Modelling as a tool to redesign livestock farming systems: a literature review

Livestock farming has recently come under close scrutiny, in response especially to environmental issues. Farmers are encouraged to redesign their livestock farming systems in depth to improve their sustainability. Assuming that modelling can be a relevant tool to address such systemic changes, we sought to answer the following question: ‘How can livestock farming systems be modelled to help farmers redesign their whole farming systems?’ To this end, we made a literature review of the models of livestock farming systems published from 2000 to mid-2009 (n = 79). We used an analysis grid based on three considerations: (i) system definition, (ii) the intended use of the model and (iii) the way in which farmers’ decision-making processes were represented and how agricultural experts and farmers were involved in the modelling processes. Consistent rationales in approaches to supporting changes in livestock farming were identified in three different groups of models, covering 83% of the whole set. These could be defined according to (i) the way in which farmers’ decisions were represented and (ii) the model's type of contribution to supporting changes. The first type gathered models that dynamically simulated the system according to different management options; the farmers’ decision-making processes are assumed to consist in choosing certain values for management factors. Such models allow long-term simulations and endorse different disciplinary viewpoints, but the farmers are weakly involved in their design. Models of the second type can indicate the best combination of farm activities under given constraints, provided the farmers’ objectives are profit maximisation. However, when used to support redesigning processes, they address neither how to implement the optimal solution nor its long-term consequences. Models of the third type enable users to dynamically simulate different options for the farming system, the management of which is assumed to be planned according to the farmers’ general objectives. Although more comprehensive, these models do not easily integrate different disciplinary viewpoints and different subsystems, which limits their usefulness as support tools for redesigning processes. Finally, we concluded about what specific requirements should be for modelling approaches if farmers were to be supported in redesigning their whole livestock farming systems using models.     

European organic dairy farmers’ preference for animal health management within the farm management system

The expertise and knowledge of veterinary advisors on improving animal health management is key towards a better herd health status. However, veterinary advisors are not always aware of the goals and priorities of dairy farmers. To dairy farmers animal health is only one aspect of farm management and resources may be allocated to other more preferred areas. Veterinary advisors may experience this as non-compliant with their advice. To explore the preferences of European Union (EU) organic dairy farmers for improved animal health management relative to other farm management areas an adaptive conjoint analysis (ACA) was performed. A total of 215 farmers participated originating from organic dairy farms in France (n=70), Germany (n=60), Spain (n=28) and Sweden (n=57). The management areas udder health and claw health represented animal health management whereas barn, calf and pasture management represented potential conflicting management areas. Results indicate that EU organic dairy farmers differ in their preferences for improved animal health management within the farming system. In general, improved calf management was the most preferred area and improved claw health management was found to be least preferred, the remaining areas were of intermediate interest. Cluster analyses on claw health measures and udder health measures resulted in respectively seven and nine distinct preference profiles. The results indicate a high degree of variation in farmers’ preference, which cannot be explained by the typical herd characteristics. With the individual preferences revealed by ACA, a veterinary advisor can now find out whether his intended advice is directed at a favourable or unfavourable management area of the farmer. If the latter is the case the veterinarian should first create awareness of the problem to the farmer. Insights in individual farmers preferences will allow veterinary advisors to better understand why farmers were incompliant with their advice and improve their advice by showing, for example, the potential benefits of their advice.     

从事有机农业对农民福祉的影响

从事有机农业的农民福祉得到改善是有机农业发展的前提条件。采用Narayan等提出的福祉框架,回顾了有关有机农业行为和支持该行为的公共部门措施对农民福祉影响研究的文献,以厘清从事有机农业与农民福祉间的关系。研究表明,农民有机农业行为对其收入、健康、社会关系、安全和自由与选择等福祉要素产生影响。收入是农民福祉的首要构成要素,但农民有机农业行为究竟是增加还是降低其收入,需要考察具体情境中产量、成本和价格的综合作用,没有一致性结论。农民有机农业行为对其社会关系的影响具有双向性,但它对他们的健康、安全和选择机会的影响是积极的。公共部门通过财政支付、支持合作、建立与完善有机认证制度和采购绿色化等措施支持有机农业,有助于改善有机农民的福祉。其中,财政支付是最重要的支持措施。研究认为不同情境的农民有机农业行为对其福祉影响的综合评价、农民有机农业行为与其福祉间因果关系的检验和公共部门有机农业政策对有机农民福祉贡献的检验,是今后研究的重要选题。     

