Written by Nathen B. Muckatira

Introduction

As one of the most well-known services provided by an array of winged species, pollination plays a crucial role in any agricultural practice. Pollination is the interaction between pollinators and plants. Pollinators are animals that induce the transfer of pollen from the stamen of one flower to the pistil of another flower (Ghazanfar et al. 2016). This interaction is mutually beneficial, as both groups rely on each other to flourish (Marshman et al. 2019). The primary benefit to the plant is the ability to sexually reproduce over larger areas, while the pollinators profit from the vitamins, lipids, sugars, and amino acids in nectar (Ghazanfar et al. 2016). Pollinator behaviours and anatomy enable them to collect and deliver pollen from one plant to another (Marshman et al. 2019), all of which constitute a staple diet of most pollinators.

Globally, pollinators assist in producing fruit and seeds in approximately 88% of all flowering plants (Sponsler et al. 2019).  In Canada, pollinators are in great demand as some crops depend on biotic pollination. One example is the Lowbush blueberry (Vaccinium angustifolium), which relies heavily on insect pollination for greater yields (Serres et al. 2014). Canada’s vast diversity in biomes allows the country to host a large variety of pollinators.  Insects tend to contribute the bulk of the pollination services along with some contribution from bats and birds. Bees are particularly specialized for pollen transport and account for the majority of pollination in wild and cultivated plants (Sponsler et al. 2019). While bees might play a dominant role in pollination, other pollinators are required for a more holistic pollination system. Organic agricultural practices facilitate the implementation of such a system and create a mutually beneficial structure for both parties involved.

Bees (Apis)

Insects are often synonymous with pollination, and bees are the most popular pollinator to both the general public and farmers. As mentioned, bees are specialized to collect, transport and deliver pollen and conduct approximately 70% of biotic pollination (Marshman et al. 2019). Thus, they are an attractive option for farmers looking to increase pollination activity on their land. One of the most commonly used bees is the honey bee, Apis mellifera. Honey bees can scout nectar sources within a 1-kilometre radius of their hive (Bishop et al. 2020). However, when floral resources are limited, bees may travel more than 10 kilometres for nectar (Bishop et al. 2020).  While honey bees are a staple in biotic pollination, other pollinators and other species of bees can be overlooked.

Types of bees

At the moment, honey bees are the most commonly managed pollinator. A significant portion of North American monocultures rely heavily on the pollination services that European bees provide (Marshman et al. 2019). However, dependence on only honey bee colonies has posed some serious disadvantages. The reasons behind these problems can be quite similar to those experienced with conventional mono-cropping systems (Marshman et al. 2019). This has opened the door for local farmers to experiment with a wider variety of pollinators.

Native bee species tend to be the next best alternative. Canada alone is home to 850 species of native pollinators, the majority of which are solitary bees that prefer to nest in the ground rather than in hives (Marshman et al. 2019). The diversity of native bee species in Canada can alleviate dependence solely on honey bees for pollination (Serres et al. 2014). For example, the genus Bombus contains a significant amount of Canada’s native bee species. This genus is known to perform floral sonication, a process in which the female bee uses her mandibles to chew at the anthers or corollas (Marshman et al. 2019). This is followed by the contraction of the bees’ indirect flight muscles to generate a sufficient vibration to cause pollen to be released from the tubal structures (Cardinal et al. 2018). Honey bees lack this ability and, therefore, are not as efficient in pollinating plants that require floral sonication (Marshman et al. 2019). Bees like the bumblebee, Bombus Latreille, and the mining bee, Andrena fabricius, that commonly perform floral sonification are capable of depositing 6.5 times more pollen per visit than honey bees (Serres et al. 2014). As with native bee species, some non-native species are used as alternatives to the honey bee.

