Future restoration should enhance ecological complexity and emergent properties at multiple scales

Ecological restoration has a paradigm of re-establishing ‘indigenous reference' communities. One resulting concern is that focussing on target communities may not necessarily create systems which function at a high level or are resilient in the face of ongoing global change. Ecological complexity – defined here, based on theory, as the number of components in a system and the number of connections among them – provides a complementary aim, which can be measured directly and has several advantages. Ecological complexity encompasses key ecosystem variables including structural heterogeneity, trophic interactions and functional diversity. Ecological complexity can also be assessed at the landscape scale, with metrics including β diversity, heterogeneity among habitat patches and connectivity. Thus, complexity applies, and can be measured, at multiple scales. Importantly, complexity is linked to system emergent properties, e.g. ecosystem functions and resilience, and there is evidence that both are enhanced by complexity. We suggest that restoration ecology should consider a new paradigm to restore complexity at multiple scales, in particular of individual ecosystems and across landscapes. A complexity approach can make use of certain current restoration methods but also encompass newer concepts such as rewilding. Indeed, a complexity goal might in many cases best be achieved by interventionist restoration methods. Incorporating complexity into restoration policies could be quite straightforward. Related aims such as enhancing ecosystem services and ecological resilience are to the fore in initiatives such as the Sustainable Development Goals and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Implementation in policy and practice will need the development of complexity metrics that can be applied at both local and regional scales. Ultimately, the adoption of an ecological complexity paradigm will be based on an acceptance that the ongoing and unprecedented global environmental change requires new ways of doing restoration that is fit for the future

Future restoration should enhance ecological complexity and emergent properties at multiple scales

Ecological restoration has a paradigm of re-establishing ‘indigenous reference' communities. One resulting concern is that focussing on target communities may not necessarily create systems which function at a high level or are resilient in the face of ongoing global change. Ecological complexity – defined here, based on theory, as the number of components in a system and the number of connections among them – provides a complementary aim, which can be measured directly and has several advantages. Ecological complexity encompasses key ecosystem variables including structural heterogeneity, trophic interactions and functional diversity. Ecological complexity can also be assessed at the landscape scale, with metrics including β diversity, heterogeneity among habitat patches and connectivity. Thus, complexity applies, and can be measured, at multiple scales. Importantly, complexity is linked to system emergent properties, e.g. ecosystem functions and resilience, and there is evidence that both are enhanced by complexity. We suggest that restoration ecology should consider a new paradigm to restore complexity at multiple scales, in particular of individual ecosystems and across landscapes. A complexity approach can make use of certain current restoration methods but also encompass newer concepts such as rewilding. Indeed, a complexity goal might in many cases best be achieved by interventionist restoration methods. Incorporating complexity into restoration policies could be quite straightforward. Related aims such as enhancing ecosystem services and ecological resilience are to the fore in initiatives such as the Sustainable Development Goals and the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Implementation in policy and practice will need the development of complexity metrics that can be applied at both local and regional scales. Ultimately, the adoption of an ecological complexity paradigm will be based on an acceptance that the ongoing and unprecedented global environmental change requires new ways of doing restoration that is fit for the future

Scoping potential routes to UK civil unrest via the food system: Results of a structured expert elicitation

We report the results of a structured expert elicitation to identify the most likely typesof potential food system disruption scenarios for the UK, focusing on routes to civil unrest. Wetake a backcasting approach by defining as an end-point a societal event in which 1 in 2000 peoplehave been injured in the UK, which 40% of experts rated as “Possible (20–50%)”, “More likely thannot (50–80%)” or “Very likely (>80%)” over the coming decade. Over a timeframe of 50 years, thisincreased to 80% of experts. The experts considered two food system scenarios and ranked theirplausibility of contributing to the given societal scenario. For a timescale of 10 years, the majorityidentified a food distribution problem as the most likely. Over a timescale of 50 years, the expertswere more evenly split between the two scenarios, but over half thought the most likely route tocivil unrest would be a lack of total food in the UK. However, the experts stressed that the variouscauses of food system disruption are interconnected and can create cascading risks, highlighting theimportance of a systems approach. We encourage food system stakeholders to use these results intheir risk planning and recommend future work to support prevention, preparedness, response andrecovery planning

