on grass-tree competition vs facilitation in a semi-arid savanna[END_REF]. To what extent HR is maintained in the context of an irrigated apple system needs to be reconsidered. First, root distribution is highly opportunistic being concentrated in the wetted zones determined by the irrigation type and scheduling [START_REF] Sokalska | Spatial root distribution of mature apple trees under drip irrigation system[END_REF] soil is dynamic depending on tree and grass age [START_REF] Scholes | Tree-grass interactions in savannas[END_REF] possibly related to changes in tree root architecture between the young and the mature stages of the tree (e.g., in peach, secondary vertical roots do not develop before the second year in a peach-grass system with regulated deficit irrigation; [START_REF] Forey | Effect of combined deficit irrigation and grass competition at plantation on peach tree root distribution[END_REF]. According to [START_REF] Demestihas | Ecosystem services in orchards. A review[END_REF] working on an apple mixed with cover crops orchard, such optimal belowground niche partitioning could be a way to decrease the loss of water and also nutrient leaching to the water table.

2. Growing apple in the shade of over-topping trees.

The possibility to grow apple trees with other, possibly over-topping, trees remains to be explored. In hot and dry summer climate, typically in the Mediterranean type climate, apple trees may be subjected to an excess of solar radiation during the summer months with known deleterious effects on fruit quality (sunburn) and leaf functioning (photooxydative damage) [START_REF] Correlli-Grappadelli | Is Maximizing Orchard Light interception Always the Best Choice?[END_REF][START_REF] Racsko | Sunburn of Apple Fruit: Historical Background, Recent Advances and Future Perspectives[END_REF]. This issue is managed using shade nets, also used as hail nets, that reduce light quantity and may also change light quality with known effects on fruit coloring [START_REF] Mupambi | The influence of protective netting on tree physiology and fruit quality of apple: A review[END_REF]. To what extent 'shade trees' may be used instead of shade nets to mitigate climate extremes (heat, light, precipitation) effects on apple, especially in the context of climate change, remains to be studied especially regarding both distances between overstory trees and apple trees and the proper pruning of the overstory trees to ensure that sufficient light reaches the apple trees. Further research in apple may take lessons from the increasing amount of works developed in the tropics on two fruit trees, cocoa and coffee, known as shade-adapted species and that are traditionally cultivated in multistrata systems. Research on architecture and ecophysiology [START_REF] Tscharntke | Multifunctional shade-tree management in tropical agroforestry landscapes -a review[END_REF][START_REF] Padovan | Water loss by transpiration and soil evaporation in coffee shaded by Tabebuia rosea Bertol. and Simarouba glauca dc. compared to unshaded coffee in sub-optimal environmental conditions[END_REF] and plant-pest interactions [START_REF] Andres | Cocoa in Monoculture and Dynamic Agroforestry. Chapter 3[END_REF] in cocoa and coffee also documents the agronomic and economic issues related to fruit-tree growing in agroforestry systems. Preliminary results obtained in our experimental AT-AFS at INRA Montpellier ('GAFA' project; Pitchers et al., this symposium) indicate that apples trees planted at 6.5 m from walnut trees beneficiate from a gap fraction (fraction of view that is unobstructed by walnut canopy, leaves and branches, in any particular direction) of ca. 70%. This value is close to the reduced photosynthetic active radiation usually measured under hail nets, i.e., 32.8%, without altering air temperature, humidity or rainfall, and slightly increasing yield (e.g., apple, [START_REF] Bosco | Microclimate alterations caused by agricultural hail net coverage and effects on apple tree yield in subtropical climate of Southern Brazil[END_REF].

Adapting apple plant material and optimizing training and pruning.

Once the whole system is designed, including structural (spatial arrangements in horizontal and vertical dimensions) and temporal aspects (e.g., simultaneous vs. delayed plantation of the various species), the choice of the rootstock and cultivar and the training and pruning of the apple trees are crucial. Semi-vigorous or high-vigor rootstocks from the Malling Merton series [START_REF] Ferree | Role of Rootstocks and Spur-type Scions for Controlling Vegetative Growth of Apple and Peach Trees[END_REF] or from the Cornell-Geneva series [START_REF] Lordan | Effects of apple (Malus ×domestica) rootstocks on scion performance and hormone concentration[END_REF][START_REF] Fazio | Evaluating and improving rootstocks for apple cultivation[END_REF] for example, should be recommended to improve anchoring in the soil, and nutrients and water absorption in a context of above and belowground competition. This choice also needs to consider the resistance or tolerance to some major pests and diseases such as fire blight caused by Erwinia amylovora, crown and root rot caused by Phytophtora cactorum, and also replant disease complexes [START_REF] Fazio | Evaluating and improving rootstocks for apple cultivation[END_REF]. The use of own-rooted trees with high vigor [START_REF] Maguylo | Growth and Fruiting Characteristics of Eight Untrained Genotypes Assessed on Both M.9 and Own-Rooted Trees in Southern France[END_REF] could also be evaluated in these contexts. After plantation, training and pruning procedures also need to be well adapted to a reduced light climate. Research developed in past decades in tree architecture management clearly indicates the importance of increasing canopy porosity to air and light through precision pruning, for example using 'artificial extinction' [START_REF] Lauri | The concept of centrifugal training in apple aimed at optimizing the relationship between growth and fruiting[END_REF][START_REF] Willaume | Light interception in apple trees influenced by canopy architecture manipulation[END_REF][START_REF] Lauri | Tree architecture, flowering and fruiting. Thoughts on training, pruning and ecophysiology[END_REF] with beneficial effects on fruit size and return-bloom [START_REF] Lauri | Centrifugal training in apple -Appraisal of a two-year experiment on cv. 'Galaxy' in southeast France[END_REF][START_REF] Tustin | Fruit set responses to changes in floral bud loada new concept for crop load regulation[END_REF][START_REF] Breen | Changes in fruit set of 'Gala' apple in response to environment and artificial spur extinction[END_REF][START_REF] Breen | Method of manipulating floral bud density affects fruit set responses and productivity in apple[END_REF][START_REF] Breen | Artificial spur extinction alters light interception by 'Royal Gala' apple trees[END_REF][START_REF] Tustin | Can light interception of intensive apple and pear orchard systems be increased with new approaches to tree design?[END_REF] and partly on pest reduction [START_REF] Simon | Does fruit-tree architecture manipulation affect the development of pests and pathogens? -a case study in apple orchard[END_REF]. However, overstory canopy also needs to be managed and partial pollarding of trees can both provide fodder, fuelwood or woodchips as a provisioning service, and improve light transmission to the understory especially the apple tree as a regulation service (Le [START_REF] Bec | Trunk-Crown growth tradeoff in pollarded trees: influence on wood production[END_REF].

