Global threat to agriculture from invasive species

The Relationship between Fungal Diversity and Invasibility of a Foliar Niche-The Case of Ash Dieback

European ash (Fraxinus excelsior) is threatened by the invasive ascomycete Hymenoscyphus fraxineus originating from Asia. Ash leaf tissues serve as a route for shoot infection but also as a sporulation substrate for this pathogen. Knowledge of the leaf niche partitioning by indigenous fungi and H. fraxineus is needed to understand the fungal community receptiveness to the invasion. We subjected DNA extracted from unwashed and washed leaflets of healthy and diseased European ash to PacBio sequencing of the fungal ITS1-5.8S-ITS2 rDNA region. Leaflets from co-inhabiting rowan trees (Sorbus aucuparia) served as a reference. The overlap in leaflet mycobiomes between ash and rowan was remarkably high, but unlike in rowan, in ash leaflets the sequence read proportion, and the qPCR-based DNA amount estimates of H. fraxineus increased vigorously towards autumn, concomitant with a significant decline in overall fungal richness. The niche of ash and rowan leaves was dominated by epiphytic propagules (Vishniacozyma yeasts, the dimorphic fungus Aureobasidion pullulans and the dematiaceous hyphomycete Cladosporium ramotenellum and H. fraxineus), and endophytic thalli of biotrophs (Phyllactinia and Taphrina species), the indigenous necrotroph Venturia fraxini and H. fraxineus. Mycobiome comparison between healthy and symptomatic European ash leaflets revealed no significant differences in relative abundance of H. fraxineus, but A. pullulans was more prevalent in symptomatic trees. The impacts of host specificity, spatiotemporal niche partitioning, species carbon utilization profiles and life cycle traits are discussed to understand the ecological success of H. fraxineus in Europe. Further, the inherent limitations of different experimental approaches in the profiling of foliicolous fungi are addressed.

Gumming Up The Works: Field Tests of a New Food-Grade Gum as Behavioral Disruptor for Drosophila suzukii (Diptera: Drosophilidae)

Drosophila suzukii Matsumura is an economically important pest of small and stone fruits. Its establishment in the Americas and Europe marked an important turning point in crop management programs. Ten years after its first detection, an effective integrated pest management program has yet to be developed and pesticides are mainly used to control this pest. Here we test a new behavioral control tool, with the aim to develop an alternative pest control strategy. A food-grade gum matrix, was evaluated under controlled and open field conditions for its ability to attract the pest and protect the ripening fruit. Here, we report that the gum effectively reduces fruit infestation when used under managed conditions. We show that a single point source can affect D. suzukii behavior over a 3.6 m radius and last for up to 21 d. Open field data reveal that the efficacy of the gum is significantly impacted by water content. We discuss these results in respect to the future implications for D. suzukii management, along with important considerations on gum mechanism of action, possible application strategies and economic suitability for growers.

Comparison and Refinement of Integrated Pest Management Tactics for Halyomorpha halys (Hemiptera: Pentatomidae) Management in Apple Orchards

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) has been managed primarily with broad-spectrum insecticides in orchard systems. Recently, IPM techniques have been developed specifically for managing H. halys in apple orchards to reduce insecticide inputs and take advantage of its perimeter-driven behavior. In 2015 and 2016, we compared these IPM tactics to one another and an untreated control to measure differences in overall crop protection and insecticide inputs. Tactics included trap-based threshold-triggered spray applications, perimeter-based attract-and-kill (AK) trees treated every 7- and 14-d, and perimeter spray applications applied every 7- and 14-d. All plots were monitored with baited black pyramid traps deployed in plot interiors. In both years, mean number of H. halys captured in untreated control plot traps was significantly greater than plots managed using IPM tactics. In 2015, significantly more insecticide applications were made in 7- and 14-d perimeter and AK plots compared with trap-based threshold plots. There was no significant difference in the percentage of injured fruit in plot interiors among IPM tactics; all were significantly lower than the control. In 2016, significantly more insecticide applications were made in 7-d perimeter spray and AK plots compared with all other treatments. Significantly less injury was detected in plot interiors for 7- and 14-d perimeter and trap-based threshold plots compared with the control and 7- and 14-d AK plots. Although all IPM tactics reduced H. halys injury in apples using a trap-based treatment threshold required fewer insecticide inputs and only during brief periods of the season, while all others required season-long maintenance.

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.

Unsung heroes: fixing multifaceted sustainability challenges through insect biological control

Insects are indispensable actors within global agri-food systems and ensure the delivery of myriad ecosystem services. A progressive decline in insect numbers - as inflicted by habitat loss, pollution or intensive agriculture - can jeopardize a sustained provisioning of those services. Though we routinely disregard how insects help meet multiple sustainable development challenges, a gradual insect decline can have grave, long-lasting consequences. Here, we describe how insect-mediated biological control not only defuses invasive pests and can reconstitute crop productivity, but equally delivers other positive social-ecological outcomes. Drawing upon the pan-tropical invasion of the cassava mealybug and its ensuing suppression by the monophagous parasitoid Anagyrus lopezi, we illuminate how biological control contributes to food security, poverty alleviation, human wellbeing and environmental preservation. Trans-disciplinary research and 'systems thinking' are needed to maximize the potential of these biodiversity-driven interventions, and thus reap the net positive spin-offs insects provide for farmers, the environment and human society.

Current and future spatial assessment of biological control as a mechanism to reduce economic losses and carbon emissions: the case of Solanum sisymbriifolium in Africa

BACKGROUND

Solanum sisymbriifolium is a native plant of South America introduced into Africa, which has detrimental effects on crop yields, and on the environment due to weed control treatment by burning. In South America, S. sisymbriifolium is naturally controlled by the beetle Gratiana spadicea, making this a potential option for its control in Africa. Here, we aim to generate current and future scenarios for the introduction of G. spadicea as a biocontrol agent in Africa, analysing: (i) current and future effective biocontrol areas; (ii) potentially avoided economic losses (AEL), and chemical control costs and savings; and (iii) avoided carbon emissions (ACE) associated with the non-burning of crop fields. We combine species distribution models (SDM) with land cover maps to estimate current and future effective biocontrol considering Representative Concentration Pathways (RCP) 4.5 and 8.5 climate change scenarios. We then estimate AEL and ACE using biocontrol, and chemical control costs and savings.

RESULTS

The effective biocontrol area reached 392 405 km² in 18 countries, representing 40% of potentially affected croplands. Climate change induced a decrease in affected croplands and effective biocontrol. The estimated AEL reached US$45 447.2 ± 5617.3 billion distributed across 16 countries, while the estimated chemical control costs and savings reached US$1988.5 billion and 1411.8 billion, respectively. Potential ACE reached 36.3 ± 5.4 Tg.

CONCLUSIONS

Our study provides evidence for the potential benefits of biological controllers on economic losses and carbon emissions, which can be incorporated into sustainable development in low-income countries.

