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The iconic European stag beetle (Lucanus cervus) (Coleoptera: Lucanidae) is one of the largest terrestrial beetles in Europe. Due to decreasing population numbers, thought to be a consequence of habitat loss, this beetle has become a near-threatened species across much of Europe, and a reliable monitoring system is required to measure its future population trends. As part of a programme aimed at conserving UK populations, we have investigated the chemical ecology of the beetle, with a view to developing an efficient semiochemical-based monitoring system. Such a scheme will be beneficial not only in the UK but across the European range of the species, where the beetle is of conservation concern. Here, we report on a surprising discovery of a male-produced pheromone, which provokes initial sexual receptivity in females, and which has not been previously identified in the animal kingdom. Furthermore, we assign sex pheromone function to a previously described female-specific compound., (© 2024. The Author(s).)

Impatiens glandulifera or Himalayan balsam is one of the most invasive weeds across Europe and can seriously reduce native plant diversity. It often forms continuous monocultures along river banks, but the mechanisms of this arrested succession are largely unknown. Here, we investigated the effect of arbuscular mycorrhizal (AM) fungi on balsam competitive ability with two native plant species, Plantago lanceolata and Holcus lanatus . We also studied how competition with Impatiens affects colonisation by foliar endophytes and mycorrhizas of two other co-occurring native species, Urtica dioica and Cirsium arvense. Mycorrhizal colonisation reduced balsam growth when the plants were grown singly, but appeared to have little effect when balsam experienced intra- or interspecific competition. Competition with balsam together with the addition of mycorrhizas had no effect on P. lanceolata biomass, suggesting that the fungi were beneficial to the latter, enabling it to compete effectively with balsam. However, this was not so with H. lanatus. Meanwhile, competition with Impatiens reduced endophyte numbers and mycorrhizal colonisation in U. dioica and C. arvense, leading to enhanced susceptibility of these plants to insect attack. Himalayan balsam is known to degrade soil fungal populations and can also reduce foliar beneficial fungi in neighbouring plants. This allows the plant to compete effectively with itself and other native species, thereby leading to the continuous monocultures.

Culinary herbs are commercially cultivated for their wide range of volatile compounds that give characteristic aromas and tastes. Rosemary ( Salvia rosmarinus Spenn.) is an excellent model for assessment of methods improvement of volatile production as cultivars offer a wide variety of aromatic profiles due to the large family of terpene synthase genes. Arbuscular mycorrhizal fungi (AMF) associations have been shown to improve essential oil production in aromatic plants and offer one approach to enhance aroma in commercial herb production. Changes in the expression of seven different terpene synthases were compared in six rosemary cultivars in response to addition of AMF to a peat substrate. Addition of AMF profoundly influenced terpene synthase expression in all cultivars and did so without impacting the optimised plant size and uniformity achieved in these conditions. In addition, two methods for AMF application, developed with the horticultural industry in mind, were tested in this study. Uniform incorporation of AMF mixed into the growing substrate prior to planting of a root plug produced the most consistent root colonisation. Overall, our findings demonstrate the potential for the use of AMF in the improvement of aroma in culinary herbs within a commercial setting but show that outcomes are likely to greatly vary depending on variety.

Almost all living plants can be simultaneously colonised by arbuscular mycorrhizal fungi in the roots and endophytes in the shoots, while also being attacked by insect herbivores. However, to date, no study has ever examined the multitrophic interactions between these two different fungal groups and insects on any species of forb. Here, we examined the effects of two commercial species mixtures of arbuscular mycorrhizal fungi (AMF) and two foliar endophytes (Colletotrichum acutatum and Cladosporium oxysporum) on the growth of an invasive weed, Impatiens glandulifera, and the aphids that attack it. AMF reduced plant biomass, which was most evident when C. oxysporum was inoculated. Mycorrhizal fungi had few effects on aphids, and these depended on the identity of the endophytes present. Meanwhile, endophytes tended to increase aphid numbers, but this depended on the identity of the AMF inoculum. Throughout, there were differences in the responses of the plant to the two mycorrhizal mixtures, demonstrating clear AMF specificity in this plant. These specific effects were also strongly affected by the endophytes, with a greater number of interactions found between the AMF and endophytes than between the endophytes themselves. In particular, AMF reduced infection levels by the endophytes, while some endophyte inoculations reduced mycorrhizal colonisation. We suggest that both AMF and endophytes could play an important part in future biological control programmes of weeds, but further multitrophic experiments are required to unravel the complexity of interactions between spatially separated parts of the plant microbiome., (© 2021. The Author(s).)

Plant performance in any one generation is affected not only by the prevailing environmental conditions, but also by the conditions experienced by the parental generation of those plants. These maternal effects have been recorded in a many plant species, but the influence of external biotic (as opposed to abiotic) factors on shaping maternal effects have been rarely examined. Furthermore, almost all previous studies have taken place over one plant generation, rather than across multiple generations. Here, we studied the influence of insect herbivory and arbuscular mycorrhizal (AM) fungal colonisation on the shaping of maternal effects in the annual forb Senecio vulgaris. We grew plants with and without aphids ( Myzus persicae ) and AM fungi (hereafter termed 'induction events') over four successive generations, wherein seeds from plants in any one treatment were used to grow plants of the same treatment in the next generation, all in identical environmental conditions. We found strong evidence of maternal effects in the second plant generation, i.e., after one induction event. These plants took longer to germinate, flowered in a shorter time, produced lighter seeds and were shorter and of lower biomass than their parents. Aphid attack tended to enhance these effects, whereas AM fungi had little influence. However, thereafter there was a gradual recovery in these parameters, so that plants experiencing three inductions showed similar life history parameters to those in the original generation. We conclude that experiments investigating maternal effects need to be performed over multiple plant generations and that biotic factors such as insects and mycorrhizas must also be taken into account, along with abiotic factors, such as nutrient and water availability.