4. Developing links with socioeconomics to optimize the market chain.

Eventually, the socioeconomic impact of such diversified systems also needs to be assessed. As mentioned by [START_REF] Smith | Silvoarable agroforestry: an alternative approach to apple production?[END_REF] in concluding remarks on two apple case studies, agroforestry seemed to have benefits in terms of reducing pest levels if apple cultivars are resistant or tolerant to major pests. It "could work well in a diverse, potentially small-scale system such as a market garden, where apples could contribute to direct marketing channels such as vegetable box schemes or farm shops" [START_REF] Smith | Silvoarable agroforestry: an alternative approach to apple production?[END_REF]. Those agroforestry systems are recent, and existing and up-coming systems are to be considered and studied as well as the agrifood system they participate in [START_REF] Grab | Associer légumes et arbres fruitiers en agroforesterie[END_REF].

CONCLUSIONS

As for the 'industrial agriculture' in general [START_REF] Struik | Sustainable intensification in agriculture: the richer shade of green. A review[END_REF]) conventional apple orchard, characterized by high level of regular inputs (water, nutrients, pesticides, mechanization), is likely to remain the dominant source of apple supply as far as external resources are kept at a rather low price and negative externalities on the environment and human health are not considered. However, such a production system cannot be sustainable in the long term and/or in all production regions in the world especially due to its dependence on non-renewable energy and also its negative long-term impacts on human health and environment. Moving towards more self-regulating, environment-friendly apple production systems, as already engaged in the last decades with IFP, OF and more recently AE, offers promising opportunities. The idea to manage more efficiently the structural and temporal design of these complex systems under the paradigm of AT-AFS may be considered as another step in the same dynamics (Figure 2). It emphasizes the interest to diversify short term and long term productions of apple and other products, to design more 'pest suppressive' and 'nitrogen-autonomous' agroecosystem and also to better explore the climate mitigation offered by the multistrata design of the system.

Implementing such systems needs more knowledge from the analytical side on how plants interact among them and with the environment with regard to access to aboveand belowground resources. It also requires more interdisciplinary approaches gathering horticultural science (e.g., yield performance of apple in reduced light climate) and ecology including chemical ecology (e.g., volatile organic compounds, VOC) and landscape ecology (e.g., effects of landscape heterogeneity on pests dissemination). So far, we lack references on complex apple-based agroecosystems, because traditional systems have almost disappeared except in few sites (e.g., cider apple orchards in Brittany, France). We make a plea for more participatory research involving growers, technicians, researchers and stakeholders in the market chain to strengthen the "economic,

  .-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

Figure 2 .

 2 Figure 2. Sorting apple agroecosystems according to the use of ecosystem services (ES) and the optimization of temporal and structural design. The horizontal axis renders, from left to right, the progressive use of ES. The conventional orchard typically relies on the use of external (mainly synthetic) inputs whereas Integrated Fruit Production (IFP) aims to efficiently manage those synthetic inputs with the possible use of some ES and alternative methods. Organic Farming (OF) includes the use of some ES, mainly natural pest regulation and nitrogen fixing by plants, and no use of external synthetic inputs. Agroecology (AE) manages the whole range of ES (see text) with a better emphasis on societal needs. OF may be considered as fully included in AE. The vertical axis renders, from bottom to top, the improvement of the structural and temporal design of the system taking advantage of concepts developed in agroforestry.There are no guidelines about inputs in agroforestry systems (AFS).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  raising the question of the compatibility between localized irrigation and the maintenance of root layering. Second, root distribution in the Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).

  Comment citer ce document : Lauri, P.-E., Pitchers, B. (Co-premier auteur), Dufour, L., Simon, S. (2018). Apple farming systems -Current initiatives and some prospective views on how to improve sustainability. In: XXX. International Horticultural Congress. Presented at 30. International Horticultural Congress IHC2018, Istanbul, TUR (2018-08-12 -2018-08-16).


Marlène Perignon

Jalila El Ati

Carole Sinfort

Sophie Drogue

Nicole Darmon

Marie Josephe Amiot-Carlin, -Medina

Which dietary changes to move towards nutritionally adequate diets without increasing their impact on biodiversity, water and land-use

Keywords: (5 keywords maximum): Sustainable diet, Nutritional adequacy, Environmental impact, Tunisia, Diet modeling Conflict of Interest Disclosure (mandatory): None