Landscape structure and climate drive population dynamics of an insect vector within intensely managed agroecosystems

Characterizing factors affecting insect pest populations across variable landscapes is a major challenge for agriculture. In natural ecosystems, insect populations are strongly mediated by landscape and climatic factors. However, it has proven difficult to evaluate if similar factors predict pest dynamics in agroecosystems because control tactics exert strong confounding effects. We addressed this by assessing whether species distribution models could effectively characterize dynamics of an insect pest in intensely managed agroecosystems. Our study used a regional multi-year data set to assess landscape and climatic drivers of potato psyllid (Bactericera cockerelli) populations, which are often subjected to calendar-based insecticide treatments because they transmit pathogens to crops. Despite this, we show that psyllid populations were strongly affected by landscape and climatic factors. Psyllids were more abundant in landscapes with high connectivity, low crop diversity, and large natural areas. Psyllid population dynamics were also mediated by climatic factors, particularly precipitation and humidity. Our results show that many of the same factors that drive insect population dynamics in natural ecosystems can have similar effects in an intensive agroecosystem. More broadly, our study shows that models incorporating landscape and climatic factors can describe pest populations in agroecosystems and may thus promote more sustainable pest management.

Seasonal polyphenism of spotted-wing Drosophila is affected by variation in local abiotic conditions within its invaded range, likely influencing survival and regional population dynamics

Overwintering Drosophila often display adaptive phenotypic differences beneficial for survival at low temperatures. However, it is unclear which morphological traits are the best estimators of abiotic conditions, how those traits are correlated with functional outcomes in cold tolerance, and whether there are regional differences in trait expression.We used a combination of controlled laboratory assays, and collaborative field collections of invasive Drosophila suzukii in different areas of the United States, to study the factors affecting phenotype variability of this temperate fruit pest now found globally.Laboratory studies demonstrated that winter morph (WM) trait expression is continuous within the developmental temperature niche of this species (10-25°C) and that wing length and abdominal melanization are the best predictors of the larval abiotic environment.However, the duration and timing of cold exposure also produced significant variation in development time, morphology, and survival at cold temperatures. During a stress test assay conducted at -5°C, although cold tolerance was greater among WM flies, long-term exposure to cold temperatures as adults significantly improved summer morph (SM) survival, indicating that these traits are not controlled by a single mechanism.Among wild D. suzukii populations, we found that regional variation in abiotic conditions differentially affects the expression of morphological traits, although further research is needed to determine whether these differences are genetic or environmental in origin and whether thermal susceptibility thresholds differ among populations within its invaded range.

Scientists' warning on invasive alien species

Biological invasions are a global consequence of an increasingly connected world and the rise in human population size. The numbers of invasive alien species – the subset of alien species that spread widely in areas where they are not native, affecting the environment or human livelihoods – are increasing. Synergies with other global changes are exacerbating current invasions and facilitating new ones, thereby escalating the extent and impacts of invaders. Invasions have complex and often immense long‐term direct and indirect impacts. In many cases, such impacts become apparent or problematic only when invaders are well established and have large ranges. Invasive alien species break down biogeographic realms, affect native species richness and abundance, increase the risk of native species extinction, affect the genetic composition of native populations, change native animal behaviour, alter phylogenetic diversity across communities, and modify trophic networks. Many invasive alien species also change ecosystem functioning and the delivery of ecosystem services by altering nutrient and contaminant cycling, hydrology, habitat structure, and disturbance regimes. These biodiversity and ecosystem impacts are accelerating and will increase further in the future. Scientific evidence has identified policy strategies to reduce future invasions, but these strategies are often insufficiently implemented. For some nations, notably Australia and New Zealand, biosecurity has become a national priority. There have been long‐term successes, such as eradication of rats and cats on increasingly large islands and biological control of weeds across continental areas. However, in many countries, invasions receive little attention. Improved international cooperation is crucial to reduce the impacts of invasive alien species on biodiversity, ecosystem services, and human livelihoods. Countries can strengthen their biosecurity regulations to implement and enforce more effective management strategies that should also address other global changes that interact with invasions.

Predicting the Potential Global Geographical Distribution of Two Icerya Species under Climate Change

Climate change is predicted to alter the geographic distribution of a wide variety of taxa, including insects. Icerya aegyptiaca (Douglas) and I. purchasi Maskell are two polyphagous and invasive pests in the genus Icerya Signoret (Hemiptera: Monophlebidae) and cause serious damage to many landscape and economic trees. However, the global habitats suitable for these two Icerya species are unclear. The purpose of this study is to determine the potentially suitable habitats of these two species, then to provide scientific management strategies. Using MaxEnt software, the potential risk maps of I. aegyptiaca and I. purchasi were created based on their occurrence data under different climatic conditions and topology factors. The results suggested that under current climate conditions, the potentially habitable area of I. aegyptiaca would be much larger than the current distribution and there would be small changes for I. purchasi. In the future climate change scenarios, the suitable habitats of these two insect species will display an increasing trend. Africa, South America and Asia would be more suitable for I. aegyptiaca. South America, Asia and Europe would be more suitable for I. purchasi. Moreover, most of the highly habitat suitability areas of I. aegyptiaca will become concentrated in Southern Asia. The results also suggested that “min temperature of coldest month” was the most important environmental factor affecting the prediction models of these two insects. This research provides a theoretical reference framework for developing policies to manage and control these two invasive pests of the genus Icerya.

Exploring farmers' behavior toward individual and collective measures of Western Corn Rootworm control - A case study in south-east Austria

Invasive species are considered a major threat for global agricultural production, biodiversity and ecosystem services. Their spread and establishment is mainly influenced by bio-physical factors, but also by people's activities such as tourism or farming. Understanding farmers' behavior is necessary to develop effective control measures. We conducted qualitative semi-structured interviews in south-east Austria to explore factors that facilitate or impede farmers' behavior to individually or collectively control the invasive Western Corn Rootworm (WCR, Diabrotica virgifera virgifera). We analyze the interview contents using the Capability-Opportunity-Motivation-Behavior model (COM-B model). Our results show that farmers' motivation and related behavior is influenced by intra- and interpersonal factors such as their knowledge about WCR control measures (capability psychological), perceived societal acceptance of WCR control measures or perceived normative obligations to participate in collective measures (opportunity social). Farmers' motivation (reflective and automatic) for implementing individual or collective WCR control measures is mainly determined by their perceived self-efficacy, their perceived efficacy of WCR control measures and the perceived severity of WCR damages. Contextual factors such as environmental conditions, legal regulations, the landscape composition, the farm type or financial impacts of WCR control measures (opportunity physical) are essential prerequisites for farmers' behavior. The results suggest that new modes of knowledge transfer are required to facilitate the proactive implementation of individual and collective WCR control measures prior to trigger events, such as severe WCR damages. The development of a trusting and communicative environment between farmers is key for collective WCR control. Exchange with residents about WCR and applied control measures may help to create a shared understanding and increase societal acceptance. Moreover, a long-term and proactive coordination which meets individual famers' needs is required to implement collective WCR control measures. Farmers who have successfully implemented individual and collective WCR measures may encourage non-applicants and sceptics by "learning from peers".

