Perceptions of disease risk: from social construction of subjective judgments to rational decision making

Many factors influence how people form risk perceptions. Farmers' perceptions of risk and levels of risk aversion impact on decision-making about such things as technology adoption and disease management practices. Irrespective of the underlying factors that affect risk perceptions, those perceptions can be summarized by variables capturing impact and uncertainty components of risk. We discuss a new framework that has the subjective probability of disease and the cost of decision errors as its central features, which might allow a better integration of social science and epidemiology, to the benefit of plant disease management. By focusing on the probability and cost (or impact) dimensions of risk, the framework integrates research from the social sciences, economics, decision theory, and epidemiology. In particular, we review some useful properties of expected regret and skill value, two measures of expected cost that are particularly useful in the evaluation of decision tools. We highlight decision-theoretic constraints on the usefulness of decision tools that may partly explain cases of failure of adoption. We extend this analysis by considering information-theoretic criteria that link model complexity and relative performance and which might explain why users reject forecasters that impose even moderate increases in the complexity of decision making despite improvements in performance or accept very simple decision tools that have relatively poor performance.     

Understanding growers' decisions to manage invasive pathogens at the farm level

Globalization causes plant production systems to be increasingly threatened by invasive pests and pathogens. Much research is devoted to support management of these risks. Yet, the role of growers' perceptions and behavior in risk management has remained insufficiently analyzed. This article aims to fill this gap by addressing risk management of invasive pathogens from a sociopsychological perspective. An analytical framework based on the Theory of Planned Behavior was used to explain growers' decisions on voluntary risk management measures. Survey information from 303 Dutch horticultural growers was statistically analyzed, including regression and cluster analysis. It appeared that growers were generally willing to apply risk management measures, and that poor risk management was mainly due to perceived barriers, such as high costs and doubts regarding efficacy of management measures. The management measures applied varied considerably among growers, depending on production sector and farm-specific circumstances. Growers' risk perception was found to play a role in their risk management, although the causal relation remained unclear. These results underscore the need to apply a holistic perspective to farm level management of invasive pathogen risk, considering the entire package of management measures and accounting for sector- and farm-specific circumstances. Moreover, they demonstrate that invasive pathogen risk management can benefit from a multidisciplinary approach that incorporates growers' perceptions and behavior.     

Effect of cassava mosaic disease,soil fertility,plant spacing and their interactions on cassava yields in Zanzibar

Improvement of farmers' decision-making has been recognised as critical for the implementation of IPM, yet practitioners lack sound knowledge on the 'how and why' of farmers' decision-making processes. This study explored the perceptions, pest management practice, decision tools and sources of information of smallholder farmers growing cotton in India and vegetables in Kenya. Farmers trained under an Insecticide Resistance Management and two IPM Farmer Field School projects were compared with untrained farmers from the same localities, using individual interviews and participatory group analysis methods. Trained farmers' decision-making was enhanced, by the use of more decision tools and new sources of information and technologies and they were generally more confident in their pest management strategies than untrained farmers. As a result, trained farmers reduced their pest management costs but did not always obtain higher gross margins. Issues of gender, sustainability, economics and group action are discussed, along with recommendations for research and extension to take a closer look at farmers' decision-making processes in cash and subsistence crops.     

Communicating risk: variability of interpreting qualitative terms

A survey to examine how verbal expressions of probability and magnitude are interpreted was conducted at an international workshop on plant pest risk analysis. Participants were asked to score words and phrases on a scale of 0 to 100 giving minimum and maximum scores. Using hierarchical clustering, expressions describing probability were categorized into three clusters. One homogeneous cluster describes likely probabilities, a second describes unlikely probabilities and a third heterogeneous group contained words that express great uncertainty rather than committing to describe events as likely or unlikely. Hierarchical clustering was also used to group expressions of magnitude into three broad clusters that basically describe small, medium and large. Qualitative risk assessment protocols that prescribe words to represent probabilities and magnitudes should take into account how widely the words can be interpreted. It is suggested that linking verbal probability terms to specific quantitative probabilities would increase transparency and improve risk communication and risk management decision making.     

