Antoine Messéan

A Comparison of Soil Microbial Community Structure, Protozoa and Nematodes in Field Plots of Conventional and Genetically Modified Maize Expressing the Bacillus thuringiens is CryIAb Toxin

Field trials were established at three European sites (Denmark, Eastern France, South-West France) of genetically modified maize (Zea mays L.) expressing the CryIAb Bacillus thuringiensis toxin (Bt), the near-isogenic non-Bt cultivar, another conventional maize cultivar and grass. Soil from Denmark was sampled at sowing (May) and harvest (October) over two years (2002, 2003); from E France at harvest 2002, sowing and harvest 2003; and from SW France at sowing and harvest 2003. Samples were analysed for microbial community structure (2003 samples only) by community-level physiological-profiling (CLPP) and phospholipid fatty acid analysis (PLFA), and protozoa and nematodes in all samples. Individual differences within a site resulted from: greater nematode numbers under grass than maize on three occasions; different nematode populations under the conventional maize cultivars once; and two occasions when there was a reduced protozoan population under Bt maize compared to non-Bt maize. Microbial community structure within the sites only varied with grass compared to maize, with one occurrence of CLPP varying between maize cultivars (Bt versus a conventional cultivar). An overall comparison of Bt versus non-Bt maize across all three sites only revealed differences for nematodes, with a smaller population under the Bt maize. Nematode community structure was different at each site and the Bt effect was not confined to specific nematode taxa. The effect of the Bt maize was small and within the normal variation expected in these agricultural systems.

Eight principles of integrated pest management

The use of pesticides made it possible to increase yields, simplify cropping systems, and forego more complicated crop protection strategies. Over-reliance on chemical control, however, is associated with contamination of ecosystems and undesirable health effects. The future of crop production is now also threatened by emergence of pest resistance and declining availability of active substances. There is therefore a need to design cropping systems less dependent on synthetic pesticides. Consequently, the European Union requires the application of eight principles (P) of Integrated Pest Management that fit within sustainable farm management. Here, we propose to farmers, advisors, and researchers a dynamic and flexible approach that accounts for the diversity of farming situations and the complexities of agroecosystems and that can improve the resilience of cropping systems and our capacity to adapt crop protection to local realities. For each principle (P), we suggest that (P1) the design of inherently robust cropping systems using a combination of agronomic levers is key to prevention. (P2) Local availability of monitoring, warning, and forecasting systems is a reality to contend with. (P3) The decision-making process can integrate cropping system factors to develop longer-term strategies. (P4) The combination of non-chemical methods that may be individually less efficient than pesticides can generate valuable synergies. (P5) Development of new biological agents and products and the use of existing databases offer options for the selection of products minimizing impact on health, the environment, and biological regulation of pests. (P6) Reduced pesticide use can be effectively combined with other tactics. (P7) Addressing the root causes of pesticide resistance is the best way to find sustainable crop protection solutions. And (P8) integration of multi-season effects and trade-offs in evaluation criteria will help develop sustainable solutions.

MASC, a qualitative multi-attribute decision model for ex ante assessment of the sustainability of cropping systems

Realistic assessments of sustainability are often viewed as typical decision-making problems requiring multi-criteria decision-aid (MCDA) methods taking into account the conflicting objectives underlying the economic, social and environmental dimensions of sustainability, and the different sources of knowledge representing them. Some MCDA-based studies have resulted in the development of sustainable agricultural systems, but the new challenges facing agriculture and the increasing unpredictability of their driving forces highlight the need for faster ex ante (‘Before-the-event’) assessment frameworks. These frameworks should also (i) provide a more realistic assessment of sustainability, by integrating a wider range of informal knowledge, via the use of qualitative information; (ii) address alternative scales, such as cropping system level, improving granularity for the handling of sustainability issues and (iii) target a larger panel of decision-makers and contexts. We describe here the MASC model, which is at the center of a framework addressing these objectives. The MASC model has at its core a decision tree that breaks the sustainability assessment decisional problem down into simpler units as a function of sustainability dimensional structure (economic, social and environmental), generating a vector of 32 holistic ‘mixed’ (quantitative and qualitative) elementary criteria rating cropping systems. The assessment process involves the calculation of these criteria, their homogenization into qualitative information for input into the model and their aggregation throughout the decision tree based on ‘If-Then’ decision rules, entered by the user. We present the model and describe its first implementation for the evaluation of four cropping systems generated from expert knowledge, and discuss its relevance to the objectives cited above. The MASC model has several advantages over existing methods, due to its ability to handle qualitative information, its transparency, flexibility and feasibility.