A dynamic model-based framework to test the effectiveness of biocontrol targeting a new plant invader- the case of Alternanthera philoxeroides in the Iberian Peninsula

Biological invasions are one of the major threats to biodiversity at the global scale, causing numerous environmental impacts and having high direct and indirect costs associated with their management, control and eradication. In this work, we present a system-dynamic modelling approach for the biocontrol of the invasive plant species Alternanthera philoxeroides using its natural predator, Agasicles hygrophila, as a biocontrol agent. We have simulated different scenarios in the Finisterre region (Spain), where a single population of the invasive plant has been recently described. To assess the effectiveness of A. hygrophila as a biocontrol agent in the region, a population dynamic model was developed in order to include the life-cycle of both species, as well as the interaction among them. The results of the simulations indicate that the control of this new invasive plant is possible, as long as several releases of the biocontrol agent are made over time. The proposed model can support the control or even the eradication of the population of A. philoxeroides with a minimal impact on the environment. Additionally, the proposed framework also represents a versatile dynamic tool, adjustable to different local management specificities (objectives and parameters) and capable of responding under different contexts. Hence, this approach can be used to guide eradication efforts of new invasive species, to improve the applicability of early management measures as biocontrol, and to support decision-making by testing several alternative management scenarios.

Dimensions of Phyllostomid Bat Diversity and Assemblage Composition in a Tropical Forest-Agricultural Landscape

Tropical rainforests are suffering rapid habitat loss with large extensions of land transformed into agriculture. We wanted to know whether the type of agricultural activity in forest-agricultural landscapes affects how species composition as well as taxonomic and functional dimensions of diversity respond. We worked in the Amazon forests of southeast Peru and used bats as model organisms. We sampled mosaics characterized by forest adjacent to papaya plantations or cattle pastures. At each sampling site we established a transect in each of the three different vegetation types: forest interior, forest edge and agricultural land. We found that vegetation type was a better predictor of species composition than the type of agricultural land present. Vegetation structure characteristics explained differences in bat species composition between forest interior and edge. Agricultural land type chosen was not irrelevant as we found higher estimated species richness in papaya than in pasture sites. Agricultural land type present in a site and vegetation type affected functional diversity, with both agricultural land types showing a lower number of functionally distinct species than forests. We found papaya plantation sites showed species more evenly dispersed in trait space, suggesting they do better at conserving functional diversity when compared to cattle pasture sites. We demonstrate that sites that harbor agricultural activities can maintain a considerable proportion of the expected bat diversity. We note that this region still has large tracts of intact forest adjacent to agricultural lands, which may explain their ability to maintain relatively high levels bat diversity.

Suitability of European Trichogramma Species as Biocontrol Agents against the Tomato Leaf Miner Tuta absoluta

The tomato leaf miner Tuta absoluta, originally from South America, is an invasive species threatening European tomato crops. Since various insecticides have become ineffective in controlling T. absoluta, effective and environmentally friendly alternatives are needed. Biological control, especially by Trichogramma parasitoids, is considered to be an effective means of reducing this pest. Thus, the aim of our study was to identify promising candidates of Trichogramma parasitoids for biological control of T. absoluta in Europe. We assessed the efficiency of nine European Trichogramma species and compared them to Trichogramma achaeae, as this species is already commercially available. Firstly, we verified species identity of the 10 rearing strains using molecular and morphological methods. Then, host acceptance, host preference (T. absoluta vs. rearing host Sitotroga cerealella eggs) and host searching capacity were tested under laboratory conditions. Our results indicated that T. nerudai, T. pintoi and T. cacoeciae achieved a similar level of parasitism on potted tomato plants as T. achaeae. For the next step, these promising strains should be tested under greenhouse conditions.

Genetic Biocontrol for Invasive Species

Invasive species are increasingly affecting agriculture, food, fisheries, and forestry resources throughout the world. As a result of global trade, invasive species are often introduced into new environments where they become established and cause harm to human health, agriculture, and the environment. Prevention of new introductions is a high priority for addressing the harm caused by invasive species, but unfortunately efforts to prevent new introductions do not address the economic harm that is presently manifested where invasive species have already become established. Genetic biocontrol can be defined as the release of organisms with genetic methods designed to disrupt the reproduction of invasive populations. While these methods offer the potential to control or even eradicate invasive species, there is a need to ensure that genetic biocontrol methods can be deployed in a way that minimizes potential harm to the environment. This review provides an overview of the state of genetic biocontrol, focusing on several approaches that were the subject of presentations at the Genetic Biocontrol for Invasive Species Workshop in Tarragona, Spain, March 31st, 2019, a workshop sponsored by the OECD’s Co-operative Research Program on Biological Resource Management for Sustainable Agricultural Systems. The review considers four different approaches to genetic biocontrol for invasive species; sterile-release, YY Males, Trojan Female Technique, and gene drive. The different approaches will be compared with respect to the efficiency each affords as a genetic biocontrol tool, the practical utility and cost/benefits associated with implementation of the approach, and the regulatory considerations that will need to be addressed for each. The opinions expressed and arguments employed in this publication are the sole responsibility of the authors and do not necessarily reflect those of the OECD or of the governments of its Member countries.

Anthropogenic factors affecting wildlife species status outcomes: why the fixation on pesticides?

Most Americans are at least three generations removed from the farm, thereby at least three generations removed from the reality of where their food comes from. Not surprisingly, there are many misconceptions about modern food production, including the potential collateral environmental damage attributed to agriculture, particularly the application of pesticides. However, the implication of conventional agriculture in the broader narrative of wildlife species status outcomes (SSOs) lacks context and relativity. Since the dawn of civilization, humans have had a profound impact on their environment. Originating as hunter-gatherer societies, our ancient ancestors initially exploited anything that could be consumed or brought to bear. With the advent of the "first proto-farmers," humans began manipulating their environments to maximize available resources. Urban centers propagated and flourished proximal to agricultural origins, where modern societies have been built primarily on an abundance of food. As societies "developed," and continue to develop, an inevitable economic transition occurs from agriculture to industry/service predominance, culminating in a corresponding shift in land use. Developed countries have typically experienced maximal expansion of the agricultural frontier, where farmland is now steadily eroding by a proverbial flood of urban development. In contrast, in developing countries, this shift in economic development has not yet fully manifested and the agricultural footprint continues to expand at the expense of native habitats. Thus, the relative influence of "agriculture" on SSOs, in terms of land use, is primarily dependent on economic developmental status, which can be, at least in part, ameliorated via technology by increasing yield from existing land. Moreover, in addition to the land use challenge, there are multiple other factors affecting wildlife SSOs, including a figurative plague of invasive species, a literal plague of disease, a barrage of buildings, bumpers, grilles, and windshields to collide with, light pollution to confuse cues with, poachers to contend with, and even more complicated factors such as climate change. Being an easy target does not mean pesticides are the right target, and this fixation can potentially detract from public awareness regarding the primary drivers affecting SSOs as well as the opportunity to proactively address them. So, relatively speaking, how do these other factors compare to "pesticides" in terms of driving SSOs? Moreover, why is the popular media so fixated on the pesticide narrative? Based on the available evidence, this manuscript attempts to address these questions from a holistic and relative perspective within the context of land use change, economic development, population growth, and associated implications of global connectivity and commerce.

