Hoover: Reliable and Effective Use of Managed Bees for Canola Pollination
Date: March 2017
Term: 3 years
Status: Completed
Researcher(s): Shelley Hoover, Alberta Agriculture and Forestry; Steve Pernal, Agriculture and Agri-Food Canada (AAFC) Beaverlodge; Ralph Cartar, University of Calgary, Andony Melathopoulos, University of Oregon
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
The abundance of pollinators in canola fields have the potential to boost yields and improve seed quality. Researchers and industry are interested in understanding pollination efficiency and economic value, how to optimize managed bees for canola hybrid-seed production and to learn more about bee behavior and health and contributions of other pollinators. Through a three-year field study in Alberta, several surveys and experiments were conducted to investigate the impact of pollinators on canola yield and pollination efficacy, and to generate a better understanding of bee behaviour. Overall, the various trials showed that managed pollinators benefit commodity and hybrid canola seed production, yields and quality at the same time as providing economic benefits to beekeepers through pollen and honey production.
In a three-year field study in Alberta, several surveys and experiments were conducted to investigate the impact of pollinators on canola yield and pollination efficacy, and to generate a better understanding of bee behaviour. In 2014 and 2015, surveys were conducted around Lethbridge and Grande Prairie in commodity canola fields to determine pollinator diversity and abundance. Surveys were conducted in about 30 fields each year at the two locations, at four distances from the field edge (five, 20, 100 and 400 metres into the field).
The results showed that in commodity fields stocked with honey bee hives, honey bees were the dominant flower visitor, followed by large flies (Muscidae, Anthomyiidae, Calliphoridae), hoverflies (Syrphidae), and wild bees. In unstocked fields, large flies were the dominant flower visitor. Although honey bees dominated in both the north and south, there were also distinct differences in the pollinator communities. While bee abundance declined with distance from the field edge, pollen deposition on flower stigmas did not decline, indicating that bee pollination accounts for only a portion of the total pollen deposited on stigmas in these commodity canola fields. Researchers also compared open-pollinated and wind-pollinated plots (caged to exclude pollinators). A preliminary analysis suggests that seed set did not continue to increase beyond 100 grains of pollen per stigma across the field. Therefore, although the open-pollinated plots had significantly more pollen per stigma than the wind-pollinated plots, overall there was no difference in seed set because both plots exceeded 100 pollen grains per stigma.
Researchers also evaluated the behavior of leafcutter and honey bees in seed-production canola fields in 2015 and 2016 to determine the effect of the presence of another bee species on foraging behaviour and whether nectar or pollen foraging honey bees are more effective pollinators in hybrid canola. The results showed a decline in pollen deposition and seed yield the further the distance from the honey bee hives into the seed production fields. This indicates that honey bees likely play a larger role in pollen deposition in the seed fields than in the commodity fields, and that role is present despite the activity of leafcutter bees in all the hybrid seed study fields. As well, placement of pollen on a pollinator's body rather than body size may reflect effectiveness of pollen deposition. Overall, female leafcutter bees, which hold their pollen on hairs located on their abdomen, were the best at depositing pollen, and were more effective at pollen deposition than honey bees and male leafcutter bees (who have much less substantial abdominal hair).
In another trial, researchers examined different factors that could influence pollinator (managed and wild) visitation to male and female hybrid canola bays in seed production fields, and how this affected pollinator movement between the bays. The results show that managed pollinators (honey bees and leafcutter bees) were not negatively influenced by pollinator density, suggesting they are more influenced by resource consumption rather than the direct presence of competitors. As well, honey bees switched bays less than leafcutter bees and pollen foragers switched less than nectar foragers. Leafcutter bees were the most willing to switch to the male bay, while honey bees were less likely to move from the male bay. Although wild pollinators may not contribute directly to pollination due to a low presence, they may still contribute to hybrid canola pollination by inducing more movement between the male and female flowers.
Researchers also compared the performance in hybrid canola pollination of two units of hives currently managed by beekeepers: singles (one honey bee brood chamber) and doubles (two brood chambers). The research found that singles could be included in hybrid canola pollination in addition to doubles, as long as a similar stocking rate of number of frames of bees per acre is met.
Another component of the study assessed the effects of hybrid canola pollination on honey bee colony health and productivity (pollen and honey), comparing two apiaries of colonies (40 in each), leaving half of each colony at the home location and moving the other half (20 each) to a canola pollination field. The results showed that the health of the colonies, based on the levels of Nosema infections, Varroa mite levels and queen loss, varied between the two source apiaries, but not the colony location. As well, over the short-term, pollen trapping during an abundant pollen flow had no impact on brood production or colony health, but had positive implications for hybrid-seed production because the bees spend more time gathering pollen and therefore pollinating more female flowers.
The study also showed that the use of pollen traps generated higher profit per colony due to the higher price garnered for bee pollen than for honey. In contrast, honey production was significantly less from colonies that were used to pollinate hybrid canola seed fields than colonies that stayed in their home apiary, however the magnitude of this effect will vary with the location of the ‘home’ apiary or honey production site, and among years. Overall, managed pollinators benefit commodity and hybrid canola seed production, yields and quality at the same time as providing economic benefits to beekeepers through pollen and honey production.
Scientific publications
Ovinge L, and Hoover S (2018) Comparison of honey bee (Hymenoptera: Apidae) colony units of different sizes as pollinators of hybrid seed canola. Journal of Economic Entomology 111(4):1535-1541. https://doi.org/10.1093/jee/toy155
Hoover S and Ovinge L (2018) Pollen collection, honey production, and pollination services: Managing honey bees (Hymenoptera: Apidae) in an agricultural setting. Journal of Economic Entomology 111 (4):1509–1516. https://doi.org/10.1093/jee/toy125
Full Report PDF: Reliable and Effective Use of Managed Bees for Canola Pollination