Features Agronomy Insect Pests
A honey of a partnership

Bees are key to hybrid seed canola production, and they can also help bump up commodity canola yields. Photo by Azara Effect Productions.

While bees are busily feeding on the pollen and nectar in canola fields and producing honey, they are also playing a vital part in canola production. Alberta researchers are exploring ways to further advance the bee-canola partnership, but growers can take steps right now to help bees that are helping their canola crops.

Insect pollinators are essential for hybrid seed canola production so managed bees are used to pollinate these crops. “Our entire seed stock depends on honey bees and leafcutter bees,” says Gregory Sekulic, agronomy specialist with the Canola Council of Canada (CCC) in Alberta’s Peace Region. “About 80,000 colonies of honey bees pollinate seed crops in southern Alberta – that’s one in every eight hives in Canada. Canola seed production is the largest contract user of bees for pollination services in Canada.”

Bees also help bump up commodity canola yields. Shelley Hoover, apiculture researcher with Alberta Agriculture and Forestry, says, “Honey bees, other bees and other pollinators can contribute to the yield of commodity canola through increased pollination. The extent to which they benefit yield seems to depend on their abundance, the variety of canola, and other environmental factors including farm management practices such as fertilizer, weather and so on.”

Some good quality research suggests fairly substantial increases in canola yields from using managed bees. According to Sekulic, some of the highest documented increases are up around the 45 per cent range, but those trials tend to be cage trials – a caged canola plant with bees compared to a caged plant without pollinating insects. “However, we don’t see such high yield increases out in the general landscape, so a lot of the yield gap must be made up for by wind pollination and by the vast suite of native pollinators,” he notes. “We expect somewhere between almost no yield increase and probably a 10 to 12 per cent increase at higher stocking rates of bees.”

Along with increasing yields, bees may shorten the crop’s blooming period and reduce green seed counts because of their efficient pollination of the crop. “Some really interesting work out of Quebec with very high stocking rates found that bees shortened canola’s flowering window by 3.8 days over the course of their trial,” Sekulic says. “Since canola flowers for 20 to 25 days or so, taking four days out of that window is pretty big in terms of maturity. But that trial had three hives per hectare. [To have such a high bee stocking rate for Canada’s commodity canola crops] would require about 100 times more bees than we have in Canada right now, so it is not feasible; that high amount of bees would only be required for the 21-day flowering period and then the beekeepers would have the cost of feeding them for the rest of the year.”

Canola crops are also very good for beekeepers and their bees. “Canola is a nutritious crop for bees both from a protein perspective in the pollen and the amount of nectar that canola creates for honey. About 70 per cent of Canada’s honey comes from canola feedstock. Canola yields a lot of honey and that honey is good quality,” Sekulic says.

He adds, “I think the thriving states of both the canola and the beekeeping industries really show that we are working and growing together.”

Helping bees to help your crop
“Most canola growers have a fantastic relationship with their beekeeper – they get a few pounds of honey every year and their crop benefits,” Sekulic says. But agricultural operations can have negative effects on bees, so the CCC has important advice for growers on how to minimize impacts on bees and other insect pollinators.

If possible, avoid spraying an insecticide on canola fields during flowering. Sekulic emphasizes, “We really encourage growers to use economic thresholds – to spray an insecticide only if the amount of pest insects present will do damage that is in excess of the cost of control. We really discourage prophylactic applications of a foliar insecticide because of the damage it can do to bees and other pollinators. There are about 970 species of identified solitary bees and bumble bees in Canada, the majority of which can be found pollinating in canola.”

Hoover adds, “We also commonly find flies in canola fields, and they can be important pollinators.”

If the pest insect is beyond the economic threshold and you decide to spray, then try to find a product with low toxicity to bees. “The insecticides available now are a lot more bee-friendly than the products used 20 or 30 years ago, but we still advise using the safest product available. Unfortunately, for most of our pest insects, there are really only one or two products registered for their control [so there may not be a good bee-friendly option],” Sekulic says.

“We also advise spraying in the evening after about 9 p.m., when bees aren’t foraging anymore, and then stopping spraying before temperatures reach about 15 C in the morning.”

As well, be sure to inform beekeepers with hives in your area before you spray. Sekulic explains, “Telling the beekeeper when a spray operation will happen allows the beekeeper to move the hives or cover them, or perhaps suggest an alternative product that is safer for bees. There is so much to gain by working together and so much to be lost by antagonism.”

He notes research on neonicotinoid seed treatments of canola indicates these treatments are not causing problems for bees. “The data really supports the fact that we are using the products quite responsibly and really limiting exposure of bees to the products,” he says. “The seed treatments are systemic so they will disperse through the plant, but the product dissipates readily to the point that we don’t find any neonicotinoid residues at all in the pollen or honey in about two-thirds of the samples collected in Alberta. And in the remaining one-third, the concentrations are well below even the most conservative estimates for behavioural effects in bees.”

