Perspective Chapter: Wild Bees – Importance, Threats, and Conservation Challenges

Abstract

Wild bees hold tremendous significance as vital natural pollinators on a global scale. Approximately 20,000 bee species have been described worldwide. They are efficient pollinators owing to their species diversity and abundance, varied floral preferences, flight times, and reliance on weather conditions. Moreover, the extent and nature of pollination services provided by wild bees differ with geographical location, landscape type, climate conditions, and floral morphology. The decline of bees can be attributed to a combination of factors, such as loss, modification, and fragmentation of habitat, pesticide utilization, climate change, and the introduction of pests and diseases. Unlike honey bees, wild bees cannot easily be cultivated or reared in artificial conditions, hence strategies are needed to protect wild bees in the field. Conservation efforts can focus on protecting and restoring their natural habitats in different types of landscapes, implementing measures in human-altered environments, and utilizing human-made tools to support their well-being.

1. Introduction

Insects are crucial pollinators; among them, bees, flies, beetles, and wasps are the significant pollinators of wild and cultivated plant species [1, 2, 3]. Bees are the foremost pollinators, with more than 20,000 species worldwide [4]. Moreover, honey bees are the main pollinators and are managed for crop pollination, though there are wild bees such as bumblebees and solitary bees (non-corbiculate and non-bombus wild bee species) being managed for improving pollination of specific crops [5, 6, 7]. Recently, wild bees have played a substantially larger role in crop pollination than honeybees. For instance, in the United Kingdom, wild bees account for 70% of crop pollination, with the remaining 30% being fulfilled by honeybees [8]. A similar study reveals that frequent visits by wild bees and hoverflies improve the fruit set of agricultural crops, even if honey bees visit regularly [9, 10, 11]. The crop yields are enhanced by the functional diversity of pollinators. Wild bees improve fruit and seed setting due to loose pollen held on body hairs and they often transfer more pollen than honey bees [12]. Wild bees are often important for wildflower pollination because rare flowers may rely on specific native wild bees for their existence. With decreased pollinator abundance, the rare flowers might not be adequately pollinated [13, 14, 15, 16, 17]. Hence, it is crucial to maintain our wild bee populations to ensure continued pollination of both crops and wildflowers [18]. However, over the century, insects have been declining at startling rates, including pollinators [19, 20, 21, 22]. The number of wild bees has decreased everywhere [23], with 52 percent in the United Kingdom [14]. As much as 9.2% of wild bees are threatened according to the Red List in Europe [24]. Understanding the reasons behind these declines is crucial to mitigate the management measures to stop the loss of natural pollinators. In this chapter, we are focusing on opportunities and challenges in conservation of wild bees.

2. Why should wild bees have the utmost priority?

The significance of native, wild bees as pollinators for crops is a subject of ongoing debate, although their importance in natural ecosystems is generally recognized [25]. Approximately 80% of flowering plants rely on pollinators for fertilization, and wild bees play a predominant role as primary pollinators in the majority of ecosystems [1, 26, 27, 28]. The wild bees’ forage in harsh climate conditions has high significance [29]. Bumble bees, in particular, forage at low temperatures, and certain flowers require high-frequency shaking, so-called sonication [30, 31]. This underscores the importance of wild bee pollination services, not only within the framework of ecosystem functioning but also in the context of global agricultural production. Many non-Apis bee species are as effective as or even better pollinators than honey bees for various crops [32, 33, 34, 35, 36, 37, 38]. The main challenge in utilizing these non-Apis species for crop pollination is not their effectiveness but rather their abundance [34, 35, 36]. Currently, management techniques are established for only a limited number of non-Apis bee taxa [39, 40, 41]. Furthermore, wild native bees that are not managed by humans also contribute to crop pollination as part of the ecosystem’s natural services. In certain agricultural contexts, unmanaged bees can fully meet a crop’s pollination requirements, and in other cases, they are frequent visitors to flowers, thereby aiding in fulfilling pollination needs for crops [42, 43, 44]. Additionally, when native bees coexist with honey bees, they can enhance the overall effectiveness of honey bee pollination [45, 46, 47]. Recognizing the role of native bees in pollinating crops serves as an important factor in garnering support for the conservation of bee populations.

