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Background: Natural environments within agricultural landscapes have been recognized as reservoirs of biodiversity and, therefore, providers of fundamental ecosystem services to human beings. Bees are the main providers of pollination and thus contribute to the production of food consumed worldwide. In this work, we evaluated the distribution of bees in an agricultural landscape of coffee plantation before and after coffee flowering. We aimed at understanding how richness, abundance and composition of bee communities vary among the different vegetation types within and around the coffee crops., Results: A total of 638 bees were collected - 312 in the dry season and 326 in the rainy season - totaling 85 species. The sampling methods collected different species, which provided complementary sampling. Only Euglossa leucotricha and Eulaema nigrita were recurrent in both seasons and vegetation types. There was no temporal difference in richness or abundance; however, both varied in relation to the vegetation type and were higher in the coffee-native transition area. Diverging from richness or abundance, the composition of the communities differed regarding season and vegetation types., Conclusion: We reinforce the importance of maintaining native vegetation in areas surrounding coffee plantations since the crop poorly hosts pollinators when it is not flowering. Natural and semi-natural areas may act as reservoirs of floral visitors, thus maintaining potential cross-pollination services available to coffee production. © 2020 Society of Chemical Industry., (© 2020 Society of Chemical Industry.)

Globally, agriculture increasingly depends on pollinators to produce many seed and fruit crops. However, what constitutes optimal pollination service for pollinator-dependent crops remains unanswered. We developed a simulation model to identify the optimal pollination service that maximizes fruit quality in crops. The model depicts the pollination (i.e., autonomous self-fertilization, pollen deposition) and post-pollination (i.e., pollen germination, and time from germination to ovule fertilization) processes leading to fruit and seed set and allows for negative flower-pollinator interactions, specifically pistil damage. We parameterized and validated the model based on empirical observations of commercial raspberry in western Argentina. To assess the effects of pollination intensity for fruit production, we conducted simulations over a range of visit number per flower by the two primary managed pollinators worldwide, Apis mellifera and Bombus terrestris. Simulations identified that ~15-35 visits per flower by A. mellifera or ~10-20 visits by B. terrestris provide adequate pollination and maximize raspberry fruit quality (i.e., estimated as the proportion of ovules that develop into drupelets). Visits in excess of these optima reduce simulated fruit quality, and flowers receiving >670 honey bee visits or >470 bumble bee visits would produce fruits of poorer quality than those receiving no bee visits. The simulations generated consistent, unbiased predictions of fruit quality for 12 raspberry fields. This model could be adapted easily to other animal-pollinated crops and used to guide efficient pollinator management in any agro-ecosystem., (© 2018 by the Ecological Society of America.)

Pollinator-dependent agriculture heavily relies upon a single pollinator-the honey bee. To diversify pollination strategies, growers are turning to alternatives. Densely planted reservoirs of pollen- and nectar-rich flowers (pollination reservoirs, hereafter "PRs") may improve pollination services provided by wild bees. Our focal agroecosystem, lowbush blueberry (Vaccinium angustifolium Aiton), exists in a simple landscape uniquely positioned to benefit from PRs. First, we contrast bee visitation rates and use of three types of PR. We consider the effects of PRs on wild bee diversity and the composition of bumble bee pollen loads. We contrast field-level crop pollination services between PRs and controls four years postestablishment. Last, we calculate the time to pay for PR investment. Social bees preferentially used clover plantings; solitary bees preferentially used wildflower plantings. On average, bumble bee pollen loads in treatment fields contained 37% PR pollen. PRs significantly increased visitation rates to the crop in year 4, and exerted a marginally significant positive influence on fruit set. The annualized costs of PRs were covered by the fourth year using the measured increase in pollination services. Our findings provide evidence of the positive impact of PRs on crop pollination services., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.)

Mass-flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi-natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape-scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator-dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator-supporting practices in agricultural landscapes., (© 2016 The Authors Ecology Letters published by CNRS and John Wiley & Sons Ltd.)

Insect pollination, despite its potential to contribute substantially to crop production, is not an integrated part of agronomic planning. A major reason for this are knowledge gaps in the contribution of pollinators to yield, which partly result from difficulties in determining area-based estimates of yield effects from insect pollination under field conditions. We have experimentally manipulated honey bee Apis mellifera densities at 43 oilseed rape Brassica napus fields over 2 years in Scandinavia. Honey bee hives were placed in 22 fields; an additional 21 fields without large apiaries in the surrounding landscape were selected as controls. Depending on the pollination system in the parental generation, the B. napus cultivars in the crop fields are classified as either open-pollinated or first-generation hybrids, with both types being open-pollinated in the generation of plants cultivated in the fields. Three cultivars of each type were grown. We measured the activity of flower-visiting insects during flowering and estimated yields by harvesting with small combine harvesters. The addition of honey bee hives to the fields dramatically increased abundance of flower-visiting honey bees in those fields. Honey bees affected yield, but the effect depended on cultivar type (p = 0.04). Post-hoc analysis revealed that open-pollinated cultivars, but not hybrid cultivars, had 11% higher yields in fields with added honey bees than those grown in the control fields (p = 0.07). To our knowledge, this is the first whole-field study in replicated landscapes to assess the benefit of insect pollination in oilseed rape. Our results demonstrate that honey bees have the potential to increase oilseed rape yields, thereby emphasizing the importance of pollinator management for optimal cultivation of oilseed rape.

Wild bees are highly valuable pollinators. Along with managed honey bees, they provide a critical ecosystem service by ensuring stable pollination to agriculture and wild plant communities. Increasing concern about the welfare of both wild and managed pollinators, however, has prompted recent calls for national evaluation and action. Here, for the first time to our knowledge, we assess the status and trends of wild bees and their potential impacts on pollination services across the coterminous United States. We use a spatial habitat model, national land-cover data, and carefully quantified expert knowledge to estimate wild bee abundance and associated uncertainty. Between 2008 and 2013, modeled bee abundance declined across 23% of US land area. This decline was generally associated with conversion of natural habitats to row crops. We identify 139 counties where low bee abundances correspond to large areas of pollinator-dependent crops. These areas of mismatch between supply (wild bee abundance) and demand (cultivated area) for pollination comprise 39% of the pollinator-dependent crop area in the United States. Further, we find that the crops most highly dependent on pollinators tend to experience more severe mismatches between declining supply and increasing demand. These trends, should they continue, may increase costs for US farmers and may even destabilize crop production over time. National assessments such as this can help focus both scientific and political efforts to understand and sustain wild bees. As new information becomes available, repeated assessments can update findings, revise priorities, and track progress toward sustainable management of our nation's pollinators.

