Showing papers by "Riccardo Bommarco published in 2015"
TL;DR: It is shown that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees, and the contribution of pesticides to the global decline of wild bees may have been underestimated.
Abstract: Understanding the effects of neonicotinoid insecticides on bees is vital because of reported declines in bee diversity and distribution and the crucial role bees have as pollinators in ecosystems and agriculture. Neonicotinoids are suspected to pose an unacceptable risk to bees, partly because of their systemic uptake in plants, and the European Union has therefore introduced a moratorium on three neonicotinoids as seed coatings in flowering crops that attract bees. The moratorium has been criticized for being based on weak evidence, particularly because effects have mostly been measured on bees that have been artificially fed neonicotinoids. Thus, the key question is how neonicotinoids influence bees, and wild bees in particular, in real-world agricultural landscapes. Here we show that a commonly used insecticide seed coating in a flowering crop can have serious consequences for wild bees. In a study with replicated and matched landscapes, we found that seed coating with Elado, an insecticide containing a combination of the neonicotinoid clothianidin and the non-systemic pyrethroid β-cyfluthrin, applied to oilseed rape seeds, reduced wild bee density, solitary bee nesting, and bumblebee colony growth and reproduction under field conditions. Hence, such insecticidal use can pose a substantial risk to wild bees in agricultural landscapes, and the contribution of pesticides to the global decline of wild bees may have been underestimated. The lack of a significant response in honeybee colonies suggests that reported pesticide effects on honeybees cannot always be extrapolated to wild bees.
812 citations
Wageningen University and Research Centre1, Rutgers University2, Spanish National Research Council3, University of Leeds4, Naturalis5, Institut national de la recherche agronomique6, Michigan State University7, University of Freiburg8, University of California, Berkeley9, University of New England (United States)10, University of Vermont11, University of California, Davis12, National University of Singapore13, Hungarian Academy of Sciences14, University of Göttingen15, Cornell University16, Swedish University of Agricultural Sciences17, Stellenbosch University18, Centre national de la recherche scientifique19, Simon Fraser University20, University of Reading21, University of Würzburg22, Plant & Food Research23, University of Giessen24, University of Texas at Austin25, University of Bern26, Hebrew University of Jerusalem27, Lund University28, Federal University of Bahia29
TL;DR: It is shown that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species, suggesting that cost-effective management strategies to promote crop pollination should target a different set of species than management Strategies to promote threatened bees.
Abstract: There is compelling evidence that more diverse ecosystems deliver greater benefits to people, and these ecosystem services have become a key argument for biodiversity conservation. However, it is unclear how much biodiversity is needed to deliver ecosystem services in a cost-effective way. Here we show that, while the contribution of wild bees to crop production is significant, service delivery is restricted to a limited subset of all known bee species. Across crops, years and biogeographical regions, crop-visiting wild bee communities are dominated by a small number of common species, and threatened species are rarely observed on crops. Dominant crop pollinators persist under agricultural expansion and many are easily enhanced by simple conservation measures, suggesting that cost-effective management strategies to promote crop pollination should target a different set of species than management strategies to promote threatened bees. Conserving the biological diversity of bees therefore requires more than just ecosystem-service-based arguments.
698 citations
TL;DR: This study provides new insights into the general mechanisms that link biodiversity to ecosystem functioning in natural animal communities and suggests that the observed responses were due to the identity and dominance patterns of the trait composition rather than the number or abundance of species per se.
Abstract: Drastic biodiversity declines have raised concerns about the deterioration of ecosystem functions and have motivated much recent research on the relationship between species diversity and ecosystem functioning. A functional trait framework has been proposed to improve the mechanistic understanding of this relationship, but this has rarely been tested for organisms other than plants. We analysed eight datasets, including five animal groups, to examine how well a trait-based approach, compared with a more traditional taxonomic approach, predicts seven ecosystem functions below- and above-ground. Trait-based indices consistently provided greater explanatory power than species richness or abundance. The frequency distributions of single or multiple traits in the community were the best predictors of ecosystem functioning. This implies that the ecosystem functions we investigated were underpinned by the combination of trait identities (i.e. single-trait indices) and trait complementarity (i.e. multi-trait indices) in the communities. Our study provides new insights into the general mechanisms that link biodiversity to ecosystem functioning in natural animal communities and suggests that the observed responses were due to the identity and dominance patterns of the trait composition rather than the number or abundance of species per se.