Study of temperature-growth interactions of entomopathogenic fungi isolated from chalk grassland in the UK

The majority of studies on the regulation of insect populations by entomopathogenic fungi have been in the context of pest control, whereas there has been little research into how they may impact on natural populations of insects. The Adonis Blue (Polyommatus bellargus) and Chalkhill Blue (Polyommatus coridon) butterflies are species of Lepidoptera with particular conservation interest in the UK. Both of these species exist on the most northern edge of their climatic range in populations that are restricted to fragmented chalk grassland habitats in the South of England. Larvae of both butterflies feed on the same single host plant species (Hippocrepis comosa) and can be found in the soil during their development. It is therefore reasonable to assume that larvae will be exposed to soil entomopathogenic fungi. Polyommatus bellargus are bivoltine, and the distribution of early season larvae is very closely linked to warmer temperatures in sheltered microhabitats. The use of turf height and shelter category can accurately predict the occupancy of sites across a landscape for P. bellargus and define optimal and sub-optimal habitats, and it is thought a similar relationship exists for P. coridon. A combination of host- and habitat- selection could result in local adaptation of entomopathogenic fungi. Because shelter category is a proxy for temperature, it is possible that one of the driving selectors is the ability of fungi to operate at certain temperatures. Soil was collected from these habitats and turf height and shelter category was recorded. A total of 130 entomopathogenic fungi were extracted from 144 soil samples using Galleria melonella as bait. The in vitro growth of 40 of these isolates was investigated at a range of four different temperatures between 10 and 25ºC. The in vitro growth of a number of selected isolates was then profiled at a wider range of temperatures

Defining the response of Mamestra brassicae to mixed infections

The analysis of multiple dose-response assays usually focuses on overall response patterns of synergism or antagonism. It is rare that more complex response patterns are described that incorporate dose-level or dose-dependent specific synergism and antagonism. We will present an example where we have adapted models from recently developed ecotoxicological mixture dose-response analysis to specifically describe the mortality response of cabbage moth larvae Mamestra brassicae exposed to combinations of pathogens and toxins. This forms part of a larger study investigating whether baculoviruses can be combined with other entomopathogens to achieve improved biological control of insect pests. Larvae of M. brassicae were exposed in the laboratory to a closely related nucleopolyhedrovirus Panolis flammea NPV (PaflNPV) or a homologous baculovirus Autographa californica NPV (AcalNPV) in mixtures with either Bacillus thuringiensis subsp. kurstaki (Btk), the pesticide Spinosad (active ingredients Spinosyns A & D) or the chemical Diethyldithiocarbamic acid (DETC) a sodium salt which has known suppression effects of the host immune system. To account for the antifeedant activity of Btk and Spinosad, the pathogen concentration received by each larva was adjusted relative to food consumption. Mortality of larvae due to each pathogen/toxin was assessed in each assay for 64 treatment combinations. Both PaflNPV and AcalNPV interacted in a similar way in mixtures with Btk and displayed a significant level of synergism across several of the doses tested. The interaction between Spinosad/PaflNPV and DETC/PaflNPV was more complex but was described by the adapted ecotoxicology independent action model. The use of such models enables us to identify doses at which synergy with another pathogen or toxin can increase baculovirus mortality in a Lepidopteran host

Dual action ectoparasite vaccine targeting 'exposed' and 'concealed' antigens

Blood-feeding ectoparasites, such as mosquitoes, sandflies and ticks, transmit many disease agents. Their control relies on large-scale, repeated use of chemical pesticides. An alternative, targeted and environmentally friendly approach is to develop anti-ectoparasite vaccines. We describe a vaccine to control ticks that targets an 'exposed' tick saliva antigen and cross-reacts with 'concealed' tick midgut antigens. Ticks feeding on immunised animals induced a cutaneous inflammatory response and increased antibody titer, while engorged ticks died following damage to their midgut. This dual action, acting at the feeding site and in the midgut, offers a self-sustaining strategy for ectoparasite control boosted by natural infestations

