Pollinators, pests and soil properties interactively shape oilseed rape yield.

[EN] Pollination, pest control, and soil properties are well known to affect agricultural production. These factors might interactively shape crop yield, but most studies focus on only one of these factors at a time. We used 15 winter oilseed rape (Brassica napus L.) fields in Sweden to study how variation among fields in pollinator visitation rates, pollen beetle attack rates and soil properties (soil texture, pH and organic carbon) interactively determined crop yield. The fields were embedded in a landscape gradient with contrasting proportions of arable and semi-natural land. In general, pollinator visitation and pest levels were negatively correlated and varied independently of soil properties. This may reflect that above- and below-ground processes react at landscape and local spatial scales, respectively. The above-ground biotic interactions and below-ground abiotic factors interactively affected crop yield. Pollinator visitation was the strongest predictor positively associated with yield. High soil pH also benefited yield, but only at lower pest loads. Surprisingly, high pest loads increased the pollinator benefits for yield. Implementing management plans at different spatial scales can create synergies among above- and below-ground ecosystem processes, but both scales are needed given that different processes react at different spatial scales.[GER] Bestäubung, Schädlingskontrolle und Bodeneigenschaften beeinflussen die Agrarproduktion. Diese Faktoren könnten interagierend den Ernteertrag beeinflussen, aber die meisten Studien konzentrieren sich auf nur einen Faktor. Wir untersuchten auf 15 Winterrapsfeldern (Brassica napus L.) in Schweden, wie die von Feld zu Feld variierenden Bestäuberbesuchsraten, Rapsglanzkäfer-Befallsraten und Bodeneigenschaften (Bodentextur, pH, organischer Kohlenstoff) wechselwirkend den Ertrag bestimmten. Die Felder repräsentierten einen Landschaftsgradienten mit unterschiedlichen Anteilen von Agrarflächen und naturnahen Arealen. Allgemein waren Bestäuberbesuch und Schädlingsbefall negativ miteinander korreliert, und sie variierten unabhängig von den Bodeneigenschaften. Dies könnte anzeigen, dass oberirdische Prozesse und Prozesse im Boden auf der Landschaftsebene bzw. der lokalen Ebene reagieren. Die oberirdischen biotischen Interaktionen und die abiotischen Bodenfaktoren beeinflussten wechselwirkend den Ertrag. Der Bestäuberbesuch war der stärkste positiv mit dem Ertrag verknüpfte Faktor. Ein hoher pH-Wert begünstigte ebenfalls den Ertrag, aber nur bei geringem Schädlingsbefall. Überraschenderweise, steigerte hoher Schädlingsbefall die positive Wirkung des Bestäuberbesuchs auf den Ertrag. Das Aufstellen von Bewirtschaftungsplänen auf unterschiedlichen räumlichen Skalen kann Synergien zwischen oberirdischen und unterirdischen Ökosystemprozessen freisetzen, aber beide Skalen werden benötigt, da unterschiedliche Prozesse auf unterschiedlichen Skalen reagierenPeer reviewe

A global synthesis reveals biodiversity-mediated benefits for crop production

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield–related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society.EEA ConcordiaFil: Dainese, Matteo. Eurac Research. Institute for Alpine Environment; ItaliaFil: Dainese, Matteo. University of Würzburg. Biocenter. Department of Animal Ecology and Tropical Biology; AlemaniaFil: Martin, Emily A. University of Würzburg. Biocenter. Department of Animal Ecology and Tropical Biology; AlemaniaFil: Aizen, Marcelo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Aizen, Marcelo Adrian. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina.Fil: Albrecht, Matthias. Agroscope. Agroecology and Environment; SuizaFil: Bartomeus, Ignasi. CSIC. Estación Biológica de Doñana. Integrative Ecology; EspañaFil: Bommarco, Riccardo. Swedish University of Agricultural Sciences. Department of Ecology; SueciaFil: Carvalheiro, Luisa G. Universidade Federal de Goias. Departamento de Ecologia; BrasilFil: Carvalheiro, Luisa G. Universidade de Lisboa. Faculdade de Ciencias. Centre for Ecology, Evolution and Environmental Changes (CE3C); PortugalFil: Chaplin-Kramer, Rebecca. Stanford University. Natural Capital Project; Estados UnidosFil: Gagic, Vesna. Commonwealth Scientific and Industrial Research Organisation (CSIRO); AustraliaFil: Garibaldi, Lucas Alejandro. Universidad Nacional de Rio Negro. Instituto de Investigaciones de Recursos Naturales, Agroecología y Desarrollo Rural; ArgentinaFil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cavigliasso, Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concordia; ArgentinaFil: Steffan-Dewenter, Ingolf. University of Würzburg. Biocenter. Department of Animal Ecology and Tropical Biology; Alemani

