Honey Bee Visitation Research Articles

Pollination limitation despite managed honeybees in South African macadamia orchards

There is growing demand for pollination services in agricultural production, which contrasts with declines of wild and managed pollinator populations. Macadamia (Macadamia integrifolia) is a mass-flowering crop that depends on pollination services and is increasingly cultivated in South Africa. We studied the crop’s pollination in South African orchards considering variation in landscape context and the spatial arrangement of managed honeybees (Apis mellifera). We conducted pollination experiments and pollinator observations on macadamia trees along a distance gradient from orchard edges that bordered either near-natural or human-modified habitats. In addition, we mapped position and density of honeybee apiaries at orchard-level. Nut set of macadamia trees strongly relied on animal-mediated pollination: pollinator exclusion reduced the initial nut set (3 weeks after pollination) by 80% and the final nut set (15 weeks after pollination) by 54%. Supplemental hand-pollination of otherwise untreated flowers increased initial and final nut set by 66% and 44%, respectively, indicating substantial pollination limitation. The landscape context only weakly affected pollinator visitation to macadamia trees, with reduced visitation closer to orchard edges bordering human-modified habitats. Furthermore, we observed almost no wild pollinator species. Instead, honeybees constituted 99% of all visits, whereby honeybee visitation rates increased with a tree’s connectivity to apiaries. However, neither initial nor final nut was related to visitation rates, and the final nut set was actually reduced where honeybee colony density was high, with a predicted 50% reduction in final nut set between the lowest and highest colony densities. Our study demonstrates a strong pollination limitation in South African macadamia orchards, where managed honeybees fail at delivering the increasing need for pollination services. Indeed, increasing their colony densities may further limit their pollination efficiency. A pollination management that also includes non-Apis managed pollinators and wild pollinators is possibly needed to increase nut set and provide solutions for increasing pollination service demands. In intensive macadamia orchards, this can also necessitate the need for more pollinator-friendly management practices, including habitat restoration and reduced pesticide application.

Increasing Honey Bee Hive Densities Promotes Pollination and Yield Components of Highbush Blueberry in Western Washington

Yield components including fruit set and berry size in northern highbush blueberry (Vaccinium corymbosum) can be limited in key production regions like western Washington. Climactic conditions influence the activity levels of blueberry’s primary commercial pollinator, honey bee (Apis mellifera). Cool springs with frequent rainfall, which are common during the spring bloom period in western Washington, can reduce honey bee activity, pollination efficiency, and subsequent fruit set and yields. Increasing honey bee hive density may be a simple technique that growers can employ to increase the number of honey bees foraging during periods of good weather, interspersed with the poor weather, and therefore, increase fruit set and related yield components. The objective of this study was to evaluate if increased honey bee hive densities improve pollination and subsequent yield components in western Washington blueberry. Three field sites with mature ‘Duke’ plants were stocked with 10 hives/ha of honey bees (control), and three other field sites (also ‘Duke’) were stocked with 20 hives/ha (high hive density). Honey bee visitation and yield components, including fruit set and berry weight, were measured. Estimated yield, seed number/berry, and fruit firmness were also monitored. There were no significant differences in fruit set regardless of honey bee hive density. However, honey bee visitation and estimated yield increased with increased honey bee hive density. Berry weight and seed number per berry were also increased with increased honey bee hive density, although firmness was unaffected. Results indicate that increasing honey bee hive densities can help blueberry growers improve berry size and overall yields, suggesting this is a practice growers can implement if their production is constrained by insufficient pollination.

Honeybee spillover reshuffles pollinator diets and affects plant reproductive success.