Potential Distribution and the Risks of Bactericera cockerelli and Its Associated Plant Pathogen Candidatus Liberibacter Solanacearum for Global Potato Production

The tomato potato psyllid (TPP), Bactericera cockerelli, is a psyllid native to North America that has recently invaded New Zealand and Australia. The potential for economic losses accompanying invasions of TPP and its associated bacterial plant pathogen Candidatus Liberibacter solanacearum (CLso), has caused much concern. Here, we employed ecological niche models to predict environments suitable for TPP/CLso on a global scale and then evaluated the extent to which global potato cultivation is at risk. In addition, at a finer scale the risk to the Australian potato acreage was evaluated. A total of 86 MaxEnt models were built using various combinations of settings and climatic predictors, and the best model based on model evaluation metrics was selected. Climatically suitable habitats were identified in Eurasia, Africa, South America, and Australasia. Intersecting the predicted suitability map with land use data showed that 79.06% of the global potato cultivation acreage, 96.14% of the potato production acreage in South America and Eurasia, and all the Australian potato cropping areas are at risk. The information generated by this study increases knowledge of the ecology of TPP/CLso and can be used by government agencies to make decisions about preventing the spread of TPP and CLso across the globe.

Multiple agents managing a harmful species population should either work together to control it or split their duties to eradicate it

The management of harmful species, including invasive species, pests, parasites, and diseases, is a major global challenge. Harmful species cause severe damage to ecosystems, biodiversity, agriculture, and human health. In particular, managing harmful species often requires cooperation among multiple agents, such as landowners, agencies, and countries. Each agent may have incentives to contribute less to the treatment, leaving more work for other agents, which may result in inefficient treatment. A central question is, therefore, how should a policymaker allocate treatment duties among the agents? Specifically, should the agents work together in the same area, or should each agent work only in a smaller area designated just for her/him? We consider a dynamic game-theoretic model, where a Nash equilibrium corresponds to a possible set of contributions that the agents could adopt over time. In turn, the allocation by the policymaker determines which of the Nash equilibria could be adopted, which allows us to compare the outcome of various allocations. Our results show that fewer agents can abate the harmful species population faster, but more agents can better control the population to keep its density lower. We prove this result in a general theorem and demonstrate it numerically for two case studies. Therefore, following an outbreak, the better policy would be to split and assign one or a few agents to treat the species in a given location, but if controlling the harmful species population at some low density is needed, the agents should work together in all of the locations.

Crop and forest pest metawebs shift towards increased linkage and suitability overlap under climate change

Global changes pose both risks and opportunities to agriculture and forestry, and biological forecasts can inform future management strategies. Here, we investigate potential land-use opportunities arising from climate change for these sectors in Europe, and risks associated with the introduction and establishment of novel insect pests. Adopting a metaweb approach including all interaction links between 126 crops and forest tree species and 89 black-listed insect pest species, we show that the metawebs shift toward increased numbers of links and overlap of suitable area under climate change. Decomposing the metaweb across regions shows large saturation in southern Europe, while many novel interactions are expected for northern Europe. In light of the rising consumer awareness about human health and environmental impacts of food and wood production, the challenge will be to effectively exploit new opportunities to create diverse local agriculture and forestry while controlling pest species and reducing risks from pesticide use.

Marc Grünig et al. report a study of land-use opportunities and risks of introducing novel insect pests in Europe that may arise from global climate change. Using a metaweb approach, they find that there is a predicted general increase in risk of pests to managed plant species under climate change due to an increase in land with suitable climate for both pests and plants.

First Report Using a Native Lacewing Species to Control Tuta absoluta: From Laboratory Trials to Field Assessment

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a destructive pest on tomato, has invaded most Afro-Eurasian countries. Recently invaded by the pest, most tomato crops in greenhouses and open fields in Tajikistan are currently suffering major damage. While failure in management using chemical insecticide has been frequently observed, alternative options such as biological control is urgently needed. In this study, we evaluated the effectiveness of the common green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) against T. absoluta. In controlled laboratory conditions, C. carnea showed high predation rate on both T. absoluta eggs (i.e., 36 ± 2 eggs within 24 h and 72 ± 4 eggs within 48 h) and larvae, especially it can attack the larvae both inside and outside the leaf galleries (i.e., an average of 22% of the larvae was killed inside, and an average of 35% was killed outside). In a cage exclusion experiment, T. absoluta showed relatively low larval density in the cages with pre-fruiting release of C. carnea, whereas the larval density was four to six times higher in the “no release” cages. In the “post-fruiting release” cages, the pest population that had already built up during the pre-fruiting stage eventually crashed. In an open-field experiment, the tomato crops in control plots were fully destroyed, whereas low levels of larvae density and damage were observed in the biocontrol plots. Moreover, the field release of C. carnea resulted in significantly higher tomato yield than those without release, despite no differences between the “pre-fruiting release” and “post-fruiting release” treatments. We conclude that the local commercial biocontrol agent C. carnea could be promising for the management of T. absoluta in Tajikistan. It is also one of the first reports showing the management of T. absoluta using a lacewing species. The effectiveness should be validated by further field trials in larger area of commercial crops and various locations.

Potential distribution of two invasive pineapple pests under climate change

BACKGROUND

The number of global invasive species has significantly increased during the past two centuries due to globalization. The understanding of species invasion under climate change is crucial for sustainable biodiversity conservation, community dynamics, ecosystem function, and resource distribution. Two invasive species, Dysmicoccus brevipes (Cockerell) and D. neobrevipes (Beardsley) have greatly expanded their ranges during recent years. These insects are now considered as extremely serious pests for various plants, especially pineapple. In addition, they are the primary vectors for pineapple wilt associated virus. However, the potential distribution range and management strategies for these pests are unclear.

RESULTS

In this study, potential risk maps were developed for these pests with MaxEnt (maximum entropy) based on occurrence data under different environmental variables. The potential distributions of these pests were projected for 2050s and 2070s under three climate change scenarios as described in the Special Report on Emissions Scenarios of the Intergovernmental Panel on Climate Change. Results showed that both pests have similar potential distributions, with high environmental suitability in South America, Africa and South Asia. In addition, potential range expansions or reductions were predicted under different climate change scenarios. The annual mean temperature was the most important factor, accounting for 43.4% of D. brevipes distribution. The minimum temperature of coldest month and mean temperature of coldest quarter was found to be responsible for 90.3% of D. neobrevipes distribution.

CONCLUSION

This research provided a theoretical reference framework to develop policies in the management and control of these invasive pests. © 2019 Society of Chemical Industry.

Monitoring Plant Health with Near-Infrared Fluorescent H2O2 Nanosensors

Near-infrared (nIR) fluorescent single-walled carbon nanotubes (SWCNTs) were designed and interfaced with leaves of Arabidopsis thaliana plants to report hydrogen peroxide (H₂O₂), a key signaling molecule associated with the onset of plant stress. The sensor nIR fluorescence response (>900 nm) is quenched by H₂O₂ with selectivity against other stress-associated signaling molecules and within the plant physiological range (10-100 H₂O₂ μM). In vivo remote nIR imaging of H₂O₂ sensors enabled optical monitoring of plant health in response to stresses including UV-B light (-11%), high light (-6%), and a pathogen-related peptide (flg22) (-10%), but not mechanical leaf wounding (<3%). The sensor's high biocompatibility was reflected on similar leaf cell death (<5%) and photosynthetic rates to controls without SWCNT. These optical nanosensors report early signs of stress and will improve our understanding of plant stress communication, provide novel tools for precision agriculture, and optimize the use of agrochemicals in the environment.

