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Modern agriculture is perceived to be unsustainable having pursued a high productivity, reductionist approach for many decades. The solution proposed for restoring 'sustainability' is often encapsulated in the term 'diversity' but this is frequently as ill-defined and open to wide interpretation as the word sustainable. Key to determining whether diversity is 'the answer' is defining what diversity means in practice in the field. We attempt to describe the concepts and components of diversity and, crucially, how they might combine and interact in agricultural systems. The key concepts are: (1) complexity, (2) variation, and (3) spatio-temporal interaction, with the latter comprising (a) heterogeneity, (b) spatial connectivity, and (c) temporal connectivity. We suggest that this might lead to new strategies of diversity deployment and an index of resilience, a key ingredient of sustainability. These measures of diversity are explored in the context of crop resistance to pests and pathogens and the potential to maximise the benefits for integrated pest management in arable crops. [ABSTRACT FROM AUTHOR]

Otiorhynchus sulcatus, known as the vine weevil, is a polyphagous pest that causes economically important damage to horticultural crops worldwide. The entomopathogenic fungus Metarhizium brunneum is widely used to control this pest. Little research has investigated variation in susceptibility to this pathogen between vine weevil populations at different locations. This study addresses this knowledge gap by comparing survival rates of larvae from adults collected in two UK areas when treated with M. brunneum. Larvae from these locations did not differ in their susceptibility, suggesting that location per se may not affect the efficacy of M. brunneum against vine weevil larvae. [ABSTRACT FROM AUTHOR]

Behavior and fitness are important ecological traits frequently measured in insect bioassays. A common method to measure them in soft‐bodied herbivorous insects involves confining individuals to plant leaves using clip cages. Although studies have previously highlighted the negative effects of clip cages on leaf physiology, little is known about the impact that using this confinement method has on insect fitness. The responses of different aphid genotypes/clones to different containment methods have not previously been investigated. Here we measured key fitness traits (intrinsic rate of natural increase, mean relative growth rate, time to reach reproductive adulthood and population doubling time) in the potato aphid, Macrosiphum euphorbiae Thomas (Hemiptera: Aphididae), when confined to plants using two methods: (1) clip cages to confine aphids to individual strawberry leaves and (2) a mesh bag to confine aphids to whole strawberry plants. Our study identified a strong negative impact on all the measured aphid fitness traits when using clip cages instead of mesh bags. We also identified genotype‐specific differences in response to confinement method, where clip cage confinement differentially affected the fitness of a given aphid genotype compared to the same genotype on whole plants. These results suggest that clip cage use should be carefully considered when experiments seek to quantify insect fitness and that whole plants should be used wherever possible. Given the prevalence of clip cage use in insect bioassays, our results highlight the need for caution when interpreting the existing literature as confinement method significantly impacts aphid fitness depending on their genotype. [ABSTRACT FROM AUTHOR]

Background: Intensive farming affects farmland biodiversity, and some arable plants in particular. Increasing crop genetic diversity can increase crop productivity or resilience and could also benefit rare arable plants. Aims: We examined whether barley presence, sowing density and genetic diversity impacted the rare plant Valerianella rimosa and explored possible underlying mechanisms. Methods: In a field study near Dundee, Scotland, we sowed plots of five single barley genotypes, and all five genotypes combined, at three densities; we also had barley-free plots. Valerianella seeds were sown into half of all plots. Measured responses included early-season cover and harvest biomass of barley and common weeds, abiotic parameters (soil moisture, light) and establishment, biomass and seed production by V. rimosa. Results: Barley presence promoted V. rimosa establishment early in the growing season, but without barley density or genetic diversity effects. By harvest, the impact of barley presence on V. rimosa abundance was lost; there were no effects on Valerianella seed production. Barley negatively impacted common weeds, but V. rimosa did not benefit from any indirect facilitation by barley, being bigger without barley. Conclusions: Early beneficial effects of barley on V. rimosa abundance appear offset by late-season competition. However, limited impacts of barley on V. rimosa reproductive success, and negative impacts on common weeds, indicate crops might play a role in conservation management of rare arable plants by creating space in the weed community. [ABSTRACT FROM AUTHOR]

Predicted changes in the frequency and intensity of extreme rainfall events in the UK have the potential to disrupt terrestrial ecosystem function. However, responses of different trophic levels to these changes in rainfall patterns, and the underlying mechanisms, are not well-characterised., This study aimed to investigate how changes in both the quantity and frequency of rainfall events will affect the outcome of interactions between plants, insect herbivores (above- and below-ground) and natural enemies., Hordeum vulgare L. plants were grown in controlled conditions and in the field, and subjected to three precipitation scenarios: ambient (based on a local 10 year average rainfall); continuous drought (40% reduction compared with ambient); drought/deluge (40% reduction compared to ambient at a reduced frequency). The effects of these watering regimes and wireworm ( Agriotes species) root herbivory on the performance of the plants, aphid herbivores above-ground ( Sitobion avenae, Metapolophium dirhodum, and Rhopalosiphum padi), and natural enemies of aphids including ladybirds ( Harmonia axyridis) were assessed from measurements of plant growth, insect abundance and mass, and assays of feeding behaviour., Continuous drought decreased plant biomass, whereas reducing the frequency of watering events did not affect plant biomass but did alter plant chemical composition. In controlled conditions, continuous drought ameliorated the negative impact of wireworms on plant biomass., Compared with the ambient treatment, aphid mass was increased by 15% when feeding on plants subjected to drought/deluge; and ladybirds were 66% heavier when feeding on these aphids but this did not affect ladybird prey choice. In field conditions, wireworms feeding below-ground reduced the number of shoot-feeding aphids under ambient and continuous drought conditions but not under drought/deluge., Predicted changes in both the frequency and intensity of precipitation events under climate change have the potential to limit plant growth, but reduce wireworm herbivory, whilst simultaneously promoting above-ground aphid numbers and mass, with these effects transferring to the third trophic level. Understanding the effect of future changes in the precipitation on species interactions is critical for determining their potential impact on ecosystem functioning and constructing accurate predictions under global change scenarios., A is available for this article. [ABSTRACT FROM AUTHOR]