Evidence for declining populations of both wild and managed bees has raised concern about a potential global pollination crisis. Strategies to mitigate bee loss generally aim to enhance floral resources. However, we do not really know whether loss of preferred floral resources is the key driver of bee decline because accurate assessment of host plant preferences is difficult, particularly for species that have become rare. Here we examine whether population trends of wild bees in The Netherlands can be explained by trends in host plants, and how this relates to other factors such as climate change. We determined host plant preference of bee species using pollen loads on specimens in entomological collections that were collected before the onset of their decline, and used atlas data to quantify population trends of bee species and their host plants. We show that decline of preferred host plant species was one of two main factors associated with bee decline. Bee body size, the other main factor, was negatively related to population trend, which, because larger bee species have larger pollen requirements than smaller species, may also point toward food limitation as a key factor driving wild bee loss. Diet breadth and other potential factors such as length of flight period or climate change sensitivity were not important in explaining twentieth century bee population trends. These results highlight the species-specific nature of wild bee decline and indicate that mitigation strategies will only be effective if they target the specific host plants of declining species.

Climate change has the potential to alter the phenological synchrony between interacting mutualists, such as plants and their pollinators. However, high levels of biodiversity might buffer the negative effects of species-specific phenological shifts and maintain synchrony at the community level, as predicted by the biodiversity insurance hypothesis. Here, we explore how biodiversity might enhance and stabilise phenological synchrony between a valuable crop, apple and its native pollinators. We combine 46 years of data on apple flowering phenology with historical records of bee pollinators over the same period. When the key apple pollinators are considered altogether, we found extensive synchrony between bee activity and apple peak bloom due to complementarity among bee species' activity periods, and also a stable trend over time due to differential responses to warming climate among bee species. A simulation model confirms that high biodiversity levels can ensure plant-pollinator phenological synchrony and thus pollination function., (© 2013 John Wiley & Sons Ltd/CNRS.)

Global demand for vegetable oil is projected to expand to 28 Mt by 2028. Oilseed rape (OSR) is the predominant oilseed crop in Europe. Its nutritional value is determined by seed oil content and fatty acids (FAs) composition. Insect pollination increases seed oil content, however, its benefit on FAs composition remains unknown. In this study, we address this gap by investigating the variation of OSR seed oil content and FAs composition along a gradient of bee abundance in farmed OSR fields. We used a pollinator exclusion experiment to disentangle the contribution of pollination processes, i.e. wind, self and insect pollination. We show that bees improved OSR nutritional value by increasing amount of poly-unsaturated FAs and decreasing the amount saturated and trans-saturated FAs. In addition, oil content was higher in seeds with than without access to pollinators. Our study provides for the first time, to the best of our knowledge, evidence that insect pollination enhances the quality value of OSR oil by affecting FAs composition. Such effect implies potential negative consequences with any further decline of pollinator abundance. More investigations are also needed to better understand the mechanisms by which insect pollination affects FAs composition, and the way to enhance such mechanisms. [ABSTRACT FROM AUTHOR]

Crop–pollinator interactions are essential for world food security. Studying crop pollination from a network approach allows identification of target pollinators for conservation and management, and gaps in our knowledge. Solanaceae represents the third highest ranked family based on economic value, and its production is highly improved by animal pollination. This study aimed to integrate global data on solanaceous crop pollination and analyse the interaction patterns using a meta‐network approach. Our questions were: (i) how are interactions structured and what are the structuring roles of species; and (ii) what are the main gaps in our knowledge?Data were obtained through a systematic review of the main scientific databases. The network structure was described using connectivity and modularity calculations, and the role of species using centrality metrics.The 251 pollinator species reported were in seven orders, mainly Hymenoptera (84.9%). The generalists Bombus and Apis species were the most common pollinators. The meta‐network was modular, and all modules mostly included bees. Most species were peripherals, around 12% were connectors, and there were no module hubs. Apis mellifera was the only network hub (supergeneralist).The most important pollinators are the most managed pollinators worldwide; however, many native species play a role in structuring the meta‐network. Main gaps include species of importance to pepper pollination, lack of species‐specific identification, and the need for more robust experimental studies evaluating the pollination efficiency of native, manageable bees. [ABSTRACT FROM AUTHOR]

Phenological overlap between crop flowering and pollinators is a crucial trait for the pollination of more than 75% of the world's crops. However, crop management rarely considers the seasonal aspect of plant–pollinator mutualism. Here, we investigate the phenological overlap between crops and pollinators and how it affects pollination and fruit production.We measured the abundance and richness of native and non‐native pollinators visiting raspberry flowers at two different times during the flowering season (i.e. early and late flowering periods) and examined their effects on crop yield in 16 fields.The community of pollinators foraging on raspberry flowers was more diverse and dominated by native pollinators during the early flowering period when most native plant species were flowering. Later in the season, when native flower resources declined in the surrounding environment, raspberry flowers were visited mainly by two non‐native bees: managed honeybees and the invasive bumblebee Bombus terrestris.Pollinator contribution to raspberry yield was twice as high in the early flowering period compared to the late period (61% vs. 31% increase in drupelet set respectively). Flower damage caused by extremely high visitation frequencies by non‐native bees in the late period was six times higher than in the early flowering period (30% vs. 5% of damaged flowers respectively).Synthesis and applications. Providing sufficient pollen and nectar resources to support wild pollinators over extended periods in agricultural landscapes can contribute to crop pollination and ensure high fruit weight and quality. This can be achieved by restoring natural and semi‐natural areas near crop fields with native, long‐flowering plant species. Growers and crop breeding programmes should consider selecting flowering times that coincide with periods of high diversity or abundance of native pollinators to reduce dependence on managed pollinators. [ABSTRACT FROM AUTHOR]

