In answer to Christina, Randy said:

The most severe effect will be colony dwindling or depopulation, the
inability to gain weight, or both.

 
He also mentions the lack of negative impacts on bees on canola.
 
I've modeled (with Gloria) bee populations and even published a bee population model that was verified with data.  I have done years of testing at acute, chronic, lethal, and sublethal doses - for pesticides, chem/bio warfare agents, and pollutants.  I agree with Randy - depopulation  decimates colonies.  There's no starting point from coming back if everyone is lost.  And it's a slow process if the colonies get knocked back to a queen and a hand-full of bees.

Loss of foragers bees can be compensated for by fielding more hive bees, a bit earlier than they might have normally started foraging.  The brood is where the impacts take longer to recover.  It's simply a matter of how long  it takes to replace the forager from an egg or larvae or pupae, versus replacement of a forager (often near the end of its life, with another existing adult bee.

During my many years of using bees as environmental sentinels, I capitalized on the dichotomy of the individual bee being a true Indicator (lives/dies) versus the colony as a whole as a Monitor (generally persists except in the most severe situations).  

But I think everyone is missing something regarding sublethal, behavioral, impacts of pesticides and other nerve agents.

Two things seem to have been forgotten in the discussion of sublethal effects such as disorientation, memory loss.  In the 'old' days, experts like Lawrence Atkins, Carl Johansen, and Daniel Mayer: 1) did notice and document such effects, there's nothing unique about neonics and these types of effects, and 2) they considered these types of behavioral effects to be protective of the colony - serve a useful purpose.

I can verify this from my own research for the DoD looking at sublethal, behavioral responses.. 1) Many of these effects are transitory; much like you or I getting a buzz or stumbling drunk on alcohol.  Unless we over-dose, after the hang-over, we go about our business.   2) Guard bees are extremely sensitive to any bees entering the hive, exhibiting these behaviors (and I assume perhaps reeking of the chemical(s)).  The guards will block entry, cast out.  We've seen this even at doses that are so low, we (the humans) had stopped seeing observable effects, yet if we dose individual bees externally to the hive, then release the dosed bees, the guards usually reject them.

My 'heroes', the three experts who did so much of the work we now recognize as setting the cornerstone for pesticide label registrations, considered this to be a good thing - the colony won't let the sick and dying bees back in, and if they do manage to slip in, they probably miscommunicate where they've been, so they're not sending other bees out to the same place.
 
J.J. Bromenshenk


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