One such species is the lucerne leafcutting bee, Megachile rotundata. Originating from Europe, these bees arrived in North America in the 1940s (Merfield 2016). Lucerne leafcutting bees are growing in demand, as they not only specialize in the pollination of alfalfa but also aid in the pollination of cranberries, oil seed rape, and blueberries (Merfield 2016). Currently, in Canada, 50% of all oil seed rape production is assisted by lucerne leafcutting bees.  Some vegetable seed crops, such as carrots, are often challenging to pollinate. However, there are signs indicating that lucerne leafcutting bees can perform better at pollinating such crops than honey bees (Merfield 2016). The recent surge in demand for lucerne leafcutting bees has meant that beekeepers who choose to delve into the management of this newly adopted species as a pollinator must consider their difference in husbandry to the honey bee. Unlike honey bees, lucerne leafcutting bees tend to live solitary, but are gregarious when foraging (Merfield 2016).

Plants Pollinated by Bees

There is a wide array of plants naturally locked in this mutually beneficial interaction with pollinators. In the case of bees capable of floral sonication, agricultural produce of the greatest appeal includes blueberries, cranberries, kiwis, chilli peppers, eggplants, and tomatoes (Cardinal et al. 2018). This is evident in the lowbush blueberry fields in Lac-St-Jean, Quebec, where blueberry producers constitute Canada’s largest hive renters (Serres et al. 2014). Meanwhile, flowering plants often considered weeds are an important source of nectar for a great portion of pollinators (Serres et al. 2014). Many wild pollinators are generalists and will forage for a greater variety of native plant species (Marshman et al. 2019). Other pollinators are considered specialists, implying that pollen collected by these pollinators only comes from a specific plant with which they have a mutually beneficial relationship (Marshman et al. 2019). Hence, a recent surge in demand for the encouragement of wild pollinators on farmlands.

Other Pollinators

Although bees provide a significant portion of pollination services, there is a wide array of contributing species. The differing behaviours and physical features enable these pollinators to service plants that might not be suited for bee pollination. While flower preference differs between hummingbirds and bumblebees, the two pollinators have been observed foraging on the same plants at times (Bishop et al. 2020). Furthermore, they add to the biodiversity within an area, creating a richer ecosystem.

Hummingbirds

Hummingbirds are one of the larger winged pollinators in Canada. These birds’ beak structures enable them to extract sugar-rich nectar from larger flowers. The Fraser Valley in British Columbia (BC) hosts a variety of hummingbird species. Some of the most commonly found species include the Rufous (Selasphorus rufus), Anna’s (Calypte anna), Calliope (Selasphorus calliope), Black-chinned (Archilocus alexandri), and the Ruby-throated (Archilocus colubris) hummingbirds (Bishop et al. 2020). Each species differs in terms of its beak structure and length, which makes hummingbirds specialist pollinators, only able to feed from plants with flowers that correspond with the beak structure of the bird. Pollen transfer occurs as a result of pollen rubbing off onto the bird’s body from the anther. When the hummingbird moves to forage on another flower, pollen is rubbed off onto the stigma. Although not as prolific at pollinating as bees, hummingbirds provide pollination services to other plants that may not be of interest to bees.

Butterflies

Another pollinator that has gained a following in recent years is butterflies. The growing demand for insect pollinators is expected to increase, as a result of the struggles faced by the beekeeping industry (Serres et al. 2014). Butterflies are a reliable solution to this problem. As with bees, the lives of butterflies and the plants they pollinate are interlinked (Ghazanfar et al. 2016). If the population of one were to decline, so would the population of the other. However, unlike bees, butterflies often migrate over long distances, allowing the transfer of pollen between plants located far apart from each other (Ghazanfar et al. 2016). This further encourages genetic variation among plant species and, in doing so, increases the resistance of these plants to diseases (Ghazanfar et al. 2016). The different species of butterflies have varying proboscis lengths and, similar to the difference in hummingbird beak length, this enables different species of butterflies to pollinate different flower types (Ghazanfar et al. 2016).