501 citations
TL;DR: It is suggested that effects on the individual bee should be linked to both mechanisms at the sub-individual level and also to the consequences for the colony and wider bee populations as bees are increasingly facing multiple interacting pressures.
Abstract: It has been suggested that the widespread use of neonicotinoid insecticides threatens bees, but research on this topic has been surrounded by controversy. In order to synthesize which research approaches have been used to examine the effect of neonicotinoids on bees and to identify knowledge gaps, we systematically reviewed research on this subject that was available on the Web of Science and PubMed in June 2015. Most of the 216 primary research studies were conducted in Europe or North America (82%), involved the neonicotinoid imidacloprid (78%), and concerned the western honey bee Apis mellifera (75%). Thus, little seems to be known about neonicotinoids and bees in areas outside Europe and North America. Furthermore, because there is considerable variation in ecological traits among bee taxa, studies on honey bees are not likely to fully predict impacts of neonicotinoids on other species. Studies on crops were dominated by seed-treated maize, oilseed rape (canola) and sunflower, whereas less is known about potential side effects on bees from the use of other application methods on insect pollinated fruit and vegetable crops, or on lawns and ornamental plants. Laboratory approaches were most common, and we suggest that their capability to infer real-world consequences are improved when combined with information from field studies about realistic exposures to neonicotinoids. Studies using field approaches often examined only bee exposure to neonicotinoids and more field studies are needed that measure impacts of exposure. Most studies measured effects on individual bees. We suggest that effects on the individual bee should be linked to both mechanisms at the sub-individual level and also to the consequences for the colony and wider bee populations. As bees are increasingly facing multiple interacting pressures future research needs to clarify the role of neonicotinoids in relative to other drivers of bee declines.
237 citations
TL;DR: The effects of wildflower strips on bees are largely driven by the extent to which local flower richness is increased, and this measure could be enhanced by maximizing the number of bee forage species in seed mixtures, and by management regimes that effectively maintain flower richness in the strips through the years.
Abstract: Growing evidence for declines in wild bees calls for the development and implementation of effective mitigation measures. Enhancing floral resources is a widely accepted measure for promoting bees in agricultural landscapes, but effectiveness varies considerably between landscapes and regions. We hypothesize that this variation is mainly driven by a combination of the direct effects of measures on local floral resources and the availability of floral resources in the surrounding landscape. To test this, we established wildflower strips in four European countries, using the same seed mixture of forage plants specifically targeted at bees. We used a before-after control-impact approach to analyse the impacts of wildflower strips on bumblebees, solitary bees and Red List species and examined to what extent effects were affected by local and landscape-wide floral resource availability, land-use intensity and landscape complexity. Wildflower strips generally enhanced local bee abundance and richness, including Red-listed species. Effectiveness of the wildflower strips increased with the local contrast in flower richness created by the strips and furthermore depended on the availability of floral resources in the surrounding landscape, with different patterns for solitary bees and bumblebees. Effects on solitary bees appeared to decrease with increasing amount of late-season alternative floralresources in the landscape, whereas effects on bumblebees increased with increasing early-season landscape-wide floral resource availability.Synthesis and applications. Our study shows that the effects of wildflower strips on bees are largely driven by the extent to which local flower richness is increased. The effectiveness of this measure could therefore be enhanced by maximizing the number of bee forage species in seed mixtures, and by management regimes that effectively maintain flower richness in the strips through the years. In addition, for bumblebees specifically, our study highlights the importance of a continuous supply of food resources throughout the season. Measures that enhance early-season landscape-wide floral resource availability, such as the cultivation of oilseed rape, can benefit bumblebees by providing the essential resources for colony establishment and growth in spring. Further research is required to determine whether, and under what conditions, wildflower strips result in actual population-level effects. Our study shows that the effects of wildflower strips on bees are largely driven by the extent to which local flower richness is increased. The effectiveness of this measure could therefore be enhanced by maximizing the number of bee forage species in seed mixtures, and by management regimes that effectively maintain flower richness in the strips through the years. In addition, for bumblebees specifically, our study highlights the importance of a continuous supply of food resources throughout the season. Measures that enhance early-season landscape-wide floral resource availability, such as the cultivation of oilseed rape, can benefit bumblebees by providing the essential resources for colony establishment and growth in spring. Further research is required to determine whether, and under what conditions, wildflower strips result in actual population-level effects. (Less)
210 citations
TL;DR: A research agenda is proposed that identifies resource bottlenecks and interruptions over time to key beneficial organisms, emphasising their resulting population dynamics and likely to effectively increase the stock, flow, and stability of ecosystem services.
