Quantifying and comparing bumblebee nest densities in gardens and countryside habitats
TL;DR: The National Bumblebee Nest Survey (NBPS) as discussed by the authors was a structured survey carried out by 719 volunteers in the UK during early summer 2004, where the surveyors used a defined protocol to record the presence or absence of bumblebee nests in prescribed areas of gardens, short grassland, long grassland and woodland, and along woodland edge, hedgerows and fence lines.
Abstract: Summary 1. Bumblebees provide an important pollination service to both crops and wild plants. Many species have declined in the UK, particularly in arable regions. While bumblebee forage requirements have been widely studied, there has been less consideration of whether availability of nesting sites is limiting. It is important to know which habitats contain the most bumblebee nests per unit area in order to guide conservation and management options; particularly in the light of current emphasis on environmental stewardship schemes for farmed landscapes. However, it is extremely difficult to map the distribution of bumblebee nests. 2. We describe the findings of the National Bumblebee Nest Survey, a structured survey carried out by 719 volunteers in the UK during early summer 2004. The surveyors used a defined protocol to record the presence or absence of bumblebee nests in prescribed areas of gardens, short grassland, long grassland and woodland, and along woodland edge, hedgerows and fence lines. The records allowed us to estimate the density of bumblebee nests in each of these habitats for the first time. 3. Nest densities were high in gardens (36 nests ha ‐1 ), and linear countryside habitats (fence lines, hedgerows, woodland edge: 20‐37 nests ha ‐1 ), and lower in non-linear countryside habitats (woodland and grassland: 11‐15 nests ha ‐1 ). 4. Findings on nest location characteristics corroborate those of an earlier survey carried out in the UK (Fussell & Corbet 1992). 5. Synthesis and applications . Gardens provide an important nesting habitat for bumblebees in the UK. In the countryside, the area occupied by linear features is small compared with that of non-linear features. However, as linear features contain high densities of nests, management options affecting such features may have a disproportionately large effect on bumblebee nesting opportunities. Current farm stewardship schemes in the UK are therefore likely to facilitate bumblebee nesting, because they provide clear guidance and support for ‘sympathetic’ hedgerow and field margin management.
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TL;DR: The stresses bees are experiencing from climate change, infectious diseases, and insecticides are reviewed, with concern that the authors may be nearing a “pollination crisis” in which crop yields begin to fall.
Abstract: Bees are subject to numerous pressures in the modern world. The abundance and diversity of flowers has declined, bees are chronically exposed to cocktails of agrochemicals, and they are simultaneously exposed to novel parasites accidentally spread by humans. Climate change is likely to exacerbate these problems in the future. Stressors do not act in isolation; for example pesticide exposure can impair both detoxification mechanisms and immune responses, rendering bees more susceptible to parasites. It seems certain that chronic exposure to multiple, interacting stressors is driving honey bee colony losses and declines of wild pollinators, but such interactions are not addressed by current regulatory procedures and studying these interactions experimentally poses a major challenge. In the meantime, taking steps to reduce stress on bees would seem prudent; incorporating flower-rich habitat into farmland, reducing pesticide use through adopting more sustainable farming methods, and enforcing effective quarantine measures on bee movements are all practical measures that should be adopted. Effective monitoring of wild pollinator populations is urgently needed to inform management strategies into the future.
2,526 citations
Cites background from "Quantifying and comparing bumblebee..."
..., (36)] and can boost bee numbers in adjacent farmland (58)....
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...bees, particularly bumblebees and some solitary bee species, but highly urbanized environments have few bees (36, 37), and the building of roads...
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TL;DR: In this article, the authors suggest mechanisms for encouraging "wildlife-friendly" management of collections of gardens across scales from the neighbourhood to the city, where the individual garden is much smaller than the unit of management needed to retain viable populations.
