Understanding Pollinators

Pollinators are much more than honey bees. This article provides a scientifically grounded and practical overview of their diversity, their role in ecosystems and agriculture, the main pressures they face, and concrete measures to support them.

In brief

Pollination depends not on honey bees alone, but on a broad diversity of insects with complementary roles. This diversity contributes to the reproduction of wild plants, to crop quality and to ecosystem stability. The decline of many wild pollinators results from several combined pressures, notably habitat loss, insufficient floral resources, pesticides, landscape fragmentation and climate change. Protecting pollinators therefore means above all restoring varied habitats, preserving nesting sites, reducing pressures and adapting beekeeping, agricultural and municipal practices to the local context.

1. Pollination and Pollinator Diversity

Understanding what pollination is and why it cannot be reduced to the honey bee.

Pollination is the transfer of pollen from the male organs of a flower to the female organs of a flower of the same species. It precedes fertilisation and, when conditions are right, enables the formation of seeds and fruits. This process can be carried out by wind, water, self-pollination, or animals. In many terrestrial ecosystems, animals — and insects in particular — play a central role in this pollen transfer.

Pollination must therefore not be reduced to a single species. The honey bee (Apis mellifera) is the best-known pollinator among the general public, because it is managed by humans, produces honey, and can be deployed for certain crops. But it represents only a part of pollinator diversity. Pollinator communities also include wild bees, bumblebees, hoverflies, butterflies, moths, beetles, certain wasps, and other flower-visiting insects. In other parts of the world, birds, bats, or other vertebrates may also contribute to pollination.

This diversity is ancient and deeply linked to the evolution of flowering plants. Flowers are not merely aesthetic elements of the landscape: they are also reproductive structures that attract, guide, or reward animals capable of transporting pollen. Many insects, in turn, find nectar, pollen, or other resources in flowers. Pollination is thus embedded in a web of interactions between plants and animals, where the reproduction of many plants depends at least partly on a visit from a flower-visiting animal.

According to Ollerton, Winfree and Tarrant (2011), approximately 87.5% of flowering plant species are pollinated by animals. This figure does not mean that all these plants would immediately disappear without pollinators, nor that they all depend to the same degree on one particular insect. It indicates rather that animal pollination is very widespread in the plant world and contributes to the functioning of many ecosystems. In temperate regions this proportion is lower than in the tropics, but it remains significant.

Bees constitute a major group among pollinators, but the word "bee" itself covers great diversity. The honey bee lives in large colonies and is managed by humans. Wild bees, by contrast, encompass many species with very different lifestyles. Many are solitary: each female builds her nest, collects pollen for her larvae, and manages her reproduction alone. Some nest in the ground, others in hollow stems, dead wood, cavities, or rock structures. This diversity of lifestyles explains why protecting pollinators cannot be limited to installing hives.

Bumblebees occupy a particular position. Their dense hairiness, their capacity to fly in relatively cool weather, and their foraging behaviour make them effective pollinators on many plants. Some species can practise buzz pollination, or sonication: they vibrate the anthers of certain flowers to release pollen. This mechanism is particularly important for plants such as tomato. The honey bee does not practise this form of pollination, which illustrates that a very abundant pollinator is not necessarily suited to all flowers.

Hoverflies are another frequently underestimated group. They sometimes resemble bees or wasps, but they are dipterans — that is, flies. Adult hoverflies frequently visit flowers to feed on nectar and pollen. Some species also provide another ecological service: their larvae consume aphids. Rader et al. (2016) showed, in a synthesis of 39 studies across five continents, that non-bee insects — including flies, beetles, butterflies, wasps, and other groups — accounted for 25 to 50% of floral visits observed in the studied crops. Even if these insects are sometimes less efficient per visit than bees, their visit frequency can compensate for this lower individual efficiency.

It is also important to distinguish between "flower visitors" and "effective pollinators". An insect may land on a flower to consume nectar without transporting much useful pollen. Conversely, a less frequent insect may be highly efficient if it deposits pollen in the right place. The scientific assessment of pollination therefore goes beyond counting insects on flowers: it also measures efficiency per visit, the quantity of pollen deposited, fruit set, seed production, fruit quality, and the stability of the pollination service.

Discussing pollinators thus means looking beyond the hive. The honey bee is part of the pollination landscape, but it is neither the sole starting point nor the universal solution. Understanding pollinator diversity is the prerequisite for properly discussing their role, their decline, and the measures needed to protect them.

