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Roads form a vast, rapidly growing global network that has diverse, detrimental ecological impacts. However, the habitats that border roads (‘road verges’) form a parallel network that might help mitigate these impacts and provide additional benefits (ecosystem services; ES). We evaluate the capacity of road verges to provide ES by reviewing existing research and considering their relevant characteristics: area, connectivity, shape, and contextual ES supply and demand. We consider the present situation, and how this is likely to change based on future projections for growth in road extent, traffic densities and urban populations. Road verges not only provide a wide range of ES, including biodiversity provision, regulating services (e.g. air and water filtration) and cultural services (e.g. health and aesthetic benefits by providing access to nature) but also displace other habitats and provide ecosystem disservices (e.g. plant allergens and damage to infrastructure). Globally, road verges may currently cover 270,000 km2 and store 0.015 Gt C/year, which will further increase with 70% projected growth in the global road network. Road verges are well placed to mitigate traffic pollution and address demand for ES in surrounding ES‐impoverished landscapes, thereby improving human health and well‐being in urban areas, and improving agricultural production and sustainability in farmland. Demand for ES provided by road verges will likely increase due to projected growth in traffic densities and urban populations, though traffic pollution will be reduced by technological advances (e.g. electric vehicles). Road verges form a highly connected network, which may enhance ES provision but facilitate the dispersal of invasive species and increase vehicle–wildlife collisions. Synthesis and applications. Road verges offer a significant opportunity to mitigate the negative ecological effects of roads and to address demand for ecosystem services (ES) in urban and agricultural landscapes. Their capacity to provide ES might be enhanced considerably if they were strategically designed and managed for environmental outcomes, namely by optimizing the selection, position and management of plant species and habitats. Specific opportunities include reducing mowing frequencies and planting trees in large verges. Road verge management for ES must consider safety guidelines, financial costs and ecosystem disservices, but is likely to provide long‐term financial returns if environmental benefits are considered. Road verges offer a significant opportunity to mitigate the negative ecological effects of roads and to address demand for ecosystem services (ES) in urban and agricultural landscapes. Their capacity to provide ES might be enhanced considerably if they were strategically designed and managed for environmental outcomes, namely by optimizing the selection, position and management of plant species and habitats. Specific opportunities include reducing mowing frequencies and planting trees in large verges. Road verge management for ES must consider safety guidelines, financial costs and ecosystem disservices, but is likely to provide long‐term financial returns if environmental benefits are considered.

Pathogens may gain a fitness advantage through manipulation of the behaviour of their hosts. Likewise, host behavioural changes can be a defence mechanism, counteracting the impact of pathogens on host fitness. We apply harmonic radar technology to characterize the impact of an emerging pathogen--Nosema ceranae (Microsporidia)--on honeybee (Apis mellifera) flight and orientation performance in the field. Honeybees are the most important commercial pollinators. Emerging diseases have been proposed to play a prominent role in colony decline, partly through sub-lethal behavioural manipulation of their hosts. We found that homing success was significantly reduced in diseased (65.8%) versus healthy foragers (92.5%). Although lost bees had significantly reduced continuous flight times and prolonged resting times, other flight characteristics and navigational abilities showed no significant difference between infected and non-infected bees. Our results suggest that infected bees express normal flight characteristics but are constrained in their homing ability, potentially compromising the colony by reducing its resource inputs, but also counteracting the intra-colony spread of infection. We provide the first high-resolution analysis of sub-lethal effects of an emerging disease on insect flight behaviour. The potential causes and the implications for both host and parasite are discussed.

1. Whilst most studies reviewing the reliance of global agriculture on insect pollination advocate increasing the 'supply' of pollinators (wild or managed) to improve crop yields, there has been little focus on altering a crop's 'demand' for pollinators. 2. Parthenocarpy (fruit set in the absence of fertilization) is a trait which can increase fruit quantity and quality from pollinator-dependent crops by removing the need for pollination. 3. Here we present a meta-analysis of studies examining the extent and effectiveness of parthenocarpy-promoting techniques (genetic modification, hormone application and selective breeding) currently being used commercially, or experimentally, on pollinator-dependent crops in different test environments (no pollination, hand pollination, open pollination). 4. All techniques significantly increased fruit quantity and quality in 18 pollinator-dependent crop species (not including seed and nut crops as parthenocarpy causes seedlessness). The degree to which plants experienced pollen limitation in the different test environments could not be ascertained, so the absolute effect of parthenocarpy relative to optimal pollination could not be determined. 5. Synthesis and applications. Parthenocarpy has the potential to lower a crop's demand for pollinators, whilst extending current geographic and climatic ranges of production. Thus, growers may wish to use parthenocarpic crop plants, in combination with other environmentally considerate practices, to improve food security and their economic prospects.