Threats to Pollinators

In addition to global climate change, certain agricultural practices have been shown to adversely impact pollinator diversity and abundance. Failing to act on such an issue could bring detrimental impacts to produce, farmers, and the environment.

Conventional Agriculture

Agricultural intensification results in the degradation of natural habitats and has contributed greatly to the effects on pollinators among other organisms (Batáry et al. 2013; Andersson et al. 2012). The foraging area of most pollinators forces interaction with human landscapes and results in frequent encounters with harmful chemicals commonly implemented in conventional systems (Sponsler et al. 2019). Unlike organic agriculture, mass production under conventional systems utilizes synthetic pesticides and herbicides specifically designed to protect crops from organisms considered threats to yield. Neonicotinoids, in particular, draw a lot of attention, for their known effects on non-target terrestrial and aquatic species (Bishop et al. 2020).  Neonicotinoids are often used as insecticides to protect crops from pests. The effects they have on insect pollinators are significantly worse than they are for birds and mammals. Neonicotinoids come in different forms, including  Imidacloprid, Clothianidin, and Acetamiprid,  all of which have the same lethal effects on insect pollinators (Bishop et al. 2020). Imidacloprid in particular has been observed in honey bee nectar at levels capable of sublethally affecting foraging and nesting efficiency (Bishop et al. 2020). In BC, between 2017 and 2018, neonicotinoid concentrations were observed in hummingbirds, honey bee nectar, as well as in water bodies and soil neighbouring regularly sprayed blueberry fields (Bishop et al. 2020). Even though the substance is sprayed on the plants, run-off affects many potential pollinators, including various beetle species that reside in the soils and among leaf litter.

Neonicotinoids are not the only substance that poses a serious threat to pollinators. Another chemical substance of a similar nature is Flupyradifurone, a type of butanolide that has recently been introduced to the agricultural industry (Bishop et al. 2020). In Canada, the use of the substance is most prominent in BC and Saskatchewan and is commonly used on crops including berries, vegetables, and cereals (Bishop et al. 2020). A study by Bishop et al. (2020) examined the cloacal fluid of 49 hummingbirds, of which 26.5% contained Flupyradifurone (Bishop et al. 2020). The majority of the birds observed to have traces of the substance were found near sprayed blueberry fields in the Fraser Valley (Bishop et al. 2020).

With the majority of these chemicals being insecticides, honey bees in particular are under the greatest threat from foraging in chemically treated fields. This has caused significant losses to beekeepers and the blueberry industry, forcing a change in focus to alternative pollinators (Bishop et al. 2020). However, native bees are also under serious threat from the use of neonicotinoids (Bishop et al. 2020). This has highlighted the biggest downfall of relying solely on honey bees as managed pollinators, that being the vulnerability to the effects of the same threat, as commonly experienced with monocultures (Marshman et al. 2019). In this case, pesticides are not the only threat, but diseases as well increase. Both have the potential to wipe out whole colonies (Marshman et al. 2019). This is accomplished via the horizontal transmission of a disease from individual to individual of the same generation (Marshman et al. 2019). At the moment, this is the biggest threat facing Canadian beekeepers.

Other agricultural practices in the form of ploughing and the use of monocultures increase the negative impacts on local biodiversity as well. This is due to the degradation of nutritional diversity in the soil, which in turn correlates with the decline in pollinator abundance (Serres et al. 2014). The transition from unimproved natural land to managed pastures has been identified to have a significant impact on butterfly populations (Ghazanfar et al. 2016) thus further contributing to butterfly loss caused by herbicide use on cereal crops (Ghazanfar et al. 2016). Furthermore, exposure to chemical substances can still affect pollinators of organic fields, especially when these fields are close to conventionally managed systems (Bishop et al. 2018). This complicates the issue at hand, as a solution must consider proximity to conventional systems as a variable.