Honey bee, wild bees and hoverflies: three profiles not to be confused

The honey bee (Apis mellifera) is a social bee species managed by humans. It lives in large colonies and can be moved for honey production or the pollination of certain crops. Wild bees encompass many species, often solitary, that nest in the ground, in stems, dead wood, or various cavities. Hoverflies are not bees but flies. As adults they visit flowers; in some species the larvae consume aphids. All these groups can contribute to pollination, but their lifestyles, needs, and vulnerabilities are very different.

2. Why This Diversity Matters

Showing why pollinator diversity influences the quality, stability, and resilience of pollination.

Pollinator diversity is not merely a matter of biological richness. It directly influences how pollination functions in natural ecosystems and agricultural landscapes. Two landscapes may host a comparable number of flower-visiting insects yet provide different pollination services depending on the species present, their behaviours, their periods of activity, and their actual efficiency on flowers.

Not all pollinators visit the same flowers, transport pollen in the same way, or are active under the same conditions. Some wild bees are adapted to particular flowers, while others are more generalist. Bumblebees can fly in cool weather and are capable of vibrating certain flowers to release pollen. Hoverflies, butterflies, beetles, and other insects also visit flowers, sometimes at times or under conditions when bees are less present. This diversity of behaviours promotes a form of complementarity.

In a global analysis covering 89 studies and 1,475 sites, Dainese et al. (2019) showed that pollinator richness supports pollination services beyond individual abundance alone. In other words, the number of insects present matters, but species diversity matters as well. A significant part of the negative effects of landscape simplification on ecosystem services operates through the loss of species richness of the organisms that provide those services.

Functional diversity is particularly important. It refers not merely to the number of species, but to the variety of traits that influence pollination: body size, hairiness, tongue length, visiting behaviour, activity period, or floral preference. Woodcock et al. (2019) showed, in a meta-analysis focusing on oilseed rape, that pollinator abundance is important for yield, but that functional divergence between species is also positively associated with production. This supports the view that different pollinators can complement one another rather than providing exactly the same service.

This complementarity is also observed in fruit crops. Eeraerts et al. (2025) showed, in a global synthesis on apple pollination, that honey bees are often the most abundant visitors to flowers, but that wild bees — in particular solitary bees — are associated with positive effects on certain quality parameters, such as fruit weight and seed number.

Pollinator diversity also contributes to the stability of the pollination service. A community composed of several species may better buffer inter-annual variation, because not all species respond to disturbances in the same way. Senapathi et al. (2021), drawing on data from 43 studies, 21 crops, and six continents, showed that greater wild pollinator diversity is associated with greater inter-annual stability of pollinator communities in crops.

This stability is important for agriculture, but also for wild plants. Artamendi et al. (2024) showed, in a global meta-analysis, that the loss of pollinator diversity reduces the reproductive success of both wild and cultivated plants, with particularly pronounced effects for wild plants. Pollination is therefore not merely an agricultural service: it contributes to the maintenance of plant communities and the ecological networks that depend on them.

An overly simple interpretation should nevertheless be avoided. Diversity does not act as an automatic guarantee. Its effect depends on the species present, the plants concerned, the landscape, and resource availability. Reilly et al. (2024) emphasise that the total number of visits remains an important factor in explaining crop yields, but that species diversity remains positively associated with yields even when abundance is taken into account. The correct conclusion is therefore not to set abundance and diversity against each other, but to consider them together.

Pollinator diversity can thus be understood as a form of ecological insurance. It distributes functions across multiple species, reduces dependence on a single pollinator, and enables pollination to be maintained under variable conditions. For landscape management, this means that protecting pollinators consists not only of increasing the number of insects present at a given moment, but of maintaining habitats capable of hosting different species.

3. Agriculture, Crop Quality, and Food Security

Clarifying the agricultural importance of pollination without falling into oversimplified slogans.

Animal pollination plays an important role in agriculture, but this role is often misunderstood in public debate. One frequently reads that "75% of our food depends on bees". This formulation is too imprecise. It conflates several different realities: the number of crops that benefit from pollination, the total volume of food produced, the economic value of harvests, the nutritional quality of food, and the specific role of the honey bee.

Klein et al. (2007) showed that 87 of the world's main food crops depend at least partially on animal pollination, while 28 do not. But production volumes give a different picture: a large part of global food production comes from crops that are not directly dependent on pollinators, particularly the major cereal crops. Dependence on pollination is thus significant, but neither uniform nor absolute.