3. Challenges in the conservation of wild bees

Wild bees play a critical role in maintaining the fragile equilibrium of ecosystems by pollinating a wide array of crop plants that sustain human existence. These bees are experiencing significant declines, and some may even be at the menace of extinction, with the status of many remaining uncertain and encountering a myriad of challenges that imperil their numbers and habitats. These challenges encompass multiple factors such as habitat loss, pesticide use, the impacts of climate change, and invasive species.

3.1 Habitat loss and fragmentation

Habitat loss stands out as the primary and widespread cause behind the global decline of bees. This loss of natural habitat is attributed to practices in agriculture, land abandonment, and urban development, resulting in fragmented and degraded habitats, which pose a significant threat to native bee populations. The removal of native vegetation primarily affects bees by reducing their access to both flowering plants and suitable nesting sites [48]. This reduction in the diversity and abundance of flowering plants puts considerable nutritional stress on bees, particularly wild ones that are more selective in their pollen preferences compared to honeybees [49, 50, 51, 52]. Numerous bumblebee species, particularly those specialized in collecting pollen from leguminous plants, have suffered declines due to the loss of grasslands rich in flowers. Other semi-natural habitats like dunes, heathlands, and road verges have also deteriorated, impacting various bee species. Furthermore, the loss of large brownfield sites and the filling of quarries have exacerbated habitat loss. Habitat fragmentation isolates bee species, leading to reduced genetic diversity and increased vulnerability to diseases and parasites. Specialist species with limited dispersal abilities have experienced more substantial declines [14], resulting in the dominance of generalist species. Cleptoparasite species like the six-banded nomad bee and square-spotted mourning bee have seen dramatic declines, with some even facing extinction.

Changes in land use toward agriculture pose a significant threat to bee populations, resulting in the loss of grasslands and tropical forests. Intensive farming practices, such as the use of agrochemicals and soil plowing, can lead to soil degradation and the accumulation of harmful substances, further endangering the survival of both adult and larval bees [53, 54]. Reduced access to resources in agricultural landscapes negatively impacts the reproductive performance of solitary and bumblebees, leading to lower bee abundance and diversity. Ground-nesting stingless bee species like Melipona quinquefasciata are endangered due to activities such as firewood gathering and agricultural expansion, which destroy their nesting environments and floral host plants [55, 56]. The impact of urbanization on bumblebee populations is likely a complex and mixed one, with various studies suggesting both positive and negative effects [57, 58, 59, 60].

3.2 Pesticide use and pollution

Insecticides are potentially the most harmful chemicals used in agriculture and play a significant role in the decline of wild bee populations [50]. However, the susceptibility of bee species to pesticides varies based on their behavior and natural characteristics. Different types of pesticides exhibit varying levels of toxicity to different bee species [61]. Pesticides can have detrimental effects on native bee populations in two ways: directly, by acting as insecticides that kill them, or indirectly, as herbicides that eliminate the plants they rely on for food. Sub-lethal effects of pesticides can be challenging to detect, but they have a more substantial impact on bee populations, primarily affecting the sensory perception, navigation abilities, and recognition of kin among wild bees.

Bees can be exposed to pesticides in multiple ways, as residues of insecticides are often found in the pollen and nectar of both cultivated crops and wildflowers [62, 63]. Bee species that have flight periods coinciding with pesticide applications and those relying on host plants vulnerable to pesticides face an elevated risk [64]. In managed grasslands, the use of herbicides reduces the variety and abundance of flowering plants, while in arable fields, herbicides that effectively control broad-leaved weeds can decrease the number of bees foraging for pollen and nectar. Many insecticides are absorbed by the lipids in pollen grains, potentially leading to the poisoning of solitary bee broods or causing mortality in the young bees of social colonies [65]. Systemic pesticides like neonicotinoids tend to have higher concentrations in pollen compared to nectar, potentially affecting different bee species depending on their foraging behaviors [66, 67].