Simple Summary: Improving floral margins around crops can help to maintain and conserve populations of wild pollinators, mainly insects, in agroecosystems, and can improve the ecosystem services they provide, such as pollination of many crops and wild plants. Some crops, such as melon, depend on insects for reproduction, which is why they are at risk, as pollination services are declining. Our study shows that the implementation of margins around melon crops showed a positive effect on the abundance and richness of pollinating insects in general, which was stronger in the second year after establishment. Specifically, managed shrubby margins favored the populations of Syrphidae, Andrenidae, Apidae (excl. Apis mellifera), and other pollinator groups, and bee richness, suggesting that this type of margin increases pollinators' activity to a greater extent than the other two types of margins (managed and unmanaged herbaceous margins). However, the type of margin did not show any added advantages for melon yield. Melon is among the most consumed fruits in the world, being a crop that depends almost entirely on insects for its reproduction, which is why it is especially sensitive to declining pollination services. Restoration and maintenance of hedgerows and agricultural borders around crops are generally carried out by sowing flowering herbaceous plants or establishing shrubby species; however, a cost-effective and lower-maintenance alternative for farmers could be as simple as allowing vegetation to regenerate naturally without any management actions. This work aimed to test the effects of three different types of margins (managed herbaceous, managed shrubby, and unmanaged herbaceous) on the overall abundance and richness of wild pollinators in melon crops. The work was performed in three localities in southern Spain over two years. Pollinators were monitored visually using 1 × 1 m sampling squares and pan traps within melon fields. Moreover, crop yield was estimated by measuring fruit weight and the number of seeds. In general, higher abundances of pollinators were observed in melon fields during the second year. In addition, the abundances of Syrphidae, Andrenidae, Apidae (excl. Apis mellifera), and pollinators other than bees, belonging to the orders Diptera, Coleoptera, Hymenoptera, and Lepidoptera, showed higher values in melon fields with shrubby margins than in fields with herbaceous margins (managed or unmanaged). However, no effect of floral margins on the yield of melon crops was found. [ABSTRACT FROM AUTHOR]

Blueberry is one of the most relevant buzz‐pollinated crops worldwide and Chile is the most important global producer of fresh blueberries during wintertime in the Northern Hemisphere. Thousands of exotic Bombus terrestris are imported from Europe to pollinate blueberries. However, no study has investigated the performance of the native Chilean fauna to pollinate blueberry or other crops. Therefore, we aimed to compare the performance of native Chilean floral visitors with managed visitors to pollinate highbush blueberry.Per‐visit pollination performance (stigmatic pollen deposition) and floral visitation were measured and the presence of sonication behaviour of flower visitors was evaluated for five cultivars in two blueberry orchards located in southern Chile.Floral visitors showed a preference for one or more blueberry cultivars, instead of visiting all cultivars equally. Floral visits with sonication deposited more conspecific pollen on stigmas than visits without sonication. Some native sonicating bees (Cadeguala and Bombus), especially Cadeguala occidentalis, were efficient pollen vectors of blueberry and better pollinators than honeybees (5.8 times more pollen transferred) similar to that of the managed bee B. terrestris.The results indicate that some Chilean native bee species, especially those with sonication behaviour, can provide pollination service to highbush blueberry crops. [ABSTRACT FROM AUTHOR]

Supporting and promoting invertebrate diversity within agricultural ecosystems has numerous benefits, including the provision of pollination services. Many insects, including wild pollinators, require floral resources for food and structural habitat for nesting. To support pollinators, research studies and agri‐environment schemes have sought to supplement floral resources, but little is known about the value of different types of nesting habitat enhancements (e.g., trap‐nests or bee hotels). We deployed eight replicates of each of three types (bamboo reed, hardwood block and sand/cement brick) of trap‐nests at five orchards in two apple and cherry growing regions (Bilpin and Orange) in Australia. Both reed and hardwood block trap‐nests attracted a diverse array of invertebrates, such as ants, wasps, spiders and bees, including a cleptoparasitic bee species (Thyreus sp.) not previously recorded in the region. Interestingly, two taxa of native bees (Megachile [Megachile] and Megachile [Eutricharaea]) used the artificial nests and were also observed visiting apple crops. There were significantly more native bees using trap‐nests in Orange (n = 65), where orchards are surrounded by agricultural landscapes, than in Bilpin (n = 2), where orchards are surrounded by native forests. Our findings show that artificial nest enhancements are used by native bees, as well as other nontarget invertebrate taxa, some of which can be predators of bees (ants, wasps, and spiders). Nesting habitat augmentation thus has potential to be used as a conservation tool, especially in areas where nesting sites are limited. However, future studies should also consider measures to reduce colonization by non‐target taxa. [ABSTRACT FROM AUTHOR]

Melon is among the most consumed fruits in the world, being a crop that depends almost entirely on insects for its reproduction, which is why it is especially sensitive to declining pollination services. Restoration and maintenance of hedgerows and agricultural borders around crops are generally carried out by sowing flowering herbaceous plants or establishing shrubby species; however, a cost-effective and lower-maintenance alternative for farmers could be as simple as allowing vegetation to regenerate naturally without any management actions. This work aimed to test the effects of three different types of margins (managed herbaceous, managed shrubby, and unmanaged herbaceous) on the overall abundance and richness of wild pollinators in melon crops. The work was performed in three localities in southern Spain over two years. Pollinators were monitored visually using 1 × 1 m sampling squares and pan traps within melon fields. Moreover, crop yield was estimated by measuring fruit weight and the number of seeds. In general, higher abundances of pollinators were observed in melon fields during the second year. In addition, the abundances of Syrphidae, Andrenidae, Apidae (excl. Apis mellifera), and pollinators other than bees, belonging to the orders Diptera, Coleoptera, Hymenoptera, and Lepidoptera, showed higher values in melon fields with shrubby margins than in fields with herbaceous margins (managed or unmanaged). However, no effect of floral margins on the yield of melon crops was found.