During the past decades, managed honeybee stocks have increased globally. Managed honeybees are particularly used within mass-flowering crops and often spill over to adjacent natural habitats after crop blooming. Here, we uniquely show the simultaneous impact that honeybee spillover has on wild plant and animal communities in flower-rich woodlands via changes in plant-pollinator network structure that translate into a direct negative effect on the reproductive success of a dominant wild plant. Honeybee spillover leads to a re-assembly of plant-pollinator interactions through increased competition with other pollinator species. Moreover, honeybee preference for the most abundant plant species reduces its seed set, driven by high honeybee visitation rates that prevent pollen tube growth. Our study therefore calls for an adequate understanding of the trade-offs between providing pollination services to crops and the effects that managed pollinators might have on wild plants and pollinators.

Observations of Phαceliα tαnαcetifoliα as a Food Plant for Honey Bees and other insects

Three consecutive sowings of Phacelia tanacetifolia Bentham (Hydrophyllaceae) were examined for plant growth and attractiveness to bees and other insect-visitors over a three years’ study. Plants that were sown in March flowered uniformly for periods of 24 to 40 days, while those sown in June and July had a non-uniform anthesis that was impossible to estimate. Plants sown in early August, remained vegetative throughout winter and flowered the following spring. Maximum visits of honey bees were observed between 10:00 h and 17:00 h. Most honey bees (>70%) collected nectar. Seasonal differences in the ratio nectar/pollen gatherers were noted. Two species of bumble bee (B. terrestris and B. lucorum) and 9 species of solitary bee visited Phacelia.

Wildflower Plantings Do Not Compete With Neighboring Almond Orchards for Pollinator Visits.

The engineering of flowering agricultural field borders has emerged as a research and policy priority to mitigate threats to pollinators. Studies have, however, rarely addressed the potential that flowering field borders might compete with neighboring crops for pollinator visits if they both are in bloom at the same time, despite this being a concern expressed by growers. We evaluated how wildflower plantings added to orchard borders in a large (512 ha) commercial almond orchard affected honey bee and wild bee visitation to orchard borders and the crop. The study was conducted over two consecutive seasons using three large (0.48 ha) wildflower plantings paired with control orchard borders in a highly simplified agricultural landscape in California. Honey bee (Apis mellifera L.) and wild bee visitation to wildflower plots were at least an order of magnitude higher than to control plots, but increased honey bee visitation to wildflower plots did not lead to any detectable shifts in honey bee visitation to almond flowers in the neighboring orchard. Wild bees were rarely observed visiting almond flowers irrespective of border treatment, indicating a limited short-term potential for augmenting crop pollination using wild bees in highly simplified agricultural landscapes. Although further studies are warranted on bee visitation and crop yield from spatially independent orchards, this study indicates that growers can support bees with alternative forage in almond orchards without risking competition between the wildflower plantings and the crop.

Nectar properties and the role of sunbirds as pollinators of the golden-flowered tea (Camellia petelotii).

Properties of floral nectar have been used to predict if a plant species is pollinated by birds. To see whether winter-flowering plants evolve nectar properties corresponding to bird pollinators, nectar properties of several Camellia species (including the golden-flowered tea), as well as the role of floral visitors as effective pollinators, were examined. Potential pollinators of Camellia petelotii were identified at different times of day and under various weather conditions. A bird exclusion experiment was used to compare the pollination effectiveness of birds and insects. Nectar sugar components (fructose, glucose, and sucrose) from C. petelotii growing wild and another seven Camellia species and 22 additional cultivars (all in cultivation) were examined by high-performance liquid chromatography (HPLC). The sunbird Aethopyga siparaja and honeybees were the most frequent floral visitors to C. petelotii. Honeybee visits were significantly reduced in cloudy/rainy weather. The fruit and seed set of flowers with birds excluded were reduced by 64%, indicating that bird pollination is significant. For the wild populations of C. petelotii, a bagged flower could secrete 157 μL nectar; this nectar has a low sugar concentration (19%) and is sucrose-dominant (87%). The eight Camellia species and 22 cultivars had an average sugar concentration of around 30% and a sucrose concentration of 80%, demonstrating sucrose-dominant nectar in Camellia species. The nectar sugar composition of Camellia species was characterized by sucrose dominance. In addition, the large reduction in seed set when birds are excluded in the golden-flowered tea also supports the suggestion that these winter-flowering plants may have evolved with birds as significant pollinators.

