Economics of invasive species policy and management

Considering unseen arrivals in predictions of establishment risk based on border biosecurity interceptions

Assessing species establishment risk is an important task used for informing biosecurity activities aimed at preventing biological invasions. Propagule pressure is a major contributor to the probability of invading species establishment; however, direct assessment of numbers of individuals arriving is virtually never possible. Inspections conducted at borders by biosecurity officials record counts of species (or higher-level taxa) intercepted during inspections, which can be used as proxies for arrival rates. Such data may therefore be useful for predicting species establishments, though some species may establish despite never being intercepted. We present a stochastic process-based model of the arrival-interception-establishment process to predict species establishment risk from interception count data. The model can be used to estimate the probability of establishment, both for species that were intercepted and species that had no interceptions during a given observation period. We fit the stochastic model to data on two insect families, Cerambycidae and Aphididae, that were intercepted and/or established in the United States or New Zealand. We also explore the effects of variation in model parameters and the inclusion of an Allee effect in the establishment probability. Although interception data sets contain much noise due to variation in inspection policy, interception effort and among-species differences in detectability, our study shows that it is possible to use such data for predicting establishments and distinguishing differences in establishment risk profile between taxonomic groups. Our model provides a method for predicting the number of species that have breached border biosecurity, including both species detected during inspections but also "unseen arrivals" that have never been intercepted, but have not yet established a viable population. These estimates could inform prioritization of different taxonomic groups, pathways or identification effort in biosecurity programs.

The emergence of prioritisation systems to inform plant health biosecurity policy decisions

The management of risk is fundamental to biosecurity. Potential pest risks must be recognised early, with appropriate measures taken to prevent or reduce the potential damage a non-native species can cause. Risk registers are a recognised tool to support risk management, especially in project management or governance of corporate risk. The use of risk registers and risk prioritisation systems in the plant health biosecurity sphere has emerged in recent years driven by the recognition that resources to assess pest risks in detail are scarce, and biosecurity actions need to be targeted and prioritised. Individual national plant protection organisations have consequently developed a variety of tools that prioritise and rank plant pests, typically taking likelihood of pest entry, establishment, spread and impact into account. They use expert opinion to give scores to risk elements within a framework of multi-criteria decision analysis to rank pests based on the prioritisation aims of users. Knowing that biosecurity extends beyond national borders we recognise that such systems would add value to global efforts to detect and share information on emerging pests to better target actions against pests to protect plant biosecurity.

Assessing the climate suitability and potential economic impacts of Oak wilt in Canada

We assess risks posed by oak wilt—a disease caused by the fungal pathogen Bretziella fagacearum. Though not currently found in Canada, our distribution models indicate that suitable climate conditions currently occur in southern Ontario for B. fagacearum and two of its main insect dispersal vectors, Colopterus truncatus and Carpophilus sayi. Climate habitat for these species is projected to expand northward under climate change, with much of the oak range in eastern Canada becoming climatically suitable within the next two decades. Potential costs for the removal and replacement of oak street trees ranged from CDN$266 to $420 million, with variation related to uncertainty in costs, rate of tree replacement, and city-level estimates of oak street tree density. The value of standing oak timber in eastern Canada was estimated at CDN$126 million using provincial stumpage fees and as a CDN$24 million annual contribution to national Gross Domestic Product (GDP) when calculated using a combination of economic and forestry product statistics. These values can help inform the scale of eradication and/or management efforts in the event of future oak wilt introductions.

Dung beetle species introductions: when an ecosystem service provider transforms into an invasive species

