Pollination services in the UK: how important are honeybees?

Pollination services are known to provide substantial benefits to human populations and agriculture in particular. Although many species are known to provide pollination services, honeybees (Apis mellifera) are often assumed to provide the majority of these services to agriculture. Using data from a range of secondary sources, this study assesses the importance of insect pollinated crops at regional and national scales and investigates the capacity of honeybees to provide optimal pollination services to UK agriculture. The findings indicate that insect pollinated crops have become increasingly important in UK crop agriculture and, as of 2007, accounted for 20% of UK cropland and 19% of total farmgate crop value. Analysis of honeybee hive numbers indicates that current UK populations are only capable of supplying 34% of pollination service demands even under favourable assumptions, falling from 70% in 1984. In spite of this decline, insect pollinated crop yields have risen by an average of 54% since 1984, casting doubt on long held beliefs that honeybees provide the majority of pollination services. Future land use and crop production patterns may further increase the role of pollination services to UK agriculture, highlighting the importance of measures aimed at maintaining both wild and managed species

Quantifying the impact and relevance of scientific research

Qualitative and quantitative methods are being developed to measure the impacts of research on society, but they suffer from serious drawbacks associated with linking a piece of research to its subsequent impacts. We have developed a method to derive impact scores for individual research publications according to their contribution to answering questions of quantified importance to end users of research. To demonstrate the approach, here we evaluate the impacts of research into means of conserving wild bee populations in the UK. For published papers, there is a weak positive correlation between our impact score and the impact factor of the journal. The process identifies publications that provide high quality evidence relating to issues of strong concern. It can also be used to set future research agendas

Bee conservation: inclusive solutions

Conservation Biolog

Quantifying the value of ecosystem services: a case study of honeybee pollination in the UK

There is concern that insect pollinators, such as honey bees, are currently declining in abundance, and are under serious threat from environmental changes such as habitat loss and climate change; the use of pesticides in intensive agriculture, and emerging diseases. This paper aims to evaluate how much public support there would be in preventing further decline to maintain the current number of bee colonies in the UK. The contingent valuation method (CVM) was used to obtain the willingness to pay (WTP) for a theoretical pollinator protection policy. Respondents were asked whether they would be WTP to support such a policy and how much would they pay? Results show that the mean WTP to support the bee protection policy was £1.37/week/household. Based on there being 24.9 million households in the UK, this is equivalent to £1.77 billion per year. This total value can show the importance of maintaining the overall pollination service to policy makers. We compare this total with estimates obtained using a simple market valuation of pollination for the UK

Thermal biology and nest-site selection in the bee 'Halictus rubicundus' (Hymenoptera : Halictidae)

Aggregations of the ground-nesting bee Halictus rubicundus were found at several locations across the UK. The phenology, social organisation, nest architecture and foraging behaviour of this bee were described for the largest of these aggregations (Invergowrie, Scotland). This site was unusual in having an extremely high brood mortality due to the impact of an anthomyiid fly. Nest parasitism was found to be directly density-dependent and it lead to a marked decline in nest numbers over the period of this study, indicating the possible forthcoming extinction of the aggregation. The other sites contained smaller nesting aggregations and the level of parasitism was considerably less. There was a marked variation in size across UK populations and this was explained by a temperature rather than a latitudinal cline. There was no evidence from field or laboratory studies to suggest that this species is endothermic; H. rubicundus is purely a behavioural thermoregulator. The effect of size upon various rates of heat exchange were examined in the laboratory for both sexes, and related to behaviours observed at the nest-site. Thus the microclimatic windows for different activities were established. The abundance of flying individuals at the nest-site was highly predictable from ambient temperature and light intensity; with predictions during a single day being more accurate than those combining several days throughout the season. Furthermore the usefulness of standard operative temperatures in predicting flight activity was assessed. The thoracic temperature of both sexes depended on the prevailing ambient temperature and also on the size of the individual while either basking or flying. Body temperatures increased with both ambient temperature and head width. However when both these predictors were combined into a single model, then size was only a strong predictor at lower temperatures. These findings were used to explain many of the behavioural patterns observed at Invergowrie. The nest site selection behaviour of females was examined both within and across sites. H. rubicundus was able to utilise a range of edaphic and microclimatic conditions when choosing a site to excavate a nest. There were some factors with broad tolerances such as slope and hardness, and others with much narrower limits such as aspect, soil humidity and particle composition. The thermal advantages of having a warm nest meant that the most suitable areas were those with a southern aspect and a slope which maximised the absorption of solar radiation. Limited areas of substrate with the most desirable characteristics resulted in gregarious nesting ('limited substrate' hypothesis). There was a preference for softer soils, that were easier to dig, within a site with a low overall density; but in much denser aggregations problems of maintaining the structural integrity of a nest lead to the favouring of harder soils. The tendency to nest in close proximity to the natal nest (philopatry) complemented the 'limited substrate' hypothesis in producing an aggregation of nests. The spatial distributions of nests within aggregations were examined using nearest neighbour distance analyses; at low densities, microscale variation in substrate quality produced clumped patterns, whereas at high densities the risk of adjacent nests collapsing into one another forced nest spacing to be more regular. Findings concerning temperature dependence of nesting and foraging activities, and broader environmental controls on nest-site selection, are considered in relation to key aspects of bee biology: the origins and function of social behaviours, the conservation of, or provision of, nest-sites, and the utility of solitary bees as crop pollinators