The economic cost of control of the invasive yellow-legged Asian hornet

Since its accidental introduction in 2003 in France, the yellow-legged Asian hornet Vespa velutina nigrithorax is rapidly spreading through France and Europe. Economic assessments regarding the costs of invasive species often reveal important costs from required control measures or damages. Despite the rapid invasion of the Asian yellow-legged hornet in Europe and potential damage to apiculture and pollination services, the costs of its invasion have not been evaluated yet. Here we aimed at studying the costs arising from the Asian yellow-legged hornet invasion by providing the first estimate of the control cost. Today, the invasion of the Asian yellow-legged hornet is mostly controlled by nest destruction. We estimated that nest destruction cost €23 million between 2006 and 2015 in France. The yearly cost is increasing as the species keeps spreading and could reach €11.9 million in France, €9.0 million in Italy and €8.6 million in the United Kingdom if the species fills its current climatically suitable distribution. Although more work will be needed to estimate the cost of the Asian yellow-legged hornet on apiculture and pollination services, they likely exceed the current costs of control with nest destruction. It could thus be worth increasing control efforts by aiming at destroying a higher percentage of nests.

Inter-country trade, genetic diversity and bio-ecological parameters upgrade pest risk maps for the coconut hispid Brontispa longissima

BACKGROUND

Invasions of a number of tree-feeding beetles have increased globally and pose a mounting threat to the world's trees, production forests and natural habitats. An in-depth understanding of the determinants of invasion potential of a given species and invasibility of novel environments can help forecast future invasions and avert undesirable socio-economic impacts. Here, we quantitatively assess the (multivariate) drivers of historic invasions of the coconut hispid Brontispa longissima (Coleoptera: Chrysomelidae) across the Asia-Pacific region and critically assess its invasion potential for other key coconut-growing regions.

RESULTS

Genetic variation of B. longissima in its invaded range indicated multiple incursions, likely associated with (short-range) natural dispersal and (long-range) trade in ornamental palms and coconut plantlets. Interception records at China's ports of entry accentuate the role of traded planting material. The high fecundity and prolonged, yet adaptable, oviposition period of B. longissima further enhance the invasiveness of this species and aid its successful establishment. Coconut-growing areas are identified with high climatic suitability for B. longissima, and where strengthened biosecurity protocols can prevent future invasions.

CONCLUSION

A combined assessment of inter-country trade patterns, population genetics and species bio-ecology (e.g. climate-related development) illuminates the dispersal pathways of invasive species, assesses invasibility of particular geographies, guides quarantine interventions and thus can effectively avert future invasions. © 2019 Society of Chemical Industry.

Plant invasions in New Zealand: global lessons in prevention, eradication and control

The number of non-native plant species established outside of cultivation in the New Zealand archipelago is higher than for any other islands worldwide. Faced with this scale of plant invasions, there has been considerable investment in the scientific and operational aspects of prevention, eradication and control. As a result, New Zealand is ideally placed to illustrate the many challenges that plant invasions present worldwide as well as the possible solutions. New Zealand has been at the forefront of biosecurity policy developments to tackle plant invasions being one of the first countries to: (a) implement national legislation to address the management of non-native plants; (b) establish a national permitted list (white-list) for plant imports; and (c) introduce bans on the sale, distribution, or propagation of non-native plant species. However, these preventative measure are only effective where there are also adequate border inspection regimes, compliance monitoring of the horticulture industry, and surveillance of internet trade. While New Zealand has successfully eradicated several non-native plant species from its territory, the small number of successes reflects the short-term, local and often uncoordinated efforts to manage non-native plants rather than national programmes backed by legislation and financed over several decades. New Zealand supports a world-leading biological control programme, but this has led to sustained, large-scale control for only a handful of species. In natural areas, most management attempts using mechanical or herbicide treatments have failed to achieve control and there has been a progressive reduction in the area, and frequency of these programmes over time. This is illustrative of the challenges facing those responsible for managing non-native plants in any region of the world. A general insight is that a shift in mindset is required that overcomes significant cognitive biases that include succumbing to the pressure to always intervene, underestimating the non-linear trajectories of invasions, failing to articulate the values at stake, and underestimating the time programmes require to succeed. Important lessons of global relevance include the need for managers to: (a) recognise when and where sleeper weeds are likely to become a national issue, especially as a result of climate change; (b) quantify impacts on those values that stakeholders most cherish rather than those that are easy to measure; (c) provide accurate estimates of the potential future extent of the invasion in the absence of management; and (d) identify clear indicators of successful progress over the course of a long-term management programme.

Sustainability Analysis of Prosopis juliflora (Sw.) DC Based Restoration of Degraded Land in North India

Restoration of marginal and degraded lands is essential for regaining biodiversity and ecosystems services, and thereby attaining UN-Sustainable Development Goals. During the last few decades, many fast growing and hardy trees have been introduced worldwide to restore the marginal and degraded lands for ecosystem stability. Unfortunately, most of these introduced species have become invasive and invaded the nearby productive systems, leading to significant biodiversity loss and land degradation. Therefore, it is imperative to conduct a sustainability analysis of the introduced species for necessary course correction and also for preventing the future utilisation of such species for land restoration. With this backdrop, the present study was conducted to analyse the socio-ecological impacts of a widely used species, i.e., Prosopis juliflora (Sw.) DC based restoration of degraded land of Lucknow, North India. For this, ecological (soil quality and plant biodiversity) and social (livelihood) indicators have been studied over a period of two years (2015–16) through direct field sampling and questionnaire-based surveys. While there was a positive difference (p < 0.01) in the key physico-chemical properties of the P. juliflora-invaded soil than the non-invaded site, the belowground microbial load was significantly lower (19.46 × 106 g−1 of soil) in invaded land as compared to the non-invaded one (31.01 × 106 g−1). Additionally, the invasion of P. juliflora had significantly reduced the biodiversity by displacing the local flora such as Achyranthes aspera L., Amaranthus spinosus L., Cynodon dactylon (L.) Pers, Euphorbia hirta L., etc. The invaded area had only eight plant species having an effective number of species (ENS) of 7.2, whereas the non-invaded area had the presence of 26 plant species with an ENS of 23.8. Although the local people utilised P. juliflora as fuelwood mostly during summer and winter seasons, the invasion resulted in a fodder deficit of 419.97 kg household−1 y−1 leading to resource scarcity in the invaded area in comparison to the non-invaded area. Ecodistribution mapping clearly showed that P. juliflora is already found in most of the tropical and subtropical countries (~103) including in India and has become invasive in many countries. Therefore, we recommend that P. juliflora must be wisely used for the land restoration programs targeted during the United Nations Decade of Ecosystem Restoration (2021–2030) as this species has invasive traits and thereby reduces the ecosystem sustainability of the invaded areas.

AgriEnt: A Knowledge-Based Web Platform for Managing Insect Pests of Field Crops

In the agricultural context, there is a great diversity of insects and diseases that affect crops. Moreover, the amount of data available on data sources such as the Web regarding these topics increase every day. This fact can represent a problem when farmers want to make decisions based on this large and dynamic amount of information. This work presents AgriEnt, a knowledge-based Web platform focused on supporting farmers in the decision-making process concerning crop insect pest diagnosis and management. AgriEnt relies on a layered functional architecture comprising four layers: the data layer, the semantic layer, the web services layer, and the presentation layer. This platform takes advantage of ontologies to formally and explicitly describe agricultural entomology experts’ knowledge and to perform insect pest diagnosis. Finally, to validate the AgriEnt platform, we describe a case study on diagnosing the insect pest affecting a crop. The results show that AgriEnt, through the use of the ontology, has proven to produce similar answers as the professional advice given by the entomology experts involved in the evaluation process. Therefore, this platform can guide farmers to make better decisions concerning crop insect pest diagnosis and management.

