Randy/Peter, 

Not either of them  but it would be because of a couple of factors,  one  bees can and do feed almost exclusively on them during bloom,  meaning they get more exposre than any other plant.  Most data from Ohio shows corn pollen is around 10% of the diet for a 2 week window,  soybeans as high as 20% for another 2 weeks. Rape or Canola is usually 90% or better for 3-6 weeks.

Second reason I can see is that these 2 grops have been show to have the highest residual in both pollen and nectar

And lastly,  huge crop areas in Canada, Us, and Europe.  Lots of honey and bees placed on these intensive crops  If I had to guess  somewhere around 25% of the migratory hives get placed on this crop.   Clover is probably the only bigger honey crop out there (not counting almonds)




Charles

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