Sue E Hartley

Sue E Hartley
The University of York · Department of Biology

PhD York

About

135
Publications
19,193
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8,420
Citations
Citations since 2016
7 Research Items
3435 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500

Publications

Publications (135)
Article
Full-text available
Despite seminal papers that stress the significance of silicon (Si) in plant biology and ecology, most studies are focused on manipulations of Si supply and mitigation of stresses. The ecological significance of Si varies with different levels of biological organisation, and remains hard to capture. We show that the costs of Si accumulation are gre...
Article
Full-text available
Estimating plasticity of leaf silicon (Si) in response to abiotic and biotic factors underpins our comprehension of plant defences and stress resistance in natural and agroecosystems. However, how nitrogen (N) addition and intraspecific plant‐plant interactions affect Si concentration remains unclear. We grew 19 durum wheat genotypes (Triticum turg...
Article
Full-text available
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 plan...
Article
Biofumigation is an integrated pest management method involving the mulching of a glucosinolate containing cover crop into a field in order to generate toxic isothiocyanates, effective soil borne pest control compounds. Variation in biofumigation efficacy demonstrates a need to better understand the factors affecting pest control outcomes and devel...
Article
Full-text available
Background Glucosinolates, anionic sulfur rich secondary metabolites, have been extensively studied because of their occurrence in the agriculturally important brassicaceae and their impact on human and animal health. There is also increasing interest in the biofumigant properties of toxic glucosinolate hydrolysis products as a method to control ag...
Article
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 q...
Research
Full-text available
Developed at the March 2015 workshop “Working Together for Better Outcomes” by 36 participants from 21 research, funding and end-user organisations. This guide aims to alert national and international funding agencies to specific funding requirements for interdisciplinary research which involves researchers from diverse disciplines and/or non-resea...
Article
Climate change models predict more extreme rainfall patterns, ranging from droughts to deluges, which will inevitably affect primary productivity in many terrestrial ecosystems. Insects within the ecosystem, living above- and belowground, may modify plant responses to water stress. For example, some functional groups improve soil conditions via res...
Article
Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements...
Article
Hedgerows are an important semi-natural habitat for invertebrates and other wildlife within agricultural landscapes. Hedgerow quality can be greatly affected either by over- or under-management. Neglect of hedgerows is an increasingly important issue as traditional management techniques such as hedgelaying become economically unviable. In the UK, f...
Article
Understanding the impact of species on community structure is a fundamental question in ecology. There is a growing body of evidence that suggests that both subdominant species and parasites can have disproportionately large effects on other organisms. Here we report those impacts for a species that is both subdominant and parasitic, the hemiparasi...
Article
Full-text available
Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si) is laid down on...
Article
Full-text available
The objective of this study was to evaluate whether silicon (Si) amendments, known to have a prophylactic role against biotrophic and hemibiotrophic pathogens, could protect soybean against Phytophthora sojae. To fulfill this objective, the initial challenge was to develop a method of inoculation that reproduced the natural infection process while...
Article
Full-text available
Grasses have been considered to primarily employ tolerance in lieu of defense in mitigating damage caused by herbivory. Yet a number of mechanisms have been identified in grasses, which may deter feeding by grazers. These include enhanced silicon uptake, hosting of toxin-producing endophytic fungi and induction of secondary metabolites. While these...
Technical Report
Full-text available
Healthy ecosystems are essential for the long-term wellbeing of humans as they provide vital services such as food production, pollination, climate regulation and flood protection. Global trends including population growth, changing diets and consumption patterns, urbanisation and climate change will exert increasing pressure on supplies of food an...
Article
Full-text available
The exploitation of shared resources by diverse organisms underpins the structure of ecological communities. Hemi-parasitic plants and the insect herbivores feeding on them both rely, directly and indirectly, on the resources supplied by the parasite's host plant. Therefore, the identity and number of host plant species providing these resources is...
Article
Full-text available
Predicted increases in atmospheric carbon dioxide (CO2) concentrations often reduce nutritional quality for herbivores by increasing the C∶N ratio of plant tissue. This frequently triggers compensatory feeding by aboveground herbivores, whereby they consume more shoot material in an attempt to meet their nutritional needs. Little, however, is known...
Article
Full-text available
Elevated atmospheric CO2 can change foliar tissue chemistry. This alters leaf litter palatability to macroinvertebrate detritivores with consequences for decomposition, nutrient turnover, and food-web structure. Currently there is no consensus on the link between CO2 enrichment, litter chemistry, and macroinvertebrate-mediated leaf decomposition. T...