In the face of the global decline in pollinator populations, studies that serve as a basis for the conservation and management of crop pollinators are crucial. The eggplant (Solanum melongena) is a widely cultivated autogamous crop, whose production is favoured by pollination by vibrating (buzz pollinating bees). To our knowledge, thus far, no studies have tested for the pollination efficiency of non-vibrating bees, nor have any been conducted in semi-arid regions, or evaluated the influence of pollination on the chemical characteristics of the fruits. Here, we evaluated the influence of pollination by vibrating and non-vibrating pollinators on eggplant fruit set and fruit traits in two plantations within the semi-arid region of NE Brazil. We conducted 120 h of focal observations and compared the fruit set and size (weight, length, and basal and apical diameters) under different pollination treatments (open pollination, spontaneous self-pollination, hand-cross pollination and single visits by different species of pollinating bees). Nine visiting bee species were recorded, which differed in visiting frequency and behaviour, as well as in pollination efficiency. Although being autogamous, plants visited by the vibrating bee Xylocopa sp. set more fruits than open, spontaneous self- and cross-pollination. However, the fruits produced by Xylocopa sp. were lighter and smaller than those obtained through open pollination, highlighting the importance of multiple pollinator visits or pollinator diversity. Non-vibrating pollinators contributed to fruit production quantity and quality. Fruits resulting from open, hand cross-pollination and both vibrating (Euglossa sp. 1) and non-vibrating bees (Paratrigona sp.) were larger than those resulting from spontaneous self-pollination. Pollination treatments had no influence on fruit chemical properties. Our results highlight the importance of pollination to eggplant production and the benefits of both vibrating and non-vibrating pollinators. [ABSTRACT FROM AUTHOR]

Premise: Many animals provide ecosystem services in the form of pollination including honeybees, which have become globally dominant floral visitors. A rich literature documents considerable variation in single visit pollination effectiveness, but this literature has yet to be extensively synthesized to address whether honeybees are effective pollinators. Methods: We conducted a hierarchical meta‐analysis of 168 studies and extracted 1564 single visit effectiveness (SVE) measures for 240 plant species. We paired SVE data with visitation frequency data for 69 of these studies. We used these data to ask three questions: (1) Do honeybees (Apis mellifera) and other floral visitors differ in their SVE? (2) To what extent do plant and pollinator attributes predict differences in SVE between honeybees and other visitors? (3) Is there a correlation between visitation frequency and SVE? Results: Honeybees were significantly less effective than the most effective non‐honeybee pollinators but were as effective as the average pollinator. The type of pollinator moderated these effects. Honeybees were less effective compared to the most effective and average bird and bee pollinators but were as effective as other taxa. Visitation frequency and SVE were positively correlated, but this trend was largely driven by data from communities where honeybees were absent. Conclusions: Although high visitation frequencies make honeybees important pollinators, they were less effective than the average bee and rarely the most effective pollinator of the plants they visit. As such, honeybees may be imperfect substitutes for the loss of wild pollinators, and safeguarding pollination will benefit from conservation of non‐honeybee taxa. [ABSTRACT FROM AUTHOR]

Kiwifruit is a new emerging crop for the southeastern United States that requires cross-pollination to set fruit. However, the pollination requirements for varieties grown in the southeastern United States are unknown. Through insect surveys and a bagging experiment, we assessed the pollination requirements of two female kiwifruit cultivars (Actinidia chinensis var. chinensis 'AU Golden Sunshine' and A. chinensis var. chinensis 'AU Gulf Coast Gold'). For each, fruit quantity (fruit set) and fruit quality (weight, size, seed count, firmness, soluble solid content, and dry matter) were compared among three pollination treatments (wind, insect, and artificial pollination). Low abundances of insects were observed visiting female flowers of both kiwifruit cultivars, and therefore likely minimally influenced kiwifruit pollination. Artificial pollination resulted in the greatest percentages of fruit set and marketable fruits, followed by insect and wind pollination. Artificial pollination resulted in fruits that were greater in weight, size, and contained more seeds, than insect- and wind-pollinated fruits. Firmness and soluble solid content did not vary greatly between pollination treatments, yet were greater in 'AU Golden Sunshine'. Dry matter content did not vary greatly between pollination treatments or between each cultivar. To maximize yields and optimize fruit quality, these results suggest that kiwifruit producers should place more effort into artificial pollination compared to wind and insect pollination. Future research should explore the use of managed bees (e.g. honey bees and bumble bees) within kiwifruit orchards to determine ways to utilize them as a secondary source for pollination needs. [ABSTRACT FROM AUTHOR]

The study by Barahona-Segovia et al. (2023) examines the influence of edge effect, landscape composition, and local characteristics on non-bee flower visitors in apple orchards. While their article improves our understanding of ecosystem dynamics in agricultural landscapes, it has important limitations regarding the importance of non-flower visitors as pollinators and their ability to compensate for declines in wild bee populations. The study does not address the distinction between flower visitors and true pollinators, relying on indirect measures such as contact with flower reproductive parts and visitation rate as proxies for pollinator effectiveness. Therefore, the authors fail to measure the basic definition of pollination: the act of transferring pollen grains from the anther to the stigma of a flower. Thus, the methodology used and the results of the study do not support the effectiveness of non-bees as pollinators compared to wild bees. The authors should have been cautions in extrapolating the conclusions of their study for orchard management strategies. Further studies with solid evidence are needed to quantify the contribution of non-bee pollinators to crop pollination and to allow a fair comparison between bees and non-bee visitors. • Barahona-Segovia et al. (2023) study the influence of edge effect and landscape composition on non-bee flower visitors in apple orchards. • The study lacks evidence that non-bee visitors can effectively keep the pollination delivered by wild bee populations. • Caution is necessary when interpreting the study's findings and applying them to crop ecosystem management. • Direct measures of pollinator performance, such as pollen deposition, should be included in future studies. [ABSTRACT FROM AUTHOR]

