Stan,

The reason to conduct the study near Guelph, ON, aside from being close to a major university with an active bee research program that can provide healthy hives for testing, is that its just outside the normal canola growing region (you start seeing commercial fields about 30 miles to the north) and there are minimal acres of any other bee attractive crops that bloom at the same time as canola.  So it is possible to set up a field trial in which test fields are geographically isolated from other canola fields and other bee attractive crops.  It would be nearly impossible or prohibitively expensive to set up a controlled field study with fields isolated to the same degree in an area where large fields of canola are commercially grown.  

With respect to field size, Dr. Scott-Dupree has argued that bees tend to only forage as far from the hive as is necessary to obtain the resources they need.  So as long as you don't put more colonies than the test field can support (1-2 colonies per acre for canola), the bees tend to forage on-site.  This is especially expected if there are no other bee attractive crops nearby.  

Others have insisted that bees forage out 2 miles or more in all directions, a total area of more than 8,000 acres.  If this is correct then a 5 acre test field comprises less than one-tenth of one percent of the total foraging area and if the bees of a colony forage randomly or uniformly across this area, only this very tiny percentage of the pollen and nectar they collect will come from the test field.  These individuals argue that if you put bees among large fields of canola in the prairies, a much greater percentage of their food will come from canola fields (nearly all of which these days are grown from neonicotinoid-treated seeds).  

So which view is correct?  Pollen trapped from foragers returning to the hives placed at the Guelph study test fields was found to contain on average 88% canola pollen, indicating the foragers mainly foraged on site, despite the fact that they were only five acres in size.  This is actually slightly higher than the average percentage of canola pollen Bromenshenk and Henderson recently measured in pollen being brought in by foragers at hives placed at large (100+ acre) canola fields in Alberta.  It turns out that 5 acres of canola provides more than enough pollen and nectar resources for 4 HB colonies (10 frame, single brood chamber) and when there isn't much alternative forage nearby that is as attractive, they do indeed show strong fidelity to the fields at which they are placed.  

Regards to all,

Dave Fischer

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