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Results: Calcium, copper, iron (for women), magnesium and potassium intakes were below their recommendations in the mean observed diets, while sodium and fats exceeded them. Under the NUTRI scenario, i.e. reaching nutritional adequacy without controlling for the environmental impacts, the main dietary changes were the increases of vegetables, starchy foods, fish and dairy products, and decreases of fats and sweet products. All the environmental indicators were impaired, except erosion resistance and biotic production. Under the NUTRIENV scenario, i.e. when

  an epidemiological and nutritional transition resulting in an increase in overweight, obesity and co-morbidities. In the last decades, food consumption departed from traditional diets towards higher consumption of animal-based and sweet products. Tunisia also faces environmental issues such as water scarcity, soil erosion and biodiversity loss. This growing concern for health issues and climate change has emphasized the need to promote sustainable diets, i.e. nutritionally adequate, affordable, culturally acceptable, and with low environmental impact. The objective was to identify dietary changes needed to move towards nutritionally adequate diets without increasing their environmental impact. Methods: Nutrient intakes were estimated using dietary data from the nationally representative Tunisian study on food consumption (n=7209, 35-70y), and food composition from a Tunisian database and the Food Processor software. Environmental impact of diets was assessed through 6 indicators -water scarcity, biodiversity, and 4 indicators for land-use (erosion resistance, mechanical filtration, groundwater replenishment, biotic production) ? estimated for 161 foods. For each gender, two optimized diets respecting all nutritional recommendations from WHO and with minimized departure from the mean observed diet were designed with linear programming under 2 scenarios to fulfill: i) all nutritional constraints (NUTRI) and ii) all nutritional constraints without exceeding observed levels for the 6 environmental indicators (NUTRIENV).


Keywords: Araneae, biogeography, ecology, model organisms, subterranean taxa

1

Foreword

We are delighted to welcome you to the University of Nottingham for the 30th European Congress of Arachnology. We hope that whilst you are here, you will enjoy exploring some of the parks and gardens in the University's landscaped settings, which feature long-established woodland as well as contemporary areas such as the 'Millennium Garden'. There will be a guided tour in the evening of Tuesday 22nd August to show you different parts of the campus that you might enjoy exploring during the time that you are here.

Registration

Registration will be from 8.15am in room A13 in the Pope Building (see map below). We will have information here about the congress itself as well as the city of Nottingham in general. Someone should be at this registration point throughout the week to answer your questions. Please do come and find us if you have any queries. We want to make your stay in Nottingham as enjoyable as possible.

Plenary Talks

These will take place in the Pope Building in Lecture Hall C14 at the start of each conference day.

Information for Speakers

Lectures will take place in the Pope Building, in Lecture Halls C14 and C16. Each speaker will have 20 minutes (15 minutes talk + 5 minutes for questions). Please prepare talks in Powerpoint or PDF format and load onto the computers in lecture theatres using a USB pen before the session begins. Mac users please check that your presentation is compatible with Windows.

Posters

Please make posters A0 portrait size. Posters will be exhibited in rooms A13 and A14 in the Pope Building. Please bring them here on the morning of the first day of the congress (Monday 21st). There will be a map in these rooms showing where you should hang your poster. Please take posters down during the morning session of Friday 25th August.

Arrival Information and Transport

Parking is in the main visitor's car park (post-code for sat nav is NG7 2QL). There are also tram and bus services to/from the city centre. Please note that the correct tram stop is 'The University of Nottingham' and not 'Nottingham Trent University', which is another university in the city centre. Tram ticket machines take coins or cards (single journeys ~£2). Bus tickets cost about the same and are bought on board. Some buses do not give change. For those staying at Hugh Stewart Hall, please make your way to the hall's reception (accessible from the top left-hand corner of the visitors' carpark.) https://saragoodacre.wixsite.com/eca-2017/getting-from-the-city-to-campus

Evening Entertainments

The evening BBQ on the night of the 21 st August and the conference dinner on the evening of the 24 th August will both take place in Hugh Stewart Hall of

Residence. There will be an excursion into Nottingham city centre on Tuesday 22nd August to show you some of Nottingham's finest pubs. The Russian Party, a highlight of the congress, will be held on Wednesday 23rd in the ESCL building next to the lecture theatre venue. Finally, a 'Ceilidh' will be held in A13/A14 of the Pope building after the conference dinner on the evening of the 24 th .

The Venue

See map on page 3.

Talks, Posters and Lunches

Talks will take place in the Pope Building in lecture theatres C14 and C16.

Posters displays and lunches will be in the same building in rooms A13 and A14.

Excursions

Excursion day is Wednesday 23rd August. Further information about the different excursions will be provided at registration.

Post-congress Event

There will be an excursion to visit the local Attenborough Nature Reserve on the morning of Saturday 26th. Details will be provided at registration. The

  AbbeyHouse Ancaster

World experts of different disciplines, from molecular biology to macroecology, recognize the value of cave ecosystems as ideal ecological and evolutionary laboratories. Among other subterranean taxa, spiders stand out as intriguing model organisms for their ecological role of top-predators, their unique adaptations to the hypogean medium and their sensitivity to anthropogenic disturbance. Here, we provide a general overview of the spider families recorded in hypogean habitats in Europe -20 families including nearly 500 species, most of them with restricted distributions. We also review the different adaptations of hypogean spiders to subterranean life and summarize the information gathered so far about their origin, population structure, ecology and conservation status. Taxonomic knowledge on subterranean spiders in Europe appears to be well, but not exhaustively documented. The origin of the European assemblages is mostly explained by past climate dynamics, although other factors are likely to be involved. Most of the macroecological issues related to spiders in European caves are based on qualitative assessments or have been quantified only at a sub-regional scale. In order to shed light on cave spiders' biogeography and the macroecological patterns driving the diversity of European subterranean spiders we created the CAWEB network, a spontaneous collaboration between subterranean arachnologists from 30 different European countries. We here present the team and provide some preliminary results, which highlight Southern Europe as an important hot-spot for the European subterranean spider diversity.


M Gosme

Panozzo

Innovations in agroforestry

Keywords: alley cropping, Triticum durum, shade tolerance, screening

Current varieties of cereals have been selected for conventional agriculture, in full sun conditions. It might be possible to increase crop yield in agroforestry conditions through plant breeding. A total of 31 genotypes (10 pure lines, 14 populations and 7 genetic resources) of durum wheat were tested over three years in two Mediterranean sites in both agroforestry and full sun control. As was expected, yield was reduced in most cases (except in 2015), but the reduction ranged from 8% to 80% depending on the genotypes. In the tested conditions, genetically diverse cultivars (populations) were not better adapted to agroforestry conditions than pure lines. Although no variety performed consistently well in agroforestry throughout all sites and years, the responses of genotypes to the presence of trees were diverse, indicating that selection for agroforestry might be possible. Future breeding programs should focus on improving durum wheat fertility in the shade.