To mitigate the effects of habitat loss on bee conservation and crop pollination, farmers are encouraged to plant flowers along the edges of crop fields. However, it is unclear where and to what degree these flower plantings are effective. Recent studies suggest that flower plantings may be less effective if they are established in landscapes with either very low or very high amounts of non-crop habitat. Moreover, while field edge flower plantings often increase the abundance and richness of bees in field edges, it is unclear whether this improves crop pollination or bee nesting success, which could increase bee populations over time. In this study we examined how field edge flower plantings and the landscape context in which they are established affect wild bee conservation and crop pollination. Across two years we established flower plantings of 0.1–0.5 ha along the edges of 17 of 34 commercial cucumber fields arranged across a gradient of landscape complexity. We then measured wild bee abundance, richness, and crop pollination in and around cucumber fields with and without plantings and assessed the nesting success of stem-nesting bees. We found that both field edge flowers and landscape-scale non-crop habitat had independent, positive effects on bee abundance, richness, nesting, or crop pollination in one of the two years of the study, and that the effects of field edge flowers on bees and crop pollination were not influenced by the surrounding landscape. We also found that managing field edges in a way that maintains naturally-occurring flowers may matter as much or more than flower plantings for short-term increases in bee abundance and richness. However, certain species of planted flowers might be associated with improved bee nesting success, an outcome important for both bee conservation and sustained crop pollination. • Examined how flower plantings and landscape affect wild bees and crop pollination. • Local flowers and surrounding landscape had positive effects in 1 of 2 study years. • Effects of field edge flowers were not influenced by the surrounding landscape. • Managing field edges to maintain naturally occurring flowers is important. • Local flowers may improve success of stem-nesting bees. [ABSTRACT FROM AUTHOR]

Introduction: The species and functional diversity of pollinators are important components for the reproduction of cultivated plants. More information is necessary about this diversity and its geographical variation in crops such as Cucurbita pepo, an important crop in global agriculture. Objective: To describe the taxonomic diversity, geographic variation and foraging patterns of the community of bees that visit C. pepo crops in Costa Rica. Methods: Squash fields were visited at 11 locations within three geographic regions of the country, where the groups of bees and their relative frequency were determined. Through video recordings, information was obtained on their behavior at two locations. Results: A minimum of 27 species belonging to 19 genera and 2 families of bees were found. Three species were dominant in 10 localities (Eucera limitaris, Apis mellifera and Trigona corvina). Altitude reduces bee diversity due to the dominance of Bombus ephipiatus in high regions. Two genera of halictids (Megalopta and Caenaugochlora) that are rarely reported in this crop were frequently observed. Trigona bees dominated among the flowers later in the morning, lacerating nectary holes to facilitate nectar collection. Conclusions: Squash fields in Costa Rica are visited by a highly diverse bee community, which may ensure pollination via complementarity in the face of spatial or seasonal changes in environmental conditions. [ABSTRACT FROM AUTHOR]

Wild bees supply sufficient pollination in Cucurbita agroecosystems in certain settings; however, some growers continue to stock fields with managed pollinators due to uncertainties of temporal and spatial variation on pollination services supplied by wild bees. Here, we evaluate wild bee pollination activity in wholesale, commercial pumpkin fields over 3 yr. We identified 37 species of bees foraging in commercial pumpkin fields. Honey bees (Apis mellifera L. [Hymenoptera: Apidae]), squash bees (Eucera (Peponapis) Say, Dorchin [Hymenoptera: Apidae]), and bumble bees (Bombus spp., primarily B. impatiens Cresson [Hymenoptera: Apidae]) were the most active pollinator taxa, responsible for over 95% of all pollination visits. Preference for female flowers decreased as distance from field edge increased for several bee taxa. Visitation rates from one key pollinator was negatively affected by field size. Visitation rates for multiple taxa exhibited a curvilinear response as the growing season progressed and responded positively to increasing floral density. We synthesized existing literature to estimate minimum 'pollination thresholds' per taxa and determined that each of the most active pollinator taxa exceeded these thresholds independently. Under current conditions, renting honey bee hives may be superfluous in this system. These results can aid growers when executing pollination management strategies and further highlights the importance of monitoring and conserving wild pollinator populations. [ABSTRACT FROM AUTHOR]

The preservation of pollinator habitat on croplands in the form of hedgerows, wildflower strips, and natural and semi-natural areas can help maintain and enhance wild bee populations in agricultural landscapes. However, there have been few comparisons of the effectiveness of different types of field-margin pollinator habitat in maintaining bee diversity and pollination of the focal crops. We compared wild bee abundance, species richness and community composition between strawberry crops bordered by hedgerows, and those bordered by larger expanses of natural land (forests). Strawberry is an ideal crop in which to investigate pollinator export from field margins as the rows are covered with straw, which reduces habitat for ground-nesting bees within the crop; thus, most wild pollinators need to enter the crop from the margins. We sampled bees in six strawberry fields with hedgerow margins and six strawberry fields with forested margins of at least 200 m in length, using a paired design. We examined strawberry pollen deposition at regular intervals into the fields, and the magnitude of pollinator export from the field margins towards the centre of the crops. We found that bees as a group were no more species-rich or abundant in crops bordered by forests than in crops bordered by hedgerows, although large-bodied bees were more abundant in the former than the latter. Regardless of field-margin type, we found that small wild bee abundance declined significantly from the edge to the centre of the crop, but honey bee (Apis mellifera L.) and large-bodied bee abundance did not. Strawberry pollen deposition also did not decline with distance into the crop. Although previous work indicates that small wild bees are more effective (yield-increasing) pollinators of strawberry on a per-visit basis, their limited foraging ranges suggest they may only pollinate areas near the crop margins, given typical field sizes in our area. [ABSTRACT FROM AUTHOR]