The effect of protective covers on pollinator health and pollination service delivery

Protective covers (i.e., glasshouses, netting enclosures, and polytunnels) are increasingly used in crop production to enhance crop quality, yield, and production efficiency. However, many protected crops require insect pollinators to achieve optimal pollination and there is no consensus about how best to manage pollinators and crop pollination in these environments. We conducted a systematic literature review to synthesise knowledge about the effect of protective covers on pollinator health and pollination services and identified 290 relevant studies. Bees were the dominant taxon used in protected systems (90%), represented by eusocial bees (e.g., bumble bees (Bombus spp.), honey bees (Apis spp.), stingless bees (Apidae: Meliponini)) and solitary bees (e.g., Amegilla spp., Megachile spp., and Osmia spp.). Flies represented 9% of taxa and included Calliphoridae, Muscidae, and Syrphidae. The remaining 1% of taxa was represented by Lepidoptera and Coleoptera. Of the studies that assessed pollination services, 96% indicate that pollinators were active on the crop and/or their visits resulted in improved fruit production compared with flowers not visited by insects (i.e., insect visits prevented, or flowers were self- or mechanically pollinated). Only 20% of studies evaluated pollinator health. Some taxa, such as mason or leafcutter bees, and bumble bees can function well in covered environments, but the effect of covers on pollinator health was negative in over 50% of the studies in which health was assessed. Negative effects included decreased reproduction, adult mortality, reduced forager activity, and increased disease prevalence. These effects may have occurred as a result of changes in temperature/humidity, light quality/quantity, pesticide exposure, and/or reduced access to food resources. Strategies reported to successfully enhance pollinator health and efficiency in covered systems include: careful selection of bee hive location to reduce heat stress and improve dispersal through the crop; increased floral diversity; deploying appropriate numbers of pollinators; and manipulation of flower physiology to increase attractiveness to pollinating insects. To improve and safeguard crop yields in pollinator dependent protected cropping systems, practitioners need to ensure that delivery of crop pollination services is compatible with suitable conditions for pollinator health

Evaluating predictive performance of statistical models explaining wild bee abundance in a mass‐flowering crop

Wild bee populations are threatened by current agricultural practices in many parts of the world, which may put pollination services and crop yields at risk. Loss of pollination services can potentially be predicted by models that link bee abundances with landscape‐scale land‐use, but there is little knowledge on the degree to which these statistical models are transferable across time and space. This study assesses the transferability of models for wild bee abundance in a mass‐flowering crop across space (from one region to another) and across time (from one year to another). The models used existing data on bumblebee and solitary bee abundance in winter oilseed rape fields, together with high‐resolution land‐use crop‐cover and semi‐natural habitats data, from studies conducted in five different regions located in four countries (Sweden, Germany, Netherlands and the UK), in three different years (2011, 2012, 2013). We developed a hierarchical model combining all studies and evaluated the transferability using cross‐validation. We found that both the landscape‐scale cover of mass‐flowering crops and permanent semi‐natural habitats, including grasslands and forests, are important drivers of wild bee abundance in all regions. However, while the negative effect of increasing mass‐flowering crops on the density of the pollinators is consistent between studies, the direction of the effect of semi‐natural habitat is variable between studies. The transferability of these statistical models is limited, especially across regions, but also across time. Our study demonstrates the limits of using statistical models in conjunction with widely available land‐use crop‐cover classes for extrapolating pollinator density across years and regions, likely in part because input variables such as cover of semi‐natural habitats poorly capture variability in pollinator resources between regions and years