Introduction

Agroforestry, i.e. a land use that combines agriculture and forestry, including the agricultural use of trees [START_REF] Van Noordwijk | Central hypotheses for the third agroforestry paradigm within a common definition[END_REF]), provides diverse ecosystem services [START_REF] Torralba | Do European agroforestry systems enhance biodiversity and ecosystem services? A meta-analysis[END_REF]) and as such attracts more and more attention from scientists and some pioneering farmers. However, when considering only crop yield, agroforestry usually results in a decrease compared to the pure crop because of the competition for resources between the crop and the trees [START_REF] Cannell | The central agroforestry hypothesis: the trees must acquire resources that the crop would not otherwise acquire[END_REF][START_REF] Jose | Interspecific interactions in temperate agroforestry[END_REF]). However, as the current varieties of durum wheat were selected for conventional agriculture [START_REF] Wolfe | Developments in breeding cereals for organic agriculture[END_REF], it is possible that there is room for improving the performance of the crop in agroforestry conditions through plant breeding. Furthermore, it is often claimed that genetic diversity improves the resistance of crops to biotic and abiotic stresses [START_REF] Reiss | Cultivar mixtures: a meta-analysis of the effect of intraspecific diversity on crop yield[END_REF], so we wanted to test if population varieties were more adapted to agroforestry than pure line varieties. The aim of this work was thus to assess the performance of several varieties of durum wheat (elite pure lines, populations and genetic resources) in different agroforestry conditions as well as in full sun conditions, in order to (i) test the hypothesis that genetically diverse varieties are less negatively impacted by agroforestry conditions than pure lines, (ii) characterize desirable traits of the crop for cultivation in agroforestry systems and (iii) identify interesting varieties to be used as parents in future plant breeding programs for agroforestry.

Materials and methods

The experiment was conducted in two sites over three years (2014-2015, 2015-2016 and 2016-2017, subsequently only the year of harvest is indicated). The first site was located at INRA Melgueil experimental station, South-East of Montpellier in France, which is managed organically by INRA personnel. The second site was located in Restinclières Agroforestry Platform (43°42N, 3°51E), North of Montpellier, which is managed by a conventional farmer. In each site, durum wheat varieties were sown in agroforestry (AF) and full sun (FS) conditions. 4

th European Agroforestry Conference -Agroforestry as Sustainable Land Use The plots used for the experiment contained different tree species, creating different shade intensity and dynamics (Table 1), depending on tree size and type (evergreen/deciduous). In Restinclières, the agroforestry plot in 2015 contained poplars planted in 1999 with 13 m between tree rows and 6 m between trees along the row. In 2016, it contained ash trees planted in 1995 in a 13m x 4m pattern. At INRA, the agroforestry plot contained olive trees planted in 2003 in a 6m x 5m pattern. A total of 31 durum wheat genotypes (10 elite pure lines (PL), 14 populations (POP) and 7 genetic resources (GR), chosen for their phenotypic variability) were tested over the three years, with two replicate microplots in each condition at INRA and 3 replicates in Restinclières. In each microplot, the yield and yield components (plants/m², tillers/plant, spikes/tiller, grains/spike and thousand kernel weight) were measured. Relative yield and yield components were computed as the ratio of the value in agroforestry (averaged for the 2 or 3 microplots of the genotype in a given site-year) on the value in full sun (averaged in the same manner). Data were analysed first with mixed models using package lme4 of R statistical language, considering the genotype as random effect, to test the effect of the conditions (AF, FS), for each site and year separately (INRA 2015-2016[START_REF] Reiss | Cultivar mixtures: a meta-analysis of the effect of intraspecific diversity on crop yield[END_REF], Restinclières 2015and 2016) on each of the yield components. The two modalities were then compared using Tukey contrasts using package multcomp of R statistical language. The effect of the type of cultivar on the relative components of yield was tested with two-way anovas (conditions, type, and double interactions). In order to study the possibility to predict the suitability for cultivation in agroforestry conditions of a cultivar, we fitted a Partial Least Squares Regression with the components of yield in agroforestry, full sun and as relative values as predictor variables and the yield in agroforestry and the relative yield as response variables. In order to compare varieties in terms of adaptation to cultivation in agroforestry conditions, we computed the average, for each variety, of the yield in full sun expressed as a percentage of the mean yield of the site-year in full sun and the average, for each variety, of the yield in agroforestry conditions expressed as percentage of the yield in full sun conditions.

Results

Due to floods in autumn 2014, wheat sowing was delayed until December 2014 at INRA experimental station and January 2015 in Restinclières. In this latter site, the farmer could not treat the experiment with the rest of his wheat plots so no herbicides or fertilizers were applied. Therefore in this site-year, wheat yield was very low (mean over all varieties and conditions = 0.41 tons of grain dry matter per hectare) compared to the other site-years (1.

Effect of agroforestry on yield components of durum wheat

Agroforestry conditions significantly reduced grain yield compared to full sun conditions, except in 2015, were grain yield was higher in agroforestry than full sun (significantly so in Restinclières). Relative yields were (mean ± standard deviation) 1.27±0.44, 0.54±0.28, 0.67±0.37, 1.55±0.96 and 0.29±0.09 at INRA in 2015, 2016, 2017, Restinclières 2015 and 2016 respectively. The yield component that was most negatively impacted by agroforestry was the number of grains per spike (in average -31% in agroforestry compared to full sun) and the number of tillers per plant (-25%) (Figure 1). For these two yield components, the value in agroforestry was always significantly lower than in full sun, except in Restinclières 2015 for the number of tillers/plant and at INRA in 2015 for the number of grains per spike, where the difference was not significant. For the other yield components the effect of agroforestry was less clear (Table 2).