Dung beetle introduction programmes were designed to accelerate exotic livestock dung degradation and to control dung breeding pestiferous flies and livestock parasites. The introduction programmes provided exotic dung beetle species with an opportunity to cross natural barriers and spread beyond their native range. There are no reports that explain what probable adaptation mechanisms enable particular dung beetle species to be the most successful invader. Here we identify the morphological, biological, physiological, ecological and behavioural attributes of the four most widespread and successful dung beetle species in introduced areas on a global scale in relation to the assumption that these species are different from other exotic and native dung beetles. We have recognised Digitonthophagus gazella (Fabricius), Onthophagus taurus (Schreber), Euoniticellus intermedius (Reiche) and Aphodius fimetarius (Linnaeus) as the most successful invaders based on their spread, predominance, distribution range and the reports of invasion. Each of these four species has different natural history traits that increase their fitness making them successful invaders. D. gazella has high fecundity and spreading ability, can instantly locate and colonise fresh and nutritious dung, and has a broad thermal window. O. taurus has morphological plasticity, high fecundity, high brood survival rate due to bi-parenting, and is adapted to extreme thermal and moisture conditions. E. intermedius has remnant-dung feeding abilities, a wide thermal window, functioning best at upper-temperature levels, and successful breeding and survival abilities at extremely low soil moisture conditions. A. fimetarius is small-sized, has high breeding and dispersal abilities, and is adapted to lower thermal and upper moisture extremes and variable soil conditions. Discussed here are perspectives on adaptive attributes of dung beetle species that are important to consider during their selection for redistributions. We have elaborated on the fitness and success characteristics of the four species individually. Further, we recommend a prior-introduction baseline monitoring of native dung beetle assemblages so as to evaluate the future impact of exotic dung beetle introductions on the recipient ecosystem.

CONTAIN: Optimising the long-term management of invasive alien species using adaptive management

Invasive Alien Species (IAS) threaten biodiversity, ecosystem functions and services, modify landscapes and impose costs to national economies. Management efforts are underway globally to reduce these impacts, but little attention has been paid to optimising the use of the scarce available resources when IAS are impossible to eradicate, and therefore population reduction and containment of their advance are the only feasible solutions.

CONTAIN, a three-year multinational project involving partners from Argentina, Brazil, Chile and the UK, started in 2019. It develops and tests, via case study examples, a decision-making toolbox for managing different problematic IAS over large spatial extents. Given that vast areas are invaded, spatial prioritisation of management is necessary, often based on sparse data. In turn, these characteristics imply the need to make the best decisions possible under likely heavy uncertainty.

Our decision-support toolbox will integrate the following components:

(i) the relevant environmental, social, cultural, and economic impacts, including their spatial distribution;

(ii) the spatio-temporal dynamics of the target IAS (focusing on dispersal and population recovery);

(iii) the relationship between the abundance of the IAS and its impacts;

(iv) economic methods to estimate both benefits and costs to inform the spatial prioritisation of cost-effective interventions.

To ensure that our approach is relevant for different contexts in Latin America, we are working with model species having contrasting modes of dispersal, which have large environmental and/or economic impacts, and for which data already exist (invasive pines, privet, wasps, and American mink). We will also model plausible scenarios for data-poor pine and grass species, which impact local people in Argentina, Brazil and Chile.

We seek the most effective strategic management actions supported by empirical data on the species’ population dynamics and dispersal that underpin reinvasion, and on intervention costs in a spatial context. Our toolbox serves to identify key uncertainties driving the systems, and especially to highlight gaps where new data would most effectively reduce uncertainty on the best course of action. The problems we are tackling are complex, and we are embedding them in a process of co-operative adaptive management, so that both researchers and managers continually improve their effectiveness by confronting different models to data. Our project is also building research capacity in Latin America by sharing knowledge/information between countries and disciplines (i.e., biological, social and economic), by training early-career researchers through research visits, through our continuous collaboration with other researchers and by training and engaging stakeholders via workshops. Finally, all these activities will establish an international network of researchers, managers and decision-makers. We expect that our lessons learned will be of use in other regions of the world where complex and inherently context-specific realities shape how societies deal with IAS.

Early warning systems in biosecurity; translating risk into action in predictive systems for invasive alien species

Invasive alien species (IAS) are one of the most severe threats to biodiversity and are the subject of varying degrees of surveillance activity. Predictive early warning systems (EWS), incorporating automated surveillance of relevant dataflows, warning generation and dissemination to decision makers are a key target for developing effective management around IAS, alongside more conventional early detection and horizon scanning technologies. Sophisticated modelling frameworks including the definition of the ‘risky’ species pool, and pathway analysis at the macro and micro-scale are increasingly available to support decision making and to help prioritise risks from different regions and/or taxa. The main challenges in constructing such frameworks, to be applied to border inspections, are (i) the lack of standardisation and integration of the associated complex digital data environments and (ii) effective integration into the decision making process, ensuring that risk information is disseminated in an actionable way to frontline surveillance staff and other decision makers. To truly achieve early warning in biosecurity requires close collaboration between developers and end-users to ensure that generated warnings are duly considered by decision makers, reflect best practice, scientific understanding and the working environment facing frontline actors. Progress towards this goal will rely on openness and mutual understanding of the role of EWS in IAS risk management, as much as on developments in the underlying technologies for surveillance and modelling procedures.