Susceptibility of faba bean (Vicia faba L.) to heat stress during floral development and anthesis

Experiments were conducted over two years to quantify the response of faba bean (Vicia faba L.) to heat stress. Potted winter faba bean plants (cv. Wizard) were exposed to temperature treatments (18/10; 22/14; 26/18; 30/22; 34/26°C day/night) for five days during floral development and anthesis. Developmental stages of all flowers were scored prior to stress, plants were grown in exclusion from insect pollinators to prevent pollen movement between flowers, and yield was harvested at an individual pod scale, enabling effects of heat stress to be investigated at a high resolution. Susceptibility to stress differed between floral stages, flowers were most affected during initial green-bud stages. Yield and pollen germination of flowers present before stress showed threshold relationships to stress, with lethal temperatures (t50) ~28°C and ~32°C, while whole plant yield showed a linear negative relationship to stress with high plasticity in yield allocation, such that yield lost at lower nodes was partially compensated at higher nodal positions. Faba bean has many beneficial attributes for sustainable modern cropping systems but these results suggest that yield will be limited by projected climate change, necessitating the development of heat tolerant cultivars, or improved resilience by other mechanisms such as earlier flowering times

Robotic bees for crop pollination: why drones cannot replace biodiversity

The notion that robotic crop pollination will solve the decline in pollinators has gained wide popularity recently (Fig. 1), and in March 2018 Walmart filed a patent for autonomous robot bees. However, w present six arguments showing that this is a technically and economically inviable 'solution' at present and poses substantial ecological and moral risks: (1) despite recent advances, robotic pollination is far from being able to replace bees to pollinate crops efficiently; (2) using robots is very unlikely to be economically viable; (3) there would be unacceptably high environmental costs; (4) wider ecosystems would be damaged; (5) it would erode the values of biodiversity; and, (6) relying on robotic pollination could actually lead to major food insecurity

Insect pollination reduces yield loss following heat stress in faba bean (Vicia faba L.)

Global food security, particularly crop fertilization and yield production, is threatened by heat waves that are projected to increase in frequency and magnitude with climate change. Effects of heat stress on the fertilization of insect-pollinated plants are not well understood, but experiments conducted primarily in self-pollinated crops, such as wheat, show that transfer of fertile pollen may recover yield following stress. We hypothesized that in the partially pollinator-dependent crop, faba bean (Vicia faba L.), insect pollination would elicit similar yield recovery following heat stress. We exposed potted faba bean plants to heat stress for 5 days during floral development and anthesis. Temperature treatments were representative of heat waves projected in the UK for the period 2021-2050 and onwards. Following temperature treatments, plants were distributed in flight cages and either pollinated by domesticated Bombus terrestris colonies or received no insect pollination. Yield loss due to heat stress at 30°C was greater in plants excluded from pollinators (15%) compared to those with bumblebee pollination (2.5%). Thus, the pollinator dependency of faba bean yield was 16% at control temperatures (18 to 26°C) and extreme stress (34°C), but was 53% following intermediate heat stress at 30°C. These findings provide the first evidence that the pollinator dependency of crops can be modified by heat stress, and suggest that insect pollination may become more important in crop production as the probability of heat waves increases

Elevated temperature drives a shift from selfing to outcrossing in the insect pollinated legume, faba bean (Vicia faba)

Climate change can threaten the reproductive success of plants, both directly, through physiological damage during increasingly extreme weather events, and indirectly, through disruption of plant–pollinator interactions. To explore how plant–pollinator interactions are modified by extreme weather, we exposed faba bean (Vicia faba) plants to elevated temperature for 5 d during flowering, simulating a heatwave. We then moved the plants to flight cages with either bumblebees or no pollinators, or to two field sites, where plants were enclosed in mesh bags or pollinated by wild insect communities. We used a morphological marker to quantify pollen movement between experimental plants. There was a substantial increase in the level of outcrossing by insect pollinators following heat stress. Proportion outcrossed seed increased from 17 % at control temperature to 33 % following heat stress in the flight cages, and from 31 % to 80 % at one field site, but not at the other (33 % to 32 %). Abiotic stress can dramatically shift the relative contributions of cross- and self-pollination to reproduction in an insect pollinated plant. The resulting increases in gene flow have broad implications for genetic diversity and functioning of ecosystems, and may increase resilience by accelerating the selection of more stress-tolerant genotypes