Background: Vegetated building envelopes (VBEs), such as vegetated roofs and facades, are becoming more frequent in urban planning nowadays. However, harsh growing conditions restrain the application of VBEs. Plant growth-promoting microbes (PGPMs) might help ease the stresses, but first, it is necessary to investigate how to ensure their survival and growth under VBE conditions., Methods: We conducted three experiments to test the impact of various factors on the microbial populations of inoculated PGPMs in VBEs, a mycorrhizal fungus Rhizophagus irregularis and a bacterium Bacillus amyloliquefaciens . The first experiment was conducted by inoculating the two PGPMs separately in Sedum roof plots, and the microbial populations associated with Poa alpina was monitored for two consecutive years under local weather conditions. The second experiment was conducted in a laboratory testing the effect of substrate pH (substrates collected from balcony gardens) on R. irregularis population associated with Trifolium repens and Viola tricolor . The third experiment was conducted on a meadow roof testing the effect of biochar amendment on R. irregularis population associated with Thymus serpyllum and Fragaria vesca ., Results: In the first experiment, Bacillus was found to associate with P. alpina , but Rhizophagus wasn't. Yet, the fungus induced high Bacillus population density in the Rhizophagus treated plots in the first year. In the second experiment, Rhizophagus abundance in T. repens was higher in the neutral substrate (6-6.5), while V. tricolor was more colonized in acidic substrate (5-5.5), suggesting an important interactive effect of substrate pH and plant species on Rhizophagus abundance. The third experiment suggested a negligible impact of biochar amendment on Rhizophagus abundance for both host plants., Conclusion: Three experiments demonstrate that PGPM inoculation on VBEs is feasible, and various factors and interactions affect the PGPM populations. This paper provides reference and inspiration for other VBE research involving substrate microbial manipulation., Competing Interests: The authors declare no conflict of interest., (© 2022 The Author(s).)

Plant parasitic nematode (PPN) control has historically relied on the use of synthetic chemical nematicides, however many are toxic to both human health and the environment. The withdrawal of the more harmful nematicides coupled with increases in soil temperatures and increased occurrence of pests and diseases associated with climate change, may enable PPN to increase in numbers and spread globally. The need for sustainable and environmentally friendly management options is necessary while facing future food security scares in order to feed the ever-growing population. Seaweed extracts have been used for decades in agriculture and horticulture as soil biostimulants, however there is a growing body of evidence to suggest that they could be used to reduce the occurrence of damaging PPN infections. Using meta-analysis, we investigated whether seaweed extracts applied to soil could reduce root knot nematode (RKN) abundance and whether there could be confounding factors that influence their efficacy. We found that seaweed extracts reduce RKN performance and that various factors affected the efficacy of seaweed, including the seaweed species itself and the crop the seaweed was applied to. Ascophyllum nodosum extracts were found to be the most effective. Particular RKN species were more sensitive than others to seaweed species used and, in some cases, specific seaweed species only affected particular RKN species . Different life cycle stages were also differentially susceptible to seaweed application, where both egg hatching and population abundance could be reduced via seaweed use. This research indicates that seaweed extracts could potentially be used to help reduce RKN attack on plants., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Authors.)

European apple canker, caused by Neonectria ditissima, is a severe disease of apple. Achieving effective control is difficult with the currently available pesticides. Specific apple endophytes associated with cultivars may partially contribute to the cultivar response to the pathogen and thus could be used for disease management. We sought to determine whether the overall endophyte community differed among cultivars differing in their susceptibility to N. ditissima and to identify specific microbial groups associated with the susceptibility. Using Illumina MiSeq meta-barcoding, we profiled apple tree endophytes in 16 scion-rootstock combinations at two locations and quantified the relative contribution of scion, rootstock and location to the observed variability in the endophyte communities. Endophyte diversity was primarily affected by the orchard location (accounting for 29.4% and 85.9% of the total variation in the PC1 for bacteria and fungi, respectively), followed by the scion genotype (24.3% and 19.5% of PC2), whereas rootstock effects were small (<3% of PC1 and PC2). There were significant differences in the endophyte community between canker-resistant and -susceptible cultivars. Several bacterial and fungal endophyte groups had different relative abundance between susceptible and resistant cultivars. These endophyte groups included putative pathogen antagonists as well as plant pathogens. Their possible ecological roles in the N. ditissima pathosystem are discussed., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS.)

Herbaceous plants harbour species-rich communities of asymptomatic endophytic fungi. Although some of these endophytes are entomopathogenic, many are not, and remarkably little is known about how the presence of these fungi in plant tissues affects phytophagous insects. Here we show through a meta-analysis that both entomopathogenic and nonentomopathogenic endophytes have a negative effect on insect herbivores. Growth and performance of polyphagous and sucking insects are reduced by nonentomopathogenic endophytes, but monophages are unaffected, likely because the latter are better adapted to secondary metabolites produced or induced by the fungi. Furthermore, studies using excised leaves report weaker effects than those with intact plants, likely caused by chemical changes being masked by leaf excision. Most surprisingly, endophyte infection of seeds produces the greatest effect on insect herbivores in subsequent mature plants, even though the usual mode of fungal transmission is infection of leaves by airborne spores. We conclude that these ubiquitous hidden fungi may be important bodyguards of plants. However, in order to fully understand their roles in plant protection, we must be aware that minor differences in experimental design can lead to contradictory results., (© 2019 The Authors. New Phytologist © 2019 New Phytologist Trust.)

Thermal melanism theory states that dark-colored ectotherm organisms are at an advantage at low temperature due to increased warming. This theory is generally supported for ectotherm animals, however, the function of colors in the fungal kingdom is largely unknown. Here, we test whether the color lightness of mushroom assemblages is related to climate using a dataset of 3.2 million observations of 3,054 species across Europe. Consistent with the thermal melanism theory, mushroom assemblages are significantly darker in areas with cold climates. We further show differences in color phenotype between fungal lifestyles and a lifestyle differentiated response to seasonality. These results indicate a more complex ecological role of mushroom colors and suggest functions beyond thermal adaption. Because fungi play a crucial role in terrestrial carbon and nutrient cycles, understanding the links between the thermal environment, functional coloration and species' geographical distributions will be critical in predicting ecosystem responses to global warming.

Premise of the Study: Fungal diversity (richness) trends at large scales are in urgent need of investigation, especially through novel situations that combine long-term observational with environmental and remotely sensed open-source data., Methods: We modeled fungal richness, with collections-based records of saprotrophic (decaying) and ectomycorrhizal (plant mutualistic) fungi, using an array of environmental variables across geographical gradients from northern to central Europe. Temporal differences in covariables granted insight into the impacts of the shorter- versus longer-term environment on fungal richness., Results: Fungal richness varied significantly across different land-use types, with highest richness in forests and lowest in urban areas. Latitudinal trends supported a unimodal pattern in diversity across Europe. Temperature, both annual mean and range, was positively correlated with richness, indicating the importance of seasonality in increasing richness amounts. Precipitation seasonality notably affected saprotrophic fungal diversity (a unimodal relationship), as did daily precipitation of the collection day (negatively correlated). Ectomycorrhizal fungal richness differed from that of saprotrophs by being positively associated with tree species richness., Discussion: Our results demonstrate that fungal richness is strongly correlated with land use and climate conditions, especially concerning seasonality, and that ongoing global change processes will affect fungal richness patterns at large scales.