Food security is currently considered a major global problem. However, increasing intensity of food production in agricultural systems has driven reductions in farmland biodiversity. A major challenge is to enable biodiversity conservation whilst addressing the problem of food security., Here we describe how facilitative plant-plant interactions in crop systems could be used to help strike this balance. An obvious example is that of intercropping systems, where combinations of crop species can - under some circumstances - deliver reduced inputs of agrochemicals (fertilizers, pesticides) per unit yield, with potential knock-on benefits for biodiversity conservation., Other facilitative processes can also play a role in biodiversity conservation. Increased intraspecific crop genetic diversity can help protect crops from pests and diseases. Although overlooked in facilitation research, we argue that the mechanisms operate in a manner which is directly analogous to associational defence against herbivores, a process well recognized in the facilitation literature. As with intercropping, the benefits to nature conservation arise from reduced pesticide use per unit harvested crop., Crops may have facilitative effects on some arable weed species, particularly those that are currently considered rare in intensive farming systems. Work is in its early stages to understand the underlying mechanisms, but it appears that crops might create niche space to which some weed species are adapted. Increasing plant species diversity through niche space creation may then have cascading benefits for other components of farmland biodiversity., Our new understanding of facilitative processes arising from work on crop systems has lessons for the study of facilitative interactions in natural and semi-natural communities. We argue that, although easier to identify and quantify in crop systems, some of these facilitative processes have to date been overlooked in studies of non-crop systems and certainly deserve further consideration., Finally, we discuss what steps may be needed to move from our understanding of the role of facilitation to the development of new agricultural practice. In some cases the challenge may be one of the encouraging uptake of existing practices, and in others more research is needed to understand how new ecological understanding might deliver more sustainable agricultural practice. [ABSTRACT FROM AUTHOR]

Aphids are important herbivorous insects that can cause significant crop damage, leading to yield reduction and economic loss. One avenue being explored to reduce aphid impacts is the development of aphid-resistant plants. Under projected climate scenarios, it is expected that plants will be exposed to greater biotic and abiotic stress, including increased herbivorous insect infestation and exposure to prolonged periods of environmental stress, particularly drought. In response to these projections, plant–aphid interactions under drought conditions have been a subject of growing interest; however, few studies have looked at the impact of drought stress on plant resistance to aphids despite the potential importance for plant breeding. Here, we examine the latest scientific advances regarding variation in plant resistance to aphids under drought, emphasizing underlying mechanisms and functional trade-offs and propose a conceptual model relating plant tolerance to drought with plant resistance to aphids. [ABSTRACT FROM AUTHOR]

Facultative endosymbionts can induce benefits and costs to their aphid hosts. In the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), infection with the γ‐proteobacterium Hamiltonella defensa Moran et al. can confer resistance against parasitoids, but may also reduce the frequency of aggressive and escape behaviours exhibited in response to predators. In potato aphids, Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae), H. defensa does not appear to influence susceptibility to parasitism, but its impact on anti‐predator behaviours remains unexplored. Here we investigated defensive behaviours in two pea aphid lines (differing in H. defensa‐infection status) and four potato aphid lines (that additionally differed in genotype‐associated parasitism susceptibility) when faced with foraging ladybirds – Adalia bipunctata (L.) (Coleoptera: Coccinellidae) – and lacewings – Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). In response to ladybirds, symbiont‐infected pea aphids exhibited proportionately fewer evasive defences (dropping and walking away) than non‐infected (cured) pea aphids, but more frequent aggressive kicking. Ladybirds provoked more evasive, aggressive, and total defensive behaviours than lacewings. For potato aphids, symbiont status, predator type, and aphid genotype (i.e., assumed parasitism susceptibility) all influenced behavioural repertoires. Overall, infected lines showed greater differentiation in behaviours in response to the two predators than the uninfected lines. The presence of the symbiont H. defensa may be a key determinant of aphid anti‐predator behaviours, but the fitness consequences of this are unresolved. In our study, neither symbiont infection status nor aphid genotype affected the number of aphids consumed by predators. [ABSTRACT FROM AUTHOR]

The principal dietary source to humans of the essential cationic mineral elements potassium, magnesium and calcium is through edible plants. The accumulation of these elements in edible portions is the product of selective transport processes catalysing their short-distance and long-distance movement within a plant. In this article we review recent work describing the identification and characterisation of the molecular mechanisms catalysing the uptake and distribution of potassium, magnesium and calcium between organs, cell types and subcellular compartments. Although potassium and magnesium are redistributed effectively within the plant, calcium concentrations in phloem-fed tissues, such as fruits, seeds and tubers, are generally low. However, limitations to the redistribution of mineral elements within the plant, and its consequences for the biofortification of edible crops, can be overcome by appropriate mineral fertilisation and plant breeding strategies. The techniques of ionomics can help identify better genotypes. [Copyright &y& Elsevier]

Purpose: Silicon (Si) accumulation in plant tissues plays a vital role in alleviating biotic and abiotic stresses, including drought. Temperate regions are predicted to experience reductions in the quantity and frequency of rainfall events, potentially impacting plant Si uptake via the transpiration stream. Despite the importance for predicting plant responses to Si amendments, the effects of changes in rainfall patterns on Si uptake in cereals have not been characterised. Methods: Five watering regimes were applied based on predicted precipitation scenarios, varying the quantity of water delivered (ambient, 40% or 60% reduction) and watering frequency (40% reduction in quantity, applied 50% or 25% of ambient frequency), and the effects on growth and leaf Si concentrations of a barley landrace and cultivar were determined. Results: Reductions in the quantity of water reduced plant growth and yield, whereas reducing the watering frequency had little impact on growth, and in some cases partially ameliorated the negative effects of drought. Reductions in quantity of water lowered leaf Si concentrations in both the cultivar and landrace, although this effect was alleviated under the drought/deluge watering regime. The landrace had greater leaf Si concentration than the cultivar regardless of watering regime, and under ambient watering deposited Si in all cells between trichomes, whereas the cultivar exhibited gaps in Si deposition. Conclusion: The impact of future reductions in rainfall on barley productivity will depend upon how the water is delivered, with drought/deluge events likely to have smaller effects on yield and on Si uptake than continuous drought. [ABSTRACT FROM AUTHOR]

Examines the effects of nonylphenol on the growth and morphologies of the filamentous fungus Neurospora crassa and the diploid yeast Candida albicans. Effects of nonylphenol on N. crassa growth; N. crassa rates of excised hyphal tip extension; Radial growth and bifurcation index; Oxygen uptake and total protein.

