It is widely known that pollinators around the world are dying out, although many efforts are being made to save them. In Quebec, the tendency is to create a symbiosis between agriculture and beekeeping by introducing hives of honeybees, Apis mellifera, near market gardening crops. Although they are undoubtedly efficient in pollinating flowering plants, they are not the only ones at work! There are approximately 350 species of wild bees in Quebec alone that also contribute to the pollination of not only ornamental plants and vegetable crops, but also native plants.
Impressive, These Local Bees
Wild bees are less well known than honeybees, but no less important. Compared to their domestic cousins who reside in hives, nearly 70% of wild bees live in burrows under the ground, while 30% live in branches, holes in trees or in galleries left by other insects or small animals. Moreover, they do not produce honey. Some species of wild bees are very selective and will only forage on a limited variety of flowers, including native flowering plants. Other wild bee species, like honeybees, are not as selective and will forage on virtually any flower that provides nectar and pollen.
Wild bees and bumblebees have been shown to be more efficient pollinators on an individual basis. By producing vibrations while foraging, they are able to release, collect and transport larger quantities of pollen. Some cultivated plants, such as tomatoes and blueberries, are more efficiently pollinated by wild bees because of these vibrations. So why introduce honeybees near farmland?
With monocultures, an interest in commercial beehives has arisen, as wild pollinators are not sufficient for the task. Wild pollinators are deprived of a diversity of flowering plant species to forage on when there are endless fields of non-diverse vegetation. In addition, wild bees here travel substantially shorter distances than honeybees. Honeybees can travel a radius of 3 to 5 kilometers in search of nectar and pollen, compared to wild species that rarely leave a radius of more than 400 meters. The challenge of wild bees in the face of large monocultures is insurmountable for the less adventurous bees.
Honey bees also offer a major advantage to pollination and, consequently, to the agri-food industry: strength in numbers! Indeed, honeybees live in numerous colonies that can vary from 40,000 to 80,000 individuals compared to wild bees, which are mostly solitary.
The introduction of commercial beehives offers market gardeners allies without whom our eating habits would be very different today. For the time being, the honeybee is the champion of pollination in our agricultural lands. However, a devastating scourge is currently affecting hives of honeybees, which are experiencing massive population declines, called hive collapse syndrome, caused by the presence of neonicotinoids in pesticides applied to crops. To make the problem more complicated, add to the list of threats: degradation of natural habitats, reduction of biodiversity, contamination of water sources, parasitic infections, and so on!
Wild Bees to the Rescue!
There are several strategies that can be put in place to encourage the presence of wild bees near fields. Some vegetable producers are currently collaborating on studies to find alternatives to the introduction of commercial hives. Valérie Fournier, professor of agricultural entomology at Laval University, is interested in the use of Osmia tersula, a wild bee, for the pollination of fruit and greenhouse crops.. By pollinating our crops with such wild bees, we limit the introduction of honeybees.
Another study conducted by Mathilde Tissier, a postdoctoral researcher under the supervision of Valérie Fournier, is looking at the implementation of flower strips in crop environments. For native pollinators, integrating flowering plants into fields in this way could provide a much more inviting and suitable environment than monocultures. Choosing the most appropriate wild species for each crop is not an easy task, as native pollinators have specific needs. Among other things, they will need to find suitable nesting areas in the vicinity of the crops, in an adequate climate, offering sufficient food, and giving a helping hand (or wing!) to the producers.
In addition, the foraging period of wild bees is sometimes very short and specifically synchronized with the flowering of native plants. For example, the genera Andrena and Lasioglossum, two types of spring bees, forage on the flowers of native plants such as willows (Salix), cherries (Prunus) and raspberries (Rubus). Their activity period is earlier than that of honeybees. However it is much less extensive throughout the summer period. The matchmaking between wild pollinators and vegetable crops is a major challenge!
On a Smaller Scale
Whether in an urban or rural setting, there are many simpler and more accessible ways for avid gardeners to attract pollinators to their homes. Adding a variety of flowering plants, especially native flowering plants, is an easy solution to declining populations. In addition, planting several species of plants with different blooming times offers food resources from spring to fall, providing a rich environment for our precious allies.
Reduce your interventions in the garden as much as possible. Insects overwinter in plants that die in the fall and in organic debris such as dead branches, as well as in soil. Therefore, refrain from doing a fall clean-up and keep dead leaves on the ground. If you don’t need to, don’t disturb the soil to avoid killing the insects in it. In the spring, wait a few weeks after the risk of frost has passed before cleaning up your flowerbeds, or don’t do it at all. You need to give pollinating insects time to come out of their winter slumber. Access to water is also an important factor in the survival of our little friends.
And in the Long Term?
The root of the problem lies in the way we cultivate the farmland. For Nicolas Derome, a professor in the Department of Biology at Laval University, reinventing farming strategies would make it possible to eliminate many of the obstacles to the pollination of the plants on which we depend so much to feed ourselves. Eliminating monocultures and favoring a diversity of crops on a given area could be a more sustainable and ecological solution to food production. Although complex to implement in the short term, this solution holds the promise of a more harmonious and balanced relationship with our food-producing lands. Rome was not built in a day, but it is still standing!