Central place foragers, such as pollinating bees, typically develop circuits (traplines) to visit multiple foraging sites in a manner that minimizes overall travel distance. Despite being taxonomically widespread, these routing behaviours remain poorly understood due to the difficulty of tracking the foraging history of animals in the wild. Here we examine how bumblebees (Bombus terrestris) develop and optimise traplines over large spatial scales by setting up an array of five artificial flowers arranged in a regular pentagon (50 m side length) and fitted with motion-sensitive video cameras to determine the sequence of visitation. Stable traplines that linked together all the flowers in an optimal sequence were typically established after a bee made 26 foraging bouts, during which time only about 20 of the 120 possible routes were tried. Radar tracking of selected flights revealed a dramatic decrease by 80% (ca. 1500 m) of the total travel distance between the first and the last foraging bout. When a flower was removed and replaced by a more distant one, bees engaged in localised search flights, a strategy that can facilitate the discovery of a new flower and its integration into a novel optimal trapline. Based on these observations, we developed and tested an iterative improvement heuristic to capture how bees could learn and refine their routes each time a shorter route is found. Our findings suggest that complex dynamic routing problems can be solved by small-brained animals using simple learning heuristics, without the need for a cognitive map.

The causes underlying the increased mortality of honeybee Apis mellifera colonies observed over the past decade remain unclear. Since so far the evidence for monocausal explanations is equivocal, involvement of multiple stressors is generally assumed. We here focus on various aspects of forage availability, which have received less attention than other stressors because it is virtually impossible to explore them empirically. We applied the colony model BEEHAVE, which links within-hive dynamics and foraging, to stylized landscape settings to explore how foraging distance, forage supply, and “forage gaps”, i.e. periods in which honeybees cannot find any nectar and pollen, affect colony resilience and the mechanisms behind. We found that colony extinction was mainly driven by foraging distance, but the timing of forage gaps had strongest effects on time to extinction. Sensitivity to forage gaps of 15 days was highest in June or July even if otherwise forage availability was sufficient to survive. Forage availability affected colonies via cascading effects on queen’s egg-laying rate, reduction of new-emerging brood stages developing into adult workers, pollen debt, lack of workforce for nursing, and reduced foraging activity. Forage gaps in July led to reduction in egg-laying and increased mortality of brood stages at a time when the queen’s seasonal egg-laying rate is at its maximum, leading to colony failure over time. Our results demonstrate that badly timed forage gaps interacting with poor overall forage supply reduce honeybee colony resilience. Existing regulation mechanisms which in principle enable colonies to cope with varying forage supply in a given landscape and year, such as a reduction in egg-laying, have only a certain capacity. Our results are hypothetical, as they are obtained from simplified landscape settings, but they are consistent with existing empirical knowledge. They offer ample opportunities for testing the predicted effects of forage stress in controlled experiments.

1. Foraging range is a key aspect of the ecology of 'central place foragers'. Estimating how far bees fly under different circumstances is essential for predicting colony success, and for estimating bee-mediated gene flow between plant populations. It is likely to be strongly influenced by forage distribution, something that is hard to quantify in all but the simplest landscapes; and theories of foraging distance tend to assume a homogeneous forage distribution. 2. We quantified the distribution of bumblebee Bombus terrestris L. foragers away from experimentally positioned colonies, in an agricultural landscape, using two methods. We mass-marked foragers as they left the colony, and analysed pollen from foragers returning to the colonies. The data were set within the context of the 'forage landscape': a map of the spatial distribution of forage as determined from remote-sensed data. To our knowledge, this is the first time that empirical data on foraging distances and forage availability, at this resolution and scale, have been collected and combined for bumblebees. 3. The bees foraged at least 1·5 km from their colonies, and the proportion of foragers flying to one field declined, approximately linearly, with radial distance. In this landscape there was great variation in forage availability within 500 m of colonies but little variation beyond 1 km, regardless of colony location. 4. The scale of B. terrestris foraging was large enough to buffer against effects of forage patch and flowering crop heterogeneity, but bee species with shorter foraging ranges may experience highly variable colony success according to location.

