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Wild bees (Hymenoptera: Anthophila) are important pollinators and essential for maintaining ecosystem health. The majority of bee species are ground‐nesting, and all bees spend most of their lifetime inside the nest. Still, most studies and monitoring schemes assess wild bees during flower visitation, allowing no conclusion about their nest sites. Methods for locating and assessing the ground nests of bees are currently limited, hindering scientific progress and conservation efforts. To evaluate and improve methods for locating and assessing ground nests, we combined information from a literature review and our own empirical studies. Methods ranging from established field methods (visual nest observations and emergence traps) to new technological approaches (marking and tracking individuals) are compared in terms of success in catching nesting bees and identifying nest locations, time effort required to implement the methods, and limitations. We provide guidelines and recommendations on the use of the different methods depending on the data requirements and study locations. We also present a novel emergence trap design and two newly developed marking methods, using a radioactive tracer substance and a retroreflective pigment, and show that these methods can be used to successfully locate and assess ground‐nesting habitats of bees. With this work, we address gaps in current research methods and aim to enhance the efficiency of field research that explicitly targets ground‐nesting bees and their nest sites in various environments. By providing a comprehensive overview for researchers and practitioners, we demonstrate how to improve knowledge about the ecology and life history of ground‐nesting bees and thus support efforts for their conservation. Zusammenfassung Wildbienen (Hymenoptera: Anthophila) sind wichtige Bestäuber und spielen eine entscheidende Rolle bei der Aufrechterhaltung intakter Ökosysteme. Die Mehrheit aller Wildbienenarten nistet im Boden und alle Bienen verbringen den Großteil ihres Lebens in ihrem Nest. Dennoch werden in den meisten Studien Bienen während ihres Blütenbesuches erfasst, wodurch keine Rückschlüsse auf ihre Nistplätze möglich sind. Es mangelt derzeit noch an geeigneten Methoden, um Bodennester von Bienen aufzuspüren und zu erfassen. Wissenschaftliche Fortschritte wie auch Schutzmaßnahmen werden hierdurch erschwert. Um Methoden zur Lokalisierung und Erfassung von Bodennisthabitaten zu bewerten und zu verbessern, kombinierten wir Daten aus einer Literaturrecherche mit Daten aus eigenen empirischen Studien. Die dabei untersuchten Methoden umfassen sowohl etablierte Erfassungsmethoden (visuelle Nestbeobachtungen und Emergenzfallen) wie auch neue technologische Ansätze (Markierung und Aufspürung von Individuen). Diese Methoden werden hinsichtlich ihres Erfolgs beim Fang nistender Bienen und der Lokalisierung von Neststandorten, ihres zeitlichen Aufwandes sowie ihrer jeweiligen Einschränkungen miteinander verglichen. Wir präsentieren Leitlinien und Empfehlungen, welche Methoden je nach Fragestellung und Studienstandort eingesetzt werden sollten. Zudem stellen wir ein neues Emergenzfallen‐Design sowie zwei neu entwickelte Markierungsmethoden vor, bei denen eine radioaktive Tracersubstanz bzw. ein retroreflektierendes Pigment zum Einsatz kommt, und zeigen, dass diese Methoden geeignet sind, Bodennisthabitate von Wildbienen zu lokalisieren und zu beurteilen. Mit der vorliegenden Arbeit adressieren wir Lücken in den derzeitigen Forschungsmethoden. Ziel unserer Arbeit ist es, die Effizienz von Feldstudien zu steigern, die gezielt auf die Erfassung bodennistender Bienen und ihrer Nester in unterschiedlichen Lebensräumen ausgerichtet sind. Durch die Bereitstellung eines umfassenden methodischen Überblicks für Forschende und Praktiker*innen zeigen wir, wie der Wissensstand zur Ökologie und Naturgeschichte bodennistender Bienen und damit die Bemühungen zu ihrem Schutz verbessert werden können.

Most of the world's crops depend on pollinators, so declines in both managed and wild bees raise concerns about food security. However, the degree to which insect pollination is actually limiting current crop production is poorly understood, as is the role of wild species (as opposed to managed honeybees) in pollinating crops, particularly in intensive production areas. We established a nationwide study to assess the extent of pollinator limitation in seven crops at 131 locations situated across major crop-producing areas of the USA. We found that five out of seven crops showed evidence of pollinator limitation. Wild bees and honeybees provided comparable amounts of pollination for most crops, even in agriculturally intensive regions. We estimated the nationwide annual production value of wild pollinators to the seven crops we studied at over $1.5 billion; the value of wild bee pollination of all pollinator-dependent crops would be much greater. Our findings show that pollinator declines could translate directly into decreased yields or production for most of the crops studied, and that wild species contribute substantially to pollination of most study crops in major crop-producing regions.