Toward a Reduced Reliance on Conventional Pesticides in European Agriculture

Whether modern agriculture without conventional pesticides will be possible or not is a matter of debate. The debate is meaningful within the context of rising health and environmental awareness on one hand, and the global challenge of feeding a steadily growing human population on the other. Conventional pesticide use has come under pressure in many countries, and some European Union (EU) Member States have adopted policies for risk reduction following Directive 2009/128/EC, the sustainable use of pesticides. Highly diverse crop production systems across Europe, having varied geographic and climatic conditions, increase the complexity of European crop protection. The economic competitiveness of European agriculture is challenged by the current legislation, which banned the use of many previously authorized pesticides that are still available and applied in other parts of the world. This challenge could place EU agricultural production at a disadvantage, so EU farmers are seeking help from the research community to foster and support integrated pest management (IPM). Ensuring stable crop yields and quality while reducing the reliance on pesticides is a challenge facing the farming community is today. Considering this, we focus on several diverse situations in European agriculture in general and in European crop protection in particular. We emphasize that the marked biophysical and socio-economic differences across Europe have led to a situation where a meaningful reduction in pesticide use can hardly be achieved. Nevertheless, improvements and/or adoption of the knowledge and technologies of IPM can still achieve large gains in pesticide reduction. In this overview, the current pest problems and their integrated management are discussed in the context of specific geographic regions of Europe, with a particular emphasis on reduced pesticide use. We conclude that there are opportunities for reduction in many parts of Europe without significant losses in crop yields.

Feral genetically modified herbicide tolerant oilseed rape from seed import spills: are concerns scientifically justified?

One of the concerns surrounding the import (for food and feed uses or processing) of genetically modified herbicide tolerant (GMHT) oilseed rape is that, through seed spillage, the herbicide tolerance (HT) trait will escape into agricultural or semi-natural habitats, causing environmental or economic problems. Based on these concerns, three EU countries have invoked national safeguard clauses to ban the marketing of specific GMHT oilseed rape events on their territory. However, the scientific basis for the environmental and economic concerns posed by feral GMHT oilseed rape resulting from seed import spills is debatable. While oilseed rape has characteristics such as secondary dormancy and small seed size that enable it to persist and be redistributed in the landscape, the presence of ferals is not in itself an environmental or economic problem. Crucially, feral oilseed rape has not become invasive outside cultivated and ruderal habitats, and HT traits are not likely to result in increased invasiveness. Feral GMHT oilseed rape has the potential to introduce HT traits to volunteer weeds in agricultural fields, but would only be amplified if the herbicides to which HT volunteers are tolerant were used routinely in the field. However, this worst-case scenario is most unlikely, as seed import spills are mostly confined to port areas. Economic concerns revolve around the potential for feral GMHT oilseed rape to contribute to GM admixtures in non-GM crops. Since feral plants derived from cultivation (as distinct from import) occur at too low a frequency to affect the coexistence threshold of 0.9% in the EU, it can be concluded that feral GMHT plants resulting from seed import spills will have little relevance as a potential source of pollen or seed for GM admixture. This paper concludes that feral oilseed rape in Europe should not be routinely managed, and certainly not in semi-natural habitats, as the benefits of such action would not outweigh the negative effects of management.