Role of modelling in improving nutrient efficiency in cropping systems

The applicability of models in addressing resource management issues in agriculture has been widely promoted by the research community, yet examples of real impacts of such modelling efforts on current farming practices are rare. Nevertheless, simulation models can compliment traditional field experimentation in researching alternative management options. The first objective of this paper is, therefore, to provide four case study examples of where models were used to help research issues relating to improved nutrient efficiency in low-input cropping systems. The first two cases addressed strategies of augmenting traditional farming practices with small applications of chemical fertilizer (N and P). The latter two cases explicitly addressed the question of what plant genetic traits can be beneficial in low-nutrient farming systems. In each of these case studies, the APSIM (Agricultural Production Systems Simulator) systems model was used to simulate the impacts of alternative crop management systems.The question of whether simulation models can assist the research community in contributing to purposeful change in farming practice is also addressed. Recent experiences in Australia are reported where simulation models have contributed to practice change by farmers. Finally, current initiatives aimed at testing whether models can also contribute to improving the nutrient efficiency of smallholder farmers in the SAT are discussed.     

A preference-based approach to deriving breeding objectives: applied to sheep breeding

Using internet-based software known as 1000Minds, choice-experiment surveys were administered to experts and farmers from the Irish sheep industry to capture their preferences with respect to the relative importance - represented by part-worth utilities - of target traits in the definition of a breeding objective for sheep in Ireland. Sheep production in Ireland can be broadly separated into lowland and hill farming systems; therefore, each expert was asked to answer the survey first as if he or she were a lowland farmer and second as a hill farmer. In addition to the experts, a group of lowland and a group of hill farmers were surveyed to assess whether, and to what extent, the groups' preferences differ from the experts' preferences. The part-worth utilities obtained from the surveys were converted into relative economic value terms per unit change in each trait. These measures - referred to as 'preference economic values' (pEVs) - were compared with economic values for the traits obtained from bio-economic models. The traits 'value per lamb at the meat processor' and 'lamb survival to slaughter' were revealed as being the two most important traits for the surveyed experts responding as lowland and hill farmers, respectively. In contrast, 'number of foot baths per year for ewes' and 'number of anthelmintic treatments per year for ewes' were the two least important traits. With the exception of 'carcase fat class' (P < 0.05), there were no statistically significant differences in the mean pEVs obtained from the surveyed experts under both the lowland and hill farming scenarios. Compared with the economic values obtained from bio-economic models, the pEVs for 'lambing difficulty' when the experts responded as lowland farmers were higher (P < 0.001); and they were lower (P < 0.001) for 'carcase conformation class', 'carcase fat class' (less negative) and 'ewe mature weight' (less negative) under both scenarios. Compared with surveyed experts, pEVs from lowland farmers differed significantly for 'lambing difficulty', 'lamb survival to slaughter', 'average days to slaughter of lambs', 'number of foot baths per year for ewes', 'number of anthelmintic treatments per year for ewes' and 'ewe mature weight'. Compared with surveyed experts, pEVs from hill farmers differed significantly for 'lambing difficulty', 'average days to slaughter of lambs' and 'number of foot baths per year for ewes'. This study indicates that preference-based tools have the potential to contribute to the definition of breeding objectives where production and price data are not available.     