Article
Climatic warming has induced marked shifts in the geographical distribution and seasonal phenology of many species, although the impacts of climatic changes on the interactions between species across trophic levels are far less well known.Freshwater microcosms were used to test the effect of temperature on the life history traits of a prey species,...
Article
Silica defences in grasses have recently been suggested to be a potential driver of vole population dynamics. However, the ability of grasses to induce silica in response to herbivory has not been tested in northern ecosystems where small rodents are important herbivores. We conducted a large-scale field experiment in subarctic tundra using three r...
Article
Full-text available
Research investigating interactions between aboveground (AG) and below-ground (BG) herbivores has been central to characterizing AG-BG linkages in terrestrial ecosystems, with many of these interactions forming the basis of complex food webs spanning the two subsystems. Despite the growing literature on the effects of AG and BG herbivores on each o...
Article
Plant secondary metabolites (PSMs) such as terpenes and phenolic compounds are known to have numerous ecological roles, notably in defence against herbivores, pathogens and abiotic stresses and in interactions with competitors and mutualists. This book reviews recent developments in the field to provide a synthesis of the function, ecology and evol...
Article
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...
Article
The elemental analysis of plant material is a frequently employed tool across biological disciplines, yet accurate, convenient and economical methods for the determination of some important elements are currently lacking. For instance, digestion-based techniques are often hazardous and time-consuming and, particularly in the case of silicon (Si), c...
Article
Plant secondary metabolites (PSMs) such as terpenes and phenolic compounds are known to have numerous ecological roles, notably in defence against herbivores, pathogens and abiotic stresses and in interactions with competitors and mutualists. This book reviews recent developments in the field to provide a synthesis of the function, ecology and evol...
Article
1 The vine weevil Otiorhynchus sulcatus is a major pest of horticultural crops worldwide, with root‐feeding larvae causing most damage. Adult oviposition aboveground may therefore influence levels of damage as the larvae are relatively immobile after oviposition. 2 The present study investigated feeding and oviposition behaviour on red raspberry Ru...
Article
Full-text available
Some grass species mount a defensive response to grazing by increasing their rate of uptake of silica from the soil and depositing it as abrasive granules in their leaves. Increased plant silica levels reduce food quality for herbivores that feed on these grasses. Here we provide empirical evidence that a principal food species of an herbivorous ro...
Article
Full-text available
The need for policy makers to understand science and for scientists to understand policy processes is widely recognised. However, the science-policy relationship is sometimes difficult and occasionally dysfunctional; it is also increasingly visible, because it must deal with contentious issues, or itself becomes a matter of public controversy, or b...
Data
The questions submitted to this exercise. (DOCX)
Article
Black vine weevil (Otiorhynchus sulcatus) is regarded as a damaging pest of horticultural crops, yet empirical data about its population dynamics and effects on crop yield are largely lacking. This paper reports a four year (2007–2010) field study that simulated colonisation by O. sulcatus in a red raspberry (Rubus idaeus) plantation comprising two...
Article
Full-text available
The need for policy makers to understand science and for scientists to understand policy processes is widely recognised. However, the science-policy relationship is sometimes difficult and occasionally dysfunctional; it is also increasingly visible, because it must deal with contentious issues, or itself becomes a matter of public controversy, or b...
Article
1. Root hemiparasites are common components of many ecosystems and can affect both the biomass and the nutritional quality of the plants they infect. The consequences of these modifications for the preference and performance of three herbivore feeding guilds sharing a host with the hemi-parasite were examined. 2. It was predicted that as the hemipa...
Article
Full-text available
The preference-performance hypothesis has principally considered insect herbivores with aboveground lifecycles, although the hypothesis could be equally relevant to insects with life stages occurring both aboveground and belowground. Moreover, most studies have focussed on either laboratory or field experiments, with little attempt to relate the tw...
Article
Full-text available
The herbivore defence system of true grasses (Poaceae) is predominantly based on silicon that is taken up from the soil and deposited in the leaves in the form of abrasive phytoliths. Silicon uptake mechanisms can be both passive and active, with the latter suggesting that there is an energetic cost to silicon uptake. This study assessed the effect...
Article
1. A substantial amount of research on host-plant selection by insect herbivores is focused around the preference–performance hypothesis (PPH). To date, the majority of studies have primarily considered insects with aboveground life cycles, overlooking insect herbivores that have both aboveground and belowground life stages, for which the PPH could...