/m2 > - > > - tillers/plant < < < - < spikes/tiller - > < - - grains/spike - < < < < TKW - > - > - Yield - < < > <

Effect of genetic diversity on relative yield components and relative yield

There was no effect of the type of variety (pure line, population or genetic resource) on relative number of plants/m 2 , tillers/plant nor spikes per tiller. There was a significant effect of the type on the relative TKW only at INRA in 2016 with GR>(PL~POP) and in Restinclières in 2016 (PL>POP); and a significant effect on the relative yield only at INRA in 2017, with POP significantly higher than PL but GR not significantly different from POP nor PL. site-year 4 th European Agroforestry Conference -Agroforestry as Sustainable Land Use

Indicators of suitability for cultivation in agroforestry

The PLSR results showed that the variables most correlated with yield in agroforestry and relative yield were the number of grains per spike and the relative number of grains per spike, respectively (Figure 2).

Interesting genotypes for further breeding programs

Due to the experimental problems in 2015 (floods in autumn 2014 that delayed sowing), this year was removed from the subsequent analysis. There was a high variability in the sensitivity of cultivars to agroforestry conditions: considering both sites together, the reduction of yield in AF compared to FS ranged from -8.6% to -79.6% depending on the variety. The performance of each cultivar was considered along two axes: yield in full sun (as a percentage of the mean of all varieties in a given site-year) and relative yield (yield in agroforestry as a percentage of yield in full sun) (Figure 3). Interesting varieties for a future breeding program would have both high yield in full sun and low yield reduction in AF. Based on the result from INRA experiment, these would be POP PROT, POP HR, DAKTER and "POP F2 leg Salernes". Unfortunately, except for POP HR, which has a good relative yield (but a low yield in FS) in Restinclières, the varieties that are identified as interesting in Restinclières (Claudio and Pop Algérie 3) are not the same as at INRA. 3: "Performance" of each variety in terms of yield in full sun (expressed as a percentage of the mean yield of the site-year in full sun) and yield in agroforestry (expressed as a percentage of the yield in full sun conditions of the given variety in the given site-year). Horizontal and vertical lines indicate the overall means, dividing the map into 4 groups: 1: high yield in full sun and low reduction in AF; 2: high yield in full sun and high reduction in AF; 3: low yield in full sun and low reduction in AF; 4: low yields in all conditions. Data from 2015 were removed prior to the analysis.

Morphological measurements seem to indicate that plant height and distance from last leaf to spike might be useful for discriminating between the groups, but further analyses are needed to confirm this result.

Discussion and conclusion

As was expected, yield was reduced in most cases (in 2016 and 2017, 90% of the tested genotypes had a relative yield (AF/FS) lower than 1), however, in 2015, 71% of the genotypes had a relative yield higher than 1, indicating that in some conditions (e.g. late sowing), agroforestry can improve yield. Yield reduction ranged from 8% to 80% depending on the genotype. Contrary to our hypothesis, genetically diverse cultivars (populations) were not better adapted to agroforestry conditions than pure lines: except at INRA in 2017, where populations had a high relative yield, populations did not yield significantly better than pure lines and did not have higher yield components. The number of grains per spike was the component of yield that was most negatively impacted by agroforestry and it seems to be a relevant indicator of suitability of plants for cultivation in agroforestry. This may be due to light reduction, which is known to affect cereal fertility. Future breeding programs should focus on improving wheat fertility in the shade. The variability of the genotypes' responses to the presence of trees indicates that selection for agroforestry might be possible. The two agroforestry designs were totally different: the plants were submitted to heavy and constant shade at INRA site (olive trees are evergreen), whereas in Restinclières, the shade varied over time, which might explain why none of the genotypes tested in this experiment performed consistently well in all sites and years. Further analyses are needed in order to disentangle the effects of agroforestry from the effects of the specific sites and years.

Figure 1 :

 1 Figure 1: Yield formation in agroforestry (red angles and solid lines) vs full sun (pink angles and dashed lines), average over all sites, years and genotypes.

Figure 2 :

 2 Figure 2: Circle of correlations of the predictor variables (in black) and response variables (in red).

  Conference -Agroforestry as Sustainable Land Use

Figure

  Figure3: "Performance" of each variety in terms of yield in full sun (expressed as a percentage of the mean yield of the site-year in full sun) and yield in agroforestry (expressed as a percentage of the yield in full sun conditions of the given variety in the given site-year). Horizontal and vertical lines indicate the overall means, dividing the map into 4 groups: 1: high yield in full sun and low reduction in AF; 2: high yield in full sun and high reduction in AF; 3: low yield in full sun and low reduction in AF; 4: low yields in all conditions. Data from 2015 were removed prior to the analysis.

Table 1 :

 1 Proportion of light (sum over the period) available to the crops in agroforestry in comparison with the full sun condition at different periods and different sites. M: measured with light sensors, C: calculated through analysis of hemispherical photographs.

	Site	Period	2015	2016		2017
			Dates	Proportio	Dates	Proportio	Dates	Proportio
				n light		n light		n light
				(%)		(%)		(%)
	Restinclière	Before	12 Jan 15-	M: n.a.	2 Nov 15-	M: 55%
	s	budbrea	9 Apr 16	C: 55%	1 Mar 16	C: 70%
		k
		After	9 Apr 16-	M: 41%	1 Mar 16-	M: 50%
		budbrea	30 Jun 16	C: 40%	6 Jul 16	C: 42%
		k
	INRA station Winter	19 Dec 14	M: 65%	18 Nov 15-	M: 62%	3 Dec 16-	M: 62%
			30 Mar 15		30 Mar 16		30 Mar 17
		Spring	1 Apr 15-	M: 70%	1 Apr 16-	M: 75%	1 Apr 16-	M: 70%
			26 Jun 15		25 Jun 16		26 Jun 17

Table 2 :

 2

	2015-

Effect of agroforestry conditions (AF>FS, AF<FS or no significant effect) on yield components in each site-year (I=INRA site, R=Restinclières Estate site, 15-17=years