For herbivorous insects, dropping from the host plant is a commonly-observed antipredator defence. The use of dropping compared to other behaviours and its timing in relation to contact with a predator was explored in both pea aphids (Acyrthosiphon pisum) and potato aphids (Macrosiphum euphorbiae). Pea aphids dropped more frequently in response to ladybird adults (Adalia bipunctata) than lacewing larvae (Chrysoperla carnea). Potato aphids mainly walked away or backed-up in response to both predator types; but they dropped more frequently relative to other non-walking defences when faced with ladybird adults. Contact with a predator was an important influencer of dropping for both species, and most drops occurred from adjacent to the predator. Dropping appears to be a defence adaptively deployed only when the risk of imminent predation is high; factors that increase dropping likelihood include presence of faster-foraging predators such as adult ladybirds, predator proximity, and contact between aphid and predator. [ABSTRACT FROM AUTHOR]

Dropping behavior is an effective antipredator defense utilized by many insects including aphids, which drop from plants to lower plant parts or underlying substrates to avoid attack from predatory invertebrates. While research commonly focusses on triggers of dropping, less attention is given to what happens to prey individuals following escape drops. In this study, the duration of tonic immobility, recovery rates, and cases of "instant recovery" (re-clinging to lower plant parts) exhibited by potato aphids (Macrosiphum euphorbiae) that dropped from potted seedlings in response to introduced ladybird (Adalia bipunctata) adults, lacewing (Chrysoperla carnea) larvae, and a standardized tactile stimulus were investigated in relation to a range of environmental factors. Air temperature had a negative correlation with the duration of post-dropping tonic immobility; as temperature increased, time spent motionless decreased. Aphids also showed a pattern of increased recovery rate at higher temperatures. Aphids may be selected to move off the substrate quicker to avoid risks of overheating/desiccation at higher temperatures; and/or higher body temperature facilitates locomotion. Stimulus type also influenced recovery rate back to the original seedling, with aphids generally recovering after the standardized stimulus quicker than after dropping triggered by a real predator. Considering cases of instant recovery onto lower-reaches of the host seedling, seedling height influenced the likelihood of re-clinging, with aphids that managed to instantly recover dropping from, on average, taller seedlings than aphids that dropped to the substrate. Plant architecture could mitigate the costs of dropping for aphids, but further studies quantifying understory foliage cover are needed. [ABSTRACT FROM AUTHOR]

Understanding species coexistence and regulation of biodiversity are major research challenges, yet there is no consensus on the effects of diversity on diversity, including their mediation through plant-plant interactions., We examined how the diversity of recipient communities impacted on the establishment of colonising species. We ran a greenhouse-based community experiment, creating artificial arable crop communities with varying levels of barley genotype and weed species diversity, analysed with structural equation modelling of responses across trophic levels., Colonising arable weed species establishment was significantly reduced when the recipient communities' weed species richness, but not barley genotype richness, increased. Recipient plant communities with higher species richness occupied more total niche space and showed stronger competition with colonising species. In contrast, recipient plant communities with higher genotype richness, even though they had slightly greater niche space occupancy, had no significant effects on the colonisation of additional species., Responses were species specific: colonising common weed species establishment was less affected by the recipient plant communities than that of colonising rare weed species. Strong responses of colonising rare species were related to the abiotic rather than the biotic environment created by the recipient communities. The stronger response of colonising rare species suggests greater niche overlap with and competitive inferiority to the recipient plant community, whereas the relative independence of colonising common species indicates less niche overlap and/or competitive equality or superiority., We observed a negative species diversity effect on colonising species, with the effect size increasing with increasing rarity of the colonising species. This differential responsiveness of colonising rare and common arable weed species to the presence of and diversity in the recipient arable plant communities may be crucial in understanding rarity and may result from differential evolutionary pathways in response to interactions. [ABSTRACT FROM AUTHOR]

Ecologically significant symbiotic associations are frequently studied in isolation, but such studies of two-way interactions cannot always predict the responses of organisms in a community setting. To explore this issue, we adopt a community approach to examine the role of plant–microbial and insect–microbial symbioses in modulating a plant–herbivore interaction. Potato plants were grown under glass in controlled conditions and subjected to feeding from the potato aphid Macrosiphum euphorbiae. By comparing plant growth in sterile, uncultivated and cultivated soils and the performance of M. euphorbiae clones with and without the facultative endosymbiont Hamiltonella defensa, we provide evidence for complex indirect interactions between insect– and plant–microbial systems. Plant biomass responded positively to the live soil treatments, on average increasing by 15% relative to sterile soil, while aphid feeding produced shifts (increases in stem biomass and reductions in stolon biomass) in plant resource allocation irrespective of soil treatment. Aphid fecundity also responded to soil treatment with aphids on sterile soil exhibiting higher fecundities than those in the uncultivated treatment. The relative allocation of biomass to roots was reduced in the presence of aphids harbouring H. defensa compared with plants inoculated with H. defensa-free aphids and aphid-free control plants. This study provides evidence for the potential of plant and insect symbionts to shift the dynamics of plant–herbivore interactions. [ABSTRACT FROM AUTHOR]

The increase in the global atmospheric CO2 concentration projected for 2050 increases the productivity of temperate forests by a quarter; but it is by no means clear that such increased productivity will lead to more long-term carbon sequestration. [Copyright &y& Elsevier]

To achieve the triple challenge of food security, reversing biodiversity declines plus mitigating and adapting to climate change, there is a drive to embed ecological principles into agricultural, value-chain practices and decisionmaking. By diversifying cropping systems at several scales there is potential to decrease reliance on inputs, provide resilience to abiotic and biotic stress, enhance plant, microbe and animal biodiversity, and mitigate against climate change. In this review we highlight the research performed in Scotland over the past 5 years into the impact of the use of ecological principles in agriculture on sustainability, resilience and provision of ecosystem functions. We demonstrate that diversification of the system can enhance ecosystem functions. Soil and plant management interventions, including nature-based solutions, can also enhance soil quality and utilization of legacy nutrients. Additionally, this is facilitated by greater reliance on soil biological processes and trophic interactions. We highlight the example of intercropping with legumes to deliver sustainability through ecological principles and use legumes as an exemplar of the innovation. We conclude that there are many effective interventions that can be made to deliver resilient, sustainable, and diverse agroecosystems for crop and food production, and these may be applicable in any agroecosystem. [ABSTRACT FROM AUTHOR]

Crops are exposed to myriad abiotic and biotic stressors with negative consequences. Two stressors that are expected to increase under climate change are drought and infestation with herbivorous insects, including important aphid species. Expanding our understanding of the impact drought has on the plant–aphid relationship will become increasingly important under future climate scenarios. Here we use a previously characterized plant–aphid system comprising a susceptible variety of barley, a wild relative of barley with partial aphid resistance, and the bird cherry-oat aphid to examine the drought–plant–aphid relationship. We show that drought has a negative effect on plant physiology and aphid fitness, and provide evidence to suggest that plant resistance influences aphid responses to drought stress. Furthermore, we show that the expression of thionin genes, plant defensive compounds that contribute to aphid resistance, increase in susceptible plants exposed to drought stress but remain at constant levels in the partially resistant plant, suggesting that they play an important role in determining the success of aphid populations. This study highlights the role of plant defensive processes in mediating the interactions between the environment, plants, and herbivorous insects. [ABSTRACT FROM AUTHOR]

