•Honeybees are less likely to transfer pollen to oilseed rape than solitary bees.•Though less common solitary bees may contribute significantly to pollination.•The importance of solitary bees is ...particularly high away from honeybee hives.•Management for wild pollinators is crucial where honeybee hives are infrequent.
In Europe, oilseed rape is the principal crop used in the production of edible and renewable fuel oil products. Insect pollinators, in particular bees, have been shown to have a positive effect on the seed set of this crop. We undertook experiments looking at behavioural differences between honeybees, bumblebees and solitary bees visiting oilseed rape flowers, and related this to landscape scale responses in visitation rates. We found that behavioural differences between honeybees, bumblebees and solitary bees alter the likelihood of pollen transfer from their bodies to the plant stigma. Solitary bees and bumblebees tend to have greater rates of stigmal contact than honeybees. The interactions between the likelihood of free pollen on bodies and the probability of stigmal contact suggest that only 34.0% of visitations by honeybees were likely to result in pollen transfer to the stigma, relative to 35.1% for the bumblebees and 71.3% for solitary bees. Visitation rates were higher for honeybees in high quality landscapes with relatively large areas of alternative foraging habitat. Visitation rates of honeybees were also more frequent in the vicinity of managed hives. For solitary bees and bumblebees visitation rates did not respond to landscape structure, although more species of solitary bees were found in landscapes with a high cover of semi-natural grassland. While honeybees may be less efficient in pollen transfer per unit visit, where they numerically outweigh other types of bees in a crop (e.g. around managed hives) this may not be important. For this reason the relative ease with which hives can be moved across landscape means that honeybees are perhaps the most suitable taxa for use as a pro-active mitigation measure against pollinator deficits. However, the greater efficiency of solitary bees compensates for the effort required to implement longer term management (i.e. the establishment of flower rich field margins and open soil nesting sites) to support their populations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
1. Declines in abundance and diversity of bumble bees (Bombus spp.) in Europe have been linked to agricultural intensification and the resulting loss of suitable foraging and nesting habitats. ...Environmental Stewardship (ES) is a new scheme in England offering the opportunity to restore habitats of value for these important pollinators to agricultural land. Scientific evaluation of the options prescribed within the scheme is essential to ensure that their objectives are met and that the benefits can be realized by the full bumble bee species assemblage. 2. We compared the efficacy of different ES options for field margins on arable land in enhancing the abundance and diversity of flowering resources and foraging bumble bees. Our study was conducted over 3 years using a multisite experiment. 3. Overall, uncropped margins sown with mixtures containing nectar and pollen-producing plants were more effective in providing bumble bee forage than margins sown with a grass mix, allowed to regenerate naturally or managed as conservation headlands. 4. A mixture of agricultural legumes established quickly and attracted on average the highest total abundance and diversity of bumble bees, including the rare long-tongued species Bombus ruderatus and Bombus muscorum. However, marked differences were observed between species and sexes in their responses to field margin management over time. 5. A diverse mixture of native wildflowers attracted more of the shorter-tongued Bombus spp. and provided greater continuity of forage resources, especially early in the season. Allowing Cirsium spp. to flower on such margins also increased their attractiveness to male bumble bees. 6. Synthesis and applications. Our results suggest that the legume-based 'pollen and nectar flower mix', as prescribed under Entry Level Stewardship in England, can quickly provide a highly attractive forage resource for bumble bees, but that issues of seasonal flowering phenology and longevity of the mixture need to be addressed. Establishment of 'floristically enhanced margins' under Higher Level Stewardship will be important to provide diverse perennial communities of forage plants and to support a greater range of Bombus spp. and other pollinators. The population-level responses of bumble bees to introduced seed mixtures and other agri-environment options require further study in order to maximize the benefits of such schemes in intensively farmed landscapes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Glycolysis and gluconeogenesis are central pathways of metabolism across all domains of life. A prominent enzyme in these pathways is phosphoglucose isomerase (PGI), which mediates the ...interconversion of glucose-6-phosphate and fructose-6-phosphate. The predatory bacterium
leads a complex life cycle, switching between intraperiplasmic replicative and extracellular 'hunter' attack-phase stages. Passage through this complex life cycle involves different metabolic states. Here we present the unliganded and substrate-bound structures of the
PGI, solved to 1.74 Å and 1.67 Å, respectively. These structures reveal that an induced-fit conformational change within the active site is not a prerequisite for the binding of substrates in some PGIs. Crucially, we suggest a phenylalanine residue, conserved across most PGI enzymes but substituted for glycine in
and other select organisms, is central to the induced-fit mode of substrate recognition for PGIs. This enzyme also represents the smallest conventional PGI characterized to date and probably represents the minimal requirements for a functional PGI.
