Search

Agricultural intensification and expansion are regarded as main drivers of biodiversity loss. This conclusion is mainly based on observed declines of local diversity (α-diversity), while effects on community composition homogenization (decrease of β-diversity) at a larger spatial scale are less well understood. Carabid beetles and spiders represent two widespread guilds and are important predators of pest species. Here we surveyed carabid beetles and spiders in 66 winter wheat fields in four northwestern European countries (Germany, the Netherlands, Sweden and UK) and analyzed how their community composition was related to geographic distance (separation distance between any pairwise fields) and three environmental variables: crop yield (proxy for land-use intensity), percentage cropland (proxy for landscape complexity) and soil organic carbon content (proxy for local soil conditions). We further analyzed whether the relationship between carabid beetle and spider community composition and geographic distance was influenced by environmental variables. We found that, 55 % and 75 % of all observed carabid and spider individuals, respectively, belonged to species that occurred in all four countries. However, individuals of species that were unique to a particular country only accounted for 3 % of all collected individuals for both taxa. Furthermore, we found a negative relationship between distance and similarity of spider communities but not for carabid beetle communities. None of the environmental variables were related to similarity of carabid beetle and spider communities, nor moderated the effects of distance. Our study indicates that across a great part of the European continent, arthropod communities (especially carabid beetles) in agricultural landscapes are composed of very similar species that are robust to current variations in environment and land-use. [ABSTRACT FROM AUTHOR]

There is increasing evidence that farmers in many areas are achieving below maximum yields due to insufficient pollination. Practical and effective approaches are needed to maintain wild pollinator populations within agroecosystems so they can deliver critical pollination services that underpin crop production. We established nesting and wildflower habitat interventions in 24 UK apple orchards and measured effects on flower‐visiting insects and the pollination they provide, exploring how this was affected by landscape context. We quantified the extent of pollination deficits and assessed whether the management of wild pollinators can reduce deficits and deliver improved outcomes for growers over 3 years. Wildflower interventions increased solitary bee numbers visiting apple flowers by over 20%, but there was no effect of nesting interventions. Other pollinator groups were influenced by both local and landscape‐scale factors, with bumblebees and hoverflies responding to the relative proportion of semi‐natural habitat at larger spatial scales (1000 m), while honeybees and other flies responded at 500 m or less. By improving fruit number and quality, pollinators contributed more than £16 k per hectare. However, deficits (where maximum potential was not being reached due to a lack of pollination) were recorded and the extent of these varied across orchards, and from year to year, with a 22% deficit in output in the worst (equivalent to ~£14 k/ha) compared to less than 3% (equivalent to ~£2 k/ha) in the best year. Although no direct effect of our habitat interventions on deficits in gross output was observed, initial fruit set and seed set deficits were reduced by abundant bumblebees, and orchards with a greater abundance of solitary bees saw lower deficits in fruit size. The abundance of pollinators in apple orchards is influenced by different local and landscape factors that interact and vary between years. Consequently, pollination, and the extent of economic output deficits, also vary between orchards and years. We highlight how approaches, including establishing wildflower areas and optimizing the ratio of cropped and non‐cropped habitats can increase the abundance of key apple pollinators and improve outcomes for growers. [ABSTRACT FROM AUTHOR]

Sown wildflower areas are increasingly recommended as an agri-environmental intervention measure, but evidence for their success is limited to particular insect groups or hampered by the challenges of establishing seed mixes and maintaining flower abundance over time. We conducted a replicated experiment to establish wildflower areas to support insect pollinators in apple orchards. Over three years, and across 23 commercial UK orchards with and without sown wildflowers, we conducted 828 transect surveys across various non-crop habitats. We found that the abundance of flower-visiting solitary bees, bumblebees, honeybees, and beetles was increased in sown wildflower areas, compared with existing non-crop habitats in control orchards, from the second year following floral establishment. Abundance of hoverflies and other non-syrphid flies was increased in wildflower areas from the first year. Beyond the effect of wildflower areas, solitary bee abundance was also positively related to levels of floral cover in other local habitats within orchards, but neither local nor wider landscape-scale context affected abundance of other studied insect taxa within study orchards. There was a change in plant community composition on the sown wildflower areas between years, and in patterns of flowering within and between years, showing a succession from unsown weedy species towards a dominance of sown species over time. We discuss how the successful establishment of sown wildflower areas and delivery of benefits for different insect taxa relies on appropriate and reactive management practices as a key component of any such agri-environment scheme. [ABSTRACT FROM AUTHOR]