Development of agri-environmental indicators to assess dairy farm sustainability in Quebec,Eastern Canada

Agri-environmental indicators are commonly used to assess agricultural sustainability. In North America, few are designed to be easily used by dairy farmers. As farmers assume more responsibility for managing natural resources, they play an increasingly important role in assessing sustainable agriculture. This paper describes the development of an indicator-based self-assessment tool for use at the farm level to evaluate dairy farm sustainability from an environmental standpoint. The agri-environmental indicator set was selected by using two participatory processes: the Delphi method and a focus group. The framework for developing the assessment tool consisted of six steps: (1) Defining the concept of environmental sustainability at the farm level; (2) setting up goals and principles for the assessment; (3) identifying potential indicators and selecting candidate indicators; (4) defining reference values, aggregating indicators into components, and establishing relative weights for indicators; (5) testing the candidate indicators on dairy farms, and (6) selecting the final indicator set. Six criteria were used to evaluate either the practicality or usefulness of indicators. Thirteen indicators were chosen, one of which was divided into four sub-indicators. These indicators were aggregated into four components: soil quality, cropping practices, fertilization management, and farmland management. Expert participation was the first validation of the indicator set. A compromise between feasibility, practicality, and relevance of measurement was found among indicators. When applied to 40 farms over two contrasting regions, the indicator set identified scores that differed according to production context. The tool is user-friendly and well-adapted to dairy farming systems.     

Impacts of organic and conventional dairy farmer attitude,behaviour and knowledge on farm biodiversity in Ireland

Agricultural intensification has caused significant declines in biodiversity. Agri-environmental schemes (AES), including organic farming, are thought to benefit biodiversity. However, under similar production conditions and in comparable locations and schemes, farms are not managed in the same way, with variable consequences for production and the environment. Understanding farmer attitude, behaviour and knowledge of the environment and their impacts on biodiversity may help us understand the variable impacts of AES on biodiversity. We combined a sociological survey of nine organic and eight conventional dairy farmers (measuring environmental and achievement attitudes; environmental and production-orientated behaviours and environmental knowledge), in Ireland, with a biodiversity (using plant richness as an indicator) assessment of their farms. We found higher plant richness on organic farms than conventional. Organic and conventional farmers had similar attitudes to farming achievement and the environment but organic farmers were better informed about environmental issues and carried out more environmentally orientated behaviours. Biodiversity was positively related to the amount of environmentally orientated behaviours and negatively related to production-orientated behaviours carried out on farms. Organic farmers who had more positive attitudes to the environment and were better informed about it had higher biodiversity on their farms compared to less positively inclined, less informed organic farmers. We show disparities between attitude and actual behaviour in relation to the environment, with organic farmers sharing similar attitudes to conventional farmers, but more prepared to inform themselves about and carry out environmentally friendly farming. Results indicate that organic farming and environmentally orientated behaviours benefit biodiversity and that there is an important link between farmer environmental attitudes and knowledge and the beneficial effects of organic farming on biodiversity. We encourage conservation orientated thinking and better environmental education among farmers, including those who already participate in an AES. This way, the benefits of the AES for the environment may be maximised.     

生物技术学和害虫综合防治对热带亚洲小农户的重要意义(英文)

作者是澳大利亚著名昆虫学家,长期在东南亚农村工作,积累了宝贵经验。他在文中提出,害虫综合防治（ＩＰＭ）的含义是综合害虫治理的方法以达到农业上的最大收益和持续发展,同时注意对环境有良好的影响。对小农户应提供确实可行的整套害虫治理方法,并开创他们能自行选择的机会;他们经过田间学校培训后可成为农作物管理专家,并对怎样防治害虫能作出有根据的抉择。与ＩＰＭ有关的生物防治最近的发展包括：对害虫的准确鉴定、经生物工程处理和未处理过的生物杀虫药的应用、对转基因动植物的利用、及情报资料的收集。文章讨论了这些生物技术在东南亚地区水稻和蔬菜综合治理中的应用,以8及巴西大豆害虫和越南稻瘟病的治理,阐明通过农户、技术员和研究人员通力合作所获得的成绩对农业持续的发展起了主要的推动作用。     