Agricultural intensification is likely to have been a major factor leading to serious declines in bumblebee abundance and diversity in the UK and elsewhere over recent decades. Opportunities to ...restore habitat for bumblebees on uncropped arable field margins are now available, although the methods by which this restoration can be achieved have not been fully investigated. We present the results of a three year study undertaken to investigate the response of foraging bumblebees to five different arable field margin treatments (sown and unsown), as part of a replicated field experiment on arable farmland in northern England (UK). Bumblebee abundance was closely linked to successional changes in availability of suitable forage plant species. Field margin treatments sown with a `grass and wildflower' mixture had the highest bumblebee abundance, and provided a consistent supply of forage species, with different components of the seed mixture flowering in each year. The unsown natural regeneration treatment attracted foraging bumblebees in only the second year due to the local abundance of thistles, so we consider this option to be both inconsistent in terms of forage provision and agronomically unacceptable. Our results are discussed in terms of developing suitable measures to achieve the restoration of habitats for bumblebees on arable farmland.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The provision of overwintering refuges has important implications for both conservation of invertebrate biodiversity on farmland and biological control of crop pests. In this study we carried out a ...systematic investigation of the effects of habitat type and age on the quality of overwintering refuges for Coleoptera and Araneae on an arable farm in the UK. Hedgerow habitats contained taller and more diverse vegetation with a greater proportion of bare ground compared with field margins. Vegetation height and diversity, and the richness and cover of forbs all increased significantly with habitat age. Soil organic matter content also increased with habitat age, suggesting a more favourable structure for burrowing Coleoptera. Total abundance and richness of Coleoptera and Araneae were significantly higher in hedgerow habitats compared with the field margins. This largely reflected the response of staphylinid beetles, the most abundant group recorded. There was no effect of habitat age on overall abundance or diversity, suggesting the good dispersal ability of many farmland invertebrates, but also reflecting the close relationship between habitat age and type. The response of individual invertebrate species was more mixed: 10 species were recorded in significantly higher densities in the hedge base compared with one in the field margin. Similarly, eight species were recorded in significantly higher densities in mature habitats compared with four in recently established vegetation. There were significant interactions between habitat type and age for six species, of which four showed a marked preference for the base of mature hedgerows. These included both important predators of cereal aphids and crop pests. It was concluded that hedgerows provided the highest quality overwintering habitat for invertebrates emphasising the importance of strategies directed at conserving and enhancing this habitat. However, newly created field margins fulfilled a useful role in rapidly providing overwintering refuges for a more limited group of invertebrate species.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The conservation and management of biodiversity requires accurate, repeatable and cost-effective monitoring techniques. In this study, a simple and rapid methodology was employed to measure the ...quality of different habitats for butterfly species on 10 arable farms in lowland Britain. This habitat monitoring was seven times more rapid than the traditional species-based butterfly monitoring. Data on butterfly abundance were combined with the information gathered on habitat quality at five of the farms using stepwise regression. These models had a consistently high degree of explanatory power for the summary variables of total butterfly abundance and species richness, and the functional groupings of mobile and immobile species. There was good agreement between observed and predicted estimates of species richness and abundance when the models were validated on a further five independent sites. Models to predict the abundance of 11 common butterfly species were also produced. These varied considerably in their predictive power and validity between species. The results clearly demonstrated the beneficial effects of targeted habitat creation for butterflies which is promoted under the Agri-environment Schemes, especially the recently introduced pollen and nectar seed mixtures (WM2) available under the Countryside Stewardship Scheme. The models confirmed the importance of shelter, floristically diverse field margins and the availability of nectar resources from legume species in explaining the abundance of immobile butterfly species in arable landscapes. These sources of nectar and the presence of larval host plants in the crucifer family were important factors in explaining the abundance of mobile species. The results are discussed in terms of the potential of this approach for: (i) assessing habitat quality for butterflies in intensively managed landscapes; (ii) enhancing the value of butterfly monitoring schemes in explaining changes in butterfly abundance at the site and national scale; and (iii) informing habitat management and restoration guidelines for butterfly conservation on arable farmland.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