Major cereals such as wheat, rice, and maize are pollinated primarily by wind or self-pollination. By contrast, many fruit, vegetable, oilseed, seed, and nut crops benefit strongly from insect visits. Pollination is therefore particularly important for dietary diversity, product quality, and the economic value of many crops.

The contribution of pollinators is not limited to quantity of yield. In several crops, adequate pollination also improves harvest quality: fruit size, shape, seed number, homogeneity, commercial appearance, or shelf life. Gazzea et al. (2023) show, in a global meta-analysis, that inadequate animal pollination can reduce several quality dimensions of fruit and vegetables.

Studies on apple illustrate this complexity well. Eeraerts et al. (2025) show that honey bees are often the most frequent visitors to flowers, but that wild bees contribute positively to certain quality parameters, particularly fruit weight and seed number. Visit frequency alone does not always suffice to measure the importance of a pollinator: efficiency per visit and the quality of the pollen transferred also matter.

Garibaldi et al. (2013) showed, in a global analysis of 41 cropping systems, that wild insects improve fruit set independently of honey bee abundance. Reilly et al. (2024) add a complementary nuance: in an analysis based on 93 studies, honey bees and wild insects contribute on average comparably to crop yields. These results do not contradict each other: they indicate that both groups can be important depending on the crop, landscape, and agricultural practice.

Certain crops depend on particular pollination behaviours. Tomato benefits from buzz pollination, a behaviour practised by bumblebees and certain wild bees, but not by the honey bee. Cooley and Vallejo-Marín (2021) show that pollinators capable of vibrating flowers can improve certain production parameters of tomato. This example illustrates an important limitation of generalisation: a species highly efficient for one crop may be poorly suited to another.

The economic value of pollination is real, but must be presented with caution. Gallai et al. (2009) estimated the global economic value of insect pollination at approximately €153 billion for the year 2005, based on the assumptions and method used. This estimate depends notably on agricultural prices, the crops included, and the substitution possibilities assumed. It should therefore be understood as a historical order of magnitude, not a fixed current value.

For Switzerland, Agroscope has for the first time estimated the direct economic value of insect pollination in agriculture. This value amounts to approximately CHF 342 million per year, with a range of CHF 205 to 479 million (Sutter et al., 2017). Insect-pollinated crops cover approximately 50,000 ha, representing around 5% of agricultural land and 14% of arable land. This estimate does not account for the value of pollination of wild plants, nor indirect, security-related, or non-utilitarian values.

Swiss data also show that the crops concerned are not evenly distributed. Fruit and berries have high added value and depend strongly on adequate pollination. In the Agroscope study, the value of pollination amounts to approximately CHF 244 million for fruit and CHF 39 million for berries. Major insect-pollinated arable crops, such as oilseed rape, cover large areas, even though their dependence on pollination is more variable.

In summary, animal pollination is a major agricultural ecosystem service, but its importance must be stated precisely. It does not mean that all our food depends on bees, nor that the honey bee alone ensures the pollination of crops. It means that many products important to the quality, diversity, and value of our diet depend on the joint activity of managed and wild pollinators.

"75% of our food depends on bees" — true or false?

The formula is compelling, but misleading. It confuses the number of crops that benefit from pollination with the total volume of food produced. Many crops important for human caloric intake, such as wheat, rice, or maize, are not directly dependent on pollinating insects. However, many fruits, vegetables, oilseeds, berries, nuts, and seed crops benefit strongly from animal pollination. A more accurate statement would be: a significant share of the diversity and quality of our diet depends on pollinators — but not all of our food.

4. Honey Bee and Wild Pollinators: Complementarity, but Not Substitution

Accurately positioning the role of the honey bee without casting it as either a universal solution or a problem in itself.

The honey bee (Apis mellifera) is an important pollinator. A colony can mobilise tens of thousands of workers, intensively exploit a flowering period, and provide a predictable pollination service in certain agricultural contexts. This capacity is valuable for crops that flower abundantly and in a concentrated period of time.

It would nevertheless be incorrect to conclude that the honey bee can replace wild pollinators. Garibaldi et al. (2013) showed that wild insects improve fruit set independently of honey bee abundance. Reilly et al. (2024) show in turn that both groups can contribute comparably to yields on average. The most robust conclusion is therefore one of complementarity: both groups are important, but they are not interchangeable.