The role of food plant and pathogen-induced behaviour in the persistence of a nucleopolyhedrovirus

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Exploiting pathogens and their impact on fitness costs to manage the evolution of resistance to Bacillus thuringiensis

1. Sustainable insect control requires effective management of the evolution of resistance to pesticides. Resistance management may ultimately depend on a range of diverse strategies. We explored how combining the use of a pathogen with an integrated pest management (IPM)-compatible pesticide, Bacillus thuringiensis (Bt), could affect the evolution of resistance. 2. We used fitness and laboratory selection experiments to explore whether the use of a nucleopolyhedrovirus could alter the rate of evolution of resistance to a Bt toxin. These results were incorporated into simulation modelling to investigate how pathogens could best be exploited in resistance management. 3. Simultaneous exposure to virus and Bt toxin (mixed sprays) reduced the fitness of Bt-resistant insects compared with treatments with toxin alone. Moreover, Bt resistance incurred additional fitness costs, in terms of egg fertility, in the presence of virus. 4. In a selection experiment with caged insects, spraying toxin-free refugia with virus slowed the evolution of resistance relative to unsprayed refugia, confirming the results of two fitness experiments that indicated that virus would increase the fitness costs of resistance. The impact of virus-mediated costs was explored further in simulation models. 5. Simulations showed that large virus-mediated fitness costs (a reduction in fecundity of 35%) with partially dominant inheritance could lead to effective resistance management with a Bt/virus rotation. Modest fitness costs could, however, markedly improve a rotation strategy with a pathogen that could replicate post-application. 6. Synthesis and applications. Mixed sprays of virus and resistance-prone pesticides such as Bt have the potential to slow the evolution of resistance within an integrated pest management context. However, the efficacy of mixed-spray strategies depends upon precise dosages and/or the presence of a spray-free refuge. In contrast, rotations of pesticides with pathogens that could replicate after application slow the evolution of resistance over a wider range of conditions and control insects cost-effectively. This efficacy is dependent on the co-occurrence of persistent pathogen and pesticide reducing the relative fitness of resistant individuals

Historical distribution and regional dynamics of two Brassica species

Plants often show a patchy distribution. This can be related to the discontinuous distribution of environmental variables that define suitable habitat. Metapopulation theory suggests that additional patchiness may be caused by the dynamics of local extinctions and recolonisations. However, the contribution of these two mechanisms to explaining the observed patterns, and thus the applicability of metapopulation theory to plants remains controversial partly because population turnover may occur at long time-scales not usually covered by ecological studies. We analyzed the role of environmental variation and population turnover in determining the distribution of two Brassica species, an annual and a perennial, along 44 km of coastline in Dorset, UK. Mapped occurrence and abundance of both species in recent years was compared with distributions from a 70 yr-old dataset and a survey of present-day environmental parameters. Abiotic and vegetation parameters were correlated with the occurrence of both species in binary logistic regression models and explained spatial auto-correlation in the Brassica distributions. These regression models suggest that neither species is occupying all potential habitat in the region studied. The relationship between historical and present distributions differed between the species. While an historical signal was very weak in the annual B. nigra, it had a large influence in predicting the present distribution of the perennial B. oleracea. This suggests local extinction and colonisation events for B. nigra over the 70 yr period, but not for B. oleracea which showed little evidence of population turnover. Our results demonstrate that the consideration of large time-scales can reveal patterns of regional dynamics. We conclude that metapopulation dynamics might be possible for our annual but can be ruled out for our perennial study species over the past 70 yr. We argue that beyond this time-scale possible metapopulation dynamics may be overridden by faster processes of environmental change