Ecological science for ecosystem services and the stewardship of Natural Capital

1. National and international assessments are increasingly highlighting the unsustainable use of earth's natural resources in the face of population increase, growing material affluence and global change. In all likelihood, the use and degradation of natural resources will continue. 2. In contrast to resource depletion, the concept of natural capital emphasises how the environment is an asset to be managed, to ensure that the benefits which flow from it are sustained for future generations. These benefits are the ecosystem goods and services upon which all people rely for their continued survival and well-being both now and, ideally, in perpetuity. 3. Despite their importance, the evidence-base and quantitative understanding of links between biodiversity, ecosystem function and ecosystem services are insufficient to allow informed use and management. Moreover, the concepts of natural capital and ecosystem services are insufficiently mainstream to influence decisions that currently favour the production of food and fibre rather than less tangible services such as climate regulation, air and water purification, pollination or the contributions of environment to health. 4. There are specific challenges to ecological science in this interdisciplinary endeavour: specifically, to develop frameworks for identifying and monitoring natural capital; to parameterise factors affecting ecosystem services and their resilience to change; to integrate the complexity of ecological systems into ecosystem service valuation; and to characterise the synergies and trade-offs between ecosystem services in different management and policy scenarios. 5. Synthesis and applications. The five papers in this Special Profile exemplify just some of the leading work through which ecologists in the UK are contributing nationally and internationally to these needs, stemming from the UK National Ecosystem Assessment - the first national scale exercise of its type in the world. We expect a major, worldwide increase in work on ecosystem services and natural capital in future as decisions on ecosystem use of management are squeezed increasingly between the needs of exploitation and protection

Towards a risk register for natural capital

1. Natural capital is essential for goods and services on which people depend. Yet pressures on the environment mean that natural capital assets are continuing to decline and degrade, putting such benefits at risk. Systematic monitoring of natural assets is a major challenge that could be both unaffordable and unmanageable without a way to focus efforts. Here we introduce a simple approach, based on the commonly used management tool of a risk register, to highlight natural assets whose condition places benefits at risk. 2. We undertake a preliminary assessment using a risk register for natural capital assets in the UK based solely on existing information. The status and trends of natural capital assets are assessed using asset–benefit relationships for ten kinds of benefits (food, fibre (timber), energy, aesthetics, freshwater (quality), recreation, clean air, wildlife, hazard protection and equable climate) across eight broad habitat types in the UK based on three dimensions of natural capital within each of the habitat types (quality, quantity and spatial configuration). We estimate the status and trends of benefits relative to societal targets using existing regulatory limits and policy commitments, and allocate scores of high, medium or low risk to asset–benefit relationships that are both subject to management and of concern. 3. The risk register approach reveals substantial gaps in knowledge about asset–benefit relationships which limit the scope and rigour of the assessment (especially for marine and urban habitats). Nevertheless, we find strong indications that certain assets (in freshwater, mountain, moors and heathland habitats) are at high risk in relation to their ability to sustain certain benefits (especially freshwater, wildlife and climate regulation). 4. Synthesis and applications. With directed data gathering, especially to monitor trends, improve metrics related to asset–benefit relationships, and improve understanding of nonlinearities and thresholds, the natural capital risk register could provide a useful tool. If updated regularly, it could direct monitoring efforts, focus research and protect and manage those natural assets where benefits are at highest risk

Variation in life history and flight morphological traits in Speckled Wood (Pararge aegeria) butterflies infected with a baculovirus.

Sub-lethal impacts are known to affect the insect-host relationship and have an important role in describing host dynamics. The impact of sub-lethal infections of pathogens on life history traits of affected hosts has been understudied in natural or semi-natural systems. The Speckled Wood (Pararge aegeria) is a satyrine butterfly that is common in temperate zones and has been extensively used as a model system for evolutionary ecology studies. It is known that the deployment of the immune system within this species, as with other invertebrates, is energetically costly and may result in trade-offs with fitness-related traits. In this study, we investigated the sub-lethal effect of exposure to Autographa californica multiple nucleopolyhedrovirus (AcMNPV) on life history and flight morphological traits of P. aegeria. Larvae were inoculated with increasing doses of AcMNPV and measurements made of life history and flight morphology traits. Generally, larvae exposed to virus took longer to develop to pupae and larval mass acquisition per day was significantly reduced in viral exposed larvae. However, viral exposed larvae were able to attain the same pupal mass and their duration as pupae was the same as controls. Forewing length, forewing aspect ratio, dry thorax mass and forewing loading were related to sex and bioassay differences but there was no evidence of any viral impact on these measures. Adult male butterflies had significantly less basal wing melanisation when exposed to virus compared to control males but there was no difference between females. Implications for population dynamics of P. aegeria are discussed

Why small is beautiful: wing colour is free from thermoregulatory constraint in the small lycaenid butterfly, Polyommatus icarus