Organic Farming in the Nordic Countries – Animal Health and Production

Organic farming (or ecological agriculture) is of growing importance in the agricultural sector worldwide. In the Nordic countries, 1–10% of the arable land was in organic production in 1999. Organic farming can be seen as an approach to agriculture where the aim is to create integrated, humane, environmentally and economically sustainable agricultural production systems. Principles like nutrient recycling, prevention rather than treatment and the precautionary principle are included in aims and standards. Animal welfare is another hallmark of organic livestock production but despite this, several studies have indicated severe health problems e.g. in organic poultry production in Denmark. Also the quality of animal food products in relation to human health, particularly the risk of zoonotic infections, has been debated. For these reasons there is a need for improvement of production methods and animal health status. Vets play an important role in this development through work in clinical practice and in research. On-farm consultancy should be tailored to the individual farmers needs, and the practitioner should be willing to take up new ideas and when needed, to enter a critical dialogue in relation to animal welfare. Better base line data on animal health and food safety in organic food systems are needed.     

Long‐term farming systems and last crop sown shape the species and functional composition of the arable weed seed bank

Questions: The assembly of arable weed communities is the result of local filtering by agricultural management and crop competition. Therefore, soil seed banks can reflect the effects of long‐term cumulative field management and crop sequences on weed communities. Moreover, soil seed banks provide strong estimates of future weed problems but also of potential arable plant diversity and associated ecological functions. For this, we evaluated the effects of different long‐term farming systems under the same crop rotation sequence on the abundance, diversity and community assembly of weed seed bank, as well as on the functional diversity and composition. Location: DOK (biodynamic [D], bioorganic [O], conventional [K]) long‐term trial, Therwil, Switzerland. Methods: The effects of long‐term contrasted farming systems (i.e., biodynamic, organic, conventional, mineral and unfertilised systems) and last crop sown (i.e., wheat and maize) were evaluated on different indicators of species and functional diversity and composition of the weed soil seed bank. Results: The results showed significant influences of 40 years of contrasted farming systems on the diversity and composition of the seed bank, with higher diversities being found in unfertilised and organic farming systems, but also higher abundances than those found under conventional systems. Organic farming also allowed higher functional richness, dispersion and redundancy. Different farming systems triggered shifts in species and functional assemblies. Conclusions: The results highlight the importance of organic management for the maintenance of a diverse arable plant community and its functions. However, such results emphasise the need for appropriate yearly management to reduce the abundance of settled weediness and prevent affecting crop production. The farm management filtered community composition based on functional traits. Although the soil seed bank buffers the long‐term farming and crop sequence, the last crop sown and, thus, the yearly management were important determinants of seed bank composition.     

Chemical and biological indicators of soil quality in organic and conventional farming systems in Central Italy

In the past decade, there has been increased scientific interest in the so-called organic farming, especially in comparison with conventional agriculture. Many recent studies compare these two fundamentally different systems for soil properties, in different regions of the world. In this study, two adjacent fields in Central Italy, one managed according to organic, and the other according to conventional farming methods, were studied to determine the effects of these two agricultural systems on soil quality indicators at the farm level. Chemical and microbiological properties were chosen as indicators of soil quality and were measured at soil depth intervals of 5–20 and 20–35 cm, after 7 years of organic certified and conventional management methods. The field under organic management showed significantly better soil nutritional and microbiological conditions; with increased level of total nitrogen, nitrate and available phosphorus, and an increased microbial biomass content, and enzymatic activities (acid phosphatase, protease and dehydrogenase). No consistent increase in total organic carbon was observed. Results of the study suggest that, over the period of 7 year, organic management method strongly affects soil quality indicators. Large differences between the two soils were found in terms of microbiological properties, which are sensitive soil indicators of changes occurred under the different farming systems.     

Could energy flow in agro-ecosystems be used as a “tool” for crop and farming system replacement?