The biodiversity‐centred approach to conservation prioritizes rare species, whereas the ecosystem services approach prioritizes species that provide services to people. The two approaches align when rare species provide ecosystem services, or when both groups of species benefit from the same management action. We use data on bee pollinators and the plant species they forage on to determine if there are rare species among the most important crop pollinators, and the extent to which plant species selected to support crop pollinators would support rare species as well.We used pre‐existing, regional‐scale datasets to determine which bee species are regionally rare, and which are regionally important crop pollinators. To assess the plant preferences of these two groups of bee species, we collected two datasets on plant–pollinator interactions, one experimental and one observational. The experiment consisted of monospecific plots of 17 plant species from which we collected bees over 3 years. The observational data consisted of bees collected from 66 species of plants growing in semi‐natural meadows, also over 3 years.Nineteen percent of the dominant crop‐pollinating species were regionally rare. Both rare species and crop‐pollinating species had strong preferences for certain plants, and the preferences of rare and crop‐pollinating bees were significantly but not strongly (r ≤.54) correlated. Ten plant species were significantly preferred by both rare and crop‐pollinating bees.Synthesis and applications. We found several dominant crop pollinators that are rare at a regional scale, supporting the idea that rare species can be important providers of ecosystem services. The flower preferences of rare and crop‐pollinating bees are significantly positively associated, suggesting that plants chosen to support crop pollinators will benefit rare species as well. We identify plant species that are preferred by regionally rare bees and by crop pollinators, including 10 plant species preferred by both types of bees, and recommend these for use in pollinator habitat plantings. [ABSTRACT FROM AUTHOR]

It has been proposed that species-rich insect communities and species turnover across landscapes enhance the pollination efficiency of crops through complementarity, where both the dominant and less abundant species contribute to reaching a yield threshold from pollination. Alternatively, fluctuations in the most abundant pollinator species, rather than changes in species richness, may drive temporal variation in pollination services. In this study, we used Cucurbita moschata as a model to investigate temporal variation in pollinator communities in a Mexican tropical dry forest region. We sampled floral visitors in the coastal region of Jalisco during the wet and dry seasons and determined the pollination efficiency of all floral visitors. Our results showed that there was temporal variation in the pollinator community and in the pollination efficiency of the main pollinators of Cucurbita moschata crops. In the wet season, native bees of the genus Peponapis were the most frequent and effective pollinators of C. moschata, whereas in the dry season, Peponapis bees were scarce and Apis mellifera became the most frequent floral visitor. Apis mellifera transfers smaller pollen loads than Peponapis, but it provides an effective pollination service in conjunction with other native bees during the dry season. There was also an interaction between flower gender and pollinator species, where A. mellifera had higher visitation rate to female C. moschata flowers, and Peponapis bees to staminate flowers. Mean visitation rate by Peponapis female bees was 17 times higher than visitation rate by male bees. This is the first report of a vis-à-vis relationship of pollinator gender with respect to plant gender in which plants of the genus Cucurbita that produce unisexual staminate and pistillate flowers are differentially visited by Peponapis male and female bees, where females are the main pollinators. Understanding the temporal variation in pollinator communities and the contribution of the different species of pollinators to the reproductive success of different crop species and varieties can be crucial to maintaining pollination services under the current global pollination crisis. [ABSTRACT FROM AUTHOR]

Although several studies have shown that the presence of bees results in increased crop yields, the mechanisms that determine pollination service across different spatial scales are still largely unknown. Here, we evaluated the influence of landscape structure over bee community composition and coffee ( Coffea arabica ) pollination. Our study was undertaken in one of the most important coffee-producing regions of Brazil, and comprised nine landscapes of sun coffee plantations surrounded by different amounts of Atlantic Forest remnants. Using floral exclusion experiments we evaluated fruit set in 15 coffee shrubs per landscape. We also sampled the bees visiting coffee flowers. Our analyses were made at two landscape scales, with 1 and 2 km radii, and one shrub scale, with 300 m radius around each coffee shrub. We collected 241 bee individuals and identified a total of 22 species. The honeybee Apis mellifera (Apini) was the most abundant flower visitor followed by Trigona spinipes (Meliponini). Native bee abundance, richness and diversity were positively affected by forest cover at the shrub scale. Honeybee abundance, on the other hand, was negatively affected by forest cover at the shrub scale. The presence of bees resulted in an increase in coffee fruit set of 28%. A. mellifera abundance positively affected fruit set across spatial scales, while the composition of the native bee community affected fruit set differently at the landscape scales than at the shrub scale. Our work shows that bee pollination services are affected by landscape structure at different spatial scales. These findings can be used in conservation and agricultural planning to maximize crop production while safeguarding biodiversity and the provision of pollination services. [ABSTRACT FROM AUTHOR]

Solitary bees are receiving increasing attention as they are very effective crop pollinators. However, widespread implementation of pollination management with solitary bees is hampered by a lack of targeted and practical guidelines. Indeed, little evidence-based guidelines exist about the preferred type of nesting material, how to control nest-associated macroparasites and how to promote a healthy offspring with sufficient female bees. This study investigated whether different types of artificial nesting materials – paper straws and wooden grooved boards – are preferred by the European orchard bee (Osmia cornuta). In addition, we explored how the bee nesting success and infestation of macroparasites are influenced by type of nesting material, landscape complexity and timing throughout the active nesting period of O. cornuta. We found that O. cornuta preferred to nest in paper straws compared to wooden grooved boards. The number of produced brood cells and the offspring sex-ratio (i.e. the ratio of female:male bees) were higher in wooden grooved boards. Number of brood cells, successful cocoon development and the sex-ratio all decreased throughout the nest-construction period of the bees. The sex-ratio also increased with increasing landscape complexity. Paper straws had a reduced infestation rate of kleptoparasitic mites. In addition, the infestation rate of both kleptoparasitic mites and kleptoparasitic drosophilid flies increased with time throughout the bees' nest-construction period. These findings present relevant evidence to aid successful implementation of solitary bees for crop pollination. Utilization of paper straws, or similar materials, over wooden grooved boards and closing the nests near the end of the bees' active nest-construction period should be recommended practices. Implementation of these practices will reduce parasite infestation and enhance bee nesting success. Furthermore, conservation of semi-natural habitat or planting pollinator-friendly vegetation around fields is also advised to promote the proportion of female bees in the offspring. • O. cornuta prefers to nest in paper straws compared to wooden grooved boards. • Paper straws reduced the infestation rate of kleptoparasitic mites. • Bee nesting success decreased throughout the nest-construction period of the bees. • Infestation of mites and drosophilid flies increased through the nesting period. • The offspring's sex-ratio increased with increasing landscape complexity. [ABSTRACT FROM AUTHOR]