L Canario

L Flatres-Grall

Genetics of tail-biting receipt in gilts from the Tai Zumu line

Keywords: social genetic effects, tail-biting receipt, gilt, sire-environment interaction

Tail-biting (TB) receipt was recorded at the end of the fattening period on 33,266 gilts of the Tai Zumu population, that were raised in groups of 6 to 20 females. This study aimed at quantifying the contribution of social genetic effects to TB receipt, and at assessing the importance of the environment on the genetic expression of this behaviour (GxE). Models for TB receipt included the fixed effects of number of group mates, (herd)-year-month, and the random effects of group, litter, and direct and social additive genetic effects. The model was applied to the complete gilt population and separately to 2 sub-populations, corresponding to 2 of the 3 nucleus herds raising that line, where TB receipt frequency differed and was high enough (>5%). TB receipt was analysed as a linear trait, following a normal distribution with the restricted likelihood methodology applied to an animal model. Social genetic effects contributed 81% to 93% of total heritable variance, which equalled 40 to 80% of phenotypic variation. The variance components varied between herds. The analysis of sire by environment interactions indicated re-ranking of sires between the 2 nucleus herds, according to both their direct and total breeding values.

Introduction

Pig behaviour refers to complex traits which expression depends on physical and social environments. Tail-biting (TB) is a damaging behaviour that is highly detrimental to animal welfare, resulting in stress, pain, and removal of strongly attacked pigs. Genetic studies of TB are scarce [START_REF] Breuer | Heritability of clinical tail-biting and its relation to performance traits[END_REF] because the frequency of TB is low in pig populations -except outbreaks -and in addition can be under recorded. Bitten tails are more accessible records than the TB activity itself. TB receipt information refers to the receivers of tail bites. Between-breed variation exists for this trait with, for instance, Yorkshire pigs being tail-bitten more often than Landrace pigs [START_REF] Sinisalo | Tail biting and production performance in fattening pigs[END_REF].

In the fattening period, group structure and social relationships might influence the emergence of a TB attack. Social effect of a pig on the phenotypes of its social partners may have a genetic component [START_REF] Griffing | Selection in reference to biological groups. I. Individual and group selection applied to populations of unordered groups[END_REF][START_REF] Moore | Interacting Phenotypes and the Evolutionary Process: I. Direct and Indirect Genetic Effects of Social Interactions[END_REF], known as an Indirect Genetic Effect (IGE). IGEs refer to the effects of an individual's genes on the trait values of other individuals. We hypothesized that TB receipt is affected by IGEs, so that pigs would participate to the emergence of tail bites in their groupmates. Moreover, estimates for the social genetic effect are sensitive to environmental conditions (e.g., [START_REF] Bijma | Breeding for social interaction, for animal welfare[END_REF][START_REF] Canario | The early-life environment of a pig shapes the phenotypes of its social partners in adulthood[END_REF]. The response to selection against TB receipt might be quite different if pen size, group size, as well as food availability, varied between herds. Our objectives were to estimate the genetic parameters for TB receipt with social genetic effects, and to evaluate sire by environment interactions (GxE) for this trait in differing nucleus herds.

Material and methods

Animals and data

The Tai Zumu line is a composite line made from the combination of Meishan and Large White genetics. Animals are raised in 3 nursing-fattening nucleus herds located in diverse regions of France. Connectedness was ensured by use of common AI boars across herds (among 1010 sires with progeny records, >200 enabled to connect the differing herds 2 by 2). Piglets are half tail-docked in the first 24h after birth, experience mixing after weaning, and then pigs entering the fattening unit are not mixed again (Herds 1 and 3) or split into 2 groups (Herd 2). During the fattening period, average group size of the female population was 12.3 (SD 3.6). The 3 herds differed in average group size : 8.5 (SD 1.0), 12.7 (SD 1.9) and 14.7 (SD 3.9) animals/pen in Herds 1, 2 and 3 (p<0.0001). Herds also differed in the number of litters of origin included in a group: 5.3 (SD 1.1), 6.8 (SD 1.8) and 6.1 (SD 1.4) in Herds 1, 2 and 3 (p<0.0001). Such contrasts remained after adjustment for group size, with mean values of 5.9, 6.4 and 5.4 in Herds 1 to 3 (p<0.0001). Pigs were raised in single sex-groups and fed ad libitum from one single trough (Herds 1 and 2) or a dry feeder (Herd 3). The stocking density was 0.78, 0.82 and 0.85 pigs/m² in Herds 1 to 3. The TB receipt information was summed up as a yes/no trait, from tail bite(s) records realized by a single observer for all 3 herds, at time of control when pigs reach 100kg on average. Data used in the current study were collected between 2006 and 2017 from 2970 fattening groups. The number of litters of origin to form a group varied between 1 and 12, with total group size ranging between 6 and 20. The TB receipt involved 852 groups (31% of groups), in which on average 2.8 (SD 2.4 range 1-17) pigs were injured. The removal of injured pigs before the end of the fattening period was infrequent, so severity of tail bites was not high.

Statistical analyses

Data were edited with the SAS software to create group and batch variates and groupmates identities. In the complete data base, 7.9% of females that were measured became mothers and 2.9% of females with tail injured became mothers. TB receipt was analysed as a linear trait with the REML procedure of the ASReml software [START_REF] Gilmour | ASReml User Guide Release 4[END_REF]. The pedigree included information from animals recorded over the 11 years plus was traced back 2 generations more.