Abstract: As urbanisation increases globally and the natural environment becomes increasingly fragmented, the importance of urban green spaces for biodiversity conservation grows. In many countries, private gardens are a major component of urban green space and can provide considerable biodiversity benefits. Gardens and adjacent habitats form interconnected networks and a landscape ecology framework is necessary to understand the relationship between the spatial configuration of garden patches and their constituent biodiversity. A scale-dependent tension is apparent in garden management, whereby the individual garden is much smaller than the unit of management needed to retain viable populations. To overcome this, here we suggest mechanisms for encouraging 'wildlife-friendly' management of collections of gardens across scales from the neighbourhood to the city.
1,234 citations
TL;DR: Both bee abundance and species richness were significantly, negatively affected by disturbance, however, the magnitude of the effects was not large and the only disturbance type showing a significant negative effect, habitat loss and fragmentation, was statistically significant only in systems where very little natural habitat remains.
Abstract: Pollinators may be declining globally, a matter of concern because animal pollination is required by most of the world's plant species, including many crop plants. Human land use and the loss of native habitats is thought to be an important driver of decline for wild, native pollinators, yet the findings of published studies on this topic have never been quantitatively synthesized. Here we use meta-analysis to synthesize the literature on how bees, the most important group of pollinators, are affected by human disturbances such as habitat loss, grazing, logging, and agriculture. We obtained 130 effect sizes from 54 published studies recording bee abundance and/or species richness as a function of human disturbance. Both bee abundance and species richness were significantly, negatively affected by disturbance. However, the magnitude of the effects was not large. Furthermore, the only disturbance type showing a significant negative effect, habitat loss and fragmentation, was statistically significant only in systems where very little natural habitat remains. Therefore, it would be premature to draw conclusions about habitat loss having caused global pollinator decline without first assessing the extent to which the existing studies represent the status of global ecosystems. Future pollinator declines seem likely given forecasts of increasing land-use change.
847 citations
National Scientific and Technical Research Council1, University of Buenos Aires2, University of Würzburg3, University of California, Berkeley4, Swedish University of Agricultural Sciences5, Commonwealth Scientific and Industrial Research Organisation6, University of Göttingen7, Michigan State University8, Hebrew University of Jerusalem9, University of Queensland10, University of Reading11, Jagiellonian University12, Federal University of Bahia13, Rutgers University14, Lüneburg University15
TL;DR: Wild pollinators are relevant for crop productivity and stability even when honey bees are abundant, and policies to preserve and restore natural areas in agricultural landscapes should enhance levels and reliability of pollination services.
Abstract: Sustainable agricultural landscapes by definition provide high magnitude and stability of ecosystem services, biodiversity and crop productivity However, few studies have considered landscape effects on the stability of ecosystem services We tested whether isolation from florally diverse natural and semi-natural areas reduces the spatial and temporal stability of flower-visitor richness and pollination services in crop fields We synthesised data from 29 studies with contrasting biomes, crop species and pollinator communities Stability of flower-visitor richness, visitation rate (all insects except honey bees) and fruit set all decreased with distance from natural areas At 1 km from adjacent natural areas, spatial stability decreased by 25, 16 and 9% for richness, visitation and fruit set, respectively, while temporal stability decreased by 39% for richness and 13% for visitation Mean richness, visitation and fruit set also decreased with isolation, by 34, 27 and 16% at 1 km respectively In contrast, honey bee visitation did not change with isolation and represented > 25% of crop visits in 21 studies Therefore, wild pollinators are relevant for crop productivity and stability even when honey bees are abundant Policies to preserve and restore natural areas in agricultural landscapes should enhance levels and reliability of pollination services
751 citations
Cites background from "Quantifying and comparing bumblebee..."
...nest in disturbed areas such as gardens, hedgerows and fence lines (Osborne et al. 2008)....
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...Moreover, this weaker effect is also expected because some Bombus spp. nest in disturbed areas such as gardens, hedgerows and fence lines (Osborne et al. 2008)....
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Utrecht University1, Institut national de la recherche agronomique2, French Institute of Health and Medical Research3, University of Sussex4, Natural Resources Canada5, Purdue University6, Helmholtz Centre for Environmental Research - UFZ7, Smithsonian Institution8, University of Saskatchewan9, Université catholique de Louvain10, Washington State University11, University of Bergen12
TL;DR: Enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.