Hitchhikers on floats to Arctic freshwater: Private aviation and recreation loss from aquatic invasion

This study of aviation-related recreation loss shows that a survey primarily aimed at collecting information on invasive species' pathways can also be used to estimate changes in pathway-related ecosystem services. We present a case study for Elodea spp. (elodea), Alaska's first known aquatic invasive plant, by combining respondents' stated pre-invasion actual flights with stated post-invasion contingent behavior, plane operating costs, and site quality data. We asked pilots about the extent of continued flights should destinations become invaded and inhibit flight safety. We estimate a recreation demand model where the lost trip value to the average floatplane pilot whose destination is an elodea-invaded lake is US$185 (95 % CI $157, $211). Estimates of ecosystem damages incurred by private actors responsible for transmitting invaders can nudge actors to change behavior and inform adaptive ecosystem management. The policy and modeling implications of quantifying such damages and integration into more complex models are discussed.

Pathologists and entomologists must join forces against forest pest and pathogen invasions

The world’s forests have never been more threatened by invasions of exotic pests and pathogens, whose causes and impacts are reinforced by global change. However, forest entomologists and pathologists have, for too long, worked independently, used different concepts and proposed specific management methods without recognising parallels and synergies between their respective fields. Instead, we advocate increased collaboration between these two scientific communities to improve the long-term health of forests.

Our arguments are that the pathways of entry of exotic pests and pathogens are often the same and that insects and fungi often coexist in the same affected trees. Innovative methods for preventing invasions, early detection and identification of non-native species, modelling of their impact and spread and prevention of damage by increasing the resistance of ecosystems can be shared for the management of both pests and diseases.

We, therefore, make recommendations to foster this convergence, proposing in particular the development of interdisciplinary research programmes, the development of generic tools or methods for pest and pathogen management and capacity building for the education and training of students, managers, decision-makers and citizens concerned with forest health.

Analysis of Recent Interception Records Reveals Frequent Transport of Arboreal Ants and Potential Predictors for Ant Invasion in Taiwan

We uncovered taxonomic diversity, country of origin and commodity type of intercepted ants at Taiwanese borders based on an 8 year database of 439 interception records. We found intercepted ants arrived predominantly via timber, a pattern likely reflecting the high domestic demand for foreign timber in Taiwan. The most frequently intercepted species were either arboreal or wood-dwelling ants, raising a concern of these ants constituting a next wave of ant invasion in Taiwan. Further analyses indicate that the taxonomic composition of intercepted ants does not match that of established non-native ant species, suggesting that interception data alone fails to provide adequate power to predict the establishment success of ants. Yet, interception frequency and selected life-history traits (i.e., flexible colony founding mode and general nesting habits) were shown to jointly serve as a practical predictor of the establishment risk of non-native ants. Consistent with other border interception databases, secondary introduction (i.e., species arriving from their introduced ranges instead of their native ranges) also represents a major pathway for transport of invasive ants into Taiwan, suggesting its role in shaping the global invasion of ants. Our findings offer baseline information for constructing a prediction framework for future ant invasions and assist in the decision-making process of quarantine authorities in Taiwan.