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More diverse biological communities may provide ecosystem services that are less variable over space or time. However, the mechanisms underlying this relationship are rarely investigated empirically in real-world ecosystems. Here, we investigate how a potentially important stabilising mechanism, response diversity, the differential response to environmental change among species, stabilises pollination services against land-use change. We measured crop pollination services provided by native bees across land-use gradients in three crop systems. We found that bee species responded differentially to increasing agricultural land cover in all three systems, demonstrating that response diversity occurs. Similarly, we found response diversity in pollination services in two of the systems. However, there was no evidence that response diversity, in general, stabilised ecosystem services. Our results suggest that either response diversity is not the primary stabilising mechanism in our system, or that new measures of response diversity are needed that better capture the stabilising effects it provides. [ABSTRACT FROM AUTHOR]

Wild bees that provide pollination services to vegetable crops depend on forage resources, nesting sites, and overwintering sites in the agricultural landscape. The scale at which crop-visiting bees use resources in the landscape can vary regionally, and has not been characterized in the Midwestern United States. We investigated the effects of seminatural land cover on wild bee visitation frequency to cucumber (Cucumis sativus L.) and on wild bee species richness on 10 organic farms in Indiana. We estimated the spatial scale at which the effects of land cover were strongest, and also examined the effects of nonlandscape factors on wild bees. The visitation frequency of wild bees to cucumber was positively related to the proportion of seminatural land in the surrounding landscape, and this relationship was strongest within 250 m of the cucumber patch. The species richness of wild cucumber visitors was not affected by land cover at any spatial scale, nor by any of the nonlandscape factors we considered. Our results indicate that wild, crop visiting bees benefit from seminatural areas in the agricultural landscape, and benefit most strongly from seminatural areas within 250 m of the crop field. This suggests that setting aside natural areas in the near vicinity of vegetable fields may be an effective way to support wild, crop-visiting bees and secure their pollination services. [ABSTRACT FROM AUTHOR]

ABSTRACT Acerola (Malpighia emarginata DC; Malpighiaceae) is an important fruit crop in Brazil. Among its pollinators, Centris (Heterocentris) analis (F.) stands out due to its abundance at flowers and prompt acceptance of trap-nests. For the first time, we propose the commercial use of Centris bees as orchard pollinators. To develop protocols for rearing and management of these bees, we analyzed trap-nest acceptance, brood-cell construction, and larval diet in Acerola orchards. Although Centris species, in general, use numerous pollen host plants, females of C. analis showed remarkable flower fidelity to Acerola for pollen supply when nesting in the orchard. Such fidelity was previously expected only for floral oil collection. The ease of acceptance of trap-nests by females of C. analis, their prolonged yearly activity period, multivoltine life history, and high pollinator efficiency characterize C. analis as an excellent potentially manageable pollinator in Acerola orchards. [ABSTRACT FROM AUTHOR]

Non-bee insects have been identified as important crop pollinators globally. However, strategies to protect pollinators and enhance crop pollination usually focus on supporting bees. This study examined the effects of landscape structure, location within field, and floral resources on pollinators' visits on mass-flowering caraway (Carum carvi L.) in boreal farmland, and the effects of the visits on caraway yield. Pollinator visits on caraway flowers were monitored and caraway yield measured in 30 fields at landscapes ranging from field-dominated to forest-dominated landscapes. Hoverflies were the most abundant flower-visitors of caraway, followed by honeybees. Hoverflies and other flies made more flower visits on caraway than all bee species combined. Pollinator groups differed in their responses to landscape and local factors. Flies were most abundant near field edges and in landscapes with high forest cover. Non-syrphid flies and solitary bees responded positively to the cover of flowering herbs in the adjacent field margins. Flower visits by honeybees, instead, were positively related to the flowering crop cover in the study fields. Caraway seed yield increased with increasing number of flower visits by honeybees, hoverflies and all pollinators together. Pollinator exclusion reduced caraway fruit set (i.e. the number of fruits per flower) by 13% and seed yield by 40%. Our study is the first to report the high importance of flies to crop pollination in boreal farmland, where caraway is an important export crop. The results highlight the need of taking flies and their habitat requirements into account when developing strategies to enhance crop pollination. • Hoverflies were the most frequent flower-visitors on caraway, followed by honeybees. • Flies made more flower visits than all bee species combined. • Flies were abundant near field edges and in landscapes with high forest cover. • Honeybees responded positively to the flowering crop cover. • Flower visits by both honeybees and hoverflies increased caraway yield. [ABSTRACT FROM AUTHOR]

1. Concern about a global decline in wild pollinators has increased interest in how pollinators are affected by human land use, and how this, in turn, affects crop pollination. 2. We measured wild bee visitation to four summer vegetable crops, and investigated associations between flower visitation rates and land-use intensity at local and landscape scales. We studied 29 farms in New Jersey and Pennsylvania, USA. Over 2 years we recorded >7400 bee visits to crop flowers and identified 54 species of wild bees visiting crops. 3. Wild bees were the dominant flower visitors at three of the four crops studied; domesticated honeybees, Apis mellifera L., provided the remainder of visits. 4. Ordination of the two best studied crops showed that the wild bee species visiting tomato, Solanum lycopersicum L., were distinct from those visiting watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai. 5. Crop visitation by wild bees was not associated with organic farming, nor with natural habitat cover at either local or landscape scale. 6. Synthesis and applications. The extent of crop visitation by wild bees observed in this study is among the highest recorded. In contrast to previous studies of crop visitation by wild bees, we did not find negative effects of conventional farming or natural habitat loss. In our study system, organic and conventional farms differ little in field size, crop diversity and weedy flower diversity, unlike some systems where organic farms have smaller fields with greater crop and weed diversity. Such variables may be more important than organic vs. conventional farming practices. Second, small patches of natural habitat are dispersed throughout our entire study system, and this habitat heterogeneity may support high bee abundance even in landscapes with a low proportion of natural habitat overall. Our findings suggest that agri-environment schemes and similar programmes that work through local habitat restoration should target farms in intensively agricultural (homogeneous) landscapes to gain maximum conservation benefits. [ABSTRACT FROM AUTHOR]