CAPRA: the EPPO Computer Assisted PRA scheme*

The EPPO Secretariat has developed computer software for Pest Risk Analysis (PRA) within the EC 7th Framework Programme PRATIQUE (Enhancements of Pest Risk Analysis Techniques) and with the support of the EPPO Panels. The software, Computer Assisted PRA (CAPRA), aims to assist pest risk analysts to run the EPPO Decision‐support scheme for pest risk analysis [EPPO Standard PM 5/3(5) Decision‐support scheme for quarantine pests], and other decision‐support schemes. It is freely avaliable on the EPPO website or on http://capra.eppo.org/ .     

Financial benefit of using crop protection decision rules over systematic spraying strategies

ABSTRACT Decision rule models are considered to be one of the main cornerstones of the implementation of integrated pest management (IPM) programs. Even if the need for such programs to offer cost advantages over conventional strategies is a major incentive for IPM adoption, few studies focus on this financial dimension. In this article, a modeling approach of the response of a pathosystem to a disease control method and of the predictive performance of decision rules is used to explore how some basic factors act on the likelihood of adoption of decision rule models strategies (such as using an IPM system) over systematic strategies (such as systematic-spraying and never-spraying strategies). Even if the average cost of using the decision rule strategies is always lower than the average cost of systematic strategies in several different scenarios, the models developed here showed strong effects of different pathosystems and decision rules on financial benefits. The number of production situations where decision rules are of interest is highly correlated with their accuracy. However, because of the inescapable trade-offs between decision rule accuracy and limiting factors such as its user-friendly characteristics, the use of decision rules is unlikely to reduce costs to <70% of the costs of systemic strategies. In more general terms, this study provides quantitative guidelines on the financial advantage that decision rules can offer in plant protection as well as a better understanding of their potential usefulness.     

植保有害生物风险分析理论体系的探讨

植保有害生物风险分析需要正确地收集大量数据。并急需建立实用的或可操作的有害生物风险分析体系，针对这种情况，本文将风险相关因素归纳为天气，地理和生物3大类，提出了有害生物的天气-地理-生物复合体系。该体系以生态网为出发点，对有害生物风险条件，事件及风险种类按层次和等级进行风险因子划分，然后进行风险因子模拟，风险分析和计算，实现有害生物的多因子调控管理。从而在风险分析，风险预测和风险决策的基础上，完成从风险确定，风险评价，风险管理到风险交流的风险全过程管理。     

Decision aids for multiple-decision disease management as affected by weather input errors

Many disease management decision support systems (DSSs) rely, exclusively or in part, on weather inputs to calculate an indicator for disease hazard. Error in the weather inputs, typically due to forecasting, interpolation, or estimation from off-site sources, may affect model calculations and management decision recommendations. The extent to which errors in weather inputs affect the quality of the final management outcome depends on a number of aspects of the disease management context, including whether management consists of a single dichotomous decision, or of a multi-decision process extending over the cropping season(s). Decision aids for multi-decision disease management typically are based on simple or complex algorithms of weather data which may be accumulated over several days or weeks. It is difficult to quantify accuracy of multi-decision DSSs due to temporally overlapping disease events, existence of more than one solution to optimizing the outcome, opportunities to take later recourse to modify earlier decisions, and the ongoing, complex decision process in which the DSS is only one component. One approach to assessing importance of weather input errors is to conduct an error analysis in which the DSS outcome from high-quality weather data is compared with that from weather data with various levels of bias and/or variance from the original data. We illustrate this analytical approach for two types of DSS, an infection risk index for hop powdery mildew and a simulation model for grass stem rust. Further exploration of analysis methods is needed to address problems associated with assessing uncertainty in multi-decision DSSs.     