Abstract: A common suggestion to support ecosystem services to agriculture provided by mobile organisms is to increase the amount of natural and seminatural habitat in the landscape This might, however, be inefficient, and demands for agricultural products limit the feasibility of converting arable land into natural habitat To develop more targeted means to promote ecosystem services, we need a solid understanding of the limitations to population growth for service-providing organisms We propose a research agenda that identifies resource bottlenecks and interruptions over time to key beneficial organisms, emphasising their resulting population dynamics Targeted measures that secure the continuity of resources throughout the life cycle of service-providing organisms are likely to effectively increase the stock, flow, and stability of ecosystem services
197 citations
National University of Río Negro1, Spanish National Research Council2, Swedish University of Agricultural Sciences3, University of Freiburg4, Commonwealth Scientific and Industrial Research Organisation5, National University of Comahue6, University of Reading7, University of Brasília8, University of Leeds9, Naturalis10, University of California, Berkeley11, University of Koblenz and Landau12, University of Bern13, National University of Tucumán14, Federal University of Ceará15, University of Würzburg16, University of Göttingen17, Lund University18, University of Hamburg19, ETH Zurich20, University of Queensland21, Cornell University22, University of Vermont23, Central University of Kerala24, Universidad de las Américas Puebla25, Federal University of Bahia26, Jagiellonian University27
TL;DR: Pollinator species with traits matching those of the focal crop, as well as the enhancement of pollinator richness and evenness, will increase crop yield beyond current practices, and field practitioners can predict and manage agroecosystems for pollination services based on knowledge of just a few traits that are known for a wide range of flower visitor species.
Abstract: Fil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Universidad Nacional de Rio Negro. Sede Andina; Argentina
140 citations
TL;DR: Considering the functional trait composition of communities provides a more mechanistic understanding of the processes shaping the strength of trophic interactions in terrestrial ecosystems, thus improving predictive power.
95 citations
TL;DR: The differential response of the three cultivars suggested opportunities to use cultivars that are less dependent on insect pollination in landscapes where this service has been deteriorated, and increased access of nitrogen seems to partly compensate yield losses from poor Insect pollination.
67 citations
TL;DR: In this paper, the authors 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.
50 citations
01 Jan 2015
TL;DR: Overall, research and innovation such as those successfully supported by the STEP project, contribute to greening the economy and making development sustainable.
Abstract: Natural Capital, and the ecosystem services derived from it, are essential to human well-be- ing and economic prosperity. Indeed, nature inspires and provides many solutions that can help us tackle some of the most pressing challenges of our time. For example, pollinators matter because a majority of European crops depend or benet from insect pollination. Another example is the contribution of pollinators to preserving cherished natural and cultural landscapes through wildower pollination. However, due to a cocktail mix of drivers of change, pollinator species are disappearing and pollinator populations are declining. ese losses accentuate several of our societal chal- lenges, including food security and ecosystem degradation. Hence, building knowledge on the causes behind pollinator decline, and the eects of pollinator decline on other species and ecosystems is essential. e STEP project has contributed signicantly within this eld, with a particular focus on the status and drivers behind trends in European pollinators. Furthermore, research into the dierent solutions for maintaining or enhancing pollinator populations is crucial. ese activities enrich the knowledge base on Nature-based solu- tions, solutions that are inspired by or supported by nature and address societal challenges while maintaining or enhancing our natural capital. Overall, research and innovation ac- tions such as those successfully supported by the STEP project, contribute to greening the economy and making development sustainable.
TL;DR: In this article, the plant community in previously abandoned but now restored semi-natural pastures was surveyed along a distance gradient from the border between the restored pastures and adjacent fields towards the centre of the pastures.