The native bee Nannotrigona perilampoides Cresson (Apidae: Meliponini) has been evaluated with promising results in greenhouse pollination of Solanaceae in Mexico. However, no comparison has been done with imported bumble bees (Apidae: Bombini), which are the most common bees used for greenhouse pollination. We compared the foraging activity and fruit production of habanero pepper. Capsicum chinense Jacquin, by using N. perilampoides and Bombus impatiens Cresson in pollination cages. Both bee species collected pollen on a similar number of flowers per unit time, but N. perilampoides visited significantly more flowers per trip, lasted longer on each flower, and spent more time per foraging trip. Ambient temperature and light intensity significantly affected the foraging activity of N. perilampoides. Light intensity was the only environmental variable that affected B. impatiens. Except for the fruit set, there were not significant differences in the quality of fruit produced by both bee species; however, N. perilampoides and B. impatiens performed better than mechanical vibration for all the variables measured. The abortion of fruit caused the low fruit set produced by B. impatiens, and we speculate it might be due to an excessive visitation rate. Pollination efficiency per visit (Spear's pollination efficiency index) was similar for both bee species in spite of the significantly lower amount of pollen removed by N. perilampoides. We suggested that the highest number of flowers visited per foraging trip coupled with adequate amounts of pollen transported, and transferred between flowers, could explain the performance of N. perilampoides as a good pollinator of habanero pepper. Our experiments confirm that N. perilampoides could be used as an alternative pollinator to Bombus in hot pepper under tropical climates. [ABSTRACT FROM AUTHOR]

Abstract: Pollination provided by bees enhances the production of many crops. However, the contribution of wild bees remains unmeasured for many crops, and the effects of anthropogenic change on many bee species are unstudied. We experimentally investigated how pollination by wild bees affects tomato production in northern California. We found that wild bees substantially increase the production of field-grown tomato, a crop generally considered self-pollinating. Surveys of the bee community on 14 organic fields that varied in proximity to natural habitat showed that the primary bee visitors, Anthophora urbana Cresson and Bombus vosnesenskii Radoszkowski, were affected differently by land management practices. B. vosnesenskii was found primarily on farms proximate to natural habitats, but neither proximity to natural habitat nor tomato floral abundance, temperature, or year explained variation in the visitation rates of A. urbana. Natural habitat appears to increase B. vosnesenskii populations and should be preserved near farms. Additional research is needed to determine how to maintain A. urbana. Species-specific differences in dependency on natural habitats underscore the importance of considering the natural histories of individual bee species when projecting population trends of pollinators and designing management plans for pollination services. Thus, to maintain an entire bee community, multiple approaches, including maintaining natural habitat, should be implemented. [Copyright &y& Elsevier]

By causing extinctions and altering community structure, anthropogenic disturbances can disrupt processes that maintain ecosystem integrity. However, the relationship between community structure and ecosystem functioning in natural systems is poorly understood. Here we show that habitat loss appeared to disrupt ecosystem functioning by affecting extinction order, species richness and abundance. We studied pollination by bees in a mosaic of agricultural and natural habitats in California and dung burial by dung beetles on recently created islands in Venezuela. We found that large-bodied bee and beetle species tended to be both most extinction-prone and most functionally efficient, contributing to rapid functional loss. Simulations confirmed that extinction order led to greater disruption of function than predicted by random species loss. Total abundance declined with richness and also appeared to contribute to loss of function. We demonstrate conceptually and empirically how the non-random response of communities to disturbance can have unexpectedly large functional consequences. [ABSTRACT FROM AUTHOR]

We studied the oxygen consumption of two megachilid bees (Hymenoptera: Megachilidae), Megachile rotundata (F.) and Osmia lignaria Say, at selected, biologically relevant intervals throughout their respective life cycles. The U-shaped oxygen consumption curve and the static weights of wintering (nonfeeding) prepupae that we observed during the life cycle of M. rotundata support previous arguments for a winter diapause similar to that observed in other Hymenoptera. For O. lignaria, which overwinters as an adult, we found stepwise increases in oxygen consumption and continuous weight loss throughout the wintering period. However, our observations on adult O. lignaria wintering requirements are consistent with the previously published results for overwintering M. rotundata prepupae and reveal sharply increasing survival rates when wintered for a minimum of 3 mo. We interpret the greatly reduced survival in both M. rotundata and O. lignaria, as an indication that a critical biological process, diapause, is disrupted among individuals wintered for <3 mo. In the continued development of these two species as commercial scale pollinators on an ever-increasing list of target crops, any similarities or contrasts observed between the "summer bee," M. rotundata, and the "spring bee," O. lignaria, although of interest from a biological perspective, will probably have important implications in the continued development of sustainable population management protocols. [ABSTRACT FROM AUTHOR]

The importance of wild bees for crop pollination is well established, but less is known about which species contribute to service delivery to inform agricultural management, monitoring and conservation. Using sites in Great Britain as a case study, we use a novel qualitative approach combining ecological information and field survey data to establish a national list of crop pollinating bees for four economically important crops (apple, field bean, oilseed rape and strawberry). A traits data base was used to establish potential pollinators, and combined with field data to identify both dominant crop flower visiting bee species and other species that could be important crop pollinators, but which are not presently sampled in large numbers on crops flowers. Whilst we found evidence that a small number of common, generalist species make a disproportionate contribution to flower visits, many more species were identified as potential pollinators, including rare and specialist species. Furthermore, we found evidence of substantial variation in the bee communities of different crops. Establishing a national list of crop pollinators is important for practitioners and policy makers, allowing targeted management approaches for improved ecosystem services, conservation and species monitoring. Data can be used to make recommendations about how pollinator diversity could be promoted in agricultural landscapes. Our results suggest agri-environment schemes need to support a higher diversity of species than at present, notably of solitary bees. Management would also benefit from targeting specific species to enhance crop pollination services to particular crops. Whilst our study is focused upon Great Britain, our methodology can easily be applied to other countries, crops and groups of pollinating insects. • Bees provide critical ecosystem services, yet currently there are no lists of crop pollinators to advise management. • We outline a novel approach to identify bee species important for crop pollination at a national scale. • Whilst a small number of common species make the majority of flower visits, many more also contribute to pollination. • Our results show that management to support pollinators need to be targeted, and benefit a greater diversity of species. [ABSTRACT FROM AUTHOR]