Hi:
 
Okay, as to iron and rust.  Bees don't use iron to transport oxygen like
mammals, they use copper.  So, they probably don't need lots of iron.
Like any element, bees, mammals, people, have more or less fixed tolerance
ranges.  Within the tolerance range, the body can probably regulate the levels in tissues
via  a variety of mechanisms, such as excreting excessive amounts.
Elements like iron generally have to be present at some minimal level for
healthly bees, but too much is not necessarily better or good.
 
Is rust harmful?  If it is, lots of bees are exposed.  You certainly are
not the only beekeeper to use rusty pails, tanks, etc.  Many years ago in
central Europe, beekeepers trying to keep bees alive near aluminum
smelters fed bees iron (often by simply using rusty buckets)to mitigate
the lethal effects of too much fluoride.  Did it work??? Who knows, the
literature claims that it did, but I have never tested this notion.
 
Obviously, since the beekeepers thought that the bees did better, it at
least wasn't any worse than fluoride and may have been beneficial.
 
Should one use rusty equipment?   I'd say no, not because I have any
evidence of any harm, but because I am against introducing high levels of
any chemical into a food producing system.  You don't know what it will
do to the bees (the effects, if any, are likely to be suitable and hard
to identify - although they could be economically costly), and you don't
know how much might get into the honey (probably most likely if you are
providing water on hot days in rusty containers).
 
Unless you really dose them with iron, I doubt that you will see piles of
dead bees.  Fluoride rarely results in that scenario.  However, low level
toxic effects often sap the vigor of colonies, cause them to be slow
growing, and more susceptible to other stressors.  If the levels
accumulate to high enough values in bees, you will get a pronounced
mortality (but usually only in the context of additional stress such as
marginal nutrition, mites, etc.).
 
Jerry Bromenshenk
The University of Montana
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