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.

A remark on "Biological control through provision of additional food to predators: A theoretical study" [Theor. Popul. Biol. 72 (2007) 111-120]

Biological control, the use of predators and pathogens to control target pests, is a promising alternative to chemical control. It is hypothesized that the introduced predators efficacy can be boosted by providing them with an additional food source. The current literature (Srinivasu, 2007; 2010; 2011) claims that if the additional food is of sufficiently large quantity and quality then pest eradication is possible in finite time. The purpose of the current manuscript is to show that to the contrary, pest eradication is not possible in finite time, for any quantity and quality of additional food. We show that pest eradication will occur only in infinite time, and derive decay rates to the extinction state. We posit a new modeling framework to yield finite time pest extinction. Our results have large scale implications for the effective design of biological control methods involving additional food.

Establishment in an Introduced Range: Dispersal Capacity and Winter Survival of Trissolcus japonicus, an Adventive Egg Parasitoid

The herbivorous brown marmorated stink bug, Halyomorpha halys, has spread globally, and one of its key parasitoids, Trissolcus japonicus, has recently been detected in the pest's introduced range. For an exotic natural enemy to impact its targeted host in a novel environment, it must disperse, locate hosts, and potentially be redistributed to susceptible sites. Through intentionally releasing T. japonicus across four Oregon eco-regions, we investigated an introduced parasitoid's dispersal capacity in urban sites and in two perennial crops, hazelnut and raspberry. In a second paired field and laboratory study, we investigated T. japonicus survival in different plant materials. Within three days of release, adult T. japonicus located host egg masses at 45% of sites and, one year later, were detected at 40% of release sites. Areas where released wasps survived winter were mostly urban or semi-natural. In commercial crop release experiments, we recovered the highest percentage of wasps in raspberry within 5 m of the release site but found no statistical difference in dispersal distance with some wasps dispersing up to 50 m. Adult parasitoids survived up to 16 weeks outdoors in the winter, with greater survival over time in bark compared to leaf litter. Wasp survival remained above 50% over the course of a simulated winter environment without precipitation. Our work affirms the continuation of H. halys parasitism by T. japonicus in novel environments and provides insight into the high population sizes necessary to survive winter and locate host egg masses the following season.

Native and Invasive Small Mammals in Urban Habitats along the Commercial Axis Connecting Benin and Niger, West Africa

Based on compiled small mammal trapping data collected over 12 years from Benin and Niger (3701 individual records from 66 sampling sites), located in mainland Africa, we here describe the small mammal community assemblage in urban habitats along the commercial axis connecting the two countries, from the seaport of Cotonou to the Sahelian hinterland, with a particular focus on invasive species. In doing so, we document extant species distributions, which highlight the risks of continuing the range expansion of three synanthropic invasive rodent species, namely black rats (Rattus rattus), brown rats (R. norvegicus), and house mice (Mus musculus). Using various diversity estimates and community ecology approaches, we detect a latitudinal gradient of species richness that significantly decreased Northward. We show that shrews (Crocidura) represent a very important component of micro-mammal fauna in West African towns and villages, especially at lower latitudes. We also demonstrate that invasive and native synanthropic rodents do not distribute randomly in West Africa, which suggests that invasive species dynamics and history differ markedly, and that they involve gradual, as well as human-mediated, long distance dispersal. Patterns of segregation are also observed between native Mastomys natalensis and invasive rats R. rattus and R. norvegicus, suggesting potential native-to-invasive species turn over. Consequences of such processes, especially in terms of public health, are discussed.

A New System for Detecting Initial Colonization by Invasive Pests and Their Locations

Quarantine pests in plants can be a serious agricultural problem; many eradication programs using area-wide control measures have been implemented worldwide to combat this threat. Surveillance measures using sex pheromone (in general, male-attractant) traps are also widely implemented for rapid control and eradication of invasive pests. If initial pest colonization can be determined based on temporal count data of trapped insects (i.e., males), and countermeasures are applied only during colonization, costs incurred by these countermeasures would be dramatically reduced, especially in areas with frequent invasions. In this study, we developed a system to detect initial pest colonization, and to narrow down colonized regions using estimated temporal count data of the sweet potato weevil, Cylas formicarius Fabricius (Coleoptera: Curculionidae), in Tsuken Island, Okinawa, Japan. We verified the system by comparing our estimates to actual colonization data obtained via regular host plant surveys. Results indicated that our system was able to successfully detect pest colonization and estimate colonized regions. In this study, we discuss the conditions (i.e., pest biology, environment, etc.) that are optimal for application of our system.

Demographic amplification is a predictor of invasiveness among plants

Invasive plant species threaten native biodiversity, ecosystems, agriculture, industry and human health worldwide, lending urgency to the search for predictors of plant invasiveness outside native ranges. There is much conflicting evidence about which plant characteristics best predict invasiveness. Here we use a global demographic survey for over 500 plant species to show that populations of invasive plants have better potential to recover from disturbance than non-invasives, even when measured in the native range. Invasives have high stable population growth rates in their invaded ranges, but this metric cannot be predicted based on measurements in the native ranges. Recovery from demographic disturbance is a measure of transient population amplification, linked to high levels of reproduction, and shows phylogenetic signal. Our results demonstrate that transient population dynamics and reproductive capacity can help to predict invasiveness across the plant kingdom, and should guide international policy on trade and movement of plants.

Agricultural insect hybridization and implications for pest management

Biological invasions, the expansion of agricultural frontiers, and climate change favor encounters of divergent lineages of animals and plants, increasing the likelihood of hybridization. However, hybridization of insect species and its consequences for agroecosystems have not received sufficient attention. Gene exchange between distinct and distant genetic pools can improve the survival and reproduction of insect pests, and threaten beneficial insects in disturbed agricultural environments. Hybridization may be the underlying explanation for the recurrent pest outbreaks and control failures in putative hybrid zones, as suspected for bollworm, corn borer, whiteflies, and stink bugs. Reliable predictions of the types of changes that can be expected in pest insect genomes and fitness, and of their impacts on the fate of species and populations remain elusive. Typical steps in pest management, such as insect identification, pest monitoring, and control are likely affected by gene flow and adaptive introgression mediated by hybridization, and we do not have ways to respond to or mitigate the problem. To address the adverse effects of farming intensification and global trade, we must ensure that current integrated pest management programs incorporate up-to-date monitoring and diagnostic tools. The rapid identification of hybrids, quantification of levels of introgression, and in-depth knowledge of what genes have been transferred may help to explain and predict insect population outbreaks and control failures in the future. © 2019 Society of Chemical Industry.