This distinction helps avoid two opposing errors. The first consists of presenting the honey bee as the general solution to pollinator decline. Installing hives can support beekeeping activity or contribute to the pollination of certain crops, but it does not restore habitats, does not create nesting sites for wild bees, and does not protect hoverflies, butterflies, beetles, or other flower-visiting insects. The second error would be to present the honey bee as a problem in itself. It is not the mere presence of hives that is automatically problematic, but their density, their location, the health status of colonies, and the availability of floral resources.

Complementarity does not exclude competition. Honey bees and wild pollinators can exploit the same flowers, particularly when floral resources are concentrated or limited. A colony places a high demand on nectar and pollen. When many colonies are placed in a confined area, this demand can alter resource availability for other flower-visiting insects. This risk is particularly discussed in sensitive natural habitats, protected areas, certain urban environments, and flower-poor landscapes.

Mallinger et al. (2017), in a systematic review, examined the potential effects of managed bees on wild bees from three perspectives: competition for resources, indirect effects on plant communities, and pathogen transmission. Results are variable: some studies report negative effects, others none. Iwasaki and Hogendoorn (2022) note an increase in studies indicating negative effects of managed or introduced bees on wild bees. This literature argues for a precautionary approach, without justifying excessive generalisation.

Pathogen transmission is another sensitive point. Honey bees can harbour viruses, microsporidia, and other pathogens. Certain flowers can serve as meeting points between insects and become interfaces for transmission. Fürst et al. (2014) showed an association between honey bees and bumblebees for certain infectious agents, notably Deformed Wing Virus (DWV). This issue must be framed precisely: detecting a pathogen, demonstrating its active replication in a wild host, measuring its effect on an individual, and establishing an impact on a population are distinct levels of evidence. The presence of a virus in a bumblebee does not automatically mean that the virus is actively replicating there or causing disease.

The health of managed colonies is therefore not only a concern for the beekeeper. Good disease management in apiaries can also reduce the risks of pathogen circulation within pollinator communities. This does not mean that the honey bee is the primary cause of wild pollinator decline: the major factors remain habitat loss, agricultural intensification, pesticides, insufficient floral resources, climate change, and landscape fragmentation.

In the Swiss agricultural context, Agroscope showed that the potential geographical coverage of insect-pollinated crops by honey bee colonies is relatively good at the national average, but shows gaps in certain regions, particularly on the western Plateau and in Valais (Sutter et al., 2017). This indication concerns potential coverage by honey bee colonies, not wild bee species richness. It must therefore be interpreted with caution: low coverage signals a potential risk, but does not in itself prove yield losses due to pollination deficit.

The case of urban beekeeping also illustrates the need for nuance. Cities can host an interesting diversity of wild pollinators when they offer parks, gardens, brownfields, embankments, and a diverse flowering supply. But installing hives in cities is not automatically a biodiversity measure. If the number of colonies increases faster than the available floral resources, the potential competition with wild pollinators may intensify. The available urban studies — predominantly correlational — establish negative associations between hive density and wild pollinator activity, without always being able to establish experimental causality. They justify reflection on the floral carrying capacity of cities, but not a blanket condemnation of urban beekeeping.

The same caution applies in protected areas. These spaces often have the primary objective of conserving rare species, habitats, and ecological interactions. It is not a matter of claiming that all beekeeping is incompatible with all protected areas, but of recognising that the decision must be based on conservation objectives, the richness of wild communities, floral availability, and the period of hive presence.

For beekeepers, this discussion should not be understood as an indictment. Beekeeping has cultural, economic, educational, and agricultural value. But in an article devoted to pollinators, it is necessary to draw a clear distinction between the keeping of honey bees and the conservation of wild pollinators. These two objectives can be compatible, but they are not identical.

Does installing a hive help biodiversity?

Not necessarily. A hive can be useful for beekeeping, honey production, or the pollination of certain crops. But it does not create habitats for wild bees, does not provide nesting sites, does not reduce pesticides, and does not replace communities of wild pollinators. In certain contexts — particularly when floral resources are limited or colony densities are high — adding hives can intensify competition for nectar and pollen. To genuinely help pollinators, the priority must be to promote flowers, habitats, bare ground, hedgerows, extensive meadows, and environmentally sound land management.

5. Decline: Clarifying the Confusion

Distinguishing colony losses in managed bees, the decline of wild species, and the broader decline of certain insects.