Energy flow in orchards can be used to determine first the best management practices and second the possibility of using those which have best environmental advantages. Conventional and organic peach and kiwi orchards were selected in order to (a) determine energy flow of the farming systems, and (b) reveal the importance of energy inputs in crop and farming system replacement. Fifteen farms (four conventional and three organic kiwi orchards; four conventional and four organic peach orchards) were selected with proportional stratified random sampling during the years 2010–2013. The Hierarchical Cluster Analysis (HCA) method was applied using nine production coefficients' variables (fertilizers, fungicides, insecticides, weed control, diesel, labor, irrigation, branches shoring, and machinery) and revealed three groups of the studied orchards. The highest contributors in cluster formation were weed control, branches shoring, labor, and machinery. The effect of the production coefficients on the grouping of the studied orchards reveals their importance for these crops and farming systems. Most of the production coefficients showed their lowest values in organic kiwi orchards (Group 3), so it could be said that they can play a key role in the replacement of the peaches, and conventional kiwi orchards. It seems that production coefficients can be used as a “tool” for decision makers who are seeking for crops and farming systems with low energy inputs and best environmental advantages in order to use them in crop replacement in agro-ecosystems.     

Breeding Barn Swallows Hirundo rustica on organic and conventional arable farms in the Netherlands

Populations of farmland birds are under pressure as a result of agricultural intensification. It has been proposed that less intensive approaches to farming, such as organic farming methods, may halt these population declines. In addition, organic farmers may have a more positive attitude towards nature and the environment which can possibly also have positive effects on the populations of breeding birds. We have compared the attitude of conventional and organic farmers towards the presence of Barn Swallows Hirundo rustica and the abundance of breeding Barn Swallows on organic and conventional arable farms in the Netherlands. We found that the abundance of breeding Barn Swallows did not differ between these two types of farms an that both organic and conventional farmers had a positive attitude towards the presence of Barn Swallows on their farms. Our results show that organic farming does not attract more Barn Swallows. However, agricultural intensification could have resulted in lower breeding success and, consequently, population declines, although there may be other contributory factors as well.     

Decreased functional diversity and biological pest control in conventional compared to organic crop fields

Organic farming is one of the most successful agri-environmental schemes, as humans benefit from high quality food, farmers from higher prices for their products and it often successfully protects biodiversity. However there is little knowledge if organic farming also increases ecosystem services like pest control. We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded vascular plants, pollinators, aphids and their predators. Further, five conventional fields which were treated with insecticides were compared with 10 non-treated conventional fields. Organic fields had five times higher plant species richness and about twenty times higher pollinator species richness compared to conventional fields. Abundance of pollinators was even more than one-hundred times higher on organic fields. In contrast, the abundance of cereal aphids was five times lower in organic fields, while predator abundances were three times higher and predator-prey ratios twenty times higher in organic fields, indicating a significantly higher potential for biological pest control in organic fields. Insecticide treatment in conventional fields had only a short-term effect on aphid densities while later in the season aphid abundances were even higher and predator abundances lower in treated compared to untreated conventional fields. Our data indicate that insecticide treatment kept aphid predators at low abundances throughout the season, thereby significantly reducing top-down control of aphid populations. Plant and pollinator species richness as well as predator abundances and predator-prey ratios were higher at field edges compared to field centres, highlighting the importance of field edges for ecosystem services. In conclusion organic farming increases biodiversity, including important functional groups like plants, pollinators and predators which enhance natural pest control. Preventative insecticide application in conventional fields has only short-term effects on aphid densities but long-term negative effects on biological pest control. Therefore conventional farmers should restrict insecticide applications to situations where thresholds for pest densities are reached.     

Enhancing pollination is more effective than increased conventional agriculture inputs for improving watermelon yields

