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Date: | Mon, 27 May 1996 10:11:38 -0700 |
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Re. Blueberry Pollination
Just to add to Stan's comments about (highbush) blueberry pollination.
Indeed native pollinators especially bumbles are much more effective as
pollinator on a per bee basis than honeybees. Here in the Fraser
Valley, blueberry is a major crop and many of the producers on the
northshore (close to the mountain slopes with bush and undisturbed
vegetation) derive great benefit from the wild populations of
bumblebees. But, in the central and western parts of the valley, the
abundance of these populations is believed much less. Also, wild
populations tend to fluctuate wildly from one year to the next,
something larger growers can not rely on for securing proper
pollination.
In recognition of the effective blueberry pollination by bumblebees, it
has now been explored to use commercially reared bumbles for this
purpose. I have cautioned growers not to have unrealistic expectations
of using these very costly bumblebee units. (PS. Part of the enthusiasm
stems from the phenomenal success of bumbles in greenhouse crop
pollination).
As Stan pointed out, bumblebees may be much more effective pollinators
in blueberry (and cranberry) but the number of available pollinating
insects in a commercial planting is an important consideration.
Consider the fact that for every acre of mature highbush blueberry
planting an estimated 5million flowers must be pollinated. Most
plantings are over 10 acres and in some cases, several hundred acres.
Commercial bumblebee nests harbor between 100 and 150 individuals of
which only a portion would be actively foraging at any one time. It
seems a pretty daunting task for such small number of insects to cover
that many flowers effectively.
Some recent field visits also revealed that the honeybee colonies were
much more active under the same lousy spring conditions we have had
compared to the bumblebees. This was rather surprising since it has
always been reported that bumblebees remain active foragers at lower
temperatures than honeybees. Please don't interpret all this as a
popularity contest between honeybees versus bumblebees. It is strictly
a question how these two different insect species compare in a field
setting. Ultimately, the grower who pays for the pollination service
must get maximum benefit from the insects he uses. As prices stand
today, a grower can rent three strong honeybee pollination units for one
bumblebee nest. I can not see that under the present price structure,
bumblebees (or anyother non-Apis pollinator) are more cost effective
than honeybees.
I should point out that because of the serious impact parasitic mites
have had on the honeybee population, bumblebees and other pollinating
insects have become valuable, complementary pollinators to all growers.
We therefore also encourage growers to preserve habitat near plantings
to enhance the presence of wild bee populations.
Paul van Westendorp [log in to unmask]
Provincial Apiarist
British Columbia
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