A Real-Time PCR Assay for Rapid Identification of Tuta absoluta (Lepidoptera: Gelechiidae)

The tomato leafminer, Tuta absoluta (Meyrick), is a highly destructive pest of tomatoes, causing damage to leaves, stalks, buds, and fruits. Native to South America, T. absoluta is now found throughout Europe, South Asia, Africa, parts of Central America, and the Caribbean. Adults are small, with a wingspan of approximately one cm and lack distinctive markings, making morphological identification difficult. Larvae are also difficult to identify and resemble those of many other gelechiids. Due to the extensive time spent and expertise required for morphological identification, and the imminent threat to the North American tomato crop, we have developed a rapid molecular test for discriminating individual specimens of T. absoluta using a probe-based real-time polymerase chain reaction (PCR) assay. The assay is able to quickly distinguish T. absoluta from similar-sized moth specimens that are attracted to T. absoluta pheromone lures in the United States and is also able to identify larvae of T. absoluta. Decreased identification time for this critical pest will lead to more rapid identification at ports of entry and allow for more efficient trap screening for domestic monitoring programs.

Communicating with the Public about Emerald Ash Borer: Militaristic and Fatalistic Framings in the News Media

Invasive species can spread to new landscapes through various anthropogenic factors and negatively impact urban ecosystems, societies, and economies. Public awareness is considered central to mitigating the spread of invasive species. News media contributes to awareness although it is unclear what messages are being communicated. We incorporated Frame Theory to investigate newspapers’ coverage of the emerald ash borer (EAB; Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)), which has killed millions of ash trees in the continental United States. We conducted a content analysis of 924 news articles published between 2002 and 2017 to examine language framing (how a phenomenon like invasive species is constructed and communicated), information sources, management methods, recommended actions for the public and whether this communication changed overtime. Seventy-seven percent of articles used language evocative of distinctive risk framings, with the majority of these using negative attribute frames like invasion-militaristic and/or fatalistic language to describe EAB management. Few discussed positive impacts like galvanizing public support. Most articles used expert sources, primarily government agents. We recommend that public communications regarding invasive species be cautious about language evoking militarism and fatalism. Furthermore, invasive species communication requires a broader diversity and representation of voices because invasive species management requires community effort.

Control of Invasive Forest Species through the Creation of a Value Chain: Acacia dealbata Biomass Recovery

In Portugal, some species are now considered invasive by law and have proliferated in recent years. Among these, Acacia dealbata stands out. This work investigated the behavior of this species, in order to characterize and evaluate its potential as raw material for biomass pellets production, while controlling its proliferation. It was found that A. dealbata has a large capacity for raw material supply, as cutting 2 ha resulted in about 140 tons of biomass. Thus, the attribution of a market value for this material could result in a reduction in the area occupied by the invasive species, once the demand for it increases, causing a pressure over the resource. This pressure on the species must be duly followed by other control measures, such as reducing the population and mitigating its proliferation. Laboratory tests have shown that both the raw material and the finished product are similar to those obtained with other species normally used for biomass pellet production, such as Pinus pinaster and Eucalyptus globulus. Thus, it can be concluded that there is a high potential for this species in the production of biomass pellets for energy, and that this may be an important contribution to controlling the proliferation of this invasive species.

Applying optimal control theory to complex epidemiological models to inform real-world disease management

Mathematical models provide a rational basis to inform how, where and when to control disease. Assuming an accurate spatially explicit simulation model can be fitted to spread data, it is straightforward to use it to test the performance of a range of management strategies. However, the typical complexity of simulation models and the vast set of possible controls mean that only a small subset of all possible strategies can ever be tested. An alternative approach-optimal control theory-allows the best control to be identified unambiguously. However, the complexity of the underpinning mathematics means that disease models used to identify this optimum must be very simple. We highlight two frameworks for bridging the gap between detailed epidemic simulations and optimal control theory: open-loop and model predictive control. Both these frameworks approximate a simulation model with a simpler model more amenable to mathematical analysis. Using an illustrative example model, we show the benefits of using feedback control, in which the approximation and control are updated as the epidemic progresses. Our work illustrates a new methodology to allow the insights of optimal control theory to inform practical disease management strategies, with the potential for application to diseases of humans, animals and plants. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'. This theme issue is linked with the earlier issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'.