Agricultural practices to improve yields in small‐scale farms in Africa usually focus on improving growing conditions for the crops by applying fertilizers, irrigation, and/or pesticides. This may, however, have limited effect on yield if the availability of effective pollinators is too low. In this study, we established an experiment to test whether soil fertility, soil moisture, and/or pollination was limiting watermelon (Citrullus lanatus) yields in Northern Tanzania. We subjected the experimental field to common farming practices while we treated selected plants with extrafertilizer applications, increased irrigation and/or extra pollination in a three‐way factorial experiment. One week before harvest, we assessed yield from each plant, quantified as the number of mature fruits and their weights. We also assessed fruit shape since this may affect the market price. For the first fruit ripening on each plant, we also assessed sugar content (brix) and flesh color as measures of fruit quality for human consumption. Extra pollination significantly increased the probability of a plant producing a second fruit of a size the farmer could sell at the market, and also the fruit sugar content, whereas additional fertilizer applications or increased irrigation did not improve yields. In addition, we did not find significant effects of increased fertilizer or watering on fruit sugar, weight, or color. We concluded that, insufficient pollination is limiting watermelon yields in our experiment and we suggest that this may be a common situation in sub‐Saharan Africa. It is therefore critically important that small‐scale farmers understand the role of pollinators and understand their importance for agricultural production. Agricultural policies to improve yields in developing countries should therefore also include measures to improve pollination services by giving education and advisory services to farmers on how to develop pollinator‐friendly habitats in agricultural landscapes.     

BIOTECHNOLOGY AND IPM: THE RELEVANCE TO SMALL SCALE FARMERS IN TROPICAL ASIA*

Abstract This paper deals with the relevance of biotechnology and IPM to small scale farmers in South and Southeast Asia. IPM may be defined as the combination and integration of approaches to pest management. which maximizes real profitability and genuine sustainability for the users and farming system and gives due regard to the environment. Alternative and practical pest management options should be developed for small scale farmers who could become experts in crop management and capable of making informed decisions through training in field schools. The latest development of biotechnology includes diagnostics, biological pesticides (either genetically manipulated or not genetically manipulated), transgenic plants and animals (vertebrates and invertebrates) and informatics. The place of biotechnology in rice IPM and vegetable IPM in South and Southeast Asia is discussed. Examples of soybean caterpillar in Brazil and rice blast in Vietnam illustrate the benefits of a strong working partnership between farmers, trainers and researchers in creating new knowledge which promotes sustainable agriculture.     

Phosphorus feeding practices,barriers to and motivators for minimising phosphorus feeding to dairy cows in diverse dairy farming systems

Minimising phosphorus (P) feeding to dairy cows can reduce feed costs and minimise water pollution without impairing animal performance. This study aimed to determine current P feeding practices and identify the barriers to and motivators for minimising P feeding on dairy farms, using Great Britain (GB) dairy farming as an example of diverse systems. Farmers (n = 139) and feed advisers (n = 31) were involved simultaneously in independent questionnaire surveys on P feeding in dairy farms. Data on the herd size, milk yield and concentrate fed were analysed using ANOVA to investigate the effect of farm classification, region, and feed professional advice. Chi-square tests were used to investigate associations between farm characteristics and implemented P feeding and management practices. Most farmers (72%) did not know the P concentration in their lactating cow’s diet and did not commonly adopt precision P feeding practices, indicating that cows might have been offered dietary P in excess of recommended P requirement. Farmers’ tendency to feed P in excess of recommendations increased with herd size, but so did their awareness of P pollution issues and likeliness of testing manure P. However, 68% of farmers did not analyse manure P, indicating that mineral P fertiliser application rates were not adjusted accordingly, highlighting the risk of P being applied beyond crops’ requirement. Almost all farmers (96%) were willing to lower dietary P concentration but the uncertainty of P availability in feed ingredients (30%) and concerns over reduced cow fertility (22%) were primary barriers. The willingness to reduce dietary P concentrations was driven by the prospect of reducing environmental damage (28%) and feed costs (27%) and advice from their feed professionals (25%). Most farmers (70%) relied on a feed professional, and these farmers had a higher tendency to analyse their forage P. However, farmers of pasture-based systems relied less on feed professionals. Both farmers (73%) and feed advisers (68%) were unsatisfied with the amount of training on P management available. Therefore, the training on P management needs to be more available and the influence that feed professionals have over P feeding should be better utilised. Study findings demonstrate the importance of considering type of dairy farming systems when developing precision P feeding strategies and highlight the increasing importance of feed professionals in minimising P feeding.     