Biodiversity regulates ecosystem functions such as productivity, and experimental studies of species mixtures have revealed selection and complementarity effects driving these responses. However, the impacts of intraspecific genotypic diversity in these studies are unknown, despite it forming a substantial part of the biodiversity., In a glasshouse experiment we constructed plant communities with different levels of barley ( Hordeum vulgare) genotype and weed species diversity and assessed their relative biodiversity effects through additive partitioning into selection and complementarity effects., Barley genotype diversity had weak positive effects on aboveground biomass through complementarity effects, whereas weed species diversity increased biomass predominantly through selection effects. When combined, increasing genotype diversity of barley tended to dilute the selection effect of weeds., We interpret these different effects of barley genotype and weed species diversity as the consequence of small vs large trait variation associated with intraspecific barley diversity and interspecific weed diversity, respectively. The different effects of intra- vs interspecific diversity highlight the underestimated and overlooked role of genetic diversity for ecosystem functioning. [ABSTRACT FROM AUTHOR]

Summary: Plant‐associated microbiomes assist their host in a variety of activities, spanning from nutrition to defence against herbivores and diseases. Previous research showed that plant‐associated microbiomes shift their composition when plants are exposed to stressors, including herbivory. However, existing studies explored only single herbivore‐plant combinations, whereas plants are often attacked by several different herbivores, but the effects of multiple herbivore types on the plant microbiome remain to be determined. Here, we first tested whether feeding by different herbivores (aphids, nematodes and slugs) produces a shift in the rhizosphere bacterial microbiota associated with potato plants. Then, we expanded this question asking whether the identity of the herbivore produces different effects on the rhizosphere microbial community. While we found shifts in microbial diversity and structure due to herbivory, we observed that the herbivore identity does not influence the diversity or community structure of bacteria thriving in the rhizosphere. However, a deeper analysis revealed that the herbivores differentially affected the structure of the network of microbial co‐occurrences. Our results have the potential to increase our ability to predict how plant microbiomes assemble and aid our understanding of the role of plant microbiome in plant responses to biotic stress. [ABSTRACT FROM AUTHOR]

1. There is increasing evidence that many above-ground and below-ground processes are tightly linked through plant-mediated mechanisms, including indirect interactions between foliar and root herbivores underpinned by changes in host plant chemistry (e.g. defensive or nutritional status). To date, studies addressing interactions involving nutritional mechanisms have relied on rudimentary chemical measurements (e.g. total/soluble nitrogen), overlooking other nutrients such as minerals and specific amino acids. 2. This study investigated how the nutrient composition of barley ( Hordeum vulgare) responded to separate and simultaneous attack by root-feeding wireworms ( Agriotes spp.) and foliar-feeding aphids ( Rhopalosiphum padi) after short and long exposures to herbivory, and determined whether the two insects indirectly interacted with each other. 3. Wireworms significantly reduced total plant mass and leaf dry mass by up to 25%, but had little impact on nutritional chemistry compared with aphids. Aphids did not affect plant growth but caused significant reductions in most leaf minerals: nitrogen (N), sulphur (S), calcium (Ca) and phosphorus (P). In contrast, aphids increased root mineral concentrations: N, S, Ca and potassium (K). Aphid-induced changes occurred in both short and long exposure experiments, with the exception of leaf Ca, and root N and K which were only significantly affected in the short exposure experiment. 4. Above-ground and below-ground herbivory had several interactive (often reversible) effects on plant nutrients. For example, wireworms strengthened the aphid-driven increases in root S by 35% after short exposure, but reduced aphid-induced increases by 10% after longer exposure. 5. There was evidence for positive bi-directional interactions between above-ground and below-ground herbivores, with wireworms promoting aphid numbers by 30% and aphids increasing wireworm mass by 25%. 6. Contrary to previous mechanistic explanations, below-ground herbivory had little impact on foliar amino acid concentrations, whereas aphids caused significant (approximately 50%) reductions in essential amino acids. However, after longer exposure to wireworm herbivory, aphid-driven reductions in essential amino acids were attenuated. Aphids caused significant increases in root mineral concentrations (especially root S) which potentially promoted wireworm performance. 7. The significance of these findings is discussed in the context of current hypotheses of above-ground × below-ground herbivore interactions. In particular, examining specific plant nutrients could be critical to understanding conditional outcomes of insect × plant interactions. [ABSTRACT FROM AUTHOR]

Aphids are abundant in natural and managed vegetation, supporting a diverse community of organisms and causing damage to agricultural crops. Due to a changing climate, periods of drought are anticipated to increase, and the potential consequences of this for aphid–plant interactions are unclear.Using a meta‐analysis and synthesis approach, we aimed to advance understanding of how increased drought incidence will affect this ecologically and economically important insect group and to characterize any potential underlying mechanisms. We used qualitative and quantitative synthesis techniques to determine whether drought stress has a negative, positive, or null effect on aphid fitness and examined these effects in relation to (a) aphid biology, (b) geographical region, and (c) host plant biology.Across all studies, aphid fitness is typically reduced under drought. Subgroup analysis detected no difference in relation to aphid biology, geographical region, or the aphid–plant combination, indicating the negative effect of drought on aphids is potentially universal. Furthermore, drought stress had a negative impact on plant vigor and increased plant concentrations of defensive chemicals, suggesting the observed response of aphids is associated with reduced plant vigor and increased chemical defense in drought‐stressed plants.We propose a conceptual model to predict drought effects on aphid fitness in relation to plant vigor and defense to stimulate further research. [ABSTRACT FROM AUTHOR]