Organics in Alleviating Threats to Pollinators

One fundamental rule in organics is the absence of pesticides, herbicides and other synthetic chemicals in the everyday management of crops. Instead, organic producers depend on biological methods of pest management, natural chemicals like lime sulphur and crop rotations with nitrogen-fixing plants (Sponsler et al. 2019; Andersson et al. 2012). Such practices contribute towards the paradigm referred to as Integrated Pest Management (IPM). IPM aims to create a balance between pest control and the well-being of humans and the environment (Sponsler et al. 2019). In doing so, IPM encourages the use of non-chemical methods to reduce the damage to non-target species (Sponsler et al. 2019). This plays a huge role in alleviating threats to pollinators. Organics often accommodate richer biodiversity, which is more inclusive of pollinators in the region (Batáry et al. 2013).

Organic practices not only support greater species richness but also improve the resources and functions associated with the local ecosystem (Batáry et al. 2013). This creates a holistic approach inclusive of the various components of an ecosystem and their dependence on other components to flourish. Organic farming has been observed to benefit several taxonomic groups (Andersson et al. 2012), often resulting in the stabilization of the population of species occupying different trophic levels. For example, the absence of herbicides ensures the presence of some flowering weeds that produce nectar commonly consumed by a variety of pollinators, encouraging the presence of an array of pollinator species (Batáry et al. 2013). Thus, organics provides a framework in which pollinator richness permits the improvement within community composition, frequency of visits, and foraging behaviours (Andersson et al. 2012). As observed by Andersson et al. (2012), pollination rates increase in a relatively short time following the conversion of a conventional system to an organic system. In their study, the change in pollination rate was indicated by the increase in butterfly richness and abundance, a clear sign of the improvements such a transition has on the health of a system from a bottom-up perspective.

Effect of Pollinators on Organic Agriculture

The relationship between organic agriculture and pollinators is mutually beneficial. because the well-being of one requires the well-being of the other. As mentioned, an organic approach significantly benefits pollinators. The same can be said when roles are reversed. According to a study conducted by Batáry et al. (2013), biotic-pollinated plants were observed to perform better than abiotic-pollinated plants under organic conditions, thus supporting the general idea that abundances of biotic-pollinated plants correlate to the pollinator species richness and abundance (Andersson et al. 2012).

Even though a great portion of major crops do not depend on pollinators, a significant amount of the nutrients we receive are sourced from crops that rely heavily on pollination services (Andersson et al. 2012). One such plant is the strawberry, which is dependent on a rich composition of pollinator communities (Andersson et al. 2012). A rich composition entails individuals of different sizes. In the case of strawberry plants, smaller bees tend to pollinate the bottom parts of the plants, while larger bees pollinate the upper parts (Andersson et al. 2012). Furthermore, Andersson et al. (2012) observed that organically grown strawberries that were biotically pollinated lacked malformations, and exhibited a greater proportion of fully pollinated berries than those plants grown under conventional methods and lacked biotic pollination activity. The conversion from conventional to organic practices allows an increase in pollinator numbers and functionality which in turn improves pollination services, leading to increased yield quantity and quality (Andersson et al. 2012).

Organics without Pollinators

The absence of pollinators would be detrimental to the success of organic agriculture. Without one to support the other, the mutually beneficial relationship is broken and would require significant efforts to replicate the responsibilities of pollinators. For example, reduced pollinator diversity would induce the loss of pollinator-dependent plant species, specifically, those plants that have coevolved with pollinators (Marshman et al. 2019) and require them as the sole mode of reproduction. This scenario has not only been speculated but is currently in progress. Declines in pollinator populations have been the main driver behind recent pollination deficiency in crops (Andersson et al. 2012).  In addition, we could expect to experience none of the beneficial interactions between pollinators and organic agriculture, as previously discussed.

