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Pollination Ecology

bullet Over time, growers have increased number of bees introduced into fields, and crowded bee shelters
bullet14-16,000 female bees per acre
bullet140-160,000 female bees per shelter
bullet Density dependent mortality factors like chalkbrood and parasites have increased.
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Notes:

Over the years, growers have increased the number of bees that they introduce into their fields and into crowded bee shelters, until now densities of 14-16,000 female bees per acre, and 10 times that number per nesting shelter are introduced. With such large populations, it is no wonder that density dependent mortality factors like chalkbrood and parasites have increased. Furthermore, bees from Canada have been relatively inexpensive, reducing the incentive for Northwest growers to manage for high bee return. When bee prices are high and/or seed prices are low, concern increases about improving bee yields.

The desire for a sustainable yield of bees in the Northwest is not universal. Canadian alfalfa seed growers donít want it; they get a large portion of their income from selling bees. The growers who use the largest bee populations realize that these populations are not sustainable, but apparently are resigned to this. As one grower puts it, bees are like fertilizer, an expense that you budget for each year.

A few growers, particularly in isolated areas, are able to provide their own bees without buying from Canada, because they use relatively low numbers of bees, and/or supplement bees from their fields with bees trapped in nearby wild areas. They have achieved local sustainability, but note that they still may have to supplement the bee populations in their seed fields. Rather than buying from Canada, they put in their own time and equipment to find the excess bees.