Pesticide exposure has also been linked to various physiological problems in bees, including immunosuppression, reduced thoracic temperatures in Osmia bicornis, altered mitochondrial functions in Bombus terrestris, and a decline in the production of new queens in Bombus terrestris [68]. Furthermore, bees exposed to pesticides may experience reduced development of ovaries, decreased male fertility, lower production of offspring, a skewed male-dominated sex ratio, and increased mortality of eggs and larvae. These effects contribute to the decline of solitary bee populations in pesticide-intensive agricultural systems.

3.3 Climate change

Climate change represents an additional peril to wild bees, posing potential risks such as reduced numbers, shifts in habitats, and an increased menace of extinction, particularly for specialist or geographically limited species and small isolated populations. Climate change is also anticipated to lead the habitat loss, disrupt interspecies interactions, and jeopardize the survival and reproductive success of bees. Climate change may result in mismatches between the timing of flower blooms and bee emergence [69], leading to ecological imbalances where pollinators lose synchronization with their food plants due to shifting seasonal patterns. This could reduce the availability of floral resources for bees, particularly those with specific dietary preferences. In contrast, generalist species are expected to be less affected by these mismatches since they can visit multiple plant species.

Global warming led to a shift in the species such as the Yellow-legged mining bee, Hairy-footed flower bee, Buff-tailed bumblebee, Vestal cuckoo bee, Sharp-collared furrow bee, Painted nomad bee, and Dark blood bee to shift away from their traditional habitats [70]. Extreme weather events like droughts, floods, and storms may have a direct impact on bee populations. This is especially problematic for native bees as they cannot regulate their body temperature. Temperature fluctuations can affect various aspects of bee physiology and behavior. For instance, high temperatures during the summer can influence bee development, reproduction, and physical characteristics, including tongue length. Some bee species demonstrate phenotypic plasticity in response to climate change, leading to changes in species composition and traits. Warmer temperatures can also impact the size of bumblebee queens and the duration of winter hibernation, making them more vulnerable in the spring [57].

3.4 Invasive alien species

Invasive non-native species, diseases, and pathogens pose a significant risk to wild pollinators. Managed bees, like honeybees and bumblebees, can introduce harmful pathogens and parasites to wild bee populations, with the global increase in managed honeybee colonies and the importation of these bees being potential sources of exotic diseases for wild bees. Invasive alien species can, directly and indirectly, impact native biodiversity [71], raising concerns about the loss of pollination services for both wild plants and crops [14, 27, 72]. The consequences of invasive alien species can extend beyond pollination services, affecting entire ecosystems. Invasive alien plants often do not offer suitable rewards to native bees and can even be detrimental to them. Studying the impact of invasive alien plants on native bees at the individual level (changes in foraging behavior, survival, etc.) is relatively straightforward, but it’s more challenging to assess their effects on bee populations and communities. Surprisingly, laboratory studies have shown that despite being separated for over 70 million years, honey bee pathogens can harm bumble bees [73, 74, 75], and vice versa [74]. These pathogens have also been found in various wild bee species, though their impact on species beyond Bombus remains poorly understood. Domesticated bumble bees and honey bees are the primary vehicles for the pathogens to spread to new areas, it’s crucial to monitor and control these colonies to protect wild bee populations. Introducing new diseases is a major concern, and some declining wild bee species may suffer due to pathogen-related issues. For example, the rapid decline in Bombus sensu stricto is linked to infection by the potentially introduced fungal pathogen Nosema bombi, which is rarely found in co-occurring species from other Bombus subgenera [76]. The impact of invasive alien plants on native pollinators, especially bees, is not well-documented. Some invasive plants have flowers specialized for pollination by animals other than bees, making it difficult for native bees to access nectar and pollen. For instance, Salvia splendens has nectar concealed deep within long corolla tubes, which native bees struggle to reach [77]. In some cases, invasive alien flowers require specific behaviors that native bees lack. For example, native bees in Tasmania cannot handle the flowers of the invasive alien Lupinus arboreus, which necessitates large, powerful bees to expose stamens and stigma [78]. Similarly, native halictid bees cannot perform buzz pollination on the flowers of the invasive alien Solanum torvum because they cannot sonicate the anthers. Consequently, native bees tend to avoid these invasive alien plants as they aren’t suitable food sources for them. We see that there are significant challenges that hinder the conservation efforts aimed at safeguarding wild bee populations. From habitat loss and pesticide use to climate change and disease, each challenge poses a unique threat, requiring careful consideration and proactive solutions. By understanding these challenges, we can begin to develop effective strategies to protect these crucial pollinators and the ecosystems that rely on them.