Evidence for pollinator declines largely originates from mid-latitude regions in North America and Europe. Geographical heterogeneity in pollinator trends combined with geographical biases in pollinator studies can produce distorted extrapolations and limit understanding of pollinator responses to environmental changes. In contrast with the declines experienced in some well-investigated European and North American regions, honeybees seem to have increased recently in some areas of the Mediterranean Basin. Because honeybees can have negative impacts on wild bees, it was hypothesized that a biome-wide alteration in bee pollinator assemblages may be underway in the Mediterranean Basin involving a reduction in the relative number of wild bees. This hypothesis was tested using published quantitative data on bee pollinators of wild and cultivated plants from studies conducted between 1963 and 2017 in 13 countries from the European, African and Asian shores of the Mediterranean Sea. The density of honeybee colonies increased exponentially and wild bees were gradually replaced by honeybees in flowers of wild and cultivated plants. The proportion of wild bees at flowers was four times greater than that of honeybees at the beginning of the period, the proportions of both groups becoming roughly similar 50 years later. The Mediterranean Basin is a world biodiversity hotspot for wild bees and wild bee-pollinated plants, and the ubiquitous rise of honeybees to dominance as pollinators could in the long run undermine the diversity of plants and wild bees in the region.

Wild and managed bees are well documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25–50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.

In diverse pollinator communities, interspecific interactions may modify the behaviour and increase the pollination effectiveness of individual species. Because agricultural production reliant on pollination is growing, improving pollination effectiveness could increase crop yield without any increase in agricultural intensity or area. In California almond, a crop highly dependent on honey bee pollination, we explored the foraging behaviour and pollination effectiveness of honey bees in orchards with simple (honey bee only) and diverse (non-Apis bees present) bee communities. In orchards with non-Apis bees, the foraging behaviour of honey bees changed and the pollination effectiveness of a single honey bee visit was greater than in orchards where non-Apis bees were absent. This change translated to a greater proportion of fruit set in these orchards. Our field experiments show that increased pollinator diversity can synergistically increase pollination service, through species interactions that alter the behaviour and resulting functional quality of a dominant pollinator species. These results of functional synergy between species were supported by an additional controlled cage experiment with Osmia lignaria and Apis mellifera. Our findings highlight a largely unexplored facilitative component of the benefit of biodiversity to ecosystem services, and represent a way to improve pollinator-dependent crop yields in a sustainable manner.

1. Changes in agricultural practice across Europe and North America have been associated with range contractions and a decline in the abundance of wild bees. Concerns at these declines have led to the development of flower-rich agri-environment schemes as a way to enhance bee diversity and abundance. Whilst the effect of these schemes on bumblebee species (Bombus spp.) has been well studied, their impact on the wider bee community is poorly understood. 2. We used direct observations of foraging bees and pollen load analysis to quantify the relative contribution that sown flowers (i.e. those included in agri-environment scheme seed mixes) make to the pollen diets of wild solitary bees on Higher Level Stewardship farms (HLS) implementing pollinator-focused schemes and on Entry Level Stewardship farms (ELS) without such schemes in southern England, UK. 3. HLS management significantly increased floral abundance, and as the abundance of sown flowers increased, these sown plants were utilized for pollen by a greater proportion of the solitary bee species present. However, the overall proportion of pollen collected from sown plants was low for both direct observations (27.0%) and pollen load analysis (23.3%). 4. At most only 25 of the 72 observed species of solitary bee (34.7%) were recorded utilizing sown plants to a meaningful degree. The majority of solitary bee species did not collect pollen from flower species sown for pollinators. 5. Total bee species richness was significantly associated with plant species richness, but there was no difference in the total species richness of either bee or flowering plant species between HLS and ELS farms. 6. Synthesis and applications. Our results show that the majority of solitary bee species present on farmland in the south-east of England collect most of their pollen from plants that persist unaided in the wider environment, and not from those included in agri-environment schemes focused on pollinators. If diverse bee communities are to be maintained on farmland, existing schemes should contain an increased number of flowering plant species and additional schemes that increase the diversity of flowering plants in complementary habitats should be studied and trialled.

A diverse array of wild bee species may provide more effective pollination than the widely employed European honey bee (Apis mellifera L.). High species richness within crop pollinator assemblages has been linked to enhanced fruit and seed yields, but species richness is often confounded with abundance in studies of pollinator communities. We investigated the effects of bee diversity and species identity on pollen deposition and crop yield in the strawberry (Fragaria × ananassa) variety Jewel through a field experiment that independently manipulated the species richness and abundance of flower visitors. We used a new pollen deposition measurement technique to determine the pollen contribution of individual bees in an assemblage of flower visits. We compared the performance of wild bee species and managed honey bees, as pollinators of strawberry. We also calculated the influence of species richness, visit frequency and visitor identity on fruit mass, using the fruit that developed from each sampled flower. Species richness of flower visitors did not influence floral pollen loads or strawberry mass. Honey bees and wild bees deposited the same amount of pollen per visited flower. However, strawberries that developed from flowers visited by wild bees were heavier than flowers visited by honey bees. In addition, flowers visited by a combination of wild and honey bees produced strawberries that weighed less than flowers receiving purely WB visits. Synthesis and applications. Our findings show that honey bee pollination results in lower yields than wild bee pollination in a strawberry crop. Consequently, if managed honey bees in strawberry fields displace wild pollinators, growers may obtain suboptimal yields. Management efforts aimed at the maintenance or enhancement of wild pollinator populations may therefore be a cost‐effective way to increase both crop yield and biodiversity on strawberry farms. Our findings show that honey bee pollination results in lower yields than wild bee pollination in a strawberry crop. Consequently, if managed honey bees in strawberry fields displace wild pollinators, growers may obtain suboptimal yields. Management efforts aimed at the maintenance or enhancement of wild pollinator populations may therefore be a cost‐effective way to increase both crop yield and biodiversity on strawberry farms.