The use of digital video recorders in pollination biology

1. Digital video recording (DVR) devices, such as the GoPro Hero, have the potential to greatly benefit pollination ecology, but the advantages of digitally recording pollinator activity over direct human observation have not been formally assessed.2. Two plant taxa, Lavandula angustifolia and Canna ‘sp.’, with differing floral morphology, were used to compare the value of DVR and direct observations in estimating honeybee (Apis mellifera) visitation, flower density and number of flowers visited per foraging bout.3. The two methods yielded identical results when observing the structurally simple L. angustifolia at both high (10.54 ± 0.52 per plant) and low honeybee density (2.24 ± 0.20 per plant). However, DVR underestimated the number of flowers scored in the field of view (28.7 ± 1.8 direct vs. 22.7 ± 0.9 DVR), the number of honeybees observed (5.3 ± 0.8 direct vs. 3.7 ± 0.7 DVR) and the number of flowers visited during foraging bouts (8.3 ± 1.2 direct vs. 5.5 ± 1.0 DVR) on the more complex Canna ‘sp.’4. It is concluded that portable weatherproof DVR devices such as the GoPro Hero are valuable tools for pollination biologists, allowing a single researcher to make simultaneous observations of multiple plants in one or more sites, whilst also allowing the footage to be reviewed. However, DVR devices are limited by their depth and field of view when target plants are large or structurally complex.

Using the waggle dance to determine the spatial ecology of honey bees during commercial crop pollination

Managed honey bees play an important role in global crop pollination. Maximizing their potential is likely to be of increasing importance to the global human supply. We explored the potential of waggle dance data to determine the spatial ecology of honey bees sited in a crop under commercial pollination. Over two springs, we video recorded and then decoded 834 waggle dances from colonies located in two apple and pear farms in Kent, U.K. We also obtained pollen samples from returning foragers and quantified the insects visiting apple and pear flowers. The vast majority (84%) of dances were for locations outside of the orchards in which our colonies were located. Accounting for the distance of orchards and oilseed rape fields from the study colonies, the amount of foraging per hectare in oilseed rape fields was greater than in orchards. The results of the present study indicate that maximizing the pollination services of managed honey bee colonies requires an landscape level approach that takes into account farm and foraging scale, as well as competing floral sources. The data also suggest that oilseed rape is a significant competitor to apple and pear flowers for honey bee visits.

Honey Bee Activity in Northern Highbush Blueberry Differs across Growing Regions in Washington State

Commercial production of northern highbush blueberry (Vaccinium corymbosum) is dependent upon rented colonies of honey bees (Apis mellifera) for meeting pollination requirements. Despite the prevalent use of honey bees, growers in Washington State and the greater Pacific Northwest (PNW), particularly those located in the western regions, claim pollination is limited and yield potential is subsequently reduced due to pollination deficits. However, there have been no studies or surveys that document this occurrence for this economically important region of blueberry production. The objective of this study was to survey honey bee activity in commercial plantings of ‘Duke’ highbush blueberry in western and eastern Washington and to assess the relationship between honey bee activity, growing region, and select yield components. Honey bee colony strength was also assessed to evaluate this variable’s relationship to honey bee activity and measured yield components. Sixteen and 18 commercial ‘Duke’ blueberry fields across Washington State were surveyed in 2014 and 2015, respectively. Average number of honey bee visitations per plant and honey bee colony strength were determined to evaluate overall honey bee activity. Estimated yield, berry number per plant, berry size (mass), and seed number per berry were also determined and analyzed to determine their relationship to honey bee activity through regression analysis. Honey bee visitation rates differed between western and eastern Washington, with western Washington sites consistently below recommended honey bee densities. Colony strength was also below recommended levels, but was lower for western Washington relative to eastern Washington. Estimated yield and berry number differed across sites and years, but were not related to honey bee visitation rates. Regression analysis revealed few significant relationships, although honey bee visitation rates were positively related to seed number per berry and seed number was positively related to berry size (R2 = 0.25 and 0.16, respectively). Berry size was also positively related to colony strength (R2 = 0.63). This study demonstrates that honey bee activity is limited in Washington blueberry production, particularly in western Washington, when compared with recommendations for optimal honey bee activity in blueberry. However, yields were unaffected between the compared regions. The lack of a relationship between honey bee visitation rates and yields suggests that pollination is sufficient for ‘Duke’ blueberry in Washington State and pollination deficits do not limit yield for this cultivar under the conditions of the study.