We review the need for increasing agricultural sustainability, how this can in part be delivered by positive biodiversity–ecosystem function (BEF) effects, the role within these of plant–plant facilitation, and how a better understanding of this role may help to deliver sustainable crop (particularly arable) production systems.Major challenges facing intensive arable production include overall declines in biodiversity, poor soil structure and health, nutrient and soil particle run‐off, high greenhouse gas emissions, and increasing costs of synthetic inputs including herbicides, pesticides and fertilisers.Biodiversity–ecosystem function effects have the potential to deliver win–wins for arable food production, whereby enhanced biodiversity is associated with 'good outcomes' for farming sustainability, albeit sometimes through negative BEF effects for some components of the system. Although it can be difficult to separate explicitly from niche differentiation, evidence indicates facilitation can be a key component of these BEF effects.Explicit recognition of facilitation's role brings benefits to developing sustainable crop systems. First, it allows us to link fundamental ecological studies on the evolution of facilitation to the selection of traits that can enhance functioning in crop mixtures. Second, it provides us with analytical frameworks which can be used to bring structure and testable hypotheses to data derived from multiple (often independent) crop trials.Before concrete guidance can be provided to the agricultural sector as to how facilitation might be enhanced in crop systems, challenges exist with respect to quantifying facilitation, understanding the traits that maximise facilitation and integrating these traits into breeding programmes, components of an approach we suggest could be termed 'Functional Ecological Selection'.Synthesis. Ultimately, better integration between ecologists and crop scientists will be essential in harnessing the benefits of ecological knowledge for developing more sustainable agriculture. We need to focus on understanding the mechanistic basis of strong facilitative interactions in crop systems and using this information to select and breed for improved combinations of genotypes and species as part of the Functional Ecological Selection approach. [ABSTRACT FROM AUTHOR]

The weevil superfamily Curculionoidea is the largest insect group and so the largest animal group on earth. This taxon includes species which represent an important threat to many economically important crops and, therefore, pose a risk to agriculture and food security. Insect–bacteria associations have been recognised to provide the insect host with many benefits, such as ensuring the acquisition of essential nutrients or protecting the host from natural enemies. The role of bacteria associations within the weevil superfamily remains nonetheless understudied in comparison with other insect taxa. This review draws together existing knowledge on the influence of bacteria associated with weevils known to be agricultural pest species. The implications of these weevil–bacterial associations in determining pest status and their relevance to targeted pest management interventions are discussed. Specific consideration is given to the role of bacteria in cuticle formation, flight activity, reproduction manipulation and adaptation to different environments and food sources. [ABSTRACT FROM AUTHOR]

The intensity of pastoral management in areas of High Nature Value farming is declining in some regions of Europe but increasing in others. This affects open habitats of conservation concern, such as the British uplands, where bird species that benefit from low‐intensity grazing may be most sensitive to such polarization. While experimental manipulations of livestock grazing intensities have improved our understanding of upland breeding bird responses in the short term, none have examined the long‐term impacts of altered management on reproductive success.Using a replicated landscape‐scale experiment that started in 2003, we investigated the effects of four grazing treatments (intensive sheep; low‐intensity sheep; low‐intensity mixed sheep and cattle; and no grazing) on the breeding productivity of meadow pipits Anthus pratensis, the most common upland passerine. Surveys were carried out systematically during early (2003 and 2004) and late (2015 and 2016) sampling periods of the experiment to compare the short‐ and long‐term effects of grazing treatments on breeding density and productivity of pipits specifically, but also on the overall bird community.Pipit breeding density was lowest under low‐intensity sheep grazing while the highest egg‐stage nest survival was observed in the same treatment, although no significant treatment effects were detected on overall nest survival or fledgling output. There were no significant differences in treatment effects between the sampling periods on any breeding variable, but overall nest survival was lower in the later sampling period across all treatments.Breeding bird species richness differed between treatments in the later sampling period, with highest species richness in the ungrazed treatment.Synthesis and applications. Livestock grazing management can have different outcomes for different upland birds. Our results showed that, with time, meadow pipit breeding productivity tended to be higher when sheep grazing intensity was reduced and/or mixed with cattle, and lower when livestock were removed, but not significantly so. Removal of grazing, however, can significantly increase bird species richness. The long‐term experiment showed an overall decline in fledglings regardless of grazing treatments, potentially a result of increased predator numbers harboured by nearby developing woodland, highlighting the importance of considering wider landscape processes in grazing management decisions. [ABSTRACT FROM AUTHOR]

Aphid populations frequently include phenotypes that are resistant to parasitism by hymenopterous parasitoid wasps, which is often attributed to the presence of 'protective' facultative endosymbionts residing in aphid tissues, particularly Hamiltonella defensa. In field conditions, under parasitoid pressure, the observed coexistence of aphids with and without protective symbionts cannot be explained by their difference in fitness alone.Using the cereal aphid Rhopalosiphum padi as a model, we propose an alternative mechanism whereby parasitoids are more efficient at finding common phenotypes of aphid and experience a fitness cost when switching to the less common phenotype.We construct a model based on delay differential equations and parameterize and validate the model with values within the ranges obtained from experimental studies. We then use it to explore the possible effects on system dynamics under conditions of environmental stress, using our existing data on the effects of drought stress in crops as an example.We show the 'switching penalty' incurred by parasitoids leads to stable coexistence of aphids with and without H. defensa and provides a potential mechanism for maintaining phenotypic diversity among host organisms. We show that drought‐induced reduction in aphid development time has little impact. However, greater reduction in fecundity on droughted plants of symbiont‐protected aphids can cause insect population cycles when the system would be stable in the absence of drought stress.The stabilizing effect of the increased efficiency in dealing with more commonly encountered host phenotypes is applicable to a broad range of consumer–resource systems and could explain stable coexistence in competitive environments. The loss of stable coexistence when drought has different effects on the competing aphid phenotypes highlights the importance of scenario testing when considering biocontrol for pest management. [ABSTRACT FROM AUTHOR]

Bacterial endosymbionts have enabled aphids to adapt to a range of stressors, but their effects in many aphid species remain to be established. The bird cherry‐oat aphid, Rhopalosiphum padi (Linnaeus), is an important pest of cereals worldwide and has been reported to form symbiotic associations with Serratia symbiotica and Sitobion miscanthi L‐type symbiont endobacteria, although the resulting aphid phenotype has not been described. This study presents the first report of R. padi infection with the facultative bacterial endosymbiont Hamiltonella defensa. Individuals of R. padi were sampled from populations in Eastern Scotland, UK, and shown to represent seven R. padi genotypes based on the size of polymorphic microsatellite markers; two of these genotypes harbored H. defensa. In parasitism assays, survival of H. defensa‐infected nymphs following attack by the parasitoid wasp Aphidius colemani (Viereck) was 5 fold higher than for uninfected nymphs. Aphid genotype was a major determinant of aphid performance on two Hordeum species, a modern cultivar of barley H. vulgare and a wild relative H. spontaneum, although aphids infected with H. defensa showed 16% lower nymph mass gain on the partially resistant wild relative compared with uninfected individuals. These findings suggest that deploying resistance traits in barley will favor the fittest R. padi genotypes, but symbiont‐infected individuals will be favored when parasitoids are abundant, although these aphids will not achieve optimal performance on a poor quality host plant. [ABSTRACT FROM AUTHOR]