Article
The effect of monoterpene concentrations in Sitka spruce (Picea sitchensis) foliage on the browsing behaviour and preferences of red deer (Cervus elaphus) was studied in a series of 18 choice trials. During each trial, individual hinds were given access to 16 saplings arranged in a symmetrical array and aspects of their feeding behaviour were recor...
Article
Summary1. We conducted a large-scale field study to determine how the interactive effects of earthworms (Aporrectodea caliginosa) and summer drought affected plant communities containing barley (Hordeum vulgare), shepherd’s purse (Capsella bursa-pastoris) and common groundsel (Senecio vulgaris), and how such effects then influenced populations of t...
Article
1. Individual plants are often simultaneously consumed by many different organisms and mediate important indirect interactions between their consumers, even when their consumers are phylogenetically distant and feed on different parts of the plant. 2. We examined the effects on two xylem feeders of sharing a plant host in greenhouse pot trials and...
Article
Full-text available
Tree seedlings in tropical rain forests are subject to both damage from natural enemies and intense interspecific competition. This leads to a trade-off in investment between defense and growth, and it is likely that tree species specialized to particular habitats tailor this balance to correspond with local resource availability. It has also been...
Article
1. Both top-down and bottom-up influences, such as grazing herbivores and edaphic factors, may maintain species-rich vegetation by preventing dominant plants from reducing diversity. However, the interaction between grazing and other processes maintaining diversity, particularly in ecosystems with multiple herbivores, is poorly understood. We manip...
Article
Grasses, which dominate many terrestrial ecosystems, sustain high densities of grazing mammals, so are of great economic and ecological importance. Traditionally, grasses are thought to be adapted to tolerate grazing rather than defend against it; however, silica deposited in the leaves of grasses has recently been shown to act as a feeding deterre...
Article
1. Euedaphic collembola alter their soil distribution in response to above-ground aphid herbivory of Poa annua L. Graminae, a host grass. 2. Two mechanisms potentially underpin this effect. Carbon-rich aphid honeydew falling onto the soil surface may affect mycophagous collembola; alternatively aphid-induced changes in root biomass may be necessary...
Article
Full-text available
We consider how fungi that form symbiotic associations with plants interact with insect herbivores attacking the same plants. Both endophytes and mycorrhizae have significant impacts on herbivores with which they are in relatively intimate contact, but weaker effects on those from which they are spatially separated. Generalist insects are usually a...
Article
Insect herbivores were collected from five species of dipterocarp tree seedling within a large-scale reciprocal transplant experiment in Sabah, Malaysia, on alluvial and sandstone soils in both gap and understory plots. The aim was to determine whether the location and ecological specialization of seedlings influenced the herbivore communities foun...
Article
1. Silica in the leaves of grasses can act as a defence against both vertebrate and invertebrate herbivores. The mechanisms by which silica affects herbivore performance are not well characterized. Here we expose an insect herbivore Spodoptera exempta to high-silica diets and test two mechanisms by which silica has been proposed to act as a defence...
Article
Full-text available
Understanding the factors that drive species population dynamics is fundamental to biology. Cyclic populations of microtine rodents have been the most intensively studied to date, yet there remains great uncertainty over the mechanisms determining the dynamics of most of these populations. For one such population, we present preliminary evidence fo...
Article
1. The relative importance of host-plant resources and natural enemies in influencing the abundance of insect herbivores was investigated in potted plant and natural population experiments, using tephritid (Diptera: Tephritidae) flies, their host plant, creeping thistle Cirsium arvense, and their Hymenoptera parasitoids. 2. Experimental manipulatio...
Article
. 1The possibility of interactions between leaf-miners in the genus Eriocrania and Coleophora serratella L. on birch (Betula pendula Ehrh. and B.pubescens Roth.) was studied via: (i) co-occurrence patterns on random samples of leaves; (ii) palatability of Eriocraniidae-mined leaves to C.serratella, in laboratory and field preference tests.2In the f...
Article
Full-text available
An international initiative is developing a scientifically rigorous approach to evaluate the potential risks to nontarget arthropods (NTAs) posed by insect-resistant, genetically modified (IRGM) crops. It adapts the tiered approach to risk assessment that is used internationally within regulatory toxicology and environmental sciences. The approach...
Article
Full-text available
A plan for Post Market Environmental Monitoring (PMEM) of genetically modified (GM) plants is mandatory in all applications for deliberate release submitted under EU Directive 2001/18/EC and EU Regulation 1829/2003. PMEM is composed of case-specific monitoring and general surveillance of GM plants. The European Food Safety Authority (EFSA) is respo...