Bee diversity and abundance in a livestock drove road and its impact on pollination and seed set in adjacent sunflower fields

Natural and semi-natural habitats within agricultural landscapes provide food and nesting resources for wild bees, thus promoting crop pollination services. In central Spain, a large network of drove roads (DRs) crosses extensive areas of intensive agricultural fields. DRs are tracks (20⿿75m wide) with semi-natural vegetation, protected for their priority function of transhumant livestock herding. In this study, we analyse the bee community of one of the main Spanish DRs, and evaluate its effects on flower visitation and seed set in adjacent sunflower fields. We used pan traps to assess bee abundance and richness at 13 sites along the DR and in adjacent sunflower fields at 10, 75 and 150m from the DR. We also conducted visual counts to assess visitation rates to sunflower heads and measured seed set. Wild bee abundance and richness were significantly higher in the DR than in sunflower fields; but there were no significant differences among distances within sunflower fields. Honey bee abundance did not differ between the DR and sunflower fields. Wild bee visitation to sunflower heads was higher at 10m compared to 75 and 150m from the DR, but differences in honey bee visitation were non-significant. Sunflower seed set was significantly higher at 10m compared to 75 and 150m, and was associated with wild bee abundance, but not with honey bee abundance. Our results show that livestock DRs act as reservoirs of wild bee diversity within intensive agricultural matrices, enhancing wild bee visitation and seed set in adjacent sunflower crops.

Flowering ground vegetation benefits wild pollinators and fruit set of almond within arid smallholder orchards

Abstract Pollination studies tend to focus on the conventional agriculture associated with Europe and the USA, leaving a gap in our understanding of how pollination services are maintained in smallholder agricultural systems that dominate much of the developing world. In South Sinai, Egypt, almond is cultivated as part of an arid agroforestry system in traditional orchard gardens that contain a mixture of fruit trees inter‐planted with vegetables and herbs. This study investigated the relative contribution of honeybees and wild insects for pollination of almond trees and assessed how flowering ground vegetation influenced pollinator densities and fruit set. Results showed that almond was highly dependent on insect pollination, with bagged flowers producing less than 8% of the fruit set of insect‐ and hand‐pollinated flowers. Fruit set was correlated with wild pollinator visitation, but not with honeybee visitation. Furthermore, the presence of honeybee hives had no effect upon fruit set. The abundance and species richness of flowering ground vegetation was positively related to pollinator abundance within the gardens and associated with enhanced fruit set. Over half of the flowering ground flora were minority crops grown alongside almond, suggesting that facilitation can occur between simultaneously flowering crops. In these diverse orchard gardens, flowering minority crops benefited wild pollinators and increased fruit set in the primary orchard crop. If mutual facilitation occurs between other crop species, then the diverse cropping systems associated with smallholder farms are likely to enhance pollination services within traditional agricultural landscapes.

Differential attractiveness of sunflower cultivars to the honeybeeApis melliferaL.