Aphids, including the bird cherry-oat aphid (Rhopalosiphum padi), are significant agricultural pests. The wild relative of barley, Hordeum spontaneum 5 (Hsp5), has been described to be partially resistant to R. padi , with this resistance proposed to involve higher thionin and lipoxygenase gene expression. However, the specificity of this resistance to aphids and its underlying mechanistic processes are unknown. In this study, we assessed the specificity of Hsp5 resistance to aphids and analysed differences in aphid probing and feeding behaviour on Hsp5 and a susceptible barley cultivar (Concerto). We found that partial resistance in Hsp5 to R. padi extends to two other aphid pests of grasses. Using the electrical penetration graph technique, we show that partial resistance is mediated by phloem- and mesophyll-based resistance factors that limit aphid phloem ingestion. To gain insight into plant traits responsible for partial resistance, we compared non-glandular trichome density, defence gene expression, and phloem composition of Hsp5 with those of the susceptible barley cultivar Concerto. We show that Hsp5 partial resistance involves elevated basal expression of thionin and phytohormone signalling genes, and a reduction in phloem quality. This study highlights plant traits that may contribute to broad-spectrum partial resistance to aphids in barley. [ABSTRACT FROM AUTHOR]

Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), commonly known as black vine weevil or simply vine weevil, is an important pest of soft fruit and ornamental crops. This species is endemic to temperate areas of Europe but has spread to many other areas over the last century, including North America and Australasia. The ability of vine weevils to adapt to such different environments is difficult to reconcile with the parthenogenetic reproduction strategy, which is likely to underpin a low genetic diversity. It is therefore tempting to hypothesize that weevil adaptation to different environments is mediated, at least partly, by the microbial communities inhabiting these insects. As a first step towards testing this hypothesis we characterized the composition of the bacterial microbiota in weevils from populations feeding on strawberry plants across four geographically separate locations in the UK. We performed 16S rRNA gene Illumina amplicon sequencing, generating 2 882 853 high‐quality reads. Ecological indices, namely Chao1 and Shannon, revealed that the populations used for this study harboured a low diversity and an uneven bacterial microbiota. Furthermore, β‐diversity analysis failed to identify a clear association between microbiota composition and location. Notably, a single operational taxonomic unit phylogenetically related to Candidatus Nardonella accounted for 81% of the total sequencing reads for all tested insects. Our results indicate that vine weevil bacterial microbiota resembles that of other insects as it has low diversity and it is dominated by few taxa. A prediction of this observation is that location per se may not be a determinant of the microbiota inhabiting weevil populations. Rather, other or additional selective pressures, such as the plant species used as a food source, ultimately shape the weevil bacterial microbiota. Our results will serve as a reference framework to investigate other or additional hypotheses aimed at elucidating vine weevil adaptation to its environment. The bacterial community of vine weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae), populations collected from strawberry plants at various sites across the UK was characterized by sequencing a fragment of the 16S rRNA gene with Illumina MiSeq technology. The bacterial microbiota of the tested populations shows low diversity and is dominated by a highly abundant sequence classified as Candidatus Nardonella. These results could help to understand vine weevil biology and could provide insights to develop new biocontrol strategies. [ABSTRACT FROM AUTHOR]

The maternal rearing environment can affect offspring fitness or phenotype indirectly via ‘maternal effects’ and can also influence a mother’s behaviour and fecundity directly. However, it remains uncertain how the effects of the maternal rearing environment cascade through multiple trophic levels, such as in plant-insect herbivore-natural enemy interactions. Pea aphids (Acyrthosiphon pisum) show differential fitness on host legume species, while generalist aphid parasitoids can show variable fitness on different host aphid species, suggesting that maternal effects could operate in a plant-aphid-parasitoid system. We tested whether the maternal rearing environment affected the behaviour and fitness of aphids by rearing aphids on two plant hosts that were either the same as or different from those experienced by the mothers. A similar approach was used to test the behaviour and fitness of parasitoid wasps in response to maternal rearing environment. Here, the host environment was manipulated at the plant or plant and aphid trophic levels for parasitoid wasps. We also quantified the quality of host plants for aphids and host aphids for parasitoid wasps. In choice tests, aphids and parasitoid wasps had no preference for the plant nor plant and aphid host environment on which they were reared. Aphid offspring experienced 50.8% higher intrinsic rates of population growth, 43.4% heavier offspring and lived 14.9% longer when feeding on bean plants compared to aphids feeding on pea plants, with little effect of the maternal rearing environment. Plant tissue nitrogen concentration varied by 21.3% in response to aphid mothers’ rearing environment, and these differences correlated with offspring fitness. Maternal effects in parasitoid wasps were only observed when both the plant and aphid host environment was changed: wasp offspring were heaviest by 10.9–73.5% when both they and their mothers developed in bean-reared pea aphids. Also, parasitoid wasp fecundity was highest by 38.4% when offspring were oviposited in the maternal rearing environment. These findings indicate that maternal effects have a relatively small contribution towards the outcome of plant-aphid-parasitoid interactions. [ABSTRACT FROM AUTHOR]

1. Insecticide usage selects strongly for resistance in aphid populations, but this could entail fitness costs in other resistance traits. The potato aphid Macrosiphum euphorbiae Thomas exhibits intraspecific variation in susceptibility to parasitism by braconid wasps and provides a suitable species to study the relation between the defensive traits of parasitism and insecticide resistance. 2. Clonal lines (23 in total) of M. euphorbiae were established from aphids collected in 2013 from geographically separate populations in the U.K. Clonal lines belonged to five aphid genotypes, but one genotype predominated (78% of samples), and the facultative endosymbiont Hamiltonella defensa was detected in c. 40% of lines. 3. Total esterase activity in aphid tissues varied significantly between aphid genotypes and collection areas, but there was no clear pattern in relation to H. defensa infection or between collection sites likely to differ in insecticide pressures. 4. Five clonal lines representing low to moderate levels of enzyme activity, which included different aphid genotypes and presence/absence of H. defensa infection, were assayed for their susceptibility to the parasitoid wasp Aphidius ervi Haliday. Aphid mummification varied significantly between aphid genotypes, with low values in one genotype of aphids irrespective of H. defensa presence. 5. The results revealed that aphid lines belonging to the parasitism‐resistant genotype exhibited moderate levels of total esterase activity, indicating a competitve advantage for this genotype of M. euphorbiae when exposed to chemical and biological control factors in agroecosystems. [ABSTRACT FROM AUTHOR]