Advancing impact assessments of non-native species: strategies for strengthening the evidence-base

The numbers and impacts of non-native species (NNS) continue to grow. Multiple ranking protocols have been developed to identify and manage the most damaging species. However, existing protocols differ considerably in the type of impact they consider, the way evidence of impacts is included and scored, and in the way the precautionary principle is applied. These differences may lead to inconsistent impact assessments. Since these protocols are considered a main policy tool to promote mitigation efforts, such inconsistencies are undesirable, as they can affect our ability to reliably identify the most damaging NNS, and can erode public support for NNS management. Here we propose a broadly applicable framework for building a transparent NNS impact evidence base. First, we advise to separate the collection of evidence of impacts from the act of scoring the severity of these impacts. Second, we propose to map the collected evidence along a set of distinguishing criteria: where it is published, which methodological approach was used to obtain it, the relevance of the geographical area from which it originates, and the direction of the impact. This procedure produces a transparent and reproducible evidence base which can subsequently be used for different scoring protocols, and which should be made public. Finally, we argue that the precautionary principle should only be used at the risk management stage. Conditional upon the evidence presented in an impact assessment, decision-makers may use the precautionary principle for NNS management under scientific uncertainty regarding the likelihood and magnitude of NNS impacts. Our framework paves the way for an improved application of impact assessments protocols, reducing inconsistencies and ultimately enabling more effective NNS management.

Range-wide population genomics of the Mexican fruit fly: Toward development of pathway analysis tools

Recurrently invading pests provide unique challenges for pest management, but also present opportunities to utilize genomics to understand invasion dynamics and inform regulatory management through pathway analysis. In the southern United States, the Mexican fruit fly Anastrepha ludens is such a pest, and its incursions into Texas and California represent major threats to the agricultural systems of those regions. We developed a draft genome assembly for A. ludens, conducted range-wide population genomics using restriction site-associated DNA sequencing, and then developed and demonstrated a panel of highly differentiated diagnostic SNPs for source determination of intercepted flies in this system. Using 2,081 genomewide SNPs, we identified four populations across the range of A. ludens, corresponding to western Mexico, eastern Mexico/Texas, Guatemala/Belize/Honduras, and Costa Rica/Panama, with some intergradation present between clusters, particularly in Central America. From this population genomics framework, we developed a diagnostic panel of 28 highly differentiated SNPs that were able to recreate the genomewide population structure in this species. We demonstrated this panel on a set of test specimens, including specimens intercepted as part of regular trapping surveillance in Texas and California, and we were able to predict populations of origin for these specimens. This methodology presents a highly applied use of genomic techniques and can be implemented in any group of recurrently invading pests.

Ageratina adenophora invasions are associated with microbially mediated differences in biogeochemical cycles

Invasive plant species may alter soil nutrient availability to facilitate their growth and competitiveness. However, the roles and functional mechanisms of plant-associated microbes that mediate these soil biogeochemical cycles remain elusive. Here, we studied how soil microorganisms and their functional processes differed between soils invaded by Ageratina adenophora and adjacent non-invaded soils in a region of China with heavy invasion. Our results indicated that soil nitrogen contents were over 4.32 mg/kg higher (p < 0.05) in both rhizosphere soils and bulk soils dominated by A. adenophora as compared with those in soils dominated by non-invaded plants. Concurrently, soil microbial-mediated functional processes, i.e. nitrogen fixation rate, nitrification rate and ammonification rate, were also significantly (p < 0.05) higher in either rhizosphere soils or bulk soils of invasive A. adenophora. Using a functional gene microarray, we found higher relative abundances of soil microbial genes involved in N cycling processes in A. adenophora soils, e.g. nifH, required for nitrogen fixation, which significantly correlated with ammonia contents (r = 0.35 in bulk soils, r = 0.37 in rhizosphere soils, p < 0.05) and the nitrogen fixation rate (r = 0.44, p < 0.05). We also found that the relative abundances of labile carbon decomposition genes were higher in invasive A. adenophora soils, implying a potential higher availability of carbon. These results suggest that the soil surrounding the invasive plant A. adenophora is a self-reinforcing environment. The plant litter and rhizosphere environment of the invasive may influence soil microbial communities, promoting self-supporting soil processes. Alternatively, the regions invaded by A. adenophora may have already had properties that facilitated these beneficial microbial community traits, allowing easier invasion by the exotics. Both scenarios offer important insights for the mitigation of plant invasion and provide an ecosystem-level understanding of the invasive mechanisms utilized by alien plants.

Global distribution modelling, invasion risk assessment and niche dynamics of Leucanthemum vulgare (Ox-eye Daisy) under climate change

In an era of climate change, biological invasions by alien species represent one of the main anthropogenic drivers of global environmental change. The present study, using an ensemble modelling approach, has mapped current and future global distribution of the invasive Leucanthemum vulgare (Ox-eye Daisy) and predicted the invasion hotspots under climate change. The current potential distribution of Ox-eye Daisy coincides well with the actual distribution records, thereby indicating robustness of our model. The model predicted a global increase in the suitable habitat for the potential invasion of this species under climate change. Oceania was shown to be the high-risk region to the potential invasion of this species under both current and future climate change scenarios. The results revealed niche conservatism for Australia and Northern America, but contrastingly a niche shift for Africa, Asia, Oceania and Southern America. The global distribution modelling and risk assessment of Ox-eye Daisy has immediate implications in mitigating its invasion impacts under climate change, as well as predicting the global invasion hotspots and developing region-specific invasion management strategies. Interestingly, the contrasting patterns of niche dynamics shown by this invasive plant species provide novel insights towards disentangling the different operative mechanisms underlying the process of biological invasions at the global scale.

Biodiversity impacts due to food consumption in Europe

Food security and biodiversity conservation are closely interconnected challenges to be addressed to achieve a sustainable food system on a global scale. Due to the complex nature of food production and consumption system, quantifying the impacts of food supply chains on biodiversity is challenging. Life cycle assessment (LCA) allows for systematically addressing environmental impacts along supply chains, representing a reference methodology that can be applied for assessing food systems. In the present study, 32 representative food products of consumption in the European Union (EU) were selected and their environmental impacts calculated through a process-based LCA. The potential contribution of EU food consumption to the current biodiversity decline has been evaluated adopting both midpoint and endpoint indicators. A comparison of the impact drivers was performed. Meat products, the underpinning land use for agricultural purposes, and climate change represent the main hotspots of impacts on biodiversity. Notwithstanding several drivers of biodiversity loss can be accounted for with LCA, the evidence of the increasing biodiversity decline on both a European and a global scale indicates that the assessment system should be further expanded, especially for what concerns refining impact categories such as ecotoxicity, and including resource overexploitation, and impact due to invasive species. This study illustrates: how far the current LCA based impact assessment framework may help to address the drivers of biodiversity loss; which are the main uncertainties associated to results stemming from the application of different endpoint methods; which aspects need to be elaborated further to ensure a comprehensive assessment of biodiversity impacts due to food production and consumption.