In France, sunflower honey production has decreased since the nineties and professional beekeepers report important honey yield variability between years and locations. Consequently, melliferous potential of current sunflower cultivars is questioned as it is not part of traits held in breeding programs. To investigate this question, a 3-years study was conducted on two sites and attractiveness for honeybees of 13 current sunflower cultivars was assessed under natural conditions. The number of honeybee visits per plant was recorded daily during blooming period on cultivars randomly distributed on experimental plots. Sunflower genetic was a major factor influencing honeybee attendance on plots and discrepancy between most and least visited cultivars reached a factor of 3. Cultivars relative attractiveness was consistent between years and sites. Potential link between sunflower attractiveness for honeybees and its melliferous characteristics is discussed. If confirmed, farmers’ choice concerning cultivars at a territory scale could contribute to enhance nectar resource for pollinators and to increase viability of apicultural activity.

Long lasting summer flowerings of Lythrum salicaria as honeybee-friendly flower spots in Mediterranean basin agricultural wetlands

The purple loosestrife, Lythrum salicaria, is a species native to Eurasia. It is rustic, produces both pollen and nectar, and may be a helpful food source for bees in Mediterranean wetlands, helping them to overcome hot summer periods characterised by food paucity. In this research, we investigated the flowering of L. salicaria plants in Mediterranean agricultural wetlands, as well as pollinator diversity and abundance. L. salicaria has a long lasting flowering, with more than 640 open flowers/plant from mid-July to early September. 476 pollinators belonging to 3 orders, 7 families and 15 species of insects were studied. Scanning electron microscopy showed that all species carried L. salicaria pollen on their body parts. Hymenoptera pollinators were the most abundant (427 specimens), followed by Diptera (26) and Lepidoptera (23). Apoidea abundance reached a maximum in August and social bees largely dominate (94.38%). Apis mellifera was the most abundant species, followed by 5 bumblebees, including the endangered Bombus sylvarum. Honeybee visits on L. salicaria were higher in August over the rest of the summer and early autumn, while no differences were detected for bumblebees, Halictidae and Megachilidae. Overall, we support L. salicaria as a suitable species for bee-friendly flower spots in Mediterranean agricultural wetlands, as well as in close proximity of beehives. The latter use may facilitate the honeybees collecting pollen for the colony, thereby ensuring robustness to overcome the winter season.

Honey Bees Avoiding Ant Harassment at Flowers Using Scent Cues.

Pollinators require resources throughout the year to maintain healthy populations. Along the urban-natural interface, floral resource availability may be limited especially when the system experiences extreme drought and fire threats. In such areas, succulents, such as Aloe spp., are commonly planted to serve as functional drought-tolerant, fire-protective landscaping, which can also support pollinator populations. However, access to this resource may be restricted by competition from other floral foragers, including invasive pests. We measured free-foraging honey bee (Apis mellifera L.) visitation rate and visitation duration to aloe flowers with and without Argentine ants (Linepithema humile (Mayr)) in a drought-stressed environment and found that bees actively avoided foraging on the ant-occupied flowers. To determine the mechanisms of avoidance, our subsequent experiments assessed visitation in the absence of ants and compared aloe flowers treated with ant pheromone to unmanipulated flowers lacking ant pheromone. Bees approached all flowers equally, but accepted flowers without ants at a higher rate than flowers with ants. Visitation duration also increased twofold on ant-excluded flowers, which suggests that Argentine ants may limit resource acquisition by bees. Honey bees similarly avoided flowers with Argentine ant pheromone and preferentially visited unmanipulated flowers at threefold higher rate. This study demonstrates that honey bees avoid foraging on floral resources with invasive Argentine ants and that bees use ant odors to avoid ant-occupied flowers. Resource limitation by this invasive pest ant may have serious implication for sustaining healthy pollinator populations at the urban-natural interface.

Using Nonmetric Multidimensional Scaling to Analyze Bee Visitation in East Tennessee Crops as an Indicator of Pollination Services Provided by Honey Bees (Apis mellifera L.) and Native Bees.