Quantifying the social and economic benefits of the biological control of invasive alien plants in natural ecosystems

Invasive alien plants reduce ecosystem service delivery, resulting in environmental, economic and social costs. Here we review the returns on investment from biological control of alien plants that invade natural ecosystems. Quantifying the economic benefits of biological control requires estimates of the reductions in ecosystem goods and services arising from invasion. It also requires post-release monitoring to assess whether biological control can restore them, and conversion of these estimates to monetary values, which has seldom been done. Past studies, mainly from Australia and South Africa, indicate that biological control delivers positive and substantial returns on investment, with benefit:cost ratios ranging from 8:1 to over 3000:1. Recent studies are rare, but they confirm that successful biological control delivers attractive returns on investment, which increase over time as the value of avoided impacts accumulates.

The invasive forest pathogen Hymenoscyphus fraxineus boosts mortality and triggers niche replacement of European ash (Fraxinus excelsior)

Determining the impacts of invasive pathogens on tree mortality and growth is a difficult task, in particular in the case of species occurring naturally at low frequencies in mixed stands. In this study, we quantify such effects by comparing national forest inventory data collected before and after pathogen invasion. In Norway, Fraxinus excelsior is a minor species representing less than 1% of the trees in the forests and being attacked by the invasive pathogen Hymenoscyphus fraxineus since 2006. By studying deviations between inventories, we estimated a 74% higher-than-expected average ash mortality and a 13% slower-than-expected growth of the surviving ash trees, indicating a lack of compensation by the remaining ash. We could confidently assign mortality and growth losses to ash dieback as no mortality or growth shifts were observed for co-occurring tree species in the same plots. The mortality comparisons also show regional patterns with higher mortality in areas with the longest disease history in Norway. Considering that ash is currently mostly growing in mixed forests and that no signs of compensation were observed by the surviving ash trees, a significant habitat loss and niche replacement could be anticipated in the mid-term.

Capacity of United States federal government and its partners to rapidly and accurately report the identity (taxonomy) of non-native organisms intercepted in early detection programs

The early detection of and rapid response to invasive species (EDRR) depends on accurate and rapid identification of non-native species. The 2016–2018 National Invasive Species Council Management Plan called for an assessment of US government (federal) capacity to report on the identity of non-native organisms intercepted through early detection programs. This paper serves as the response to that action item. Here we summarize survey-based findings and make recommendations for improving the federal government’s capacity to identify non-native species authoritatively in a timely manner. We conclude with recommendations to improve accurate identification within the context of EDRR by increasing coordination, maintaining taxonomic expertise, creating an identification tools clearinghouse, developing and using taxonomic standards for naming and identification protocols, expanding the content of DNA and DNA Barcode libraries, ensuring long-term sustainability of biological collections, and engaging and empowering citizens and citizen science groups.

Distribution and Risk Assessment of Potential Invasiveness of Australoheros facetus (Jenyns, 1842) in Portugal

Invasive species are recognized as a major cause of biodiversity decline. Legal regulations relating to the prevention, control, or eradication of invasive species should always be up-to-date, as the failure to recognize the problem, lack of adequate scientific information, or long legal intervals required to prepare the legislation may result in irreversible, possibly catastrophic, outcomes. This implies constant monitoring of the species distribution and levels of establishment, as well as detailed knowledge about its biology to predict dissemination and viability under changing environmental conditions. Pre-screening kits for potential invasive species are valuable tools for policy makers, as they provide information about if and how management measures should be taken. The Freshwater Fish Invasiveness Scoring Kit (FISK) and the Aquatic Species Invasiveness Screening Kit (AS-ISK) have been suggested as reliable tools to assess the potential risk of a species becoming invasive. The present study highlights the spread of the non-native chameleon cichlid Australoheros facetus in several streams of the major river drainages in southern Portugal and compares the fish assemblages and ecological indices in two selected sites in the Vascão and Odelouca rivers. We reviewed the current knowledge on the distribution, physiology, and behavior of A. facetus, and applied the toolkits FISK v2 and AS-ISK to this species to evaluate whether the species should be classified as invasive in Portugal. Field data show high abundance of the species in most streams and dominance in specific hotspots. The scores reached by the kits (FISK v2: 23; AS-ISK: 37) places A. facetus as a species with high potential of invasiveness and support the recent inclusion of this species in the invasive species list in Portugal (Decree-Law 92/2019), but, most of all, highlights the importance of frequent updates in both the field monitoring and the legal regulation and watch lists of invasive organisms.