Bee populations are rapidly declining, and biotechnology offers scalable, sustainable solutions for bee health.Genomics and sensor-based continuous monitoring generate large, complex datasets that can be integrated by artificial intelligence (AI) to provide stressor diagnostics, inform precision beekeeping, and accelerate breeding programs for resilient bees.Molecular interventions such as RNAi and protein biologics provide targeted pest controls, and their stability can be enhanced by nanocarrier delivery systems.Natural product drug discovery and high-throughput screening facilitate the development of eco-friendly pathogen treatments for managed bee colonies.Genome editing and synthetic biology are emerging as plausible conservation and management strategies, but they face a host of practical, regulatory, and public perception challenges. Bees are vital to global food security and biodiversity but their populations are threatened by a steady flux of interacting stressors. Current mitigation strategies are failing to address the complexity and scale of these threats. Biotechnology offers innovative solutions to protect essential pollination services and secure the future of beekeeping. Omic tools guided by artificial intelligence can unlock new possibilities for strengthening bee populations and improve their ability to adapt to emerging challenges. Molecular and bio-based treatments offer precise, nonchemical inputs for managed hives. Synthetic biology enables engineered gut microbiomes, pollinator-friendly crops, and artificial diets that are tailored to bee health. We discuss recent progress and future directions of biotechnology to help bees cope with a rapidly changing world. Bees are vital to global food security and biodiversity but their populations are threatened by a steady flux of interacting stressors. Current mitigation strategies are failing to address the complexity and scale of these threats. Biotechnology offers innovative solutions to protect essential pollination services and secure the future of beekeeping. Omic tools guided by artificial intelligence can unlock new possibilities for strengthening bee populations and improve their ability to adapt to emerging challenges. Molecular and bio-based treatments offer precise, nonchemical inputs for managed hives. Synthetic biology enables engineered gut microbiomes, pollinator-friendly crops, and artificial diets that are tailored to bee health. We discuss recent progress and future directions of biotechnology to help bees cope with a rapidly changing world.

The spatial heterogeneity of urban landscapes, relatively low agrochemical use, and species-rich floral communities often support a surprising diversity of wild pollinators in cities. However, the management of Western honey bees ( Apis mellifera L.) in urban areas may represent a new threat to wild bee communities. Urban beekeeping is commonly perceived as an environmentally friendly practice or a way to combat pollinator declines, when high-density beekeeping operations may actually have a negative influence on native and wild bee populations through floral resource competition and pathogen transmission. On the Island of Montréal, Canada there has been a particularly large increase in beekeeping across the city. Over the years following a large bee diversity survey ending in 2013, there was an influx of almost three thousand honey bee colonies to the city. In this study, we examined the wild bee communities and floral resources across a gradient of honey bee abundances in urban greenspaces in 2020, and compared the bee communities at the same sites before and after the large influx of honey bees. Overall, we found a negative relationship between urban beekeeping, pollen availability, and wild bee species richness. We also found that honey bee abundance had the strongest negative effect on small (inter-tegular span <2.25 mm) wild bee species richness. Small bee species may be at higher risk in areas with abundant honey bee populations as their limited foraging range may reduce their access to floral resources in times of increased competition. Further research on the influence of urban beekeeping on native and wild pollinators, coupled with evidence-based beekeeping regulations, is essential to ensure cities contain sufficient resources to support wild bee diversity alongside managed honey bees.

In a warming climate, species are expected to shift their geographical ranges to higher elevations and latitudes, and if interacting species shift at different rates, networks may be disrupted. To quantify the effects of ongoing climate change, repeating historical biodiversity surveys is necessary. In this study, we compare the distribution of a plant–pollinator community between two surveys 115 years apart (1889 and 2005–06), reporting distribution patterns and changes observed for bumblebee species and bumblebee-visited plants in the Gavarnie-Gèdre commune in the Pyrenees, located in southwest Europe at the French–Spanish border. The region has warmed significantly over this period, alongside shifts in agricultural land use and forest. The composition of the bumblebee community shows relative stability, but we observed clear shifts to higher elevations for bumblebees (averaging 129 m) and plants (229 m) and provide preliminary evidence that some bumblebee species shift with the plants they visit. We also observe that some species have been able to occupy the same climate range in both periods by shifting elevation range. The results suggest the need for long-term monitoring to determine the role and impact of the different drivers of global change, especially in montane habitats where the impacts of climate changes are anticipated to be more extreme.