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Slide 14 of 18
In the early years of alfalfa leafcutting bee management, Northwest growers
could obtain an increase in their bee populations, which they would sell to
neighbors. This ended when chalkbrood, a fungal disease of leafcutting bees,
was discovered in the early 1970s. Although chalkbrood mortality has declined,
high larval mortality from a variety of factors means that there is not enough
local bee reproduction to meet grower demand for large bee populations.
Because of the high larval mortality, northwest growers turned to Canadian
seed growers in the 1970s to supply large bee populations for pollination.
Canadians are able to increase their bee populations 1.5 – 2 fold over
In establishing the Pollination Ecology Program at UI, growers sought
solutions to numerous bee management problems, like chalkbrood and pollen
balls, which prevent them from producing sustainable bee yields.