We also found full-size colonies to be surprisingly resilient when fed imidacloprid at doses orders of magnitude above 'field realistic' exposures.  We conducted our feeding trial during a drought, which meant the bees had little or no other options for food.  There are some interesting interactions and responses when comparing bees fed the chemical in syrup, in pollen sub, and in both syrup and pollen sub.  We're still working through the statistics and interpretation of results - its been a complex study to analyze; we're working on publication.  I can say, we expected to fill the dead bee traps with dead bees - didn't happen.  

Jerry

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