Conserving populations of environmentally vulnerable insect species requires a greater understanding of the factors that determine their abundance and distribution, which requires detailed knowledge of their population and community ecology. Chemical ecological tools such as pheromones can be used for non-destructive monitoring of scarab beetle populations, enabling European countries to detect and, in some cases, map the range of some of these species, proving a valuable technique for monitoring elusive saproxylic beetles. In this paper, we investigated the behavioural and chemical ecology of the noble chafer, Gnorimus nobilis L., a model insect species of conservation concern across a Europe-wide distribution, and a red-listed UK Biodiversity Action Plan priority species. We identified a potential pheromone of adult beetles using electrophysiological recordings, behavioural measurements and field trials in the UK. Gnorimus nobilis is highly unusual in that although both sexes produce, at high metabolic cost, the natural product 2-propyl (E)-3-hexenoate, it only attracts males. This pattern of chemical signalling makes the classification of the compound, based on current semiochemical terminology, somewhat problematic, but in our view, it should be termed an aggregation pheromone as a consequence of the production pattern. Since both sexes emit it, but apparently only males respond positively to it, 2-propyl (E)-3-hexenoate may reflect an intermediate evolutionary stage towards developing into a sex-specific signal. From an applied perspective, our study provides a model for the non-invasive surveillance of cryptic vulnerable insect species, without the need for habitat searching or disturbance, and continuous human monitoring., Competing Interests: The authors have declared that no competing interests exist.

The use of microbial inoculants containing plant growth-promoting rhizobacteria as a promoter of plant fitness and health is becoming increasingly popular in agriculture. However, whether and how these bacteria affect indigenous bacterial communities in field conditions is sparsely explored. We studied the effects of seed inoculation and field soil application of ubiquitous soil bacteria, B. cereus, B. subtilis, and B. amyloliquefaciens, on the diversity, evenness, and richness of endophytic bacterial communities in sprouting broccoli roots using high-throughput metagenome sequencing. The multiple operational taxonomic units (OTUs) assigned to different bacterial taxa clearly showed changes in ecological measures and relative abundances of certain taxa between control and treatment groups. The Bacillus inocula, themselves, failed to flourish as endophytes; however, the effects they extended on the endophytic bacterial community were both generic as well as species specific. In each case, Pseudomonadales, Rhizobiales, Xanthomonadales, and Burkholderiales were the most abundant orders in the endosphere. B. amyloliquefaciens drastically reduced the most abundant genus, Pseudomonas, while increasing the relative abundance of a range of minor taxa. The Shannon-Weiner diversity and Buzas and Gibson's evenness indices showed that the diversity and evenness were increased in both B. amyloliquefaciens and mixed treated plants. The UniFrac measurement of beta diversity showed that all treatments affected the specific composition of the endophytic bacterial community, with an apparent interspecies competition in the mixed treatment. Taken together, Bacillus species influenced the diversity, evenness, and composition of the endophytic bacterial community. However, these effects varied between different Bacillus spp. in a context-specific manner.

The uniformity of crop yield is extremely important for consumers and of as much relevance to the grower as overall yield. However, size inequality within a plant population is rarely measured and has never before been considered in relation to the use of beneficial microbes for yield enhancement. For the first time, we show that addition of soil bacteria to calabrese plants significantly increased size inequality. These effects were usually more apparent in above-ground biomass. This was caused by some (but not all) plants growing very large when inoculated with bacteria, while control plants were mostly small. We suggest that the main reason is the incompatibility of the inoculated bacteria with those already present in the rhizosphere. In some cases the inoculum matched the indigenous community, providing a benefit to plant growth, while often it did not and plants remained relatively small. We conclude that analyses of size inequality should be an integral part of experiments using microbial soil amendments. These analyses can help to inform the production of more effective microbial products and to ensure that the integration of beneficial microbes into sustainable production systems does not impair uniformity in yield.

Here we assess the impact of geographically dependent (latitude, longitude, and altitude) changes in bioclimatic (temperature, precipitation, and primary productivity) variability on fungal fruiting phenology across Europe. Two main nutritional guilds of fungi, saprotrophic and ectomycorrhizal, were further separated into spring and autumn fruiters. We used a path analysis to investigate how biogeographic patterns in fungal fruiting phenology coincided with seasonal changes in climate and primary production. Across central to northern Europe, mean fruiting varied by approximately 25 d, primarily with latitude. Altitude affected fruiting by up to 30 d, with spring delays and autumnal accelerations. Fruiting was as much explained by the effects of bioclimatic variability as by their large-scale spatial patterns. Temperature drove fruiting of autumnal ectomycorrhizal and saprotrophic groups as well as spring saprotrophic groups, while primary production and precipitation were major drivers for spring-fruiting ectomycorrhizal fungi. Species-specific phenology predictors were not stable, instead deviating from the overall mean. There is significant likelihood that further climatic change, especially in temperature, will impact fungal phenology patterns at large spatial scales. The ecological implications are diverse, potentially affecting food webs (asynchrony), nutrient cycling and the timing of nutrient availability in ecosystems., (© 2018 by the Ecological Society of America.)

Arbuscular mycorrhizal (AM) fungi are root symbionts that can increase or decrease aphid growth rates and reproduction, but the reason by which this happens is unknown. To investigate the underlying mechanisms of this interaction, we examined the effect of AM fungi on the English Grain aphid (Sitobion avenae) development, reproduction, attraction, settlement and feeding behaviour on two naturally susceptible varieties Triticum aestivum (L.) variety Solstice and T. monococcum MDR037, and two naturally resistant lines, T. monococcum MDR045 and MDR049. Mycorrhizal colonisation increased the attractiveness of T. aestivum var. Solstice to aphids, but there was no effect on aphid development on this variety. Using the Electrical Penetration Graph (EPG) technique, we found that mycorrhizal colonisation increased aphid phloem feeding on T. monococcum MDR037 and MDR045, colonisation also increased growth rate and reproductive success of S. avenae on these varieties. Mycorrhizas increased vascular bundle size, demonstrating that these fungi can influence plant anatomy. We discuss if and how this could be related to an enhanced success rate in phloem feeding in two varieties. Overall, we present and discuss how mycorrhizal fungi can affect the feeding behaviour of S. avenae in wheat, inducing susceptibility in a resistant variety.