Historical, Ethical, and (Extra)legal Perspectives on Culpability in Accidental Species Introductions

Some nonnative species benefit humans, but many become invasive, with high economic, cultural, and ecological costs. Although many introductions are considered accidental, inadvertent, or unintentional, this terminology often cannot be justified. Prevention policies have been proposed or implemented, and a diversity of proven control methods is available, but invasion problems grow, largely because feasible policy and management approaches are not implemented. The lack of action reflects willful myopia, a decision not to act because of negligence by policymakers, managers, and individuals. We explore the multidimensional ethical implications of this view and propose a continuum of ethical hazard. We relate the ethical dimensions to legal aspects of culpability and suggest a possible cutoff for legal liability. Finally, we identify four components of a desired policy response: It must ensure legal authority for action, base policy response on market forces, assure that more than simplistic economic considerations underpin decisions, and better engage the public.

Landscape beauty: A wicked problem in sustainable ecosystem management?

Recent discourses on sustainable ecosystem management have increasingly emphasized the importance of bundling relationships and interactions among multiple ecosystem services supported by similar natural and anthropogenic mechanisms within the total environment. Yet, the aesthetic benefits of ecosystems, playing critical role in management of both wild and anthropogenic landscapes, have been under-represented in these discussions. This disregard contributes to the disconnection between environmental science and practice and limits our understanding of ecological and societal implications of management decisions that either generate aesthetic benefits or impact them while targeting other ecosystem services. This discussion reviews several "wicked problems" that arise due to such limited understanding, focusing on three recognized challenges in present-day ecosystem management: replacement of natural ecosystem functions, spatial decoupling of service beneficiaries from its environmental consequences and increasing inequalities in access to services. Strategies towards solutions to such wicked challenges are also discussed, capitalizing on the potential of innovative landscape design, cross-disciplinary research and collaboration, and emerging economic and policy instruments.

Applying optimal control theory to complex epidemiological models to inform real-world disease management

Mathematical models provide a rational basis to inform how, where and when to control disease. Assuming an accurate spatially explicit simulation model can be fitted to spread data, it is straightforward to use it to test the performance of a range of management strategies. However, the typical complexity of simulation models and the vast set of possible controls mean that only a small subset of all possible strategies can ever be tested. An alternative approach-optimal control theory-allows the best control to be identified unambiguously. However, the complexity of the underpinning mathematics means that disease models used to identify this optimum must be very simple. We highlight two frameworks for bridging the gap between detailed epidemic simulations and optimal control theory: open-loop and model predictive control. Both these frameworks approximate a simulation model with a simpler model more amenable to mathematical analysis. Using an illustrative example model, we show the benefits of using feedback control, in which the approximation and control are updated as the epidemic progresses. Our work illustrates a new methodology to allow the insights of optimal control theory to inform practical disease management strategies, with the potential for application to diseases of humans, animals and plants. This article is part of the theme issue 'Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control'. This theme issue is linked with the earlier issue 'Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes'.

How to Manage Kidney Transplant Recipients: Deciding Between Glomerular Filtration Rate-Estimating Equations, Creatinine Clearance and Albumin-Creatinine Ratio, or Albumin Excretion

OBJECTIVES

Management of renal transplant recipients involves measuring glomerular filtration rate and albuminuria; however, data are conflicting on the use of estimating equations or creatinine clearance and albumin-creatinine ratio in early morning urine or albumin excretion in 24-hour urine. We aimed to determine the performance of creatinine clearance and 3 estimated creatinine-based formulas and compare the usefulness of albumin-creatinine ratio related to albumin excretion in kidney transplant patients.

MATERIALS AND METHODS

This cross-sectional study examined 300 consecutive kidney transplant patients. Serum creatinine was measured with Cobas-8000 and albumin-creatinine ratio, and albumin excretion was measured with Cobas-C311 (Roche Diagnostics, Hitachi, Tokyo, Japan). We quantified bias and percent bias, Bland-Altman results, and concordances in the classification of chronic kidney disease between formulas and creatinine clearance. We also conducted linear regression analyses of all parameters and for cutoffs of 30 and 300 mg/24 hours and determined the ability of albumin-creatinine ratio to predict abnormal albumin excretion (receiver operator characteristic curve analysis).