There have been serious global declines in diversity of bumblebees, butterflies and other pollinating insects. The most effective means of increasing abundance and diversity of bumblebees on farmland ...is to sow simple, low cost mixtures of dicotyledons rich in pollen and nectar, as prescribed under the UK agri-environment schemes. The potential benefits of this management prescription for butterflies are unknown. Similarly, more information is needed on how to manage this habitat to maximise the provision of pollen and nectar resources whilst protecting breeding habitat for butterflies. This study aimed to devise mixtures and cutting management regimes which address these issues. We found significant effects of seed mixture, timing and frequency of cutting, and removal of cut material on vegetation composition, flower resource availability and pollinators (the abundance, species richness and temporal distribution of butterflies and bumblebees, including males and queens, attracted to the mixtures). We recommend that nectar flower mixtures are refined by the inclusion of the best performing species to provide mid- and late-season forage resources (
Trifolium
spp.,
Lotus corniculatus
and
Centaurea
nigra
), and the removal of competitive grass species. Summer cutting in May or early June, with removal of herbage where possible, should be applied to half the patch to extend the flowering season, and minimise damage to butterfly breeding habitat. This should be accompanied by the typical autumn cut to the whole patch. Even with best management practice, such nectar flower mixtures are only effective for 3–4 years and this should be recognised in policies aimed at enhancing pollinator populations in agricultural landscapes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Quasi-biennial cycles are often reported in climate studies. The interannual El Niño Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) are two phenomena containing quasi-periodicities ...of approximately 2.5 and 2.2 years. It is known that ENSO affects corn yield through weather patterns, NAO affects surface temperature and cloudiness, and surface temperature, rainfall, and radiation affect corn yield. However, a quasi-biennial pattern in corn yield and the combined effect of several climate signals on long-term U.S. corn yield are not known. Here we show statistically significant 2–3 year periods in long-term corn yield from one of the world's most important corn producing regions. High (low) yields are due in part to high (low) surface radiation and low (high) temperature early in the corn growing season coupled with sufficient (insufficient) rainfall later in the growing season. A statistical model we developed using three climate indices accounts for 54% of the interannual variation in Iowa corn yield. The most significant periodicities found in the model's spectrum are similar to the quasi-biennial periodicities in observed corn yield. We classify Iowa corn yield from several regional datasets (1960–2006) for ‘low yield’ and ‘high yield’ conditions as predicted by the model. The difference between observed corn yields for ‘high’ and ‘low’ yielding years was 19% (
p
=
0.0001). The results demonstrate a quasi-biennial pattern in long-term Iowa corn yield related to large-scale climate variability. This knowledge could lead to models that help guide springtime agricultural management decisions that improve profitability and reduce nitrate flux to groundwater, streams, rivers, and coastal oceans.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Improved understanding of year‐to‐year late‐spring soil nitrate test (LSNT) variability could help make it more attractive to producers. We test the ability of the Root Zone Water Quality Model ...(RZWQM) to simulate watershed‐scale variability due to the LSNT, and we use the optimized model to simulate long‐term field N dynamics under related conditions. Autoregressive techniques and the automatic parameter calibration program PEST were used to show that RZWQM simulates significantly lower nitrate concentration in discharge from LSNT treatments compared with areas receiving fall N fertilizer applications within the tile‐drained Walnut Creek, Iowa, watershed (>5 mg N L−1 difference for the third year of the treatment, 1999). This result is similar to field‐measured data from a paired watershed experiment. A statistical model we developed using RZWQM simulations from 1970 to 2005 shows that early‐season precipitation and early‐season temperature account for 90% of the interannual variation in LSNT‐based fertilizer N rates. Long‐term simulations with similar average N application rates for corn (Zea mays L.) (151 kg N ha−1) show annual average N loss in tile flow of 20.4, 22.2, and 27.3 kg N ha−1 for LSNT, single spring, and single fall N applications. These results suggest that (i) RZWQM is a promising tool to accurately estimate the water quality effects of LSNT; (ii) the majority of N loss difference between LSNT and fall applications is because more N remains in the root zone for crop uptake; and (iii) year‐to‐year LSNT‐based N rate differences are mainly due to variation in early‐season precipitation and temperature.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Revision of a total knee arthroplasty may require an extensile approach to permit a satisfactory exposure without compromising the attachment of the patellar tendon. It has been assumed that a rectus ...snip is a relatively benign form of release, but the effect of using this approach on function, pain and patient satisfaction is not known. From January 1997 to December 1999, 107 patients who underwent revision of total knee arthroplasty were followed up at a minimum of two years (mean 40.5 months) and assessed by the Oxford Hip Score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Short-Form (SF)-12 and patient satisfaction. Co-morbidity, surgical exposure, the Hospital for Special Surgery (HSS) knee scores and the range of movement were also used. A standard medial parapatellar approach was used in 57 patients and the rectus snip in 50. The two groups were equivalent for age, sex and co-morbidity scores. The WOMAC function, pain, stiffness and satisfaction scores demonstrated no statistical difference. The use of a rectus snip as an extensile procedure has no effect on outcome.
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