Herbivorous insect pests living in the soil represent a significant challenge to food security given their persistence, the acute damage they cause to plants and the difficulties associated with managing their populations. Ecological research effort into rhizosphere interactions has increased dramatically in the last decade and we are beginning to understand, in particular, the ecology of how plants defend themselves against soil-dwelling pests. In this review, we synthesise information about four key ecological mechanisms occurring in the rhizosphere or surrounding soil that confer plant protection against root herbivores. We focus on root tolerance, root resistance via direct physical and chemical defences, particularly via acquisition of silicon-based plant defences, integration of plant mutualists (microbes and entomopathogenic nematodes, EPNs) and the influence of soil history and feedbacks. Their suitability as management tools, current limitations for their application, and the opportunities for development are evaluated. We identify opportunities for synergy between these aspects of rhizosphere ecology, such as mycorrhizal fungi negatively affecting pests at the root-interface but also increasing plant uptake of silicon, which is also known to reduce herbivory. Finally, we set out research priorities for developing potential novel management strategies. [ABSTRACT FROM AUTHOR]

Understanding how soil microbial communities influence plant interactions with other organisms, and how this varies with characteristics of the interacting organisms, is important for multiple systems. Solanum spp. are a suitable model for trophic interactions in studies of agricultural and natural systems and can also provide useful corollaries in invaded systems. This study examined the influence of soil mutualist arbuscular mycorrhizal ( AM) fungi on growth of different Solanum types fed on by the potato aphid, Macrosiphum euphorbiae, in relation to the presence of the aphid facultative endosymbiont Hamiltonella defensa., Four Solanum types comprising two wild species, S. berthaultii and S. polyadenum, and two accessions of S. tuberosum, were grown with or without AM fungi and infested with one of four clonal lines of a single M. euphorbiae genotype (two with and two without H. defensa). Two experiments were conducted to (i) characterize plant responses to AM fungi and aphids and (ii) assess whether soil AM fungi could influence the success of the parasitoid wasp Aphidius ervi when attacking aphids reared on each Solanum type., In both experiments, similar patterns of plant biomass were observed in relation to AM fungal and aphid treatments. Solanum biomass depended on plant type and aphid infection with H. defensa. Plants exposed to aphids harbouring H. defensa had smaller root biomass, and therefore total plant biomass, compared to plants infested with H. defensa-free aphids. M. euphorbiae performance varied with aphid clonal line, Solanum type and the presence of AM fungi., Parasitoid success, measured as the proportion of aphids from which a wasp emerged, was highest from aphids that had fed on plants colonized by AM fungi, although this result also varied with Solanum type and aphid clonal line., Synthesis. The presence of soil AM fungi, combined with within-species plant and insect variation in key traits, can have subtle - but significant - effects on plant fitness and insect success. This study highlights the importance of exploring genotypic variation in plant and pest responses to soil microbiota to identify suitable biocontrol options. [ABSTRACT FROM AUTHOR]

Intercropping is a farming practice involving two or more crop species, or genotypes, growing together and coexisting for a time. On the fringes of modern intensive agriculture, intercropping is important in many subsistence or low-input/resource-limited agricultural systems. By allowing genuine yield gains without increased inputs, or greater stability of yield with decreased inputs, intercropping could be one route to delivering 'sustainable intensification'. We discuss how recent knowledge from agronomy, plant physiology and ecology can be combined with the aim of improving intercropping systems. Recent advances in agronomy and plant physiology include better understanding of the mechanisms of interactions between crop genotypes and species - for example, enhanced resource availability through niche complementarity. Ecological advances include better understanding of the context-dependency of interactions, the mechanisms behind disease and pest avoidance, the links between above- and below-ground systems, and the role of microtopographic variation in coexistence. This improved understanding can guide approaches for improving intercropping systems, including breeding crops for intercropping. Although such advances can help to improve intercropping systems, we suggest that other topics also need addressing. These include better assessment of the wider benefits of intercropping in terms of multiple ecosystem services, collaboration with agricultural engineering, and more effective interdisciplinary research. [ABSTRACT FROM AUTHOR]

The marginal agricultural-systems of the Machair in the Western Isles of Scotland often have limited micronutrient availability because of alkaline soils. Traditional landraces of oats, barley and rye are thought to be better adapted to cope with the limited manganese (Mn) availability of these soils. When commercial cultivars are grown on the Machair, limited Mn-availability reduces crop yield and quality. We hypothesised that traditional cereal landraces selected on the Machair acquire Mn more effectively and that this could be linked to exudation of phytase from roots which would release Mn complexed with inositol phosphates. Growth and Mn-acquisition of five landraces and three commercial cultivars of barley and oats were determined in Machair soil. In addition, root phytase activities were assayed under Mn-starvation and sufficiency in hydroponics. In Machair soil, landraces had greater capacity for acquiring Mn and a greater ability to achieve maximum yield compared to the commercial cultivars. Under Mn-starvation, root phytase exudation was upregulated in all plants, suggesting that this trait might allow cereals to acquire more Mn when Mn-availability is limited. In the landraces, exuded phytase activity related positively to relative Mn-accumulation, whereas in the commercial cultivars this relationship was negative, suggesting that this trait may be secondary to an efficiency trait that has been lost from commercial germplasm by breeding. This research shows that cereal landraces possess traits that could be useful for improving the Mn-acquisition of commercial varieties. Exploiting the genetic diversity of landraces could improve the sustainability of agriculture on marginal calcareous lands globally. [ABSTRACT FROM AUTHOR]

Terrestrial food webs are woven from complex interactions, often underpinned by plant-mediated interactions between herbivores and higher trophic groups. Below- and above-ground herbivores can influence one another via induced changes to a shared host plant, potentially shaping the wider community. However, empirical evidence linking laboratory observations to natural field populations has so far been elusive., This study investigated how root-feeding weevils ( Otiorhynchus sulcatus) influence different feeding guilds of herbivore (phloem-feeding aphids, Cryptomyzus galeopsidis, and leaf-chewing sawflies, Nematus olfaciens) in both controlled and field conditions., We hypothesized that root herbivore-induced changes in plant nutrients (C, N, P and amino acids) and defensive compounds (phenolics) would underpin the interactions between root and foliar herbivores, and ultimately populations of natural enemies of the foliar herbivores in the field., Weevils increased field populations of aphids by ca. 700%, which was followed by an increase in the abundance of aphid natural enemies. Weevils increased the proportion of foliar essential amino acids, and this change was positively correlated with aphid abundance, which increased by 90% on plants with weevils in controlled experiments., In contrast, sawfly populations were 77% smaller during mid-June and adult emergence delayed by >14 days on plants with weevils. In controlled experiments, weevils impaired sawfly growth by 18%, which correlated with 35% reductions in leaf phosphorus caused by root herbivory, a previously unreported mechanism for above-ground-below-ground herbivore interactions., This represents a clear demonstration of root herbivores affecting foliar herbivore community composition and natural enemy abundance in the field via two distinct plant-mediated nutritional mechanisms. Aphid populations, in particular, were initially driven by bottom-up effects (i.e. plant-mediated effects of root herbivory), but consequent increases in natural enemies triggered top-down regulation. [ABSTRACT FROM AUTHOR]