Many unreported crop pests and pathogens are probably already present

Invasive species threaten global biodiversity, food security and ecosystem function. Such incursions present challenges to agriculture where invasive species cause significant crop damage and require major economic investment to control production losses. Pest risk analysis (PRA) is key to prioritize agricultural biosecurity efforts, but is hampered by incomplete knowledge of current crop pest and pathogen distributions. Here, we develop predictive models of current pest distributions and test these models using new observations at subnational resolution. We apply generalized linear models (GLM) to estimate presence probabilities for 1,739 crop pests in the CABI pest distribution database. We test model predictions for 100 unobserved pest occurrences in the People's Republic of China (PRC), against observations of these pests abstracted from the Chinese literature. This resource has hitherto been omitted from databases on global pest distributions. Finally, we predict occurrences of all unobserved pests globally. Presence probability increases with host presence, presence in neighbouring regions, per capita GDP and global prevalence. Presence probability decreases with mean distance from coast and known host number per pest. The models are good predictors of pest presence in provinces of the PRC, with area under the ROC curve (AUC) values of 0.75-0.76. Large numbers of currently unobserved, but probably present pests (defined here as unreported pests with a predicted presence probability >0.75), are predicted in China, India, southern Brazil and some countries of the former USSR. We show that GLMs can predict presences of pseudoabsent pests at subnational resolution. The Chinese literature has been largely inaccessible to Western academia but contains important information that can support PRA. Prior studies have often assumed that unreported pests in a global distribution database represent a true absence. Our analysis provides a method for quantifying pseudoabsences to enable improved PRA and species distribution modelling.

Prospects and challenges of implementing DNA metabarcoding for high-throughput insect surveillance

Trap-based surveillance strategies are widely used for monitoring of invasive insect species, aiming to detect newly arrived exotic taxa as well as track the population levels of established or endemic pests. Where these surveillance traps have low specificity and capture non-target endemic species in excess of the target pests, the need for extensive specimen sorting and identification creates a major diagnostic bottleneck. While the recent development of standardized molecular diagnostics has partly alleviated this requirement, the single specimen per reaction nature of these methods does not readily scale to the sheer number of insects trapped in surveillance programmes. Consequently, target lists are often restricted to a few high-priority pests, allowing unanticipated species to avoid detection and potentially establish populations. DNA metabarcoding has recently emerged as a method for conducting simultaneous, multi-species identification of complex mixed communities and may lend itself ideally to rapid diagnostics of bulk insect trap samples. Moreover, the high-throughput nature of recent sequencing platforms could enable the multiplexing of hundreds of diverse trap samples on a single flow cell, thereby providing the means to dramatically scale up insect surveillance in terms of both the quantity of traps that can be processed concurrently and number of pest species that can be targeted. In this review of the metabarcoding literature, we explore how DNA metabarcoding could be tailored to the detection of invasive insects in a surveillance context and highlight the unique technical and regulatory challenges that must be considered when implementing high-throughput sequencing technologies into sensitive diagnostic applications.

Many unreported crop pests and pathogens are probably already present

Invasive species threaten global biodiversity, food security and ecosystem function. Such incursions present challenges to agriculture where invasive species cause significant crop damage and require major economic investment to control production losses. Pest risk analysis (PRA) is key to prioritize agricultural biosecurity efforts, but is hampered by incomplete knowledge of current crop pest and pathogen distributions. Here, we develop predictive models of current pest distributions and test these models using new observations at subnational resolution. We apply generalized linear models (GLM) to estimate presence probabilities for 1,739 crop pests in the CABI pest distribution database. We test model predictions for 100 unobserved pest occurrences in the People's Republic of China (PRC), against observations of these pests abstracted from the Chinese literature. This resource has hitherto been omitted from databases on global pest distributions. Finally, we predict occurrences of all unobserved pests globally. Presence probability increases with host presence, presence in neighbouring regions, per capita GDP and global prevalence. Presence probability decreases with mean distance from coast and known host number per pest. The models are good predictors of pest presence in provinces of the PRC, with area under the ROC curve (AUC) values of 0.75-0.76. Large numbers of currently unobserved, but probably present pests (defined here as unreported pests with a predicted presence probability >0.75), are predicted in China, India, southern Brazil and some countries of the former USSR. We show that GLMs can predict presences of pseudoabsent pests at subnational resolution. The Chinese literature has been largely inaccessible to Western academia but contains important information that can support PRA. Prior studies have often assumed that unreported pests in a global distribution database represent a true absence. Our analysis provides a method for quantifying pseudoabsences to enable improved PRA and species distribution modelling.

Implications of land use/land cover dynamics and Prosopis invasion on ecosystem service values in Afar Region, Ethiopia

Land use/land cover (LULC) dynamics and the resulting changes in ecosystems, as well as the services they provide, are a consequence of human activities and environmental drivers, such as invasive alien plant species. This study assessed the changes in LULC and ecosystem service values (ESVs) in the Afar National Regional State, Ethiopia, which experiences a rapid invasion by the alien tree Prosopis juliflora (Swartz DC). Landsat satellite data of 1986, 2000 and 2017 were used in Random Forest algorithm to assess LULC changes in the last 31 years, to calculate net changes for different LULC types and the associated changes in ESVs. Kappa accuracies of 88% and higher were obtained for the three LULC classifications. Post-classification change analyses for the period between 1986 and 2017 revealed a positive net change for Prosopis invaded areas, cropland, salt flats, settlements and waterbodies. The rate of Prosopis invasion was estimated at 31,127 ha per year. Negative net changes were found for grassland, bareland, bush-shrub-woodland, and natural forests. According to the local community representatives, the four most important drivers of LULC dynamics were climate change, frequent droughts, invasive species and weak traditional law. Based on two different ESVs estimations, the ecosystem changes caused by LULC changes resulted in an average loss of ESVs in the study area of about US$ 602 million (range US$ 112 to 1091 million) over the last 31 years. With an increase in area by 965,000 ha, Prosopis-invaded land was the highest net change during the study period, followed by grassland (-599,000 ha), bareland (-329,000 ha) and bush-shrub-woodland (-327,000 ha). Our study provides evidence that LULC changes in the Afar Region have led to a significant loss in ESVs, with serious consequences for the livelihoods of the rural people.

Assessing the ecological and societal impacts of alien parrots in Europe using a transparent and inclusive evidence-mapping scheme

Globally, the number of invasive alien species (IAS) continues to increase and management and policy responses typically need to be adopted before conclusive empirical evidence on their environmental and socioeconomic impacts are available. Consequently, numerous protocols exist for assessing IAS impacts and differ considerably in which evidence they include. However, inclusive strategies for building a transparent evidence base underlying IAS impact assessments are lacking, potentially affecting our ability to reliably identify priority IAS. Using alien parrots in Europe as a case study, here we apply an evidence-mapping scheme to classify impact evidence and evaluate the consequences of accepting different subsets of available evidence on impact assessment outcomes. We collected environmental and socioeconomic impact data in multiple languages using a “wiki-review” process, comprising a systematic evidence search and an online editing and consultation phase. Evidence was classified by parrot species, impact category (e.g. infrastructure), geographical area (e.g. native range), source type (e.g. peer-review), study design (e.g. experimental) and impact direction (deleterious, beneficial and no impact). Our comprehensive database comprised 386 impact entries from 233 sources. Most evidence was anecdotal (50%). A total of 42% of entries reported damage to agriculture (mainly in native ranges), while within Europe most entries concerned interspecific competition (39%). We demonstrate that the types of evidence included in assessments can strongly influence impact severity scores. For example, including evidence from the native range or anecdotal evidence resulted in an overall switch from minimal-moderate to moderate-major overall impact scores. We advise using such an evidence-mapping approach to create an inclusive and updatable database as the foundation for more transparent IAS impact assessments. When openly shared, such evidence-mapping can help better inform IAS research, management and policy.