Estimating the effects of Cry1F Bt‐maize pollen on non‐target Lepidoptera using a mathematical model of exposure

Summary 1. In farmland biodiversity, a potential risk to the larvae of non‐target Lepidoptera from genetically modified (GM) Bt‐maize expressing insecticidal Cry1 proteins is the ingestion of harmful amounts of pollen deposited on their host plants. A previous mathematical model of exposure quantified this risk for Cry1Ab protein. We extend this model to quantify the risk for sensitive species exposed to pollen containing Cry1F protein from maize event 1507 and to provide recommendations for management to mitigate this risk. 2. A 14‐parameter mathematical model integrating small‐ and large‐scale exposure was used to estimate the larval mortality of hypothetical species with a range of sensitivities, and under a range of simulated mitigation measures consisting of non‐Bt maize strips of different widths placed around the field edge. 3. The greatest source of variability in estimated mortality was species sensitivity. Before allowance for effects of large‐scale exposure, with moderate within‐crop host‐plant density and with no mitigation, estimated mortality locally was <10% for species of average sensitivity. For the worst‐case extreme sensitivity considered, estimated mortality locally was 99·6% with no mitigation, although this estimate was reduced to below 40% with mitigation of 24‐m‐wide strips of non‐Bt maize. For highly sensitive species, a 12‐m‐wide strip reduced estimated local mortality under 1·5%, when within‐crop host‐plant density was zero. Allowance for large‐scale exposure effects would reduce these estimates of local mortality by a highly variable amount, but typically of the order of 50‐fold. 4. Mitigation efficacy depended critically on assumed within‐crop host‐plant density; if this could be assumed negligible, then the estimated effect of mitigation would reduce local mortality below 1% even for very highly sensitive species. 5.  Synthesis and applications. Mitigation measures of risks of Bt‐maize to sensitive larvae of non‐target lepidopteran species can be effective, but depend on host‐plant densities which are in turn affected by weed‐management regimes. We discuss the relevance for management of maize events where cry1F is combined (stacked) with a herbicide‐tolerance trait. This exemplifies how interactions between biota may occur when different traits are stacked irrespective of interactions between the proteins themselves and highlights the importance of accounting for crop management in the assessment of the ecological impact of GM plants.

Robust cropping systems to tackle pests under climate change. A review

Agriculture in the twenty-first century faces the challenge of meeting food demands while satisfying sustainability goals. The challenge is further complicated by climate change which affects the distribution of crop pests (intended as insects, plants, and pathogenic agents injurious to crops) and the severity of their outbreaks. Increasing concerns over health and the environment as well as new legislation on pesticide use, particularly in the European Union, urge us to find sustainable alternatives to pesticide-based pest management. Here, we review the effect of climate change on crop protection and propose strategies to reduce the impact of future invasive as well as rapidly evolving resident populations. The major points are the following: (1) the main consequence of climate change and globalization is a heightened level of unpredictability of spatial and temporal interactions between weather, cropping systems, and pests; (2) the unpredictable adaptation of pests to a changing environment primarily creates uncertainty and projected changes do not automatically translate into doom and gloom scenarios; (3) faced with uncertainty, policy, research, and extension should prepare for worst-case scenarios following a “no regrets” approach that promotes resilience vis-à-vis pests which, at the biophysical level, entails uncovering what currently makes cropping systems resilient, while at the organizational level, the capacity to adapt needs to be recognized and strengthened; (4) more collective approaches involving extension and other stakeholders will help meet the challenge of developing more robust cropping systems; (5) farmers can take advantage of Web 2.0 and other new technologies to make the exchange of updated information quicker and easier; (6) cooperation between historically compartmentalized experts in plant health and crop protection could help develop anticipation strategies; and (7) the current decline in skilled crop protection specialists in Europe should be reversed, and shortcomings in local human and financial resources can be overcome by pooling resources across borders.