4. Opportunities for conservation of wild bees

4.1 Habitat protection and restoration

First and foremost, it is important to protect natural environments for wild bees and to recreate large natural habitats for a diverse ecosystem [79]. Recent research revealed that the decline of terrestrial insects is less in protected areas, which emphasizes the significance of habitat protection [79]. Hence, several methods are being used to describe the protected areas, some considering species diversity alone and species distribution along with changes in climate [18, 80]. Ecological Nich Models are employed to assess the protected areas in South America for bumble bees [81]. Ecological restoration of habitats within these protected areas can significantly increase the abundance and richness of wild bee populations across different landscapes and regions [82]. The hedgerows, grasslands, and woodland margins were possible attributes for enhancement, not only for solitary, ground-dwelling bees who forage a lot of blooming plants, but also for social, above-ground nesting bees that visit a few blooms in these environments [83]. Similarly in Brazil, rainforests may enhance bees’ above-ground nesting, highlighting the significance of conservation efforts in a protected bee habitat [84]. The success of restoration efforts depends on understanding the habitat and resource preferences of the targeted wild bee species. Different habitat types can yield varying responses in wild bee abundance, depending on the ecological traits of the species [85]. Restoration methods, such as grazing and burning, can have both positive and negative effects on wild bee populations and are often context-dependent. These restoration efforts take place within the framework of LIFE plans supported by the European Union, such as LIFE Butterflies and LIFE in Quarries, which aim to restore habitats that indirectly benefit wild bees. While insect conservation is still in its early stages compared to bird and mammal conservation, some projects, like the Urban Bees LIFE project, focus on increasing bee abundance and diversity in urban environments [18]. However, such initiatives are exceptions rather than the rule. Wild bees are often absent from conservation programs at both the political and policy levels, primarily due to a lack of understanding of their requirements. There is a need to incorporate pollinators, especially in semi-natural habitats, into national and sub-national conservation programs, with a specific focus on identifying targeted species. As LIFE projects failed, similar programs such as Urban Bees LIFE are in action (www.urbanbees.eu) and are targeting management to increase the bee population and bio-diverse environment of local bees in potential urban and peri-urban areas [85]. Hall and Steiner [86] described that US state projects did not consider the significance of bees in comparison to vertebrates, leading to a lack of understanding of their needs and restoration actions.

4.2 Management of seminatural habitats

In agricultural ecosystems, semi-natural habitats offer vital supplies for wild bees. Floral resources in managed landscapes are dynamic and change across time and geography. Hence, higher levels of semi-natural habitats in agricultural landscapes are typically linked to higher pollinator abundance and richness [87] as well as improved pollination services to crops [88]. Various taxa of pollinators may be significantly influenced by the type, structure, and floral content of semi-natural habitats [89]. According to some recent research, flower-rich grasslands in Central European agricultural landscapes may have more diversified and plentiful wild bee communities than woody habitats like hedgerows and forest edges [89, 90]. Furthermore, compared to forest borders, seeded flower strips locally contribute more to the maintenance of populations of generalist wild bee species [91]. Furthermore, due to the varying flowering phenologies of the major plant species in these environments, the role of floral resources can change during the season [92, 93]. For instance, it has been demonstrated that certain bumblebee species monitor floral resources in various habitats during the course of the season [92]. As a result, they switch from woody plants, which primarily flower in spring, to herbaceous plants, which continue to bloom profusely in summer [94], which serve as their primary pollen source. According to Schlellhorn [95], conservation management should therefore take into account ways to encourage resource continuity across landscapes. Therefore, encouraging various semi-natural habitat types in landscapes may be essential to maintaining a variety of bee meta-communities throughout the season.