Encouraging Pollination: Community Approach

Due to the current path, we find ourselves on, more focus is required to ensure pollinator services continue and pollinator populations are preserved and a multitude of approaches can be adopted. One of the most promising is the “Whole-of-Community (WOC)” approach. In this approach, emphasis is placed on a community that takes into consideration all biotic components present (Marshman et al. 2019). The WOC approach builds upon the idea that social and natural aspects are co-constitutive within a collection of networks (Marshman et al. 2019). In doing so, the approach relies on the collaboration among community members to force action in support of, in this case, the preservation of pollinators and the services they provide.  This approach stems from the understanding that the community itself represents a public resource. Anything that can benefit community members must require a collective effort to ensure that it happens (Marshman et al. 2019). With the sheer volume of the ecosystem services provided by pollinators, their presence within any community is of high importance, and must therefore be of considerable importance.

Research conducted in the Laurier Centre for Sustainable Food Systems in Waterloo, Ontario, has identified a recent growth in the “Bee City” initiative (Marshman et al. 2019). The initiative relies on a WOC approach, to involve more individuals, groups and organizations to truly reflect the “city” aspect of the initiative. The city of Toronto, Ontario, is a “honeypot” for bees with 420 of the 850 Canadian species located within its boundaries (Marshman et al. 2019). This was the reason behind pollinator enthusiast and environmentalist, Shelly Candel’s successful attempt at introducing Toronto to the Bee City initiative (Marshman et al. 2019), eventually resulting in the adoption of the Bee City initiative by other cities. In 2019, Canada had 23 Bee Cities (Marshman et al. 2019). In abiding by the WOC approach, establishing a city as a Bee City involves an agreement to be signed between the respectful municipality and First Nation community (Marshman et al. 2019).

The main goal of the Bee City initiative is to find the balance between the preservation of pollinators and economic and social objectives (Sponsler et al. 2019).  To find this balance, decisions must be made that take into consideration the perspectives of all relevant stakeholders and community members (Sponsler et al. 2019). Moreover, this approach will not only spread awareness but also possibly encourage more people to participate in activities that strengthen the mutually beneficial relationship between bees and plants. One major possible outcome is the transition from conventional agriculture to organic. This may occur at various levels and might motivate individuals without large areas of land to make use of green roofs consisting of organic systems. This can be accomplished via the inclusion of bee hotels. Following its establishment as a Bee City, Toronto had almost 600 bee hotels installed in 3 years (MacIvor and Packer 2015). However, in the case of large-scale farmers looking to make the transition, an Agri-Environment Scheme (AES) could be implemented. An AES is designed to compensate farmers who are bound to experience a loss in transitioning to a less intensive form of production (Batáry et al. 2013), as long as the outcome involves proven benefits to local biodiversity and the ecosystem (Batáry et al. 2013). The transition from a conventional system to organic does fit the criteria and would encourage more producers to make the transition.

Diversifying Pollinator Management

With the recent struggles faced by honey bee colonies, it would be of utmost importance to investigate and experiment with alternatives. This should not devalue the crucial contribution honey bees provide to the global food industry. However, any efforts should prioritize the health of other pollinators, including native bee species that lack breeding programs of any real value. According to MacIvor and Packer (2015), mason bees, Osmia rufus, and lucerne leafcutting bees have been successfully nested in bee hotels (MacIvor and Packer 2015). This would make it possible for individuals looking to transition into organics to simulate the holistic approach often associated with the practice right in their backyards, permitting the mutually beneficial relationship between pollinators and organics to occur.

Conclusion

Biotic pollination supports 88% of all plant species (Batáry et al. 2013) and is a key ecosystem service to many agricultural practices. However, with greater adoption of intensive agricultural practices, especially in the form of conventional agriculture, pollinators have experienced significant declines in foraging activity and population (Batáry et al. 2013). On the other hand, the rules followed by organic agriculture create optimal conditions for pollinators, therefore creating a mutually beneficial relationship between pollinators and organics. Further promotion is required to ensure the preservation of pollination services and, in turn, crop yield in organic agriculture. Such a feat requires a collective approach in which synergies between social, human and natural capital are balanced (Marshman et al. 2019).

References

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