Pollinator decline has become a highly prominent topic in the media and in public policy. But the common expression "bee decline" is often too vague. It can refer to very different realities: losses of honey bee colonies, the health of managed bee stocks, the decline of certain wild bee species, the decrease in other pollinating insects, or the more general decline of certain insect groups.

A false quotation, a genuine intuition

The sentence frequently attributed to Einstein — according to which humanity would have only a few years left to live if bees disappeared — is in all likelihood apocryphal: no reliable source makes it possible to attribute it to Einstein with certainty. As a quotation it is therefore poorly substantiated. Yet it recurs regularly in discussions about bees, because it expresses in striking terms a collective concern: if bees are in trouble, perhaps something is going wrong in our relationship with the living world.

The history of this phrase is instructive. Similar ideas were already circulating in the early twentieth century among naturalist writers such as Maurice Maeterlinck, who stressed the close links between bees and flowering plants. A cautious attribution to Einstein then appears in beekeeping literature in the mid-twentieth century, before the dramatic version of the "few years left" was widely taken up by beekeeping associations, environmental movements, and the media (Calaprice, 2010; O'Toole, 2013).

Bees do not herald the end of humanity. The general intuition nonetheless remains relevant when reformulated rigorously: honey bees can help detect certain environmental contaminations, while wild bees provide information about habitat quality, floral diversity, and the state of ecosystems. They are not oracles, but they constitute valuable indicators of how we organise our landscapes.

The first source of confusion concerns the honey bee. Apis mellifera is a species bred and managed by humans. Its colonies can suffer significant losses, in particular in connection with Varroa destructor, viruses, pesticides, nutritional deficiencies, beekeeping practices, or climatic conditions. These losses are a serious problem for beekeeping. But they do not mean that the honey bee is threatened with extinction as a species. Managed colonies follow the dynamics of a managed stock: they can be multiplied, moved, fed, treated, and replaced.

The situation of wild pollinators is different. Wild bees, bumblebees, hoverflies, butterflies, and other flower-visiting insects are not tended by humans. They depend directly on habitat quality, the availability of flowers, nesting sites, landscape structure, and environmental pressures. When a local population disappears, it cannot simply be "reconstituted" by artificial division. The decline of wild pollinators is therefore primarily a biodiversity issue.

The available studies show that trends are not uniform. Powney et al. (2019), in an analysis of 353 wild bee and hoverfly species in Great Britain between 1980 and 2013, document a significant net loss of occupied territory, with particularly marked declines among rare species or those tied to specific habitats. At the same time, some dominant crop pollinators increased. This paradox is important: the overall decline does not preclude an increase in common generalist species. The problem is therefore not that all pollinators are disappearing everywhere at the same rate, but that the composition of communities is changing, often to the detriment of the most specialised or rarest species.

Honey bees are not a good indicator of the state of wild bees. Wood et al. (2020) show, drawing on a European comparison, that the honey bee is not a reliable proxy for tracking wild bee decline. Even when certain pressures are shared — lack of floral resources, pesticides, pathogens, or climate change — responses can diverge strongly.

Red Lists provide a complementary form of information. They assess extinction risk according to defined criteria, without always directly measuring a temporal trend. In Switzerland, the Red List of Bees published by FOEN and info fauna is the national reference source for threat figures. It records 632 bee species known in Switzerland, of which 624 are included in the list. Of the 615 species evaluated, 279 — that is, 45.4% — appear on the Red List: 59 species are considered extinct in Switzerland, 24 as critically endangered, 84 as endangered, and 112 as vulnerable (Müller & Praz, 2024).

These figures concern wild bees, including bumblebees and cuckoo bees, but not the honey bee, which was not assessed in this context. Comparison with the first Red List of 1994 must also remain cautious. Overall proportions are similar, but the two lists are not directly comparable, as the new assessment is based on a much larger dataset and a different methodology. The Red List therefore informs primarily about the threat status of species, not about a simple temporal trend.

Another frequent pitfall is to confuse the decline of pollinators with the general decline of insects. Pollinators are part of the entomofauna, but they do not represent all insects. Some studies on the biomass of flying insects attracted major media attention, but they cannot be directly translated into specific trends for each pollinator group, nor generalised from a regional context to the whole of Europe.

