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Photo by Wimverhagen1005 | Dreamstime.com
Bee on bellflower
Nettle-leavedbellflower visited by a european honeybee.
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Bee Garden
Research garden at the BC Cranberry Research Farm.
To turn flowers into food, most fruit requires the efforts of insect pollinators and European honey bees are the work horse of agriculture. But is the labour of the European honey bee enough? Can their work be supplemented and assisted?
Recognizing the importance of insect pollination to the food system, researchers set out to determine if a bumblebee-specific garden could encourage native pollinators to become helpers in cranberry production by offering some of the insect’s favourite choices for nectar before and after cranberry bloom.
The study, overseen by Renee Prasad of E.S. Cropconsult Ltd., began at the B.C. Cranberry Research Farm in 2014 when a number of plants were used to create a 2 by 20 meter bumblebee garden. She found previous studies indicated cranberry pollination is most efficiently done by bumblebees and that native bumblebees could supplement rented European honey bee pollination services.
“The goal of this garden is to provide growers with a single site where they can observe the growth and appearance of various plants and to collect data on the activity of bumblebees in the garden before and after cranberry bloom,” Prasad notes in her 2014 report.
Bumblebees need certain things to stay in an area and make it home. First, they need a supply of food. Growers want this to come from cranberry blooms, but there must be food available both before and after bloom as well. Shelter is also necessary for hive building as well as to provide a place for the queen to overwinter. This is often accommodated in tall bunching grasses, abandoned rodent holes and trees.
“Growers can also provide these resources to ensure bumble bee populations are maintained around their farms,” Prasad says in her 2015 report.
Both the 2014 and 2015 reports are available at bccranberries.com under the, ‘For Growers’ tab, notes Heather Carriere, manager of the BC Cranberry Marketing Commission.
While plenty of information exists on establishing bumblebee gardens, making it specific to cranberry growers and creating a step-by-step format, with the potential for adaptation to other fruits and berries was the challenge. Prasad used plants recommended in the 2000 study by Boss and Henderson to encourage bumblebees pre-cranberry bloom in one half of the garden and post-bloom in the other half.
From the work of Boss and Henderson, Prasad determined which plants would provide food at the right time, offer the nectar bumblebees want most and produce the flowers that attract bumblebees. Once the garden was planted, researchers observed a few species of bumblebees, other pollinators and pest behaviours in 15-minute observation periods within the garden, in the cranberry field and in the nearby Himalayan blackberries.
Pre-bloom, results from the two-year study found early blooming rhododendrons (PMJ Compacta and Red Eye) and heather (Kramer’s Red and Phoebe) were visited most often. Visits to the garden during cranberry bloom were low, but the most popular visiting location aside from the cranberry fields was the Himalayan blackberries. Post-bloom found catmint (Dropmore Blue and Walker’s Low), sedum (aka: stonecrop) and summer-flowering heather (Flamingo) were the most popular.
Renee Prasad
Renee Prasad of E.S.Cropconsult Ltd.
In her report Prasad notes plants must be well established and drought tolerant to gradually increase native bumblebee populations.
Additionally, Prasad notes Ceanothus (aka: soap bush or California lilac), Callicarpa (aka: beautyberry) and Campaula (aka: bellflowers) could be early indicators for pests like Dearness scale and cranberry fruitworm. By observing pest populations in and around indicator plants, crop monitoring and management become easier and potentially more successful.
“The cranberry industry is fortunate in that its growers support research development and projects,” Carriere says. “These kinds of studies are important to growers to take the learnings back to their farms to possibly make strategic changes to their practices in an effort to improve fruit quality and yields.”
Funds for the studies were provided by Investment Agriculture Foundation of BC. As the plants are now established, ongoing monitoring can occur easily without additional funding for planting. Results, while specific to bloom times of cranberries, help other berry growers look to plants that provide nectar to bumblebees both pre and post bloom to encourage native pollination activity. ■