Social models

With social interactions, the trait value of a pig may be affected by genes in other pigs. To investigate the magnitude of IGEs on TB receipt, we analysed the presence of tail bite(s) as a normally distributed trait, although the risk of bias exists especially when the frequencies between the two classes of the binary trait are highly unbalanced [START_REF] Meijering | Linear versus nonlinear methods of sire evaluation for categorical traits : A simulation study[END_REF]. The model included the fixed effects of number of group mates (15 levels), the combination of herd, year and month as a factor, and the random effects of the group identity and the litter of birth. The goodness of fit was used to compare nested models following a chi-square statistics. The selection of random effects was applied to 3 data bases including the complete population and 2 sub-populations originating from 2 of the 3 farms where the incidence of tail-biting was substantial (>5%). In the model for the 2 sub-populations, the combination of herd, year and month was replaced by a year and month combination. In all analyses, the selected model was as follows: where is a vector of observations on the TB receipt;

, and are known incidence matrices; is a vector for fixed effects; is a vector of direct additive genetic effects of the focal pig, and is a vector of IGEs, i.e., social genetic effects of the groupmates of the focal pig. The model accounted for a covariance between direct and indirect genetic effects, using the variance structure where denotes the matrix of additive genetic relationships with the direct additive genetic variance, the variance of an IGE expressed on a single groupmate and the co-variance between direct and indirect genetic effects. Next, is a vector of random group effects, with ; is a vector of random litter effects, with ; and is a vector of residuals, with . and are known incidence matrices for the direct and social genetic effects, linking respectively own identity and group mates to the record of a pig. The phenotypic variance was calculated as where denotes the average group size of the population. The total genetic variance equals [START_REF] Bijma | Multilevel selection 1: Quantitative genetics of inheritance and response to selection[END_REF]. The total heritable variance was expressed as = / , and the comparison between and , the classic heritability, reveals the impact of social interactions on the heritable variation that determines the potential of the population to respond to selection.

Measurement of GxE

To get an insight in the magnitude of GxE, we compared outputs from the social genetic model described above, applied within 2 sub-populations. The classic approach of carrying out a bi-variate genetic analysis, where each trait is defined by a sub-population, did not reach convergence. Breeding values for TB receipt were estimated from that refers to random direct genetic effects related to the direct estimated breeding value denoted DBV, and that corresponds to the summed social genetic effects applied from 1 pig from a group of n individuals on its group mates and is related to the social breeding value denoted SBV. The total heritable contribution of genes of a single individual i in environment j on the mean trait value, i.e., the total value (TBV ij ) was calculated as: TBV ij = DBV ij + (n-1) SBV ij with n the group size of the focal pig. Spearman rank correlations between DBVs, SBVs and TBVs for the 59 boars which were widely used as sires across the 3 herds, i.e., with ≥ 20 daughters measured for TB receipt in each herd, were calculated.

Results and discussion

Social effects on damaging behaviour may differ between sexes. The general suggestion is that female pigs are more likely to tail bite their conspecifics than male pigs, and this results in more tail damage [START_REF] Zonderland | Gender effects on tail damage development in single-or mixed-sex groups of weaned piglets[END_REF]. The frequency of TB receipt in Tai Zumu males was very low (0.06% in Herd A, 1.3% in Herd B and 3.8% in Herd C). We focused our study on female groups, where the frequency of TB receipt varied from 2.8% (Herd 1) to 10.8% with significant contrasts between herds (P<0.0001). The estimates of variance components of TB receipt obtained from use of the direct-social model are given in Table 1. 1 Estimated variances should be multiplied with a 10 -2 factor.

The direct-social model fitted the data significantly better than the direct model in the 3 (sub-

)populations (P<0.0001). The estimates for , , and were very close to those obtained from use of a direct model. The estimate for decreased by half in the all population when adding social components. The phenotypic variance varied between herds, being one and a half times higher in Herd 3 than in Herd 2. Both direct genetic variances and group variances were heterogeneous between herds. Direct heritability for TB receipt was low (0.06 to 0.08) in the 2 herds under study and estimated at 0.06 in the whole population. Group effects were moderate, and accounted for 8.7 to 14.5% of phenotypic variation. The litter effects explained a lower part of variation in Herd 2 than in Herd 3, due to the mixing of pigs from numerous litters of origin to create a group. Litter effects explained only 1.8% and 5.2% of phenotypic variation in Herds 2 and 3 respectively, that let us presume of low early-life effects on TB receipt [START_REF] Canario | The early-life environment of a pig shapes the phenotypes of its social partners in adulthood[END_REF]. The total heritable variance increased markedly with average group size, from Herd 2 to Herd 3. The contribution of social effects to heritable variation in TB receipt stands in the difference between and . Social effects contributed highly to heritable variation when the population was considered as a whole (93%), which contrasts with results obtained for growth rate (e.g., 44% in [START_REF] Canario | The early-life environment of a pig shapes the phenotypes of its social partners in adulthood[END_REF]. The contribution of social effects was high in Herds 2 and 3 (86% and 81%, respectively). Total heritable variation was moderate in the 2 herds under study. The genetic correlation between direct and social effects was null when considering the all population as well as Herds 2 and 3. Social structures might not differ between the two herds, with neutral associations among gilts meaning that gilts with a higher genetic predisposal for receiving tail bites do not increased the probability of other gilts in the group to be tail bitten.

The rank correlations of boars's direct, social and total breeding values are assumed to be consistent with the true genetic correlations [START_REF] Mclaren | Sire ranking based upon purebred vs crossbred progeny performance in swine[END_REF]. A strong re-ranking of sires in the two herds was observed. Correlations between Herds 2 and 3 were not different from zero, indicative of strong interactions with the herd environment (Table 2). Differences in average group size and feeding might be involved in the detection of sire by environment interactions. According to DBVs, the more highly used sires ranked differently between Herds 2 and 3. The correlations were far lower than those estimated by [START_REF] Wallenbeck | GxE interactions for growth and carcass leanness: Re-ranking of boars in organic and conventional pig production[END_REF] in the comparison of growth rate and backfat thickness between conventional and organic herds (r=0.48). High sire by environment interactions are not surprising for a trait that is not under control by selective breeding. It is important to account for GxE in order to increase response to selection. It should be advised to select sires that are less sensitive to environmental conditions when implementing a selection against gilts that suffer from this aberrant behaviour, i.e., that have a genetic predisposal to let others bite their tail. When considering TBV, the correlation was also zero between Herds 2 and 3. Selection based on TBV rather than DBV would not attenuate the discrepancies between the two herds in the ranking of best sires. Considering only the 19 sires with stable DBVs across the two herds, several suffered from large reranking according to TBVs (Appendix 1).