This caution is also useful when interpreting recent Swiss data on insects. Neff et al. (2026) reconstructed the evolution of species richness for 595 species of saproxylic beetles and 216 butterfly species in Switzerland between 1930 and 2021. This study concerns saproxylic beetles and butterflies, not wild bees directly, but it illustrates the variability of trajectories depending on the group, region, specialist or generalist species, and the period examined.

Communication about decline must remain precise. For a beekeeper, the crisis may mean winter mortality, varroa, or disease pressure. For a naturalist, it may mean the disappearance of specialised wild species. For a farmer, it may concern the availability of a reliable pollination service. These concerns are related, but they are not identical.

This clarification has direct practical consequences. If one believes the problem is simply a lack of honey bees, the solution will appear to be installing new hives. If one understands that many wild species are declining due to habitat loss, lack of flowers, pesticides, and the disappearance of nesting sites, then priority measures change.

"Bee decline" — which bees are we talking about?

The expression "bee decline" is too imprecise. It can refer to losses of honey bee colonies, the decline of wild bees, the decrease in other pollinators, or the more general decline of insects. The honey bee is a species managed by humans; its colonies can be diseased or suffer significant losses, but the species is not threatened with extinction in the same way as certain wild species. To act correctly, it is therefore necessary to specify which group we are discussing.

6. Multiple Causes and Pressures: A Decline That Cannot Be Explained by a Single Factor

Explaining why the decline of many pollinators results from cumulative pressures rather than a single cause.

The decline of many wild pollinators cannot be explained by a single cause. It results from a combination of pressures that often act simultaneously: habitat loss and fragmentation, landscape simplification, agricultural intensification, pesticides, scarcity of floral resources, loss of nesting sites, climate change, pathogens, invasive species, and — for certain groups — light pollution. This multifactorial dimension is essential: looking for a single culprit leads to oversimplified diagnoses and inadequate measures.

Habitat loss is one of the best-documented factors. Pollinators need flowers to feed on, but also places to nest, develop, overwinter, and move through the landscape. An extensive meadow, a diverse hedgerow, a dry embankment, a woodland edge, a brownfield, an old wall, dead wood, or an area of bare ground can provide very different resources depending on the species. When these structures disappear, pollinators lose not only flowers: they also lose breeding sites, shelters, and ecological corridors.

Habitat fragmentation aggravates this problem. Olhnuud et al. (2025), in a meta-analysis of 80 studies in 28 countries, show that fragmentation is associated with a decrease in the abundance and species richness of insect pollinators. Reduction in habitat area emerges as a particularly important factor.

The simplification of agricultural landscapes also plays a central role. Extensive monocultures, the loss of hedgerows, the reduction of flower-rich meadows, and the intensive management of field margins reduce the diversity of available resources. A field may offer very abundant flowering for a few days, then become almost devoid of food for the rest of the season. Yet many pollinators need a succession of floral resources from early spring through to late summer or even autumn.

Nesting sites are often less visible than flowers, but equally important. Many wild bees nest in the ground, sometimes in bare, sandy, or sparsely vegetated areas. Others use hollow stems, dead wood, cavities, or walls. A landscape rich in flowers but poor in nesting sites does not always suffice to sustain a diverse community.

In Switzerland, the Red List of Bees confirms that the scarcity of food resources and nesting opportunities is a central threat factor. Wild bees need an abundant and diverse supply of flowers, continuous flowering during their flight period, sun-exposed microstructures for nesting, and short distances between nest and resources. The report notes that these distances can be very limited: approximately 100 m for small species and 300 m for large species (Müller & Praz, 2024).

The most vulnerable species include in particular floral specialists (oligolectic species), ground-nesting species, species flying in summer, and lowland species. The Swiss report shows, for example, that the proportion of Red List species is higher among oligolectic species, specialised in certain plant groups, than among polylectic species. It is also higher among ground-nesting than above-ground-nesting species. These figures underline the importance of specific floral resources, bare ground, and small-scale landscape structures.

Pesticides constitute another major pressure. Their effects depend on the substances, doses, timing of application, exposure pathways, and species concerned. Knauer et al. (2025) show, in a synthesis covering 681 cultivated fields on three continents, that pesticide risks and the decrease in semi-natural habitats additively reduce the abundance and species richness of wild bees. The study also highlights an important point: the presence of semi-natural habitats is not sufficient to compensate for the negative effects of pesticides. Restoring habitats is necessary, but does not remove the need to reduce chemical risks.