Green roofs are increasing in popularity in the urban environment for their contribution to green infrastructure; but their role for biodiversity is not often a design priority. Maximising biodiversity will impact positively on ecosystem services and is therefore fundamental for achieving the greatest benefits from green roofs. Extensive green roofs are lightweight systems generally constructed with a specialised growing medium that tends to be biologically limited and as such can be a harsh habitat for plants to thrive in. Thus, this investigation aimed to enhance the soil functioning with inoculations of soil microbes to increase plant diversity, improve vegetation health/performance and maximise access to soil nutrients. Manipulations included the addition of mycorrhizal fungi and a microbial mixture ('compost tea') to green roof rootzones, composed mainly of crushed brick or crushed concrete. The study revealed that growing media type and depth play a vital role in the microbial ecology of green roofs, with complex relationships between depth and type of substrate and the type of microbial inoculant applied, with no clear pattern being observed. For bait plant measurements (heights, leaf numbers, root/shoot biomass, leaf nutrients), a compost tea may have positive effects on plant performance when grown in substrates of shallower depths (5.5cm), even one year after inoculums are applied. Results from the species richness surveys show that diversity was significantly increased with the application of an AM fungal treatment and that overall, results suggest that brick-based substrate blends are most effective for vegetation performance as are deeper depths (although this varied with time). Microbial inoculations of green roof habitats appeared to be sustainable; they need only be done once for benefits to still been seen in subsequent years where treatments are added independently (not in combination). They seem to be a novel and viable method of enhancing rooftop conditions., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Belowground tri-trophic study systems present a challenging environment in which to study plant-herbivore-natural enemy interactions. For this reason, belowground examples are rarely available for testing general ecological theories. To redress this imbalance, we present, for the first time, data on a belowground tri-trophic system to test the slow growth, high mortality hypothesis. We investigated whether the differing performance of entomopathogenic nematodes (EPNs) in controlling the common pest black vine weevil Otiorhynchus sulcatus could be linked to differently resistant cultivars of the red raspberry Rubus idaeus. The O. sulcatus larvae recovered from R. idaeus plants showed significantly slower growth and higher mortality on the Glen Rosa cultivar, relative to the more commercially favored Glen Ample cultivar creating a convenient system for testing this hypothesis. Heterorhabditis megidis was found to be less effective at controlling O. sulcatus than Steinernema kraussei, but conformed to the hypothesis. However, S. kraussei maintained high levels of O. sulcatus mortality regardless of how larval growth was influenced by R. idaeus cultivar. We link this to direct effects that S. kraussei had on reducing O. sulcatus larval mass, indicating potential sub-lethal effects of S. kraussei, which the slow-growth, high-mortality hypothesis does not account for. Possible origins of these sub-lethal effects of EPN infection and how they may impact on a hypothesis designed and tested with aboveground predator and parasitoid systems are discussed., Competing Interests: The authors have declared that no competing interests exist.

Soil microbes present a novel and cost-effective method of increasing plant resistance to insect pests and thus create a sustainable opportunity to reduce current pesticide application. However, the use of microbes in integrated pest management programs is still in its infancy. This can be attributed primarily to the variations in microbial inoculum performance under laboratory and field conditions. Soil inoculants containing single, indigenous microbial species have shown promising results in increasing chemical defenses of plants against foliar feeding insects. Conversely, commercial inoculants containing multiple species tend to show no effects on herbivore infestation in the field. We present here a simple model that endeavours to explain how single and multiple species in microbial inoculants differentially govern insect population dynamics via changes in plant chemical profiles. We discuss further how this knowledge can be applied to manipulate soil microbial species and develop 'tailored' microbial inoculants that could be used in plant protection against antagonists.

Very little is known about the impact of climate change on fungi and especially on spore production. Fungal spores can be allergenic, thus being important for human health. The aim of this study was to investigate how climate change influences the responsive ability of fungi by simulating differing environmental regimes. Fungal species with high spore allergenic potential and atmospheric abundance were grown and experimentally examined under a variety of temperatures and different nutrient availability. Each represented the average decadal air temperature of the 1980s, 1990s and 2000s in the UK, along with an Intergovernmental Panel on Climate Change (IPCC) climate change scenario for 2100. All tests were run on six fungal species: Alternaria alternata, Aspergillus niger, Botrytis cinerea, Cladosporium cladosporioides, Cladosporium oxysporum and Epicoccum purpurascens. Mycelium growth rate and spore production were examined on each single species and competitive capacity among species combinations in pairs. All fungal species grew faster at higher temperatures, and this was more pronounced for the temperature projection in 2100. Most species grew faster when there was lower nutrient availability. Exceptions were the species with the highest growth rate (E. purpurascens) and with the highest competition capacity (A. alternata). Most species (except for E. purpurascens) produced more spores in the richer nutrient medium but fewer as temperature increased. C. cladosporioides was an exception, exponentially increasing its spore production in the temperature of the 2100 scenario. Regarding competitive capacity, no species displayed any significant alterations within the environmental range checked. It is suggested that in future climates, fungi will display dramatic growth responses, with faster mycelium growth and lower spore production, with questions risen on relevant allergen potential.

Endophytic fungi live asymptomatically within plants. They are usually regarded as nonpathogenic or even mutualistic, but whether plants respond antagonistically to their presence remains unclear, particularly in the little-studied associations between endophytes and nongraminoid herbaceous plants. We investigated the effects of the endophyte Chaetomium cochlioides on leaf chemistry in Cirsium arvense. Plants were sprayed with spores; leaf material from both subsequent new growth and the sprayed leaves was analysed 2 wk later. Infection frequency was 91% and 63% for sprayed and new growth, respectively, indicating that C. cochlioides rapidly infects new foliage. Metabolomic analyses revealed marked changes in leaf chemistry with infection, especially in new growth. Changes in several novel oxylipin metabolites were detected, including arabidopsides reported here for the first time in a plant species other than Arabidopsis thaliana, and a jasmonate-containing galactolipid. The production of these metabolites in response to endophyte presence, particularly in newly infected foliage, suggests that endophytes elicit similar chemical responses in plants to those usually produced following wounding, herbivory and pathogen invasion. Whether endophytes benefit their hosts may depend on a complex series of chemically mediated interactions between the plant, the endophyte, other microbial colonists and natural enemies., (© 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.)