IPM: Overcoming Conflicts in Adoption

The diversity of competing interests in North America provides a remarkable series of divergent messages to growers. Depending on what crop they produce or how they farm, they may be heroes or villains, loyal or unpatriotic, or stewards or ravagers of the environment. Even relatively minor changes in farming practices can result in significant public or political response. Considering that growers may risk 100% of their crop yield on a potential savings of 10% (or less) for investment in pesticides, it is not surprising that growers are slow to adopt IPM programs. Well-intentioned appeals to eliminate pesticides, or save the environment at all costs, are usually not effective. Likewise, a high failure rate can be expected from attempts to legislate IPM, implement programs that focus on only part of a pest complex, or adoption strategies that do not include on-farm testing and extensive educational efforts. However, some strategies have proven effective. Growers who have experienced loss of pesticides due to resistance are receptive to management programs which avoid or delay resistance. Many programs have been adopted piecemeal, starting with sampling programs followed by treatment thresholds and modified pesticide use. One of the most successful approaches has been an economic comparison of grower standard and IPM programs using partial budgets. Increased net profits provide powerful incentives for program adoption.     

Do some IPM concepts contribute to the development of fungicide resistance? Lessons learned from the apple scab pathosystem in the United States

One goal of integrated pest management (IPM) as it is currently practiced is an overall reduction in fungicide use in the management of plant disease. Repeated and long‐term success of the early broad‐spectrum fungicides led to optimism about the capabilities of fungicides, but to an underestimation of the risk of fungicide resistance within agriculture. In 1913, Paul Ehrlich recognized that it was best to ‘hit hard and hit early’ to prevent microbes from evolving resistance to treatment. This tenet conflicts with the fungicide reduction strategies that have been widely promoted over the past 40 years as integral to IPM. The authors hypothesize that the approaches used to implement IPM have contributed to fungicide resistance problems and may still be driving that process in apple scab management and in IPM requests for proposals. This paper also proposes that IPM as it is currently practiced for plant diseases of perennial systems has been based on the wrong model, and that conceptual shifts in thinking are needed to address the problem of fungicide resistance. © 2013 Society of Chemical Industry     

Model of the probability of pest transfer from imported fruit,cut flowers or vegetable produce

A Euphresco project funded by the UK and the Netherlands had the objective of developing practical tools to assess the risk of pest transfer to domestic production from an imported commodity and to help provide an improved rationale for reduced frequency of plant health inspection. A model is described which calculates the probability, following arrival, of the transfer of insect or mite pests up to and including first egg laying, from produce (cut flowers/branches, fruits and vegetables). In case studies, probabilities were estimated for alternative states of seven variables from which a joint probability of transfer was calculated. The probability estimates were subjective but informed estimates and the large differences between the cases examined may represent a more realistic picture of comparative transfer risk than more qualitative approaches.     

Guidance on resistance risk evaluation

Evaluation of the risks of the development of resistance by pests to plant protection products is part of the (re)-registration process and is the subject of an EPPO standard. This standard indicates data requirements and the factors to be considered in evaluating resistance risk, but it does not show in detail how all these factors interrelate and should be considered in their relationships. This paper presents a decision scheme approach, providing guidance in the evaluation of the available evidence. It may also be of assistance in judging the need for optional data as indicated in the EPPO standard. The decision scheme is an aid for qualitative evaluation of resistance risks of applications of plant protection products by means of risk ranking. It recognizes six risk categories, which may overlap to some extent and should not be interpreted as absolute values. Expert judgement is called for in answering the questions of the evaluation key, which is also presented in three different flow charts. Expert judgement means, in this case only, that the evaluation should not be done in a'tick-box manner', and does not imply that evaluation is for only the super-specialist on resistance. The evaluation always concerns a given plant protection product used in a given way. It is not possible to use this guidance document for active substances only.     