Abstract: Questions
Does restoration success of formerly abandoned semi-natural pastures depend on adjacent land use? Is species richness higher in restored pastures adjacent to an intact semi-natural pasture than in restored pastures adjacent to arable land? Does community similarity between a restored and an adjacent intact pasture decrease with distance from the border between the two pastures? Do differences in species richness and community similarity decrease over time?
Location
Agricultural landscapes in south-central Sweden.
Methods
The plant community in previously abandoned but now restored semi-natural pastures was surveyed along a distance gradient from the border between the restored pastures and adjacent fields towards the centre of the pastures. The restored pastures were located adjacent to either a crop field (N = 8) or a continuously grazed pasture (N = 6), and differed in time since restoration (1–13 yr).
Results
The total species richness was higher in pastures adjoining continuously grazed pastures compared to crop fields. Richness of both total and specialist species increased with time since restoration. Irrespective of adjacent land use, richness of specialist species decreased with increasing distance from the edge, an effect that became weaker with increasing time since restoration. The similarity in species composition compared to that in adjacent continuously grazed pasture also decreased towards the centre of the restored pasture.
Conclusions
Our results suggest that restoration of biodiversity in semi-natural pastures benefits from adjacent pastures that can act as source habitats. The most likely mechanism is step-wise short-distance dispersal, but also other processes, such as more long-distance dispersal, seed bank dynamics and historical legacies are probably involved. To best succeed in habitat restoration in fragmented landscapes, the spatial location of source populations must be considered.
TL;DR: In the cross country comparison landscape complexity and agricultural intensification did not significantly affect total aphid densities, although there were marked differences between Scandinavian and central European sites with respect to the species composition of aphids and their parasitoids and parasitism rates.
Abstract: In fragmented farmland landscapes struc- tural complexity and low agricultural intensification should decrease the abundance of crop aphids due to increased abundances and species diversity of aphid enemies, including hymenopteran parasitoids. Here we study the effects of landscape structure and agricultural intensification on parasitism rates, abun- dances, and species richness of aphids and their parasitoids in five different regions in Europe. While total aphid numbers did not differ significantly among regions, we observed marked differences between Scandinavian and central European sites with respect to the species composition of aphids and their parasitoids and parasitism rates. In the cross country comparison landscape complexity and agricultural intensification did not significantly affect total aphid densities, although we observed species-specific reac- tions to land use. We also observed a tendency towards increased parasitoid species richness at low agricul- tural intensification but not at high landscape structure.
TL;DR: In this article, the authors describe a rapid assessment methodology aimed at evaluating land-cover quality for birds, plants, butterflies and bees around seven UK Natura 2000 sites, based on historical (1950, 1990), current (2000) and future (2030) landcover data, the last projected using three alternative scenarios: a growth-applied strategy, a business-as-might-be-usual (BAMBU) scenario, and sustainable European development goal (SEDG) scenario.
Abstract: Changes in landscape composition and structure may impact the conservation and management of protected areas. Species that depend on specific habitats are at risk of extinction when these habitats are degraded or lost. Designing robust methods to evaluate landscape composition will assist decision- and policy-making in emerging landscapes. This paper describes a rapid assessment methodology aimed at evaluating land-cover quality for birds, plants, butterflies and bees around seven UK Natura 2000 sites. An expert panel assigned quality values to standard Coordination of Information on the Environment (CORINE) land-cover classes for each taxonomic group. Quality was assessed based on historical (1950, 1990), current (2000) and future (2030) land-cover data, the last projected using three alternative scenarios: a growth-applied strategy (GRAS), a business-as-might-be-usual (BAMBU) scenario, and sustainable European development goal (SEDG) scenario. A quantitative quality index weighted the area of each land-cover parcel with a taxa-specific quality measure. Land parcels with high quality for all taxonomic groups were evaluated for temporal changes in area, size and adjacency. For all sites and taxonomic groups, the rate of deterioration of land-cover quality was greater between 1950 and 1990 than current rates or as modelled using the alternative future scenarios (2000–2030). Model predictions indicated land-cover quality stabilized over time under the GRAS scenario, and was close to stable for the BAMBU scenario. The SEDG scenario suggested an ongoing loss of quality, though this was lower than the historical rate of c. 1% loss per decade. None of the future scenarios showed accelerated fragmentation, but rather increases in the area, adjacency and diversity of high quality land parcels in the landscape.