There has been very little investigation into the soil microbial community on green roofs, yet this below ground habitat is vital for ecosystem functioning. Green roofs are often harsh environments that would greatly benefit from having a healthy microbial system, allowing efficient nutrient cycling and a degree of drought tolerance in dry summer months. To test if green roof microbial communities could be manipulated, we added mycorrhizal fungi and a microbial mixture ('compost tea') to green roof rootzones, composed mainly of crushed brick or crushed concrete. The study revealed that growing media type and depth play a vital role in the microbial ecology of green roofs. There are complex relationships between depth and type of substrate and the biomass of different microbial groups, with no clear pattern being observed. Following the addition of inoculants, bacterial groups tended to increase in biomass in shallower substrates, whereas fungal biomass change was dependent on depth and type of substrate. Increased fungal biomass was found in shallow plots containing more crushed concrete and deeper plots containing more crushed brick where compost tea (a live mixture of beneficial bacteria) was added, perhaps due to the presence of helper bacteria for arbuscular mycorrhizal fungi (AMF). Often there was not an additive affect of the microbial inoculations but instead an antagonistic interaction between the added AM fungi and the compost tea. This suggests that some species of microbes may not be compatible with others, as competition for limited resources occurs within the various substrates. The overall results suggest that microbial inoculations of green roof habitats are sustainable. They need only be done once for increased biomass to be found in subsequent years, indicating that this is a novel and viable method of enhancing roof community composition., (Copyright © 2014 Elsevier B.V. All rights reserved.)

To date, it has been thought that endophytic fungi in forbs infect the leaves of their hosts most commonly by air-borne spores (termed "horizontal transmission"). Here, we show that vertical transmission from mother plant to offspring, via seeds, occurs in six forb species (Centaurea cyanus, C. nigra,Papaver rhoeas,Plantago lanceolata,Rumex acetosa, and Senecio vulgaris), suggesting that this may be a widespread phenomenon. Mature seeds were collected from field-grown plants and endophytes isolated from these, and from subsequent cotyledons and true leaves of seedlings, grown in sterile conditions. Most seeds contain one species of fungus, although the identity of the endophyte differs between plant species. Strong evidence for vertical transmission was found for two endophyte species, Alternaria alternata and Cladosporium sphaerospermum. These fungi were recovered from within seeds, cotyledons, and true leaves, although the plant species they were associated with differed. Vertical transmission appears to be an imperfect process, and germination seems to present a bottleneck for fungal growth. We also found that A. alternata and C. sphaerospermum occur on, and within pollen grains, showing that endophyte transmission can be both within and between plant generations. Fungal growth with the pollen tube is likely to be the way in which endophytes enter the developing seed. The fact that true vertical transmission seems common suggests a more mutualistic association between these fungi and their hosts than has previously been thought, and possession of endophytes by seedling plants could have far-reaching ecological consequences. Seedlings may have different growth rates and be better protected against herbivores and pathogens, dependent on the fungi that were present in the mother plant. This would represent a novel case of trans-generational resistance in plants.

Vegetation community composition and the above- and below-ground invertebrate communities are linked intrinsically, though few studies have assessed the impact of non-native plants on both these parts of the community together. We evaluated the differences in the above- (foliage- and ground-dwelling) and below-ground invertebrate communities in nine uninvaded plots and nine plots invaded by the annual invasive species Impatiens glandulifera, in the UK during 2007 and 2008. Over 139,000 invertebrates were identified into distinct taxa and categorised into functional feeding groups. The impact of I. glandulifera on the vegetation and invertebrate community composition was evaluated using multivariate statistics including principal response curves (PRC) and redundancy analysis (RDA). In the foliage-dwelling community, all functional feeding groups were less abundant in the invaded plots, and the species richness of Coleoptera and Heteroptera was significantly reduced. In the ground-dwelling community, herbivores, detritivores, and predators were all significantly less abundant in the invaded plots. In contrast, these functional groups in the below-ground community appeared to be largely unaffected, and even positively associated with the presence of I. glandulifera. Although the cover of I. glandulifera decreased in the invaded plots in the second year of the study, only the below-ground invertebrate community showed a significant response. These results indicate that the above- and below-ground invertebrate communities respond differently to the presence of I. glandulifera, and these community shifts can potentially lead to a habitat less biologically diverse than surrounding native communities; which could have negative impacts on higher trophic levels and ecosystem functioning.

Foliar endophytic fungi appear to be ubiquitous in nature, occurring in a very wide range of herbaceous plants. However, their ecological role within forbs is very poorly known and interactions with foliar-feeding insects virtually unexplored. In this study, leaves of Cirsium arvense were infected with different combinations of endophyte fungi that had been previously isolated from this plant species. Two months later, leaf material was fed to larvae of a generalist insect, Mamestra brassicae, and adults of a specialist feeder, Cassida rubiginosa. Endophytes had different effects on the two insects; one species, Chaetomium cochliodes, reduced growth of M. brassicae but increased feeding by C. rubiginosa. Another species, Cladosporium cladosporioides, increased beetle feeding also, but had no effect on M. brassicae. Interactions were also seen between fungal species and dual infection with C. cladosporioides and Trichoderma viride greatly reduced beetle feeding. It is concluded that endophytes have significant effects on foliar feeding insects that differ with degree of specialism of the herbivore. We suggest that these effects are due to chemical changes in the host, brought about by fungal infection. These fungi have received remarkably little attention in the study of insect-plant interactions and yet could be important determinants of insect growth and even population dynamics.

With constant pressure on herb growers to perform to a continuous high standard, finding new ways to improve herb quality and or quantity are gaining importance, with arbuscular mycorrhizal fungi (AMF) presenting one possible solution. Viviane Schroeder, Alan Gange and Anthony Stead discuss the introduction of AMF to the herb growth cycle and discuss the benefits and costs that their symbiosis with plants bring to modern agriculture., (Copyright © 2011 Society of Chemical Industry.)

The endophytic fungus Periconia sp. produces piperine (5-(3, 4-methylenedioxyphenyl)-1-piperidinopent-2, 4-dien-1-one) under liquid culture. This is the first report of the alternative source for this chemical other than its host, Piper longum. The highly functionalized fungus-derived piperine exhibits strong antimycobacterial activity against Mycobacterium tuberculosis and M. smegmetis with minimum inhibitory concentrations of 1.74 and 2.62 μg ml(-1), respectively. The compound was crystallized and the structure was elucidated by single-crystal X-ray crystallography. This finding is of significance as piperine is a potential cancer preventative agent. It is reaffirmed by this report that important pharmaceuticals can be produced by endophytic microbes, and these molecules appear to be mimetic to their host origin. Therefore, we can enhance the bioactive principles of medicinal plants by isolating and identifying the endophytes, thereby showing the importance of preserving the biodiversity of these plants.