Climate change adds a further pressure. Changes in temperature, precipitation, and the frequency of extreme events can shift flowering periods, alter species ranges, and create mismatches between plants and pollinators. Some generalist or mobile species may adapt more easily, while specialised species may be more vulnerable. Climate does not act in isolation: its effects can be amplified by habitat fragmentation.

Pathogens and parasites constitute another factor to be considered. The health problems of the honey bee are well known to beekeepers. For wild pollinators, knowledge is more fragmentary, but several studies show that pathogens can circulate between species, in particular via shared flowers. This argues for rigorous disease management in managed colonies, without making it the sole explanation for decline.

Invasive species can also alter interactions between plants and pollinators. Certain exotic plants provide floral resources but may compete with native flora. Certain invasive animal species may predate pollinators. The magnitude of impacts depends strongly on local context and habitat function.

Light pollution constitutes a potentially significant pressure for certain nocturnal pollinators, in particular moths. Research on this topic is still developing and the evidence is less consolidated than for habitat loss or pesticides. This factor deserves mention, but with the caution warranted by the current state of knowledge.

Global syntheses confirm this multifactorial view. Potts et al. (2016) identify several major threats to pollinators, including land-use change, management intensification, pesticides, climate change, pathogens, and invasive alien species. Dicks et al. (2021) also emphasise the importance of changes in land cover and configuration, noting that the relative importance of factors varies by region.

The causes of decline cannot be reduced to pesticides

Pesticides are an important pressure for many pollinators, but they are not the only cause of decline. Habitat loss, the disappearance of flowers, lack of nesting sites, landscape fragmentation, climate change, pathogens, invasive species, and in certain contexts light pollution also play a role. A single measure rarely suffices. To support pollinators, several approaches must be combined: restoring habitats, increasing floral diversity, preserving nesting sites, reducing pesticide risks, and adapting measures to local context.

7. Taking Concrete Action: Habitats, Practices, and Considered Management

Translating scientific knowledge into concrete measures for beekeeping, agriculture, municipalities, private gardens, and citizens.

Protecting pollinators does not consist of applying a single measure. The preceding chapters have shown that pollinators need floral resources, nesting sites, ecological connectivity, reduced pesticide exposure, and — in certain contexts — considered management of bee stocks. Effective measures act simultaneously on several needs.

One fundamental recommendation emerges from the available scientific syntheses: before adding managed pollinators, the priority is to restore the living conditions of pollinators already present. The most robust studies identify the availability of floral resources, landscape quality, and the reduction of input-related risks as central levers (Dicks et al., 2021; Knauer et al., 2025; Potts et al., 2016).

In the Swiss context, practical priorities are very concrete: increasing the abundance and diversity of flowers, ensuring continuous flowering from spring to autumn, preserving sun-exposed microstructures for nest establishment, and maintaining short distances between flowers and nesting sites. Extensive meadows, dry grasslands, alluvial areas, gravel pits, ruderal sites, open woodland edges, embankments, areas of bare ground, dry stems, dead wood, and small-scale rock structures all play an important role.

For beekeepers

Beekeepers maintain colonies, produce honey, sometimes support agricultural pollination, and raise public awareness. From a biodiversity perspective, landscape-compatible beekeeping should take into account floral resources, colony health, local hive densities, and the sensitivity of habitats.

Maintain colonies in good health, in particular through rigorous monitoring of Varroa destructor, viruses, and other pathogens.
Avoid high hive densities at the same site, especially when floral resources are limited.
Adapt the number of colonies to the floral carrying capacity of the site.
Distribute apiaries rather than concentrating many colonies in one place, especially during periods of floral dearth.
Maintain adequate distance between apiaries and protected areas or sensitive natural habitats when conservation objectives require it.
Collaborate with farmers to plan treatment periods and maintain floral resources outside cultivated areas.
Avoid communicating that installing hives "saves the bees". A more accurate formulation would be: beekeeping can contribute to pollination and awareness-raising, but protecting wild pollinators depends above all on habitats, flowers, nesting sites, and the reduction of pressures.

For farmers

Agriculture can be a source of pressure on pollinators, but also part of the solution. Effective measures combine floral resources, nesting sites, and reduced input-related risks.