Integrated pest management in protected ornamentals in England1

During the past 2 years, there has been a rapid expansion of integrated pest management (IPM) in the ornamental sector of the glasshouse industry. Most of this expansion has resulted from improved availability of Amblyseius spp. for the control of thrips, although there is little information on the likelihood of success with this predator. IPM was done on 20 plant species on 21 nurseries in south-east England and there were many successes with crops that would normally receive intensive insecticide programmes to control thrips. Each plant species required its own IPM programme to be devised according to its pest complex. Techniques, particularly to monitor IPM, were devised and some staff were trained to assist in the monitoring. IPM is generally twice as expensive as routine insecticide programmes but has other advantages such as a safer environment for staff and better crop quality.     

Sampling plans,selective insecticides and sustainability: the case for IPM as ‘informed pest management’

Integrated Pest Management (IPM) is considered the central paradigm of insect pest management and is often characterized as a comprehensive use of multiple control tactics to reduce pest status while minimizing economic and environmental costs. As the principal precursor of IPM, the integrated control concept formulated the economic theory behind pest management decisions and specified an applied methodology for carrying out pest control. Sampling, economic thresholds and selective insecticides were three of the critical elements of that methodology and are now considered indispensable to the goals of IPM. We examine each of these elements in the context of contemporaneous information as well as accumulated experience and knowledge required for their skillful implementation in an IPM program. We conclude that while IPM is principally about integrating control tactics into an effective and sustainable approach to pest control, this overarching goal can only be achieved through well‐trained practitioners, knowledgeable of the tenets conceived in the integrated control concept that ultimately yield informed pest management. Copyright © 2009 Society of Chemical Industry     

Baseline toxicity and stage specificity of recently developed reduced‐risk insecticides chlorantraniliprole and spinetoram to obliquebanded leafroller,Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae)

BACKGROUND: Studies were designed to assess baseline toxicity of the two recently developed reduced‐risk insecticides chlorantraniliprole and spinetoram to obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris), and to determine stage‐specific effects of these products on OBLR, so that these new chemicals could be judiciously incorporated into IPM programs by targeting only the most susceptible stages of OBLR. RESULTS: Both chlorantraniliprole and spinetoram were highly effective against neonate OBLR larvae at much lower doses than conventional standard azinphosmethyl. Most of the mortality caused by spinetoram occurred during the 4 day exposure period, while significant delayed mortality was observed as a result of chlorantraniliprole treatment during the 7 day recovery period, indicating that chlorantraniliprole is a slower‐acting compound compared with spinetoram. Unlike broad‐spectrum predecessors, the toxicity of chlorantraniliprole significantly increased with larval age. Similarly, the toxicity of spinetoram increased as larvae grew from neonates to third instars. CONCLUSION: Chlorantraniliprole and spinetoram are highly effective against OBLR larvae, regardless of larval age. Incorporation of these reduced‐risk chemistries into IPM programs for OBLR would lead to effective management of this pest in tree fruit systems. Copyright © 2011 Society of Chemical Industry     

A web‐based decision support system to enhance IPM programs in Washington tree fruit

BACKGROUND: Integrated pest management (IPM) decision‐making has become more information intensive in Washington State tree crops in response to changes in pesticide availability, the development of new control tactics (such as mating disruption) and the development of new information on pest and natural enemy biology. The time‐sensitive nature of the information means that growers must have constant access to a single source of verified information to guide management decisions. RESULTS: The authors developed a decision support system for Washington tree fruit growers that integrates environmental data [140 Washington State University (WSU) stations plus weather forecasts from NOAA], model predictions (ten insects, four diseases and a horticultural model), management recommendations triggered by model status and a pesticide database that provides information on non‐target impacts on other pests and natural enemies. A user survey in 2008 found that the user base was providing recommendations for most of the orchards and acreage in the state, and that users estimated the value at $ 16 million per year. CONCLUSIONS: The design of the system facilitates education on a range of time‐sensitive topics and will make it possible easily to incorporate other models, new management recommendations or information from new sensors as they are developed. Copyright © 2010 Society of Chemical Industry     

AEP – Eine automatische Entscheidungshilfe-Software für den integrierten Pflanzenschutz