Foliar fungal endophytes are ubiquitous, but understudied symbionts of most plant species; relatively little is known about the factors affecting their occurrence, diversity and abundance. We tested the effects of soil nutrient content and arbuscular mycorrhizal (AM) colonization on the occurrence of foliar endophytic fungi in Cirsium arvense in two field studies. In the first study, we assessed relationships between soil moisture, organic matter, carbon and nitrogen content and plant water, nitrogen and carbon content and AM colonization and the occurrence of foliar endophytic fungal species. In the second study, we manipulated soil nutrient content and AM colonization of potted seedlings and identified differences in endophytic fungal species composition of the leaves and stems. The results reveal that endophytes can occur either more or less frequently, depending on soil nutrient and plant water content and AM colonization. We propose that these patterns were the result of differences in fungal growth responses to nutrient availability in the leaves, which can be affected by resources obtained from the soil or symbiotic fungi in the roots., (Copyright © 2010 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.)

Most macrofungi produce ephemeral fruit bodies during autumn but some have adapted to spring fruiting. In this study, temporal changes in the time of spring fruiting in Norway and the UK during 1960-2007 have been investigated by statistical analyses of about 6000 herbarium and field records, covering 34 species. Nearly 30 per cent of the temporal variation in fruiting could be ascribed to spatial and species-specific effects. Correcting for these effects, linear trends towards progressively earlier fruiting were detected during the entire period in both Norway and the UK, with a change in average fruiting day of 18 days over the study period. Early fruiting was correlated with high winter temperatures in both countries, indicating that the observed phenological changes are likely due to earlier onset of spring. There were also significant correlations between climatic conditions in one year and timing of fruiting the following year, indicating that below-ground mycelia are influenced by climatic conditions over a longer time period before fruiting. Fruiting dates were, however, not strictly related to changes in vernal accumulated thermal time. Our results indicate that global warming has lead to progressively earlier fruiting of spring fungi in northwest Europe during the last half century.

Aim: To induce the biosynthesis of silver nanoparticles (AgNPs) using Aspergillus clavatus and evaluate their antimicrobial potential., Materials & Methods: Aspergillus clavatus (AzS-275), an endophytic fungus isolated from sterilized stem tissues of Azadirachta indica A. Juss., was challenged with 1 mM AgNO(3) solution. The characterization of the AgNPs was carried out by x-ray diffraction spectrometry, transmission-electron microscopy and atomic force microscopy., Results & Discussion: The synthesized AgNPs were found to be extracellular, polydispersed spherical or hexagonal particles ranging from 10 to 25 nm in size. Antimicrobial activity was performed using a disc-diffusion method against Candida albicans, Pseudomonas fluorescens and Escherichia coli. The results showed an average minimum inhibitory concentration of 5.83 microg ml(-1) and minimum fungicidal concentration of 9.7 microg ml(-1) against C. albicans., Conclusions: AgNPs can be mycosynthesized extracellularly using A. clavatus as the fungal system, which is highly advantageous over chemical synthesis not only because it can be synthesized on a large scale, but because of the ease of downstream processing and its biomedical application in antimicrobial activity.

Mycorrhizal status of the host plant is often ignored in studies on plant-herbivore interactions, but mycorrhizal colonization is known to induce many morphological, physiological, and biochemical changes in host plants, which in turn may alter plant quality as a host for insect herbivores. Both positive and negative effects of mycorrhizal colonization of the host plant on performance and density of insect herbivores have been reported in previous studies. We have conducted a meta-analysis of 34 published and unpublished studies on this topic in order to find out the sources of variation in mycorrhizae effects on insect herbivores. Effects of mycorrhizae on chewing insects depended upon the parameter measured and the degree of herbivore feeding specialization. Density and consumption of chewing insects were higher on mycorrhizal plants, but this did not lead to greater plant damage, presumably because herbivore survival tended to be lower on mycorrhizal plants. Mono- and oligophagous chewers benefited from mycorrhizal colonization of their host plants, whereas performance of polyphagous chewers was reduced on mycorrhizal plants. Among sucking insects, phloem feeders benefited from mycorrhizal infection, but performance of mesophyll feeders was lower on mycorrhizal plants. The type of mycorrhiza was not important for chewing insects, but performance of sucking insects was increased more by arbuscular mycorrhizal fungi (AM) than by ectomycorrhizae (ECM). Among AM inoculation studies, the most commonly used fungal species, Glomus intraradices, tended to have a negative effect on chewer performance, whereas all other fungal species tended to have a positive effect. There was no significant difference in results between studies using inoculation and fungicides, field and laboratory studies, and published and unpublished studies. Mycorrhizal status of the host plant thus influences insect herbivore performance, but the magnitude and direction of the effect depend upon the feeding mode and diet breadth of the insect and the identity of fungi.

Endophytic actinomycetes from Azadirachta indica A. Juss. were screened and evaluated for their anti-microbial activity against an array of pathogenic fungi and bacteria. A total of 55 separate isolates were obtained from 20 plants, and 60% of these showed inhibitory activity against one or more pathogenic fungi and bacteria. Actinomycetes were most commonly recovered from roots (54.5% of all isolates), followed by stems (23.6%), and leaves (21.8%). The dominant genus was Streptomyces (49.09% of all isolates), while Streptosporangium (14.5%), Microbispora (10.9%), Streptoverticillium (5.5%), Sacchromonospora sp. (5.5%), and Nocardia (3.6%) were also recovered. Streptomyces isolates AzR 006, 011, and 031 (all from roots) had acute activity against Pseudomonas fluorescens, while AzR027, 032, and 051 (also all from roots) showed activity against Escherichia coli. Meanwhile, an isolate of Nocardia sp. from leaves (AzL025) showed antagonism against Bacillus subtilis. Overall, 32 of the 55 were found to have broad spectrum significant antimicrobial activity, while about 4% of them showed strong and acute inhibition to pathogenic fungi and bacteria. Isolates of Streptomyces AzR031, 008, and 047, Nocardia sp. AzL025, and Streptosporangium sp. AzR 021 and 048 are of particular interest because they showed significant antagonistic activity against root pathogens, including Pythium and Phytophthora sp. Thus, many of the isolates recovered from A. indica in this study may be used in developing potential bio-control agents against a range of pathogenic fungi and bacteria and in the production of novel natural antimicrobial compounds. These results not only further our understanding of plant-microbe interactions but also indicate that there is an untapped resource of endophytic microorganisms that could be exploited in the biotechnological, medicinal, and agricultural industries.