RESULTS

Bias (mL/min/1.73 m2), percent bias, and concordances between creatinine clearance and Cockcroft-Gault, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology Colla-boration formulas in the classification of chronic kidney disease were as follows: 15.89, 20.91%, and 0.35; 20.52, 27.89%, and 0.21; and 18.24, 25.39%, and 0.27, respectively. Regression analyses showed a weak but significantly linear relationship for the cutoff values (P < .001). Receiver operator characteristic curve analyses showed areas under the curve of 0.957 and 0.997 at cutoffs of 30 and 300 mg/24 hours. In our patients, the cutoffs were 27 mg/g (88.38% sensitivity, 92.16% specificity) and 238 mg/g (80.00% sensitivity, 97.45% specificity).

CONCLUSIONS

We suggest using estimating equations and albumin-creatinine ratio with caution. In routine management of patients with successive stable revisions, we recommended using the Cockcroft-Gault or Chronic Kidney Disease Epidemiology Collaboration formulas and albumin-creatinine ratio.

Managing invasive species

Invasive species pose considerable harm to native ecosystems and biodiversity and frustrate and at times fascinate the invasive species management and scientific communities. Of the numerous non-native species established around the world, only a minority of them are invasive and noxious, whereas the majority are either benign or in fact beneficial. Agriculture in North America, for example, would look dramatically different if only native plants were grown as food crops and without the services of the European honey bee as a pollinator. Yet the minority of species that are invasive negatively alter ecosystems and reduce the services they provide, costing governments, industries, and private citizens billions of dollars annually. In this review, I briefly review the consequences of invasive species and the importance of remaining vigilant in the battle against them. I then focus on their management in an increasingly connected global community.

Livestock Disease Management for Trading Across Different Regulatory Regimes

The maintenance of livestock health depends on the combined actions of many different actors, both within and across different regulatory frameworks. Prior work recognised that private risk management choices have the ability to reduce the spread of infection to trading partners. We evaluate the efficiency of farmers' alternative biosecurity choices in terms of their own-benefits from unilateral strategies and quantify the impact they may have in filtering the disease externality of trade. We use bovine viral diarrhoea (BVD) in England and Scotland as a case study, since this provides an example of a situation where contrasting strategies for BVD management occur between selling and purchasing farms. We use an agent-based bioeconomic model to assess the payoff dependence of farmers connected by trade but using different BVD management strategies. We compare three disease management actions: test-cull, test-cull with vaccination and vaccination alone. For a two-farm trading situation, all actions carried out by the selling farm provide substantial benefits to the purchasing farm in terms of disease avoided, with the greatest benefit resulting from test-culling with vaccination on the selling farm. Likewise, unilateral disease strategies by purchasers can be effective in reducing disease risks created through trade. We conclude that regulation needs to balance the trade-off between private gains from those bearing the disease management costs and the positive spillover effects on others.

A Framework for Optimizing Phytosanitary Thresholds in Seed Systems

Seedborne pathogens and pests limit production in many agricultural systems. Quarantine programs help prevent the introduction of exotic pathogens into a country, but few regulations directly apply to reducing the reintroduction and spread of endemic pathogens. Use of phytosanitary thresholds helps limit the movement of pathogen inoculum through seed, but the costs associated with rejected seed lots can be prohibitive for voluntary implementation of phytosanitary thresholds. In this paper, we outline a framework to optimize thresholds for seedborne pathogens, balancing the cost of rejected seed lots and benefit of reduced inoculum levels. The method requires relatively small amounts of data, and the accuracy and robustness of the analysis improves over time as data accumulate from seed testing. We demonstrate the method first and illustrate it with a case study of seedborne oospores of Peronospora effusa, the causal agent of spinach downy mildew. A seed lot threshold of 0.23 oospores per seed could reduce the overall number of oospores entering the production system by 90% while removing 8% of seed lots destined for distribution. Alternative mitigation strategies may result in lower economic losses to seed producers, but have uncertain efficacy. We discuss future challenges and prospects for implementing this approach.