Journal Article•
TL;DR: It can be concluded that in this experiment, clothianidin exposure had no effect on the prevalence or the amount of the studied pathogens and parasites in honeybee colonies.
Abstract: Sub-lethal doses of neonicotinoids have been shown to negatively impact the health of honeybees. However, most studies to date have exposed bees only artificially to these pesticides under laboratory conditions. There have been just a few well designed and replicated studies of the impacts of realistic neonicotinoid exposure on honeybees foraging under field conditions. In order to close this knowledge gap, and test the influence of the neonicotinoid clothianidin on honeybees, we used a study system of 16 paired, spatially separated (>4 km) spring oilseed rape fields in the south of Sweden. The fields were paired according to land use in the surrounding landscape and geographical proximity, using GIS. Eight of the fields were randomly assigned to be sown with clothianidin dressed Brassica napus (oilseed rape) seeds and their corresponding pairs with undressed B. napus seeds, as controls. Six equally sized Apis mellifera colonies, with known queen origin, were placed at each field resulting in a total of 96 colonies. Samples of bees, pollen and nectar taken from the colonies showed that the honeybee colonies at the treated fields were exposed to several orders of magnitude higher clothianidin concentrations than the colonies at the control sites. To determine the effect of this neonicotinoid on pathogen and parasite prevalence and quantities in honeybee colonies, samples of adult bees were taken from each colony both before and after the flowering period in the paired fields. The parasites studied included the ectoparasitic mite Varroa destructor and the microsporidian gut parasite Nosema. The pathogens studied included eight different honeybee viruses (BQCV, SBV, DWV, KBV, SBPV, CBPV, ABPV, and IAPV). Both the impact of clothianidin exposure on the prevalence (proportion of positive colonies) and the amount of parasites/pathogens in each colony (infestation rate/titres) were analysed. The infestation with V. destructor was relatively low and the exposure to clothianidin had no significant impact on the V. destructor prevalence and infestation rate of the colonies. Furthermore the exposure to clothianidin had no significant influence on the Nosema spp. prevalence or the amount of Nosema spores in infested colonies. Three out of the eight viruses studied were detected: DWV, SBV and BQCV. Both BQCV and SBV were detected in practically all colonies, both before and after the experiment, with consequently no difference in prevalence due to clothianidin exposure or season. There was also no difference in BQCV and SBV titres due to clothianidin exposure. The DWV prevalence was relatively low; 4% and 36% of colonies infected, before and after the experiment respectively. The clothianidin exposure had no effect on the DWV prevalence or on the titres in DWV positive samples. The higher prevalence of DWV in the control group compared to the treated group can be explained by the different initial conditions. It can be concluded that in this experiment, clothianidin exposure had no effect on the prevalence or the amount of the studied pathogens and parasites in honeybee colonies. 7 BQCV = Black Queen Cell Virus, SBV = Sacbrood Virus, DWV = Deformed Wing Virus, KBV = Kashmir Bee Virus, SBPV = Slow Bee Paralysis Virus, CBPV = Chronic Bee Paralysis Virus, ABPV = Acute Bee Paralysis Virus, IAPV = Israeli Acute Paralysis Virus
01 Jan 2015
TL;DR: In this paper, Honungsbin var i vart fall ingen representativ art for att avgora om vaxtskyddsmedlet har en negativ paverkan pa andra arter av bin.
Abstract: EU har sedan 2013 begransat anvandningen av tre neonikotinoider i grodor som ar attraktiva for bin. En stor del av den kunskap vi har idag om hur bin paverkas av neonikotinoider kommer fran laboratoriestudier av framforallt honungsbin som har matats med vaxtskyddsmedel. I ett forskningsprojekt har forskare fran Lunds universitet och SLU i samarbete med Jordbruksverket undersokt hur ett vaxtskyddsmedel i gruppen neonikotinoider paverkar bade honungsbin och vilda bin ute i jordbrukslandskapet.Den har rapporten sammanfattar projektets resultat.• Vi sag inga negativa effekter pa honungsbinas samhallstillvaxt, halsa och overlevnad.• For vilda bin (jordhumlor och roda murarbin) sag vi negativa effekter pa samhallstillvaxt och reproduktion.• Honungsbin var i vart fall ingen representativ art for att avgora om vaxtskyddsmedlet har en negativ paverkan pa andra arter av bin. (Less)