Pollinators face multiple pressures and there is evidence of populations in decline. As demand for insect‐pollinated crops increases, crop production is threatened by shortfalls in pollination services. Understanding the extent of current yield deficits due to pollination and identifying opportunities to protect or improve crop yield and quality through pollination management is therefore of international importance. To explore the extent of "pollination deficits," where maximum yield is not being achieved due to insufficient pollination, we used an extensive dataset on a globally important crop, apples. We quantified how these deficits vary between orchards and countries and we compared "pollinator dependence" across different apple varieties. We found evidence of pollination deficits and, in some cases, risks of overpollination were even apparent for which fruit quality could be reduced by too much pollination. In almost all regions studied we found some orchards performing significantly better than others in terms of avoiding a pollination deficit and crop yield shortfalls due to suboptimal pollination. This represents an opportunity to improve production through better pollinator and crop management. Our findings also demonstrated that pollinator dependence varies considerably between apple varieties in terms of fruit number and fruit quality. We propose that assessments of pollination service and deficits in crops can be used to quantify supply and demand for pollinators and help to target local management to address deficits although crop variety has a strong influence on the role of pollinators. [ABSTRACT FROM AUTHOR]

Abstract Insect pollination improves the yield and quality of many crops, yet there is increasing evidence of insufficient insect pollinators limiting crop production. Effective Integrated Crop Pollination (ICP) involves adaptable, targeted and cost-effective management of crop pollination and encourages the use of both wild and managed pollinators where appropriate. In this study we investigate how the addition of honeybee hives affects the community of insects visiting oilseed rape, and if hive number and location affect pollinator foraging and oilseed rape pollination in order to provide evidence for effective ICP. We found that introducing hives increased overall flower visitor numbers and altered the pollinator community, which became dominated by honeybees. Furthermore a greater number of hives did not increase bee numbers significantly but did result in honeybees foraging further into fields. The timing of surveys and proximity to the field edge influenced different pollinators in different ways and represents an example of spatial and temporal complementarity. For example dipteran flower visitor numbers declined away from the field edge whereas honeybees peaked at intermediate distances into the field. Furthermore, no significant effects of survey round on wild bees overall was observed but honeybee numbers were relatively lower during peak flowering and dipteran abundance was greater in later survey rounds. Thus combining diverse wild pollinators and managed species for crop pollination buffers spatial and temporal variation in flower visitation. However we found no effect of insect pollination on seed set or yield of oilseed rape in our trial, highlighting the critical need to understand crop demand for insect pollination before investments are made in managing pollination services. [ABSTRACT FROM AUTHOR]

Wheat ( Triticum spp.) is the most important arable crop grown in the UK, and the grain aphid ( Sitobion avenae ) is one of the key pests of this crop. Natural enemies could help suppress grain aphid and reduce unnecessary insecticide inputs, but few studies have estimated the economic value of natural pest control in this crop-pest system, which could help inform effective integrated pest management strategies. Based on a natural enemy exclusion experiment carried out in South East England, this study used an economic surplus model to estimate the value of predators and parasitoids to control summer grain aphid in wheat in this region. Incorporating three levels of spray intensity and three levels of pest infestation, the annual economic value of natural pest control service was conservatively estimated to be £0-2.3 Million. Under the medium pest infestation level, a 10% increase in the proportion of wheat fields using economic threshold-based spray method would increase this value by 23% (£0.4 Million). 71% of the value would benefit wheat growers. A potential rise in insecticide costs due to resistance development would also enhance the value of natural pest control. These findings support growing efforts from policy-makers to promote this ecosystem service in agriculture. [ABSTRACT FROM AUTHOR]