4.3 Management of urban and agricultural areas

Conservation efforts play a crucial role in urban areas, where more than 55% of the wild bee population resides. The process of urbanization tends to diminish the abundance and diversity of wild bees due to decreased food resources and nesting sites [96, 97]. When managing urban environments, it’s essential to consider ecological, economic (cost), and logistical (implementation and sustainability) factors to make these often-neglected areas more bee-friendly [98]. Protecting areas near highly urbanized regions can act as buffers for wild bee populations. Initiatives are emerging that encourage the creation and management of bee-friendly habitats in agricultural settings. Roadsides, hedgerows, parks, and urban gardens are all vital habitats for wild pollinators, supporting a high diversity of species, including rare ones. Implementing bee-friendly plans through rooftop gardens, parks, and roadsides has led to increased native bee populations in Amsterdam [99]. This environmental interconnection is essential because harmful ecological fragmentation can negatively affect small bee species, especially in these areas. Ensuring habitat connectivity is crucial, as fragmentation can impede the dispersal of smaller bee species. Conservation strategies in agricultural areas can have a positive impact depending on the specific measures, target species, and landscape composition. Restoring floral resources, such as prairies, is an effective method for promoting wild bee diversity. Agro-environmental actions like flower strips have been embraced in Europe to increase biodiversity in intensively managed agricultural landscapes [100]. These actions have proven beneficial for bumblebees, honeybees, and hoverflies in Germany, Belgium, and England [93]. Increased flower supplies have notably improved the size, density, and population of bumblebees [93, 101]. The impact of AES (Agri-Environment Schemes) has been infrequently determined [102], and Geppert [103] observed the effects of organic practices and floral strips on bee population survival and development. Both of these actions were positively associated with pollinators’ strength and the growth of bumblebee hives, but their efficiency depended on the surrounding landscape [64]. In England, Wood [93] also assessed Higher Level Stewardship farms (HLS) to experiment with the impact of cultivated flowers on native solitary bee populations. For example, honeybees and bumblebees were positively influenced by Phacelia sp., while solitary bees predominantly foraged on sunflowers and seed mixes of wildflowers [104, 105]. However, changes in floral resources among different bee environments can lead to stress, depletion of flower assets, and alterations in the crop-pollinator network [19, 106]. Agro-environmental actions like flower strips mainly benefit generalist species but may not adequately support diverse wild bee communities. The use of pesticides has varying effects on wild bees, and the sensitivity of solitary bees varies widely. It is often recommended to apply the precautionary principle and explore alternative pest management practices such as plant essential oils or biomolecules [18]. Integrated pest and pollinator management (IPPM) is suggested to integrate measures specifically benefiting pollinators into pest management. Sustainable strategies for agricultural landscapes are of utmost importance. Projects like EcoStack aim to enhance sustainability in European food production by considering ecological, economic, and social aspects. The Protecting Farmland Pollinators project in Ireland uses a scoring system to identify pollinator-friendly farming practices [85]. The Interreg-Sudoe Poll-Ole-GI project focuses on identifying effective methods, including green infrastructures, to support pollinator communities in Mediterranean crops like sunflowers and oilseed rape. These efforts in urban and agricultural areas are essential for conserving wild bees, promoting biodiversity, and ensuring the well-being of future generations. The nutritional quality and power of crops like Brassica napus can positively influence the abundance of bee populations [107, 108]. The variety of proteins and essential amino acids required for the growth and development of bee populations is crucial for bee species’ health. This can be achieved through the use of floral resources available in their habitats, especially in environments where floral resources are scarce. Different agricultural technologies, such as friendly planting, can be tested to enhance the quantity and quality of resources, as seen with strawberry Fragaria x ananassa and borage Borago officinalis [109], although their effect on pollinator abundance has not been thoroughly studied. Describing the chemical toxicity’s impact on honeybees and generalizing it to bumblebees and solitary bee taxa is challenging, as the sensitivity of solitary bees varies widely. The POSHBEE and European strategies can be beneficial in understanding how pesticides can affect native bee fauna and their synergistic effects with other factors contributing to their decline. However, it’s important to note that pesticides can also impact bee pollinators and are not a specific response to safeguard the bee world [110, 111]. Egan [111] introduced a newly designed strategy called integrated pest and pollinators management (IPPM), which aims to integrate crop pollinators, and bio-control agents, and minimize pesticide use to enhance agriculture food production [112, 113, 114, 115, 116, 117, 118]. This strategy, which we propose to call “Pollinator and Integrated Pest Management Technology (PIPMT),” represents a holistic approach to managing pests below economic injury levels while promoting agriculture food production.