Many insect herbivores and plant pathogens influence each other via plant-mediated mechanisms. Although there is speculation that these interactions may be important in structuring terrestrial food webs, few studies have empirically demonstrated the mechanisms by which pathogens manipulate the behaviour of their insect vectors. We investigated how infection of red raspberry, Rubus idaeus L. (Rosaceae), with two viral pathogens, black raspberry necrosis virus (BRNV) and raspberry leaf mottle virus (RLMV), affected the behaviour of their vector, the large raspberry aphid, Amphorophora idaei Börner (Hemiptera: Aphididae: Macrosiphini). As semi-persistently transmitted viruses, comparatively little is known about how such viruses affect vector biology. We also examined the effect of infection on plant volatile emissions and amino acid content, which could drive changes in aphid behaviour and performance. Virus-infected plants were initially more attractive to the aphid and the insects remained on infected plants for 30 min, but were found equally on uninfected plants 12 h after inoculation. Twenty-seven volatile compounds were identified. Two green leaf volatiles were emitted at higher concentrations by infected plants: ( Z)-3-hexenyl acetate and 2-hexenal. In dose-response assays, ( Z)-3-hexenyl acetate was attractive to the aphid at concentrations of 50 ng ml−1. When reared on infected plants, aphids took more than 3 days longer to reach adulthood compared with those on uninfected plants, although the number of offspring remained the same. Soluble amino acid (essential and non-essential) concentrations in raspberry leaves increased more than two-fold with virus infection. Amino acid composition was dominated by glutamate, accounting for 64 and 77% of the total in uninfected and infected leaves, respectively. Excessive glutamate may have underpinned the negative effects of viral infection on aphid performance. These results demonstrate the capacity of viruses to alter their host plant to manipulate vector behaviour, which may have evolved to be consistent with the transmission requirements of the virus. [ABSTRACT FROM AUTHOR]

• APSIM was calibrated and validated for pure cultures of wheat and faba bean. • APSIM was evaluated for wheat-faba bean pure cultures and intercrops in Europe. • APSIM reproduced pure culture aboveground dry matters and, for wheat, yields. • APSIM overestimates faba bean performance relative to wheat in intercrops. • APSIM must incorporate an alternative approach to simulate height growth. Cereal-legume intercropping can increase yields, reduce fertilizer input and improve soil quality compared with pure culture. Designing intercropping systems requires the integration of plant species trait selection with choice of crop configuration and management. Crop growth models can facilitate the understanding and prediction of the interactions between plant traits, crop configuration and management. However, currently no existing crop growth model has been calibrated and tested for cereal-legume intercrops throughout Europea. We calibrated the Agricultural Production Systems sIMulator (APSIM) for pure cultures of wheat and faba bean using data from Dutch field trials, and determined the phenological parameters to simulate pure cultures and intercrops from seven field experiments across Europe. APSIM successfully reproduced aboveground dry matters and, for wheat only, grain yields in pure cultures. In intercrops, APSIM systematically overestimated the aboveground dry matter and grain yield of faba bean and underestimated those of wheat. APSIM was reasonably capable of simulating plant heights in pure cultures, but respectively overestimated and underestimated the height of faba bean and wheat in intercrops. In order to simulate wheat-faba bean intercrops better, APSIM should be improved regarding the calculation of biomass partitioning to grains in faba bean and of height growth in both species. [ABSTRACT FROM AUTHOR]

The long-term sustainability of crop production depends on the complex network of interactions and trade-offs between biotic, abiotic and economic components of agroecosystems. An integrated arable management system was designed to maintain yields, whilst enhancing biodiversity and minimising environmental impact. Management interventions included conservation tillage and organic matter incorporation for soil biophysical health, reduced crop protection inputs and integrated pest management strategies for enhanced biodiversity and ecosystem functions, and intercropping, cover cropping and under-sowing to achieve more sustainable nutrient management. This system was compared directly with standard commercial practice in a split-field experimental design over a six-year crop rotation. The effect of the cropping treatment was assessed according to the responses of a suite of indicators, which were used to parameterise a qualitative multi-attribute model. Scenarios were run to test whether the integrated cropping system achieved greater levels of overall sustainability relative to standard commercial practice. Overall sustainability was rated high for both integrated and conventional management of bean, barley and wheat crops. Winter oilseed crops scored medium for both cropping systems and potatoes scored very low under standard management but achieved a medium level of sustainability with integrated management. In general, high scores for environmental sustainability in integrated cropping systems were offset by low scores for economic sustainability relative to standard commercial practice. This case study demonstrates the value of a 'whole cropping systems' approach using qualitative multi-attribute modelling for the assessment of existing cropping systems and for predicting the likely impact of new management interventions on arable sustainability. [ABSTRACT FROM AUTHOR]

The intensification of arable production since the 1950s has resulted in increases in yield but only at significant cost to the environment, raising serious concerns about long-term consequences for the sustainability of food production systems. While a range of policies and practices have been put in place to mitigate negative effects in terms of pollution, soil degradation and loss of biodiversity, their efficacy has not been properly quantified. Whole-system effects of management change are rarely studied and so trade-offs and conflicts between different components of the agricultural system are poorly understood. A long-term field platform was therefore established in which conventional arable management was compared with a low-input, integrated cropping system designed with the goal to maintain yields whilst enhancing biodiversity and minimizing environmental impact. Over the first rotation, only winter wheat yielded less under integrated management; yield was maintained for the remaining five crops (spring and winter barley, winter oilseed rape, potato and field beans), suggesting a negligible impact on economic returns. Beneficial broad-leaved weeds were significantly more abundant in the integrated management system across all crops whereas grass weeds showed no overall response to treatment. Soil carbon, pH and soil concentrations of the main plant growth-limiting macronutrients were enhanced under the integrated management system. The integrated system was therefore successful in meeting the goals to enhance biodiversity and reduce environmental impact without jeopardizing crop yields. [ABSTRACT FROM AUTHOR]