Vulnerability of wheat farmers: Toward a conceptual framework

Vulnerability is expected to differ based on climatic conditions as well as socio-economic attributes of farming households. In this regard, attention toward vulnerability assessments is increasing within policy-making processes, to assist in selecting suitable coping strategies and policies to reduce farmers’ vulnerability. Through identifying the main vulnerability indicators from a sustainability perspective (including social, economic, and environmental dimensions) among wheat farmers, this study is seeking an inclusive conceptual framework to assess their vulnerability to both socio-economic and environmental changes. Taking the main elements (i.e., sensitivity, exposure and adaptive capacity) of vulnerability into account, this paper tried to develop an inclusive systemic framework to understand the most important indicators of vulnerability for wheat farmers at various spatial and temporal scales. It is supposed that the framework is a useful guide for policymakers in identifying the vulnerable groups of wheat farmers and zones so that they can decide about proper coping strategies to effectively deal with adverse effects of climate and undesired socioeconomic changes in the wheat farming system.     

Farmers' perceptions, knowledge, and management of coffee pests and diseases and their natural enemies in Chiapas, Mexico

Small farmers' perceptions of coffee Coffea arabica L. herbivores and their natural enemies, how those perceptions relate to field infestation levels, and pest management practices being implemented by members from two organic and nonorganic coffee grower organizations in the Soconusco region, southeastern Mexico, were analyzed through an interview survey, diagnostic workshops, and field sampling. The terms pest, disease, and damage were commonly used as synonyms. The major phytophagous species, as perceived by the interviewees, were Hypothenemus hampei (Ferrari), and to a lesser extent the fungi Corticium koleroga Cooke (H?hnel) and Hemileia vastatrix Berkeley & Broome. Among the nonorganic farmers, other nonpest-related constraints were regarded as more important. Awareness of the existence of natural enemies was low, despite more organic farmers have used the ectoparasitoid bethylid Cephalonomia stephanoderis Betrem against H. hampei. Labor supplied by household members was most frequent for pest control; only organic farmers exchanged labor for this purpose. The levels of infestation by H. hampei, Leucoptera coffeella Guérin-Méneville, and C. koleroga were lower within the organic coffee stands. However, a low effectiveness for pest control was commonly perceived, probably due to a feeling, among the organic farmers, of a low impact of their pest management extension service, whereas a lack of motivation was prevalent among the nonorganic farmers, shown by a concern with their low coffee yields and the emigration of youth. The importance of understanding farmers' perceptions and knowledge of pests and their natural enemies and the need for participatory pest management approaches, are discussed.     

Assessing ecological quality of shallow lakes: Does knowledge of transparency suffice?

The European Water Framework Directive (WFD) requires that all aquatic ecosystems in their member states should reach ‘good’ ecological quality by 2015. To assess ecological quality, the WFD requires the definition of reference conditions using biological, physical and chemical indicators and the assignment of each water body to one of five quality classes using these indicators. Elaborate assessment schemes using large sets of variables are now being developed. Here we address the question whether all this is really needed and what the simplest assessment approach would be for the case of shallow lakes. We explore the relationships between the quality class assigned to a lake by experts in shallow lake ecology and a rich set of biological, physical, and chemical data. Multinomial logistic regression analyses were carried out based on data from 86 shallow lakes throughout Europe that were sampled in 2000 and/or 2001. Ecological quality of shallow lakes judged by experts was strongly correlated to physical and chemical variables associated with light regime and nutrients and much less to biological variables.Our regression model showed that ecological quality of this set of shallow lakes judged by experts could be predicted quite well from water transparency expressed as Secchi depth and that other variables did not contribute to it significantly. According to the WFD, lakes should at least have a ‘good’ ecological quality. Quality judged by experts and predicted quality were similar for 78% of the lakes with respect to meeting this standard. As a cautionary note we stress that Secchi depth alone will be a less useful indicator if effects of stressors other than eutrophication (e.g. lake acidification and toxic pollution) are to be considered.