Estimating the influence of IGEs on TB receipt was partly a challenge, given the substantial but low incidence of the trait in these populations. Estimates rely much on group composition, with only 29% of groups being informative, i.e., with ≥1 female with tail bitten. Another problem depended upon the extreme categories and it would be limited by use of a sire model. Some bias may result from the use of standard linear models to analyse a binary trait, but linear models are known to be robust to strong departures from normality assumptions. This study provides first estimates of tail-biting receipt genetic parameters, with account for significant social genetic effects.

Conclusion

Selection against Tai Zumu gilts that let other gilts bite their tail is feasible, and would gain from including social genetic effects as regards to response to selection. With strong GxE identified on TB receipt that resulted in important re-ranking of sires -according to breeding values -in the differing environments, we conclude that TB receipt is influenced partly by different genes in the 2 herds. Selecting for boars that maintain a low genetic merit for their gilts to be tail bitten across varying environments is relevant. Selecting for TBV instead of DBV would either decrease or accentuate the contrast in ranking of AI sires across environments. Further research will be carried out to analyse the impact of the environment on the genetics of this damaging behaviour. At the genetic level, tail biting activity is unfavorably correlated with growth rate and leanness [START_REF] Breuer | Heritability of clinical tail-biting and its relation to performance traits[END_REF]. Genetic relationships of TB receipt with performance traits will be investigated in future studies of the Tai Zumu line.

Table 1 .

 1 Variance components estimates (s.e.) for tail-biting receipt in Tai Zumu gilts from different herds and the all population.

	Herd	2	3	All population
	N	12375	11856	33266
	TB receipt (%)	6.6	10.8	7.1
		0.322 (0.066) 1	0.759 (0.157)	0.353 (0.049)
		0.012 (0.0038)	0.019 (0.005)	0.032 (0.0037)
		5.753 (0.087)	8.94 (0.157)	5.932 (0.055)
		2.300 (0.610)	3.966 (0.944)	4.749 (0.529)
		0.06 (0.01)	0.08 (0.02)	0.06 (0.01)
		0.40 (0.11)	0.44 (0.11)	0.80 (0.09)
		0.19 (0.19)	-0.13 (0.18)	0.11 (0.10)

0.717 (0.077) 1.323 (0.143) 0.519 (0.049) 0.103 (0.037) 0.467 (0.076) 0.235 (0.027)

Table 2 .

 2 Means and standard deviations (SD) of breeding values and Spearman rank correlations between DBV, SBV and TBV for the 59 more used sires across herds.

		Herd 2		Herd 3		Herds 2 vs 3
		Mean	SD	Mean	SD	Rank correlation 1 p-value
						H0: r=0
	DBV	0.0023	0.0285	-0.0128	0.0490 0.09 (-0.17 / 0.34) 0.49
	SBV	-0.0007	0.0045	0.0030	0.0069 0.12 (-0.14 / 0.36) 0.37
	TBV	-0.0038	0.0617	0.0163	0.0804 0.13 (-0.13 / 0.38) 0.32
	1 Estimated correlations between breeding values for Herd 2 in comparison to Herd 3 (2vs3)
	95% confidence intervals are given between brackets.

Appendix 1

Among the 59 sires, 19 sires with DBVs considered as stable across the 2 herds under study (Herd 2 and Herd 3) were identified (left figure )  and ranked according to TBVs (right figure)


Anais Carvalho

Nathalie Couroussé

Sabine Crochet

Sarah-Anne David

Thierry Bordeau

Estelle Godet

Benoit Piegu

Christelle Hennequet-Antier

Aurélien

Prof. S B Tzschentke

Yahav

Vitorino Carvalho

David Sarah-Anne

Bordeau Thierry

Piégu Benoît

Hennequet-Antier Christelle

Brionne Aurélien

Noirot Céline

Pitel Frédérique

Collin Anne

Coustham Vincent
email: vincent.coustham@inra.fr

Impact of embryonic thermal manipulation on quail transcriptome and methylome

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Abstract: Changes in gene activity through epigenetic alterations induced by early environmental challenges during the embryogenesis are known to impact the phenotype, health and disease risk of animals. The epigenome is therefore an essential contributor to phenotypic plasticity, and learning how environmental exposures translate into persisting epigenetic changes may open new doors to improve robustness and resilience of developing animals. Birds are agronomic species of choice to directly manipulate the embryonic environment and study its consequences on the developing animal. We previously showed that the heat tolerance of male commercial chickens was improved by cyclically elevating the egg incubation temperature. This treatment named embryonic thermal manipulation (TM) was associated with changes in gene expression that persisted during the development of chickens and enhanced gene expression response in case of heat challenge at slaughter age, 35 days post-hatch.

To further explore the molecular basis of heat acclimation, we took advantage of an inbred line of Japanese quails (Coturnix japonica) to investigate the impact of TM on bird methylome. Among other advantages, quail generation cycle is 3-4 time faster than chicken and the use of an inbred genotype should reduce the phenotype variations associated with genetic variability. A characterization of TM on quail phenotype was performed in interaction with a post-hatch heat stress at the onset of sexual maturity. Notably, we observed an impact of the embryonic treatment on the temperature and the weight of young quails, similarly to what was reported for chicken. Concomitantly we investigated the impact of TM on quail transcriptome by RNA-seq and methylome by whole genome bisulfite sequencing (WGBS) on brain tissues sampled at hatch. Several differentially expressed gene and differential methylation regions were identified. Interestingly, the nature of some transcripts seemed to be affected by the embryonic treatment at both methylation and transcript levels.

  Impact of embryonic thermal manipulation on quail transcriptome and methylome Keywords: quail, epigenetics, thermal manipulation, DNA methylation, transcriptome