A decision support software for greenhouse plant protection has to meet several requirements in order to be accepted and applied by growers. It should comply with the different operational needs of growers and should be helpful for inexperienced growers but also optimize plant protection strategies for experienced ones. Additionally a large number of cultures and pests should be covered and implementation of new crops, beneficials, pests and insecticides must be easy. Also handling should be easy and time saving. All software parameters should be adaptable to grower specific needs. The program should not decide on the control regime but rather give recommendations and provide data storage to optimize plant protection strategies. Thereby learning effects are stimulated and motivation to adapt decision processes in plant protection practice is increased.In this article we show the structure of a decision support software (AEP—Automatische Entscheidungshilfe für den integrierten Pflanzenschutz unter Glas) and describe its functionality for the model system tomato (Solanum lycopersicum)–whitefly (Trialeurodes vaporariorum)–natural enemy (Encarsia formosa).     

The role of bacillus-based biological control agents in integrated pest management systems: plant diseases

ABSTRACT Bacillus-based biological control agents (BCAs) have great potential in integrated pest management (IPM) systems; however, relatively little work has been published on integration with other IPM management tools. Unfortunately, most research has focused on BCAs as alternatives to synthetic chemical fungicides or bactericides and not as part of an integrated management system. IPM has had many definitions and this review will use the national coalition for IPM definition: "A sustainable approach to managing pests by combining biological, cultural, physical and chemical tools in a way that minimizes economic, health and environmental risks." This review will examine the integrated use of Bacillus-based BCAs with disease management tools, including resistant cultivars, fungicides or bactericides, or other BCAs. This integration is important because the consistency and degree of disease control by Bacillus-based BCAs is rarely equal to the control afforded by the best fungicides or bactericides. In theory, integration of several tools brings stability to disease management programs. Integration of BCAs with other disease management tools often provides broader crop adaptation and both more efficacious and consistent levels of disease control. This review will also discuss the use of Bacillus-based BCAs in fungicide resistance management. Work with Bacillus thuringiensis and insect pest management is the exception to the relative paucity of reports but will not be the focus of this review.     

Ergebnisse aus 10 Jahren Untersuchungen zum notwendigen Maß im Netz Vergleichsbetriebe Pflanzenschutz

The reduction of risks associated with plant protection products is the main goal of the National Action Plan on sustainable use of plant protection products. One further goal is the use of plant protection products according to the necessary minimum. This aim serves also as an indicator with the target that 95% of pesticide applications are within the necessary minimum. For this purpose, the data from the Reference Farm Network on the intensity of pesticide use are assessed. With the current study we summarize the result for arable crops over the ten-year project period and investigate in detail the assessments from 2014 until 2016. The results show, that the majority of pesticide treatments are evaluated within the necessary minimum. Deviations occur especially for fungicide and insecticide treatments. Other factors, such as regional weather and pest or disease occurrence, production specific factors as well as farmers’ decision processes additionally influence the annual pesticide use intensity and the necessary minimum. Existing technologies, decision support systems and recommendations from advisory service should be better exploited in order to minimize those deviations.     

An operational risk assessment framework for a plant health diagnostic laboratory

The establishment of an operational risk assessment framework (ORAF) for effective management of risks is vital to any organization. An ORAF at the Ministry for Primary Industries (MPI) Plant Health and Environment Laboratory (PHEL), Auckland, New Zealand has identified the key risks in the laboratory operations and methods for mitigating and managing these risks. Ultimately, clear accountabilities have been set for risk management so that PHEL can maximize its ability to meet its strategic objectives and the wider goals of MPI. In addition, this framework provides an opportunity to affirm the effectiveness of the existing business process and continuously builds upon it to address gaps and also centralizes risk management information for staff. This study presents the steps that PHEL has undertaken to develop, implement and enhance its ORAF. The potential risks faced by plant diagnostic laboratories, planning of staff resources and development of the tools required to undertake risk assessment activities are included. This study also explains how the laboratory implements treatment plans, mitigates risk events and monitors and maintains the framework. Finally, this study explains some of the challenges faced by PHEL during the establishment of the ORAF.