4.4 Nesting resources: bee hotels

Recent research has emphasized the need to enhance the availability of floral resources for pollinators but has often overlooked the equally vital aspect of providing nesting sites for these species [119]. Few studies have delved into the abiotic and biotic factors influencing nesting site selection and nesting success among different bee species [120, 121]. Endangered bees, including those with unique nesting behaviors like soil-nesting and cavity-nesting bees, such as carder bees and those that nest underground or in snail shells, can benefit from abundant nesting opportunities. It is recommended to provide ample nesting resources, including the establishment of Wild Bee Inns, especially for smaller bee species in various distribution areas (121). Maclvor and Packer [122] also introduced environmentally protective strategies to fulfill the nesting needs of wild bees. They emphasized that while approximately 50% of the occupants in bee hotels were newly introduced non-native bees, a concerning 75% of them were taken up by wasps. Worryingly, they observed a negative relationship between wild bees and the species found in bee hotels [123]. This research highlights the positive response of artificial nesting structures for native bees and underscores the importance of creating nesting sites to support the diversity of bee species crucial for crop pollination [119, 122]. It is essential to focus on the size of cavities in bee hotels, as different bee species have specific requirements for nesting [18, 85]. Smaller diameter holes can facilitate the nesting of many wild species, while larger holes may deter smaller native bees, as they are more likely to be occupied by larger non-native bees like M. sculturalis [123]. Whether it’s small patches of bare soil installations, Wild Bee Inns, or bee hotels, the practical benefits of these nesting options should be subject to thorough investigation and analysis.

4.5 Combatting invasive alien species [IAS]

Invasive alien plant species can have varied effects on wild bees, with some experiencing positive, neutral, or negative impacts [18, 85, 124]. The outcome depends on factors such as ecological context and life history traits. The sensitivity of ecosystems to invasions is influenced by the degree of disturbance and resource availability [125, 126, 127, 128]. Invasions often occur in habitats associated with human activities, where invasive plants can provide valuable food resources for generalist pollinators and restore ecological functions like pollination. However, they can harm specialist bee species with limited diet flexibility by competing with native flora and replacing plant species foraged by specialists. Efforts to combat invasive plants should be context-specific and guided by the precautionary principle, ranging from eradication to population control. A recent meta-analysis found that the impact of exotic plant species on pollinator abundance is case-specific, and there is no blanket rule that all exotic species are harmful or harmless. Invasive pollinators can directly compete for food and nesting resources, transmit pathogens, and indirectly affect food webs and plant communities [126]. For example, the Asian hornet Vespa velutina poses a potential threat to pollinators and escaped alien bumblebees used for agricultural pollination raise concerns about their impact on global diversity. The introduction of non-native bumblebee species can lead to mating with native species and the decline of native populations. Coordinated international measures to prevent biological invasions through importation policies and monitoring of invasive species are crucial. At the European level, a regulation to mitigate the effects of invasive alien species came into effect in 2015 [18, 85]. It defines preventive and curative measures for 66 invasive species to reduce their harmful effects on ecosystems. A classification system called the “Black List” categorizes invasive species based on their environmental impact. The IUCN Invasive Species Specialist Group (ISSG) works to reduce threats from invasive species through awareness, prevention, control, and eradication efforts at a global scale. Overall, managing invasive species is essential to protect native ecosystems and their associated species [18, 85].