Establish or maintain diverse wildflower strips, with species suited to the soil and region, and with staggered flowering.
Manage wildflower strips over time. Albrecht et al. (2021) show that their effectiveness may decline if floral diversity is not maintained through appropriate management; renewal or adjustment of management may then become necessary.
Maintain extensive meadows, herbaceous margins, and flowering field borders.
Leave areas of bare, sandy, or sparsely vegetated ground for ground-nesting bees.
Retain dead wood, dry stems, embankments, dry-stone walls, and semi-natural structures.
Reduce pollinator exposure to pesticides: limit treatments to necessary situations, favour integrated pest management, and avoid treatments during flowering.
Take the surrounding landscape into account. The effectiveness of wildflower strips and agri-environment measures depends strongly on landscape structure and the quality of their implementation (Batáry et al., 2015).
Do not rely solely on hive rental to secure all pollination without simultaneously acting on habitat quality and input reduction.

For municipalities and local authorities

Municipalities manage parks, embankments, roadsides, cemeteries, schoolyards, and residual areas. These spaces can host significant pollinator diversity if they are conceived as habitats.

Introduce differentiated green space management with staggered mowing schedules.
Export mown material when the aim is to progressively impoverish the soil and promote a diverse flora.
Progressively replace little-used lawns with locally appropriate wildflower meadows.
Plant trees, shrubs, and perennials with staggered flowering periods, giving preference to native species.
Eliminate or strongly reduce pesticide use in public spaces.
Preserve areas of bare ground, embankments, old walls, dead wood, and microhabitats.
Reduce nocturnal light pollution where possible.
Integrate pollinators into planning frameworks, green corridors, and roadside management.
Regulate urban beekeeping when colony densities are high or floral resources are limited.

For private gardens and citizens

Private gardens can become valuable stepping-stone habitats for pollinators. A pollinator-friendly garden does not need to be left untended; it must offer a diversity of flowers, structures, and flowering periods.

Plant a variety of flowering plants, preferably native species, with flowering periods from early spring to late autumn.
Avoid double, heavily bred, or sterile flowers, which are often poor in nectar and pollen.
Refrain from using insecticides.
Leave dry stems standing over winter, maintain a small pile of dead wood, and keep areas of bare ground for ground-nesting bees.
Avoid tidying up too early in spring.
Use insect hotels with discernment: they can help certain cavity-nesting species, but only if they are well designed, well positioned, and accompanied by suitable habitats. They do not replace flowers, bare ground, or dry stems.
Avoid becoming an amateur beekeeper solely "to save the bees". This step has no demonstrated benefit for wild biodiversity and can locally intensify competition for floral resources.

Swiss example: the "Agriculture and Pollinators" project

In the cantons of Vaud and Jura and in the Bernese Jura, the "Agriculture and Pollinators" project proposed nine agricultural measures aimed at increasing food resources, reducing certain disruptive practices, and creating habitats for pollinators (Sutter et al., 2019). These measures include undersowing with legumes, leaving 10% of the area uncut when harvesting temporary grasslands, delayed mowing, refraining from certain insecticides, mowing without a conditioner, creating nesting structures, and maintaining areas of bare ground in vineyards with high natural biodiversity.

In the first year, 962 farms took part in the project. Nearly 1,000 ha of cereals were cultivated with legume undersowing, and more than 6,600 ha were covered by mowing without a conditioner. The project provides for eight years of scientific monitoring, including 300 honey bee colonies in 30 apiaries and monitoring of wild bees across more than 80 extensive meadows. This example demonstrates the value of an approach that brings together farmers, beekeepers, researchers, and institutions.

Practical conclusion: less symbolism, more habitat

Pollinator protection benefits from being very concrete. The most useful actions are not always the most visible. A meadow mowed later in the season, a diverse hedgerow, an open embankment, a reduction in insecticides, or a well-maintained wildflower strip can matter more for wild pollinator diversity than a well-intentioned hive.

The best strategy is to move from a symbolic logic to an ecological one. It is not enough to love bees; what is needed is to understand what pollinators require to live: diverse flowers, habitats, nesting sites, connected landscapes, and fewer pressures. Only on this basis can beekeeping, agriculture, municipalities, and citizens together contribute to genuine pollinator protection.

The actions that genuinely help pollinators

The most useful actions are often simple: plant a variety of useful flowering plants from spring to autumn, avoid insecticides, mow less frequently and in a staggered manner, maintain hedgerows, leave dry stems standing, keep some dead wood, preserve areas of bare ground, and limit impermeable surfaces. Installing a hive or an insect hotel can be useful in certain cases, but it never replaces a high-quality habitat. To help pollinators, the first step is to offer them what they need to feed, nest, and survive.

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