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 adversely affected by the presence of endophytes and mycorrhizae, whereas specialist insects may often benefit. Effects on feeding guilds vary according to type of fungi; for example, aphids are often negatively affected by endophytes but respond positively to mycorrhizae, and leaf-chewers are usually negatively affected by both types of fungi. There is a strong taxonomic bias in the literature and many interactions remain little studied; laboratory studies predominate over field studies. Although some patterns emerge, there is a large amount of specificity and context dependency in the outcome of interactions, reflecting the influence of fungal and host genotype, fungal, host, and insect species, and environmental factors. Whereas some of the mechanisms underpinning these interactions are relatively well characterized, others remain unclear and await elucidation by molecular and metabolomic techniques.

Although the effects of nutrient enhancement on aquatic systems are well documented, the consequences of nutritional supplements on soil food webs are poorly understood, and results of past research examining bottom-up effects are often conflicting. In addition, many studies have failed to separate the effects of nutrient enrichment and the physical effects of adding organic matter. In this field study, we hypothesised that the addition of nitrogen to soil would result in a trophic cascade, through detritivores (Collembola) to predators (spiders), increasing invertebrate numbers and diversity. Nitrogen and lime were added to plots in an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps and identified to species. Seventeen species of Collembola were identified from the nitrogen plus lime (N+L) and control plots. Species assemblage, diversity, richness, evenness and total number were not affected by nutrient additions. However, there was an increase in the number of Isotomidae juveniles and Parisotoma anglicana trapped in the N+L plots. Of the 44 spider species identified, over 80% were Linyphiidae. An effect on species assemblage from the addition of N+L to the plots was observed on two of the four sampling dates (July 2002 and June 2003). The linyphiid, Oedothorax retusus, was the only species significantly affected by the treatments and was more likely to be trapped in the control plots.The increased number of juvenile Collembola, and change in community composition of spiders, were consequences of the bottom-up effect caused by nutrient inputs. However, despite efforts to eliminate the indirect effects of nutrient inputs, a reduction in soil moisture in the N+L plots cannot be eliminated as a cause of the invertebrate population changes observed. Even so, this experiment was not confounded by the physical effects of habitat structure reported in most previous studies. It provides evidence of moderate bottom-up influences of epigeic soil invertebrate food webs and distinguishes between nutrient addition and plant physical structure effects. It also emphasises the importance of understanding the effects of soil management practices on soil biodiversity, which is under increasing pressure from land development and food production.

Arbuscular mycorrhizal fungi (AMF) play a vital role in ecosystem functioning. In most grasslands, herbivory by both vertebrate and invertebrate herbivores is common and thus in order to assess herbivore effects on multitrophic-level interactions both should be considered. This study investigated the effects of grazing by rabbit and insect herbivores on root-colonization of grasses by AMF in two lowland grasslands in southern England, UK. A long-term exclosure site was used to provide a temporal assessment in order to elucidate whether any short-term responses to herbivore removal were sustained. Root samples from three grass species at each site were analysed in terms of total mycorrhizal colonization and proportional colonization by individual mycorrhizal structures. Colonization levels were up to 1.6 times greater under moderate levels of rabbit grazing (with summer maxima of 25% and winter minima of 11%) than in intensely grazed swards or fenced plots at both sites. The change was fast (within 8 weeks), consistent throughout the sampled field plots, and temporally sustainable over a 19-year period. There was no significant effect of insect herbivory on total colonization but proportional colonization by different AM structures was affected on some sample dates where vertebrate herbivores had been removed, indicating a slight effect on fungal structure allocation. The results suggest that the type of herbivore and perhaps more importantly the intensity of grazing are key determinants of below-ground effects upon mycorrhizal-host plant symbiosis. The data suggest that the extent of mycorrhizal colonization within grass host plants is strongly influenced by C assimilation and allocation.

Information on responses of higher organisms to climate change is dominated by events in spring. Far less is known about autumnal events and virtually nothing about communities of microorganisms. We analyzed autumnal fruiting patterns of macrofungi over the past 56 years and found that average first fruiting date of 315 species is earlier, while last fruiting date is later. Fruiting of mycorrhizal species that associate with both deciduous and coniferous trees is delayed in deciduous, but not in coniferous, forests. Many species are now fruiting twice a year, indicating increased mycelial activity and possibly greater decay rates in ecosystems.

Elevated nitrogen (N) inputs into terrestrial ecosystems are causing major changes to the composition and functioning of ecosystems. Understanding these changes is challenging because there are complex interactions between 'direct' effects of N on plant physiology and soil biogeochemistry, and 'indirect' effects caused by changes in plant species composition. By planting high N and low N plant community compositions into high and low N deposition model terrestrial ecosystems we experimentally decoupled direct and indirect effects and quantified their contribution to changes in carbon, N and water cycling. Our results show that direct effects on plant growth dominate ecosystem response to N deposition, although long-term carbon storage is reduced under high N plant-species composition. These findings suggest that direct effects of N deposition on ecosystem function could be relatively strong in comparison with the indirect effects of plant community change.

Human impacts, including global change, may alter the composition of soil faunal communities, but consequences for ecosystem functioning are poorly understood. We constructed model grassland systems in the Ecotron controlled environment facility and manipulated soil community composition through assemblages of different animal body sizes. Plant community composition, microbial and root biomass, decomposition rate, and mycorrhizal colonization were all markedly affected. However, two key ecosystem processes, aboveground net primary productivity and net ecosystem productivity, were surprisingly resistant to these changes. We hypothesize that positive and negative faunal-mediated effects in soil communities cancel each other out, causing no net ecosystem effects.