The Effects of Aphid Traits on Parasitoid Host Use and Specialist Advantage

Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and hostuse efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susceptibility to parasitoid attack. To address this question, we used data from a 13-year survey of interactions among 142 aphid and 75 parasitoid species in nine European countries. We found that only aphid traits related to local resource characteristics seem to influence the trade-off between host-range and efficiency: more specialized parasitoids had an apparent advantage (higher abundance on shared hosts) on aphids with sparse colonies, ant-attendance and without concealment, and this was more evident when host relatedness was included in calculation of parasitoid specificity. More traits influenced average assemblage specialization, which was highest in aphids that are monophagous, monoecious, large, highly mobile (easily drop from a plant), without myrmecophily, habitat specialists, inhabit non-agricultural habitats and have sparse colonies. Differences in aphid wax production did not influence parasitoid host specificity and host-use. Our study is the first step in identifying host traits important for aphid parasitoid host specificity and host-use and improves our understanding of bottom-up effects of aphid traits on aphid-parasitoid food web structure

The interplay of landscape composition and configuration: new pathways to manage functional biodiversity and agroecosystem services across Europe

Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects of landscape composition (% habitats) and configuration (edge density) on arthropods in fields and their margins, pest control, pollination and yields. Configuration effects interacted with the proportions of crop and non‐crop habitats, and species’ dietary, dispersal and overwintering traits led to contrasting responses to landscape variables. Overall, however, in landscapes with high edge density, 70% of pollinator and 44% of natural enemy species reached highest abundances and pollination and pest control improved 1.7‐ and 1.4‐fold respectively. Arable‐dominated landscapes with high edge densities achieved high yields. This suggests that enhancing edge density in European agroecosystems can promote functional biodiversity and yield‐enhancing ecosystem services

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies

CropPol: a dynamic, open and global database on crop pollination

Seventy five percent of the world's food crops benefit from insect pollination. Hence, there has been increased interest in how global change drivers impact this critical ecosystem service. Because standardized data on crop pollination are rarely available, we are limited in our capacity to understand the variation in pollination benefits to crop yield, as well as to anticipate changes in this service, develop predictions, and inform management actions. Here, we present CropPol, a dynamic, open and global database on crop pollination. It contains measurements recorded from 202 crop studies, covering 3,394 field observations, 2,552 yield measurements (i.e. berry weight, number of fruits and kg per hectare, among others), and 47,752 insect records from 48 commercial crops distributed around the globe. CropPol comprises 32 of the 87 leading global crops and commodities that are pollinator dependent. Malus domestica is the most represented crop (32 studies), followed by Brassica napus (22 studies), Vaccinium corymbosum (13 studies), and Citrullus lanatus (12 studies). The most abundant pollinator guilds recorded are honey bees (34.22% counts), bumblebees (19.19%), flies other than Syrphidae and Bombyliidae (13.18%), other wild bees (13.13%), beetles (10.97%), Syrphidae (4.87%), and Bombyliidae (0.05%). Locations comprise 34 countries distributed among Europe (76 studies), Northern America (60), Latin America and the Caribbean (29), Asia (20), Oceania (10), and Africa (7). Sampling spans three decades and is concentrated on 2001-05 (21 studies), 2006-10 (40), 2011-15 (88), and 2016-20 (50). This is the most comprehensive open global data set on measurements of crop flower visitors, crop pollinators and pollination to date, and we encourage researchers to add more datasets to this database in the future. This data set is released for non-commercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA). This article is protected by copyright. All rights reserved

Intensivierung der Landwirtschaft, biologische Schädlingsbekämpfung und räumlich-zeitliche Veränderungen in der Struktur des Nahrungsnetzes