5. Wild bees: an action for all

Effective communication and education are essential for establishing a solid basis for insect conservation. It is important to use clear terminology and unambiguous concepts in scientific communication. This includes specifying the taxonomic and geographic scale of research and clearly articulating the research’s aim and results. To build support for insect conservation, several priorities in communication and education are highlighted:

1. Citizen science programs: Developing citizen science programs that combine education and training with data collection is crucial. Despite some biases in citizen science data, it allows for the monitoring of insect populations over long time periods and contributes to mapping a significant portion of species in an area. This approach has been particularly effective in monitoring pollinators, which have garnered growing public interest.

2. Education and training: Improving school, education, and training programs is vital to enhancing public knowledge and appreciation of insects. Educating the public about the importance of natural history observation and insect conservation can lead to positive behaviors and increased awareness.

3. Media ethics training: Scientists should receive training in media ethics to effectively communicate scientific methods and processes to the public. Clear and accurate communication is essential for engaging the public in nature conservation efforts.

4. Broad and accurate communication: Communication about insects and their conservation should be broad, reaching various audiences through scholarly literature, social media, and other channels. It should also emphasize accurate reporting of the geographic and taxonomic scales of research results.

5. Changing perceptions: Overcoming common misconceptions, such as the immediate association of bees with honey, hives, and stings, is a challenge in insect communication. The focus should shift toward linking bees with their roles as pollinators and wild species.

6. Resident engagement: Engaging urban residents in insect conservation efforts is essential for long-term success. Residents should feel safe and find conservation measures esthetically pleasing. Creating areas specifically dedicated to agroecosystems, such as “pocket prairies,” can help meet resident preferences.

7. Practical support: Providing citizens and stakeholders with practical information, such as recommended plants to support bees based on their nutritional value and local context, can empower them to take effective conservation actions. Technical knowledge, like avoiding agrochemicals and following specific mowing/pruning schedules, is essential for integrating pollinators into green space management.

8. Public-private partnerships: Collaboration between NGOs, private businesses, and public authorities can lead to effective conservation actions. Examples include partnerships between a supermarket chain and an NGO in Austria, collaborations between fruit farmers and municipalities in Belgium, and partnerships involving beer brewers, NGOs, and public authorities.

In summary, effective communication, education, and collaboration among diverse stakeholders are crucial for building support and implementing successful insect conservation measures.

6. Conclusion

In conclusion, the urgency of species conservation necessitates a shift from only accumulating knowledge to taking concrete actions based on available evidence. Conservation experts must clearly define the target species for conservation efforts, recognizing the diverse ecological traits, and floral and nesting requirements of different species. While many conservation measures have been based on empirical evidence from honeybees and bumblebees, it is crucial to acknowledge that these findings may not apply universally to wild solitary bees, emphasizing the need for tailored approaches. One central aspect that demands attention is the redesign of floral resource mixes used in conservation programs. These mixes should be based on empirical studies identifying plant species that are foraged by the targeted bee species and matching their flying seasons and nutritional needs. Similarly, there is an urgent need to address nesting resources beyond bee hotels, which cater to only a fraction of bee species. Conservation programs should consider alternative floral resources, especially in anthropogenically-driven environments, but decisions must be grounded in strong empirical evidence. Furthermore, the way we manage bee-friendly areas, including finding alternatives to pesticides, needs to be rethought. The majority of habitat restoration studies have been conducted in North America and Europe, making it essential to test conservation measures in a wider range of habitats globally. Lastly, the communication and education about bees should be reshaped to move beyond associations with beehives and honey. The optimization of these actions and collaboration among conservation actors will enhance public awareness of biodiversity and ecosystem services, especially in urban areas where people are increasingly disconnected from nature.