To learn more about pesticide impacts on bees, Hoover is working with Stephen Pernal and Marta Guarna of Agriculture and Agri-Food Canada (AAFC) on a bee health study that includes testing for pesticide residues in pollen collected by bees in the Lethbridge and Beaverlodge areas of Alberta, and in Prince Edward Island. “We have pollen collections from canola and corn specifically, as well as collections from hundreds of colonies across these three sites throughout the flowering season. These samples will be analyzed for residues (including neonics). We also have parasite and pathogen data from these colonies, as well as colony size and survival.”

For growers who also want to help native pollinators, Sekulic says the key is to give them a place to live. “Fence rows, tree bluffs, low spots, wetlands, and other non-cultivated areas are places where solitary and bumble bees complete their life cycle, so they’ll have their nests there. These uncultivated areas are fantastic reservoirs for native flowering plants that provide pollen and nectar after canola has stopped flowering.” He adds, “Maintaining these areas in proximity to croplands can also reap huge rewards in terms of predation on crop pests by the good bugs such as parasitic wasps, carabid and rove beetles, and spiders.”

Bee-canola study
Hoover explains there is still a lot we need to learn about the bee-canola relationship. “We do not yet have a broad understanding of all the variables that interact to affect levels of pollination and yield, and how bees are affected by farm management practices such as pesticides, irrigation, crop variety, etc. We do not yet fully understand how to manage bees most effectively as pollinators of canola, or how the dependence of yield on pollination varies. I am interested in these types of questions because of the broad importance of bees and canola across not only Canada, but the world. These are important global questions.”

Another one of Hoover’s current projects is a three-year study on bees in canola. “The goals of this project are to understand how managed and wild bees are distributed in the canola fields (seed and commodity), their interactions with one another, and how these affect yield. We are also studying the effects of different ways to manage honey bees used in canola pollination (seed) and how use in pollination affects bee health.”

The project, which started in 2014, is funded by the Alberta Crop Industry Development Fund, Canadian Bee Research Fund, Alberta Beekeepers Commission, University of Calgary, AAFC, Alfalfa Seed Commission of Alberta, CCC, and Alberta Agriculture and Forestry.

“This study involves myself, my technician, two graduate students, a post-doctoral fellow, undergraduate students, as well as colleagues at the University of Calgary (Ralph Cartar) and AAFC (Stephen Pernal),” Hoover notes. The other key players in the project are numerous canola growers and beekeepers. “Without the cooperation and understanding of the growers and beekeepers, none of this would be possible.”

The project is taking place in the Lethbridge region, as far as Granum, Enchant and Scandia, and in the Peace Country centred around AAFC’s Beaverlodge Research Farm.

It involves a variety of experiments. Hoover explains, “Depending on the experiment, we are measuring bee abundance in the field, the behaviours of the bees, crop yield parameters, bee health and honey yield, pollen collection and rates of foraging.” Regarding crop yield, the research team is measuring factors like seed number and weight per square metre, seed number and weight per plant, average seed weight, and green count; each of these is being measured at several distances into each field. The researchers are also measuring plant traits like number of pods, number of seeds per pod, and so on.

Theyare still collecting data, so most of the results are not ready yet. “I can say that there is a large amount of variation in bee abundance within and among fields, and even within the same field on different days. How this is related to yield we are still working out, but bee abundance is correlated negatively with nectar availability – likely because the more bees you have, the more nectar they remove from the flowers. We see a lot of interactions among the bees in the field, both within a species and among the different species,” she says.

“For seed crop pollination, early indications are that there are more management options for beekeepers than what is currently common in the fields, and that these different options can be as effective as the status quo.”

The project results could have practical benefits for beekeepers and canola growers. “It is our hope that these results will provide beekeepers with information on how to manage bees in ways that are good for the bees, but also provide an effective pollination force for growers,” she says.

“We can also provide beekeepers with information on how bees act in canola fields, and what they are foraging on. For example, we are finding that in late-blooming seed fields, the bees tend to gather more corn pollen than in fields that are done bloom before the corn pollen is available. We are also finding out that there are usually a number of types of pollen coming into each colony, even when they are placed near multiple canola fields. Bees are very good at finding sources of diverse forage.

“For the growers, we hope to provide them with information as to what context adding managed bees to their field would benefit yield, and an easy method by which they can evaluate their pollinator abundance, similar to sweep netting to determine the threshold of a pest.”

November 26, 2015  By Carolyn King