A series of field and laboratory experiments were conducted to examine whether natural levels of insect herbivory affect the arbuscular mycorrhizal (AM) colonization of two plant species. The plant species were the highly mycorrhizal (mycotrophic) Plantago lanceolata, which suffers small amounts of insect damage continuously over a growing season and the weakly mycorrhizal (non-mycotrophic) Senecio jacobaea, which is frequently subject to rapid and total defoliation by moth larvae. Herbivory was found to reduce AM colonization in P. lanceolata, but had no effect in S. jacobaea. Similarly, AM colonization reduced the level of leaf damage in P. lanceolata, but had no such effect in S. jacobaea. AM fungi were found to increase growth of P. lanceolata, but this effect was only clearly seen when insects were absent. AM fungi reduced the growth of S. jacobaea irrespective of whether insects were present. It is concluded that the reduction of AM fungal colonization by herbivory in P. lanceolata is due to the reduced amount of photosynthate available to the symbiont. This may only become apparent at threshold levels of insect damage and, below these, increased photosynthesis elicited by the mycorrhiza is able to compensate for foliage loss to the insects. However, in S. jacobaea, the mycorrhiza appears to be an aggressive parasite and insect attack only exacerbates the reduction in biomass. In mycotrophic plants, insect herbivores may be responsible for poor functioning of the symbiosis in field conditions and there is a symmetrical interaction between insects and fungi. However, in non-mycotrophic plants, the interaction is strongly asymmetrical, being entirely in favour of the mycorrhiza.

Two generations of two aphid species (Myzus ascalonicus and M. persicae) were reared on Plantago lanceolata plants, with and without root colonization by the arbuscular mycorrhizal fungus, Glomus intraradices. Life history traits of the aphids measured were nymphal development time, teneral adult weight, growth rate, total fecundity, adult longevity and duration of post-reproductive life. For both aphids in both generations, mycorrhizal colonization increased aphid weight and fecundity, while other traits were unaffected. The increases were consistent between generations. In a second experiment, M. persicae was reared on plants with and without the fungus, under varying N and P regimes. The results of N addition were inconclusive because there was high aphid mortality. However, under P supplementation, positive effects of the mycorrhiza on aphid growth were seen at low and medium P levels, while at high P levels these effects disappeared. The positive effects of mycorrhizal colonization reported here are contrary to the majority of previous studies with chewing insects, which have reported negative effects. A number of possible mechanisms for this apparent discrepancy are discussed.

Many hypotheses have been developed to explain the adaptive nature of insect galls. One of these, the nutrition hypothesis, states that gall formers have advantages over other insects because gall tissue provides a better (higher quality) food source than unmodified tissue. However, this has rarely been experimentally tested. In a test of this hypothesis, we grew plants of Cirsium arvense (L.) Scop. in a factorial design with two main treatments: the addition of nitrogen (to enhance foliar N levels) and of fungicide (to reduce colonization of roots by arbuscular mycorrhizal fungi). Mycorrhizal fungi have been shown previously to reduce the N concentration of host plants. Plants were exposed to adult gall flies, Urophora cardui L., and maintained through one season to allow maturation of galls. Reduction of the percentage mycorrhizal colonization by fungicide resulted in an elevation of total stem N comparable to that achieved by N addition, but gall N concentration remained unchanged in all treatments. Nitrogen application elevated stem N levels when mycorrhizal fungi were present, but application of both compounds together did not result in any increase over either single treatment. Fungicide application resulted in larger galls, which contained more larval chambers, with more live, and heavier, larvae. However, the main effects of N were not significant, as N addition only increased fly performance on plants where mycorrhizas were not reduced. It is suggested that U. cardui gall inhabitants can manipulate N at an optimal level and thus might conform to a modified version of the nutrition hypothesis. Mycorrhizal colonization might reduce gall fly performance by delaying the appearance, or impairing the quality, of secondary nutritive tissue in the gall. Future tests of the nutrition hypothesis should include a consideration of the plant's mycorrhizal status.

A field experiment was conducted to investigate whether infection by arbuscular mycorrhizal (AM) fungi has any effect on herbivory by foliar-feeding insects. Plants of PI ant ago laureolata L. were grown in a randomized block design and natural levels of mycorrhizal infection reduced by the application of the granular fungicide iprodione. Plant growth responses were examined and herbivore bioassays performed by rearing both a chewing and sucking insect on the leaves of mycorrhizal and fungicide-treated plants. Fungicide application successfully reduced mycorrhizal infection, and this led to reductions in foliar biomass, caused by lower leaf number. However, fungicide-treated plants suffered consistently higher levels of damage by centralist chewing and leaf-mining insects, which colonized the plants. The chewing insect bioassay confirmed the field results, in that larvae of Arttia caja L. (Lepidoptera: Arctiidae) consumed more leaf material from plants in which infection was reduced. There was no evidence that AM fungi altered food quality for the chewing insect. Instead, infection caused an increase in the carbon/nutrient balance, which in turn led to increased levels of the carbon-based feeding deterrents, aucubin and catalpol, The sucking insect, Mvzus perskae (Sulzer) reacted in an opposite fashion to the ehewtr. with performance being greater on mycorrhizal plants. Again, there was no evidence that an alteration in food Quality was the cause, and in this case infection may result in changes in leaf morphology which benefit the insect. We suggest that under conditions of high light and low nutrient availability. AM infection can alter the carbon/nutrient balance of plants, leading to an increased allocation to carbon-based defences. This can have important consequences for insect herbivore performance and the patterns of herbivory in field situations.

The nature of the mortality of germinating seeds of Vicia sativa, the common vetch, was investigated in a pot trial under controlled conditions. Chafer and tipulid larvae were restricted by nylon mesh partitions to enable radicle and/or hypocotyl herbivory to occur. The effects of the two insects were very similar. In control situations, an average of 88% of the viable seed sown recruited successfully. Hypocotyl and radicle herbivory had similar effects on seedling mortality, with recruitment of viable seed sown being reduced to 52%. When both modes of attack occurred together, successful recruitment was only 34%. Feeding on both plant parts resulted in an average post-emergence mortality of 14% of the seed sown, but the effect on pre-emergence mortality was of greater importance, amounting to 41%. The mechanisms by which soil-dwelling herbivores may cause seedling mortality in the field are discussed.

The effects of root herbivory by larvae of the scarabaeid, Phyllopertha horticola, on the growth of Capsella bursa-pastoris were examined. Individuals of Aphis fabae were reared on the leaves to determine what effect, if any, root feeding has on the performance of this insect. The experiment was conducted under two watering regimes ('low' and 'high'). Low watering and root feeding caused water stress in the plants and this was reflected in a reduction in vegetative biomass and an increase in the proportion of material allocated to reproduction. Supplying plants with ample water in the 'high' treatment enabled the water stress caused by root herbivory to be offset, but not completely overcome. Low watering and root feeding caused an increase in aphid weight and growth rate, while root feeding also increased fecundity and adult longevity. These effects are attributed to an improvement in food quality, measured by total soluble nitrogen, and caused by amino acid mobilization due to the water stress. The implications of these results in agricultural and ecological situations are discussed.