Insects play a key role in the regulation and dynamics of many ecosystem services (ES). However, this role is often assumed, with limited or no experimental quantification of its real value. We examined publication trends in the research on ES provided by insects, ascertaining which ES and taxa have been more intensively investigated, and which methodologies have been used, with particular emphasis on experimental approaches. We first performed a systematic literature search to identify which ES have been attributed to insects. Then we classified the references retrieved according to the ES, taxonomic group and ecosystem studied, as well as to the method applied to quantify each ES (in four categories: no quantification, proxies, direct quantification and experiments). Pollination, biological control, food provisioning, and recycling organic matter are the most studied ES. However, the majority of papers do not specify the ES under consideration, and from those that do, most do not quantify the ES provided. From the rest, a large number of publications use proxies as indicators for ES, assuming or inferring their provision through indirect measurements such as species abundances, species density, species richness, diversity indices, or the number of functional groups. Pollinators, predators, parasitoids, herbivores, and decomposers are the most commonly studied functional groups, while Hymenoptera, Coleoptera, and Diptera are the most studied taxa. Experimental studies are relatively scarce and they mainly focus on biological control, pollination, and decomposition performed in agroecosystems. These results suggest that our current knowledge on the ES provided by insects is relatively scarce and biased, and show gaps in the least-studied functional and taxonomic groups. An ambitious research agenda to improve the empirical and experimental evidence of the role played by insects in ES provision is essential to fully assess synergies between functional ecology, community ecology, and biodiversity conservation under current global changes. [ABSTRACT FROM AUTHOR]

• Ozone modulates the effect of pesticide exposure on crop pollinators. • Interacting effects between ozone and pesticide differed between Apis and non- Apis. • Ozone negatively impacts the contribution of pollinators to crop production. • Ozone should be considered for environmental policies in favor of biodiversity. Human driven environmental changes increase the concentrations of polluting reactive compounds in the troposphere, such as ozone and nitrogen oxides. These changes lead to biodiversity losses and alter plant physiology and plant-pollinator interactions, essential for pollination services, with potential consequences for agricultural production. Here we used 133 unique sampling events from NW Europe to investigate how air pollution (ozone and nitrogen oxides) and other sources of nitrogen is related to pollinator visitation rate and their contribution to agricultural production, also considering possible interactive effects with landscape quality and pesticide input. We showed that ozone modulates the effect of pesticide exposure and temperature on crop pollinators, increasing the probability of negative impacts on crop pollination. Indeed, when ozone levels are highest, the strength of the effect of pesticide on pollinators is more than double then when ozone levels are intermediate. This indicates that air pollution should be considered in management plans and policies aiming to safeguard biodiversity and promote more sustainable food production practices. [ABSTRACT FROM AUTHOR]

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Basic & Applied Ecology is the property of Urban & Fischer Verlag and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Assessing the potential impact of future land-cover changes on habitat quality requires projections with a fine spatial and thematic resolution. The former is usually addressed by downscaling methods, often at the expense of the latter. We present a new, rule-based method to downscale land-use change scenarios to the landscape level while keeping a large number of land-cover classes (CORINE level 3). The method relies on the interpretation of European scenario storylines, the observation of past land-use changes, high-resolution regional data and expert knowledge. The results give a landscape-level transposition of the scenario storylines which reflects the local conditions. The method has a number of advantages, such as its potential application in dialogues with policy-makers and stakeholders. Possible further developments include automating the rule-based selection to overcome the current limitations of this method in terms of spatial extent. [Copyright &y& Elsevier]

Legumes are important crops for food security, consumed by millions of people especially in Africa where they are an essential protein source and provide key vitamins and minerals. Most legumes depend on insect pollination and natural pest regulation for sufficient yields, however, there is emerging evidence that yield gaps caused by lack of pollination and/or pest pressure may be common. Here we review the literature reporting on pollinators and natural enemies contributing to legume crop yields, and the impact of land-use change on the services provided by these beneficial organisms. We identify strategies for enhancing the benefits of pollination and natural pest control in legumes and propose policy and practice interventions for better utilization of pollinators and natural enemies in legume cropping systems in Africa. • Legumes are important food security crops providing essential proteins, minerals and vitamins for the diets of millions of people in Africa. • Recent consumption trends indicate increasing demand for legumes, which is projected to create major shortfalls in supply. • Seven legume crop species in Africa benefit from insect pollination and natural pest control services, which are threatened by human activities. • This review provides new insights to guide research and action for better insect derived ecosystem services and secure the future of legume crops. [ABSTRACT FROM AUTHOR]