This study investigated bee visitation on 10 agricultural crops grown on diverse small farms in Tennessee to determine the abundance of native bees and honey bees and the partitioning of visitation among crops. Summaries for each crop are used to generate mean proportions of bee visitation by categories of bees. This shows that native bee visits often occur as frequently, or in greater proportions than non-native honey bee visits. Visitation across multiple crops is then analyzed together with nonmetric multidimensional scaling to show how communities of bees that provide crop pollination change depending on the crop. Within squash and pumpkin plantings, continuous and discrete factors, such as "time of day" and "organic practices," further explain shifts in the community composition of flower visitors. Results from this study show that native bees frequently visit flowers on various crops, indicating that they are likely contributing to pollination services in addition to honey bees. Furthermore, the community of bees visiting flowers changes based on crop type, phenology, and spatial-temporal factors. Results suggest that developing pollinator conservation for farms that grow a wide variety of crops will likely require multiple conservation strategies. Farms that concentrate on a single crop may be able to tailor conservation practices toward the most important bees in their system and geographic locale.

Collateral effects of beekeeping: Impacts on pollen-nectar resources and wild bee communities

Due to the contribution of honey bees (Apis mellifera) to wild flower and crop pollination, beekeeping has traditionally been considered a sustainable practice. However, high honey bee densities may have an impact on local pollen and nectar availability, which in turn may negatively affect other pollinators. This is exacerbated by the ability of honey bees to recruit foragers to highly rewarding flower patches. We measured floral resource consumption in rosemary (Rosmarinus officinalis) and thyme (Thymus vulgaris) in 21 plots located at different distances from apiaries in the scrubland of Garraf Natural Park (Barcelona), and related these measures to visitation rates of honey bees, bumblebees (Bombus terrestris) and other pollinators. In the same plots, we measured flower density, and used pan traps to characterize the wild bee community. Flower resource consumption was largely explained by honey bee visitation and marginally by bumblebee visitation. After accounting for flower density, plots close to apiaries had lower wild bee biomass. This was due to a lower abundance of large bee species, those more likely to be affected by honey bee competition. We conclude that honey bees are the main contributors to pollen/nectar consumption of the two main flowering plants in the scrubland, and that at the densities currently occurring in the park (3.5hives/km2) the wild bee community is being affected. Our study supports the hypothesis that high honey bee densities may have an impact on other pollinators via competition for flower resources.

Using DNA Metabarcoding to Identify the Floral Composition of Honey: A New Tool for Investigating Honey Bee Foraging Preferences.

Identifying the floral composition of honey provides a method for investigating the plants that honey bees visit. We compared melissopalynology, where pollen grains retrieved from honey are identified morphologically, with a DNA metabarcoding approach using the rbcL DNA barcode marker and 454-pyrosequencing. We compared nine honeys supplied by beekeepers in the UK. DNA metabarcoding and melissopalynology were able to detect the most abundant floral components of honey. There was 92% correspondence for the plant taxa that had an abundance of over 20%. However, the level of similarity when all taxa were compared was lower, ranging from 22–45%, and there was little correspondence between the relative abundance of taxa found using the two techniques. DNA metabarcoding provided much greater repeatability, with a 64% taxa match compared to 28% with melissopalynology. DNA metabarcoding has the advantage over melissopalynology in that it does not require a high level of taxonomic expertise, a greater sample size can be screened and it provides greater resolution for some plant families. However, it does not provide a quantitative approach and pollen present in low levels are less likely to be detected. We investigated the plants that were frequently used by honey bees by examining the results obtained from both techniques. Plants with a broad taxonomic range were detected, covering 46 families and 25 orders, but a relatively small number of plants were consistently seen across multiple honey samples. Frequently found herbaceous species were Rubus fruticosus, Filipendula ulmaria, Taraxacum officinale, Trifolium spp., Brassica spp. and the non-native, invasive, Impatiens glandulifera. Tree pollen was frequently seen belonging to Castanea sativa, Crataegus monogyna and species of Malus, Salix and Quercus. We conclude that although honey bees are considered to be supergeneralists in their foraging choices, there are certain key species or plant groups that are particularly important in the honey bees environment. The reasons for this require further investigation in order to better understand honey bee nutritional requirements. DNA metabarcoding can be easily and widely used to investigate floral visitation in honey bees and can be adapted for use with other insects. It provides a starting point for investigating how we can better provide for the insects that we rely upon for pollination.

