At 06:57 AM 1/31/01 -0700, you wrote:
>>... large dosages of copper have been demonstrated not to be
>toxic to some animals, metallic elements (including copper) ... eventually
become toxic ... to those small dosages.
>> I imagine ... small dosages will not have any
>effect on honey bees because of ... short life span...
>
>I wonder if Dr. Jerry B. has any info>

Whew!  That's a very complex subject:

1.  You can't compare copper metabolism in mammals with insects with
respect to many of the issues raised.  In insects, copper is the oxygen
transport system, not iron.  So, in a sense, insects don't have iron poor
blood.  They need copper and to some extent can regulate the amount in
their bodies.

2.  Copper is an inorganic element, one of a group of elements that we
classify as metals.  Insects do accumulate many metals (such as arsenic,
lead, etc.), and at least for bees, the doses can exceed toxic levels from
either short-term acute exposure or long-term chronic (low level) exposure
- despite the short life span.

3.  Most of the original insecticides (prior to the advent of DDT in WW II,
the end of which marks the start of the proliferation, production, and use
of organic-based insecticides) were inorganic-based.  Sulfur, arsenic,
lead, etc.  Many were combined with copper (e.g. copper arsenate).  To this
day, some of the wood preservatives for posts, deck timbers, etc. are
comprised of inorganic chemicals (check the tags on green colored timbers
in your local building center - it may be a dye, or it may be a copper
compound).  On the other hand, the black railroad ties are usually
impregnated with creosote or pentachlorophenol (organic compounds)

4.  Metals, especially the ones that we call heavy metals (lead is a heavy
metal), can and do kill bees - whether in an insecticide or from another
source, such as an industrial pollutant.

5.  Early beekeepers were surprised when inorganic (usually metal-based)
insecticides killed bees in addition to killing the insects chomping on
leaves.

6.  Early beekeepers later found that insecticides were not the only source
of metals in exposure concentrations high enough to kill bees.

7.  The advent of organic insecticides, which tend to be much more toxic
over a short period of time than the inorganics, took the