On Feb 1, 2010, at 4:38 AM, [log in to unmask] wrote:
> Separating the nutritious from the toxic is something most organisms are 'designed' by nature to do.  As noted above, mammals have advanced organ system to achieve this.  I don't know how bees do it - but I'll bet that complex behaviours that avoid collecting and processing certain pollens, on a local basis, are part of it.  

Sorry Mike. Nature is not designed, it is evolved. And as such, it is full of flaws. Bees are no adept at avoiding toxic food. Any beekeeper knows that they are continually blundering into peril. They fly into hives rotten with disease so bad they stink, and gorge themselves on contaminated honey. The fly into hot vats of syrup. They gather pollen that is loaded with insecticides and feed it to their young. And yes, they unwittingly consume natural toxins.


Excerpts:

Bees are regularly confronted with the defence chemistry of plants. Are the bees able to detect and to avoid nectars and pollen rich in allelochemicals? if not, do toxic effects result? 

A number of substances proved to be unpleasant and even toxic to honeybees. A correlation between food rejection and toxicity could not be found, however. Food rejection often sets in at concentrations that exceed the respective LD50, i.e. which are already toxic. Naturally occurring bee mortality due to nectars or pollen that contain toxic substances, has been observed mainly when environmental circumstances do not provide alternative food sources. 

Thus, bees do not seem to be highly adapted to the plants' defence chemistry. It seems that the relationship between flowers and flower visitors, especially pollinators, is more complex with regard to plant allelochemicals as was generally assumed.

Attraction, deterrence or intoxication of bees (Apis mellifera) by plant allelochemicals
Andreas Detzel and Michael Wink -- Chemoecology 4/1:8-18 (1993)

* PS: I won't even go into the way that humans flock to toxins the way babies go to mother's milk

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