1. We have little idea how landscape‐scale factors influence the success of wild bumblebee nests over time. Here for the first time we use molecular markers to estimate within‐season changes in the numbers of nests. 2. Workers of two bumblebee species were sampled in an arable landscape in late May-June and late July-August, and the numbers of nests represented in each sample were estimated. We compare the methods available to estimate nest number from such samples and conclude that methods which allow for heterogeneity in the probability of capture of nests provide the best fit to our data. Changes in numbers of nests at the two time points were used to infer nest survival. 3. The two bee species appeared to differ markedly in survival over time, with estimates of 45% of nests surviving for Bombus lapidarius and 91% for B. pascuorum. However, our data suggest that the foraging range of B. pascuorum may be greater in late season, which would lead us to overestimate nest survival in this species. Differential survival may also reflect differences in phenology between the two species. 4. The land use class which had the most consistent effects on nest number and survival was gardens; for B. lapidarius, the area of gardens within a 750 and 1000 m radius positively influenced nest survival, while for B. pascuorum, the number of nests in late samples was higher at sites with more gardens within a 500 and 750‐m radius. For B. pascuorum, the area of grassland within a 250 and 500‐m radius also positively influenced nest number in late samples, probably because this is the preferred nesting habitat for this species. 5. The importance of gardens is in accordance with previous studies which suggest that they now provide a stronghold for bumblebees in an otherwise impoverished agricultural environment; furthermore, our data suggest that the positive influence of gardens on bumblebee populations can spill over at least 1 km into surrounding farmland. 6. Synthesis and applications. The substantial effects that even small areas of local resources such as rough grassland or clover leys can have on bumblebee nest numbers and survival is of clear relevance for the design of pollinator management strategies.

Nature conservation often depends on the behaviour of individuals, which can be driven by socio‐psychological factors such as a person's attitude, knowledge and identity. Despite extensive ecological research about pollinator declines, there has been almost no social research assessing the drivers of people's engagement in pollinator conservation. To address this gap, we used a large‐scale, online questionnaire in the United Kingdom, broadly framed around the Theory of Planned Behaviour. We received a total of 1,275 responses from a wide range of ages, incomes and education levels, despite a selection bias towards people with a pre‐existing interest in pollinators. A range of socio‐psychological factors predicted people's pollinator conservation actions and explained 45% of the variation. Respondents’ diversity of nature interactions and perceived behavioural control (feeling able to help pollinators) were consistently important predictors of people's pollinator conservation actions, whilst the importance of other socio‐psychological factors depended on the particular action. Notably, knowledge was far less important overall than people's perceptions and other socio‐psychological factors, highlighting a knowledge‐action gap. Further unexplained variation in people's behaviour could partly be due by structural and contextual factors, particularly regarding social norms around tidiness. From a practical perspective, our findings reveal three main insights. First, several simple, low‐cost pollinator conservation actions (reduced mowing, leaving areas unmown and creating patches of bare ground for ground‐nesting bees) are currently under‐utilised so should be priorities for pollinator conservation programmes. Second, strategies are needed to overcome reported practical barriers, for example by providing free resources (e.g. seeds of pollen‐ and nectar‐rich plants) and communicating simple beneficial actions that can be carried out with limited time, space and money. Third, knowledge is just one (relatively less important) factor that predicts pollinator conservation behaviour—other socio‐psychological factors provide potential pathways for increasing uptake, and structural and contextual limitations also need to be considered. In practice, this could be achieved by engaging, inspiring and empowering the public to help pollinators and to take responsibility for their local environment, for example through environmental education and community programmes facilitating public interest and involvement in the management of greenspace. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.

Understanding strategies used by animals to explore their landscape is essential to predict how they exploit patchy resources, and consequently how they are likely to respond to changes in resource distribution. Social bees provide a good model for this and, whilst there are published descriptions of their behaviour on initial learning flights close to the colony, it is still unclear how bees find floral resources over hundreds of metres and how these flights become directed foraging trips. We investigated the spatial ecology of exploration by radar tracking bumblebees, and comparing the flight trajectories of bees with differing experience. The bees left the colony within a day or two of eclosion and flew in complex loops of ever-increasing size around the colony, exhibiting Lévy-flight characteristics constituting an optimal searching strategy. This mathematical pattern can be used to predict how animals exploring individually might exploit a patchy landscape. The bees' groundspeed, maximum displacement from the nest and total distance travelled on a trip increased significantly with experience. More experienced bees flew direct paths, predominantly flying upwind on their outward trips although forage was available in all directions. The flights differed from those of naïve honeybees: they occurred at an earlier age, showed more complex looping, and resulted in earlier returns of pollen to the colony. In summary bumblebees learn to find home and food rapidly, though phases of orientation, learning and searching were not easily separable, suggesting some multi-tasking.

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.