Die Intensivierung der Landwirtschaft ist einer der Hauptauslöser von Verlusten in der Agrarbiodiversität und damit verbundenen Ökosystemfunktionen wie der biologischen Kontrolle. Sie beeinflusst dadurch indirekt auch die landwirtschaftliche Produktionsleistung. Durch die Intensivierung der Landwirtschaft kann sowohl die räumliche als auch die zeitliche Struktur, Zusammensetzung und Variabilität der Lebensgemeinschaften beeinflusst werden, da verschiedene Arten unterschiedlich reagieren. Von Arten, die sich am oberen Ende der Nahrungskette befinden, hoch spezialisierten Arten und Arten mit geringem Ausbreitungspotential nimmt man an, dass sie empfindlicher auf eine Intensivierung der Landwirtschaft reagieren und dass sie eine ausgeprägte räumliche und zeitliche Dynamik in ihrer Populations- und Nahrungsnetzentwicklung aufweisen. Um sowohl Muster in der Agrarbiodiversität und den damit verbundenen trophischen Wechselwirkungen als auch die durch die landwirtschaftliche Intensivierung verursachten Veränderungen in der Artenzusammensetzung verstehen zu können, ist es erforderlich, sich auf räumliche und zeitliche Veränderungen in Lebensgemeinschaften unterschiedlicher Nahrungsspezialisierung und trophischer Stufe zu konzentrieren. Ziel dieser Untersuchung ist, sich mit diesen Mustern in der Agrarbiodiversität zu befassen und ihre Verbindung mit der Funktionsweise von biologischer Kontrolle in verschiedenen Landnutzungssystemen zu untersuchen. Diese Arbeit ist ein Teil des AGRIPOPES-Projekts (http://agripopes.net) und umfasst drei Feldstudien, die alle in Deutschland in der Umgebung von Göttingen in Niedersachsen durchgeführt wurden.Wir stellten fest, dass eine komplexe Landschaftsstruktur zwar höhere Parasitierungsraten, jedoch auch einfacher strukturierte Nahrungsnetze hervorrufen kann. Dies lässt Zweifel an der generellen Wichtigkeit von Nahrungsnetzkomplexität für das Funktionieren von Ökosystemen aufkommen. In Landschaften, die durch die landwirtschaftliche Intensivierung vereinfacht wurden, können artenreiche, wenn auch hochgradig unterschiedliche Parasitoidengemeinschaften vorkommen. Die damit verbundenen Ökosystemfunktionen können jedoch anhand der festgestellten Veränderungen in der Struktur und Zusammensetzung der Lebensgemeinschaft nicht ohne weiteres vorhergesagt werden. Ökosystemfunktionen und die Struktur der Lebensgemeinschaften scheinen von der landwirtschaftlichen Intensivierung unterschiedlich beeinflusst zu werden, wobei sich die zeitlichen Veränderungen und diejenigen zwischen den trophischen Ebenen unterschiedlich abspielen. Zudem kann die landwirtschaftliche Intensivierung gegensätzliche Auswirkungen auf die Variabilität der Lebensgemeinschaften von spezialisierten, wenig ausbreitungsfähigen Parasitoiden und generalistischen, hochgradig ausbreitungsfähigen Prädatoren haben, was ihre unterschiedliche Anfälligkeit für Veränderungen in der Landschaft deutlich macht. Daher muss die Vereinfachung der Landschaft aufgrund von landwirtschaftlicher Intensivierung Lebensgemeinschaften nicht zwangsläufig aneinander angleichen, da ihre Reaktion von Artmerkmalen abhängen kann. Wir schlagen vor, dass auf die Auswirkungen der landwirtschaftlichen Intensivierung auf die Agrarbiodiversität und die biologische Kontrolle mit einem Ansatz, der möglichst viele Arten, trophische Ebenen und Landschaftsebenen einbezieht, eingegangen werden sollte, während man gleichzeitig verschiedene Ansätze, die Biodiversität zu erfassen, berücksichtigt