We examined the roles of wing melanisation, weight, and basking posture in thermoregulation in Polyommatus Icarus, a phenotypically variable and protandrous member of the diverse Polyommatinae (Lycaenidae). Under controlled experimental conditions, approximating to marginal environmental conditions for activity in the field (= infrequent flight, long duration basking periods), warming rates are maximised with fully open wings and maximum body temperatures are dependent on weight. Variation in wing melanisation within and between sexes has no effect on warming rates; males and females which differ in melanisation had similar warming rates. Posture also affected cooling rates, consistent with cooling being dependent on convective heat loss. We hypothesise that for this small sized butterfly, melanisation has little or no effect on thermoregulation. This may be a factor contributing to the diversity of wing colours in the Polyommatinae. Because of the importance of size for thermoregulation in this small butterfly, requirements for attaining a suitable size to confer thermal stability in adults may also be a factor influencing larval feeding rates, development time and patterns of voltinism. Our findings indicate that commonly accepted views of the importance of melanisation, posture and size to thermoregulation, developed using medium and large sized butterflies, are not necessarily applicable to small sized butterflies

Elevated atmospheric CO2 impairs aphid escape responses to predators and conspecific alarm signals

Research into the impact of atmospheric change on predator–prey interactions has mainly focused on density dependent responses and trophic linkages. As yet, the chemical ecology underpinning predator–prey interactions has received little attention in environmental change research. Group living animals have evolved behavioral mechanisms to escape predation, including chemical alarm signalling. Chemical alarm signalling between conspecific prey could be susceptible to environmental change if the physiology and behavior of these organisms are affected by changes in dietary quality resulting from environmental change. Using Rubus idaeus plants, we show that elevated concentrations of atmospheric CO2 (eCO2) severely impaired escape responses of the aphid Amphorophora idaei to predation by ladybird larvae (Harmonia axyridis). Escape responses to ladybirds was reduced by >50 % after aphids had been reared on plants grown under eCO2. This behavioral response was rapidly induced, occurring within 24 h of being transferred to plants grown at eCO2 and, once induced, persisted even after aphids were transferred to plants grown at ambient CO2. Escape responses were impaired due to reduced sensitivity to aphid alarm pheromone, (E)-β-farnesene, via an undefined plant-mediated mechanism. Aphid abundance often increases under eCO2, however, reduced efficacy of conspecific signalling may increase aphid vulnerability to predation, highlighting the need to study the chemical ecology of predator–prey interactions under environmental change

Top-down control by Harmonia axyridis mitigates the impact of elevated atmospheric CO2 on a plant-aphid interaction

1. The present study investigated the impact of elevated atmospheric CO2 (390 or 650 μmol/mol) on raspberry genotypes varying in resistance to the large raspberry aphid Amphorophora idaei and any subsequent impact on the coccinellid predator Harmonia axyridis. 2. CO2 enrichment promoted plant growth, ranging from 30% in the partially susceptible cultivar to a more than 100% increase for the susceptible cultivar. 3. Aphid abundance and colonization (presence–absence) on the susceptible cultivars were not influenced by CO2 enrichment. On the resistant cultivar, aphid colonisation increased from 14% in ambient CO2 to 70% in elevated CO2 with a subsequent increase in aphid abundance, implying a breakdown in resistance. Inclusion of the natural enemy on the resistant cultivar, however, suppressed the increase in aphid abundance at elevated CO2. 4. The present study highlights how crop genotypes vary in responses to climate change; some cultivars can become more susceptible to aphid pests under elevated CO2. We do, however, demonstrate the potential for top-down control to mitigate the effect of global climate change on pest populations

Root herbivores drive changes to plant primary chemistry, but root loss is mitigated under elevated atmospheric CO2

Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity

Seed bank dynamics govern persistence of Brassica hybrids in crop and natural habitats

Background and Aims: Gene flow from crops to their wild relatives has the potential to alter population growth rates and demography of hybrid populations, especially when a new crop has been genetically modified (GM). This study introduces a comprehensive approach to assess this potential for altered population fitness, and uses a combination of demographic data in two habitat types and mathematical (matrix) models that include crop rotations and outcrossing between parental species. Methods: Full life-cycle demographic rates, including seed bank survival, of non-GM Brassica rapa × B. napus F1 hybrids and their parent species were estimated from experiments in both agricultural and semi-natural habitats. Altered fitness potential was modelled using periodic matrices including crop rotations and outcrossing between parent species. Key Results: The demographic vital rates (i.e. for major stage transitions) of the hybrid population were intermediate between or lower than both parental species. The population growth rate (λ) of hybrids indicated decreases in both habitat types, and in a semi-natural habitat hybrids became extinct at two sites. Elasticity analyses indicated that seed bank survival was the greatest contributor to λ. In agricultural habitats, hybrid populations were projected to decline, but with persistence times up to 20 years. The seed bank survival rate was the main driver determining persistence. It was found that λ of the hybrids was largely determined by parental seed bank survival and subsequent replenishment of the hybrid population through outcrossing of B. rapa with B. napus. Conclusions: Hybrid persistence was found to be highly dependent on the seed bank, suggesting that targeting hybrid seed survival could be an important management option in controlling hybrid persistence. For local risk mitigation, an increased focus on the wild parent is suggested. Management actions, such as control of B. rapa, could indirectly reduce hybrid populations by blocking hybrid replenishment

A restatement of recent advances in the natural science evidence base concerning neonicotinoid insecticides and insect pollinators

A summary is provided of recent advances in the natural science evidence base concerning the effects of neonicotinoid insecticides on insect pollinators in a format (a ‘restatement’) intended to be accessible to informed but not expert policymakers and stakeholders. Important new studies have been published since our recent review of this field (Godfray et al. 2014 Proc. R. Soc. B 281,20140558. (doi:10.1098/rspb.2014.0558)) and the subject continues to be an area of very active research and high policy relevance