Abstract: We assessed the state of knowledge regarding the effects of large-scale pollution with neonicotinoid insecticides and fipronil on non-target invertebrate species of terrestrial, freshwater and marine environments. A large section of the assessment is dedicated to the state of knowledge on sublethal effects on honeybees (Apis mellifera) because this important pollinator is the most studied non-target invertebrate species. Lepidoptera (butterflies and moths), Lumbricidae (earthworms), Apoidae sensu lato (bumblebees, solitary bees) and the section “other invertebrates” review available studies on the other terrestrial species. The sections on freshwater and marine species are rather short as little is known so far about the impact of neonicotinoid insecticides and fipronil on the diverse invertebrate fauna of these widely exposed habitats. For terrestrial and aquatic invertebrate species, the known effects of neonicotinoid pesticides and fipronil are described ranging from organismal toxicology and behavioural effects to population-level effects. For earthworms, freshwater and marine species, the relation of findings to regulatory risk assessment is described. Neonicotinoid insecticides exhibit very high toxicity to a wide range of invertebrates, particularly insects, and field-realistic exposure is likely to result in both lethal and a broad range of important sublethal impacts. There is a major knowledge gap regarding impacts on the grand majority of invertebrates, many of which perform essential roles enabling healthy ecosystem functioning. The data on the few non-target species on which field tests have been performed are limited by major flaws in the outdated test protocols. Despite large knowledge gaps and uncertainties, enough knowledge exists to conclude that existing levels of pollution with neonicotinoids and fipronil resulting from presently authorized uses frequently exceed the lowest observed adverse effect concentrations and are thus likely to have large-scale and wide ranging negative biological and ecological impacts on a wide range of non-target invertebrates in terrestrial, aquatic, marine and benthic habitats.
649 citations
Cites background from "Quantifying and comparing bumblebee..."
...With impacts more pronounced when bees have to leave the colony, one might predict more marked effects when bees are foraging naturally, travelling kilometres across the landscape (Knight et al. 2005; Osborne et al. 2008)....
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References
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01 Jan 1975TL;DR: Ressenya de l'obra d'E. O. Wilson apareguda el 1975, Sociobiology. The New Synthesis.The Belknap Press of Harvard University Press.
Abstract: Ressenya de l'obra d'E. O. Wilson apareguda el 1975, Sociobiology. The New Synthesis .The Belknap Press of Harvard University Press.
6,126 citations
TL;DR: Evidence of declines (pre-versus post-1980) in local bee diversity in Britain and the Netherlands is found and a causal connection between local extinctions of functionally linked plant and pollinator species is strongly suggested.
Abstract: Despite widespread concern about declines in pollination services, little is known about the patterns of change in most pollinator assemblages. By studying bee and hoverfly assemblages in Britain and the Netherlands, we found evidence of declines (pre-versus post-1980) in local bee diversity in both countries; however, divergent trends were observed in hoverflies. Depending on the assemblage and location, pollinator declines were most frequent in habitat and flower specialists, in univoltine species, and/or in nonmigrants. In conjunction with this evidence, outcrossing plant species that are reliant on the declining pollinators have themselves declined relative to other plant species. Taken together, these findings strongly suggest a causal connection between local extinctions of functionally linked plant and pollinator species.
2,616 citations
1,810 citations
"Quantifying and comparing bumblebee..." refers background in this paper
...In social insects, in which most individuals do not reproduce, the functional unit of the population is the colony (Wilson 1975)....
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TL;DR: In this paper, the role and interactions between fields and their margins have been investigated, and the impact of these on weed flora and arthropods indicate mostly beneficial effects though conflicts exist, notably for the conservation of rare arable weed species.
739 citations
TL;DR: Overall, Fabaceae appear to be the major pollen source for most bumblebee species, but long-tongued, late emerging species such as Bombus ruderatus, Bombus humilis and Bombus subterraneus specialize heavily in gathering pollen from Fabaceae, and this group of bumblebees species have all declined.
445 citations