Identifying obstacles and ranking common biological control research priorities for Europe to manage most economically important pests in arable, vegetable and perennial crops.

EU agriculture is currently in transition from conventional crop protection to integrated pest management (IPM). Because biocontrol is a key component of IPM, many European countries recently have intensified their national efforts on biocontrol research and innovation (R&I), although such initiatives are often fragmented. The operational outputs of national efforts would benefit from closer collaboration among stakeholders via transnationally coordinated approaches, as most economically important pests are similar across Europe. This paper proposes a common European framework on biocontrol R&I. It identifies generic R&I bottlenecks and needs as well as priorities for three crop types (arable, vegetable and perennial crops). The existing gap between the market offers of biocontrol solutions and the demand of growers, the lengthy and expensive registration process for biocontrol solutions and their varying effectiveness due to variable climatic conditions and site-specific factors across Europe are key obstacles hindering the development and adoption of biocontrol solutions in Europe. Considering arable, vegetable and perennial crops, a dozen common target pests are identified for each type of crop and ranked by order of importance at European level. Such a ranked list indicates numerous topics on which future joint transnational efforts would be justified.

Guidelines to design models assessing agricultural sustainability, based upon feedbacks from the DEXi decision support system

New agricultural systems are required to satisfy societal expectations such as higher quantity and quality of agricultural products, reducing environmental impacts, and more jobs. However, identifying and implementing more suitable agricultural systems is difficult due to conflicting objectives and to the wide diversity of scientific disciplines required to solve agricultural issues. Therefore, designing models to assess the sustainability of agricultural systems requires multi-criteria decision aid methods. The French agronomist community has recently developed 11 hierarchical and qualitative models to assess sustainability using the DEXi decision aid software. Here, we give guidelines to help designers to build their own specific models. First, we present the principles and applications of the DEXi software. Then, we provide guidance on the following steps of model designing: (1) initial analysis and planning of the design process, (2) selection and hierarchy of sustainability criteria, (3) indicator selection and building, (4) parameterization, (5) evaluation, and (6) model dissemination and uses. We then discuss advantages and drawbacks of this kind of modeling formalism, the role of a participatory approach, and the main properties to consider during the design process.

Integrated management of damping-off diseases. A review

Damping-off is a disease that leads to the decay of germinating seeds and young seedlings, which represents for farmers one of the most important yield constraints both in nurseries and fields. As for other biotic stresses, conventional fungicides are widely used to manage this disease, with two major consequences. On the one hand, fungicide overuse threatens the human health and causes ecological concerns. On the other hand, this practice has led to the emergence of pesticide-resistant microorganisms in the environment. Thus, there are increasing concerns to develop sustainable and durable damping-off management strategies that are less reliant on conventional pesticides. Achieving such a goal requires a better knowledge of pathogen biology and disease epidemiology in order to facilitate the decision-making process. It also demands using all available non-chemical tools that can be adapted to regional and specific production situations. However, this still is not the case and major knowledge gaps must be filled. Here, we review up to 300 articles of the damping-off literature in order to highlight major knowledge gaps and identify future research priorities. The major findings are (i) damping-off is an emerging disease worldwide, which affects all agricultural and forestry crops, both in nurseries and fields; (ii) over a dozen of soil-borne fungi and fungus-like organisms are a cause of damping-off but only a few of them are frequently associated with the disease; (iii) damping-off may affect from 5 to 80% of the seedlings, thereby inducing heavy economic consequences for farmers; (iv) a lot of research efforts have been made in recent years to develop biocontrol solutions for damping-off and there are interesting future perspectives; and (v) damping-off management requires an integrated pest management (IPM) approach combining both preventive and curative tactics and strategies. Given the complex nature of damping-off and the numerous factors involved in its occurrence, we recommend further research on critical niches of complexity, such as seeds, seedbed, associated microbes and their interfaces, using novel and robust experimental and modeling approaches based on five research priorities described in this paper.