Per-visit pollinator performance and regional importance of wild Bombus and Andrena (Melandrena) compared to the managed honey bee in New York apple orchards

Declines in honey bee health and increasing demand for pollination services highlight a need to optimize crop pollination by wild bees. Apple is an economically important crop in eastern North America, requires insect pollination, and is visited by a diverse bee fauna, but a direct assessment of wild bee pollination in apple orchards is lacking. We combined measurements of two facets of pollination service, per-visit efficiency (fruit and seed set) and relative abundance, to estimate orchard-level, pollinator importance of mining bees (Andrena subgenus Melandrena), bumble bees (Bombus), and honey bees (Apis mellifera L.). Average pollinator importance provided a relative measure that allowed comparison of pollination service among the three focal bees across the study region. On average, a wild bee visit resulted in higher pollen transfer to stigmas, but had the same probability of setting fruit and seed as a honey bee visit. Regionally, pollinator importance of Melandrena and Bombus were 32 and 14 % that of honey bees, respectively. Because per-visit performances were similar, such disparities in importance were based largely on differences in relative abundance. Although the summed pollinator importance of Melandrena and Bombus was less than that of the honey bee, these, and other, wild pollinators have a role to play in filling future pollination gaps, and thus, warrant further study and conservation.

Ecological and social drivers of coffee pollination in Santander, Colombia

Bees and other insects provide pollination services that are key to determining the fruit set on coffee plantations. These pollination services are influenced by local ecology as well as human factors, both social and economic. To better understand these different factors, we assessed their effect on pollinators and coffee pollination services in Santander, Colombia. We quantified the effect of key ecological drivers on pollinator community composition, such as the method of farm management (either conventional or organic) and the surrounding landscape composition, specifically the proximity to forest.We found that ambient levels of pollination services provided by the local pollinator fauna (open pollination) accounted for a 10.5±2.0% increase in final coffee fruit set, and that the various pollinators are affected differently by the differing factors. For example, our findings indicate that conventional farm management, using synthetic inputs, can promote pollinators, especially if they are in close proximity to natural forest fragments. This is particularly true for stingless bees. Honeybee visitation to coffee is also positively influenced by the conventional management of farms. Factors associated with greater numbers of stingless bees on farms include greater shade cover, lower tree densities, smaller numbers and types of trees in bloom, and younger coffee plantations. A forested landscape close to farms appears to enhance these factors, giving increased stability and resilience to the pollinating bees and insects. However we found that organic farms also support diverse pollinator communities, even if distant from forest fragments.The contribution of honeybees to pollination value (US$129.6/ha of coffee) is greater than that of stingless bees (US$16.5/ha of coffee). Since the method of farm management has a major impact on the numbers and types of pollinators attracted to farms, we have analysed the statistically significant social factors that influence farmers’ decisions on whether to adopt organic or conventional practices. These include the availability of technology, the type of landowner (whether married couples or individual owners), the number of years of farmers’ formal education, the role of institutions, membership of community organizations, farm size, coffee productivity and the number of coffee plots per farm. It is hoped that the use of our holistic approach, which combines investigation of the social as well as the ecological drivers of pollination, will help provide evidence to underpin the development of best practices for integrating the management of pollination into sustainable agricultural practices.

Insect pollinators of the late winter flowering Rhamnus alaternus L., a candidate for honeybee-friendly scrubland spots in intensively managed agricultural areas

Insect pollinators of Rhamnus alaternus belong to 11 families, 17 genera and 20 species. The most abundant species is the honeybee followed by flies and bumblebees. Honeybee visits on R. alaternus decreased from late winter to early spring, highlighting the key role of this flowering in food paucity periods.