Article
Grasses have their own way of protecting themselves from attack by herbivores. They contain silica, some of which feel like mini razor blades, which is taken up from soil and is deposited in their leaves. The first experimental evidence of the effects this silica structure can have on herbivore performance includes reducing their ability to extract...
Article
Nutrient inputs to plant communities are often spatially heterogeneous, for example those deriving from the dung and urine of large grazing animals. The effect of such localised elevation of nutrients on plant growth and composition has been shown to be modified by the grazing of large herbivores. However, there has been little work on interactions...
Article
Full-text available
Induced plant responses to herbivory have major impacts on herbivore feeding behaviour, performance and population dynamics. These effects are well established for chemical defences, but induction of physical defences remains far less studied. However, for many plants, it is physical defences that play the major role in regulating the levels of her...
Article
Above-ground aphid herbivory of a shared host plant results in increased collembola populations within the rhizosphere. Three mechanisms potentially underpin this effect: honeydew deposition, aphid-induced reduction in root biomass and altered soil water content (as a result of root reduction inhibiting plant water uptake). This study focuses on th...
Article
Seedlings of five species of dipterocarp trees were planted in experimental plots in rain forest gaps in Sabah, Malaysia, and the rates of herbivory on their mature leaves recorded over 6 mo. A novel method was used to estimate the feeding pressure exerted by the local insect herbivore community, derived from the relative abundances of the dominant...
Article
Summary • The resource availability hypothesis (RAH) predicts that allocation of resources to anti-herbivore defences differs between species according to their growth rate. We tested this hypothesis by assessing the growth and defence investment strategies of 18 grass species and comparing them against vole feeding preferences. In addition, we ass...
Article
Introduction Plant-mediated indirect interactions between phytophagous insects There is increasing interest in the consequences of indirect interactions for community structure and function (Wootton 1994). Herbivory by one phytophagous species has the potential to affect other herbivores exploiting the same plant, hence plants are able to mediate i...
Article
Full-text available
The European Food Safety Authority (EFSA) is requested to assess the scientific quality of Post Market Environmental Monitoring (PMEM) plans submitted with each application for deliberate release of genetically modified (GM) plants according to part C of EU Directive 2001/18/EC and according to EU Regulation 1829/2003. PMEM aims at identifying unan...
Article
Full-text available
The impact of plant-based factors on the population dynamics of mammalian herbivores has been the subject of much debate in ecology, but the role of antiherbivore defences in grasses has received relatively little attention. Silica has been proposed as the primary defence in grasses and is thought to lead to increased abrasiveness of foliage so det...
Article
Full-text available
Transgenic insecticidal crops have the potential to pose risks to non-target organisms. These risks need to be addressed as part of the environmental risk assessment that precedes the commercialization of any novel transgenic crop. An international initiative has been launched to develop a scientifically-sound, generic, and pragma tic approach to a...
Article
Full-text available
Seedlings of five species in the Dipterocarpaceae were grown in experimental plots in Sabah, Malaysia. These were sited both in gaps and understorey and on alluvial and sandstone soils. Half of all seedlings were provided with a complete fertilizer. Herbivore damage levels were recorded on over 25 000 individual leaves in four surveys over the cour...
Article
1. Silica, deposited as opaline phytoliths in the leaves of grasses, constitutes 2-5% of dry leaf mass, yet its function remains unclear. It has been proposed that silica may act as an antiherbivore defence by increasing the abrasiveness and reducing the digestibility of grass leaves, although there is little direct experimental evidence to support...
Article
Summary1 Interspecific and intraspecific competition in seedling banks may be important determinants of regeneration success in some groups of canopy trees, e.g. dipterocarps in south‐east Asian tropical rain forests, and the outcomes of these competitive interactions may contribute to the maintenance of the high levels of plant diversity. 2 We pre...
Article
Gender-related differences in growth and concentration of secondary metabolites have been documented in dioecious plants. Males usually grow faster than females, whilst females allocate more resources to reproduction and chemical defences than males, hence their growth is reduced. This hypothesis was tested on prickly juniper (Juniperus oxycedrus m...
Chapter
Tropical ecosystems house a significant proportion of global biodiversity. To understand how these ecosystems function we need to appreciate not only what plants, animals and microbes they contain, but also how they interact with each other. This volume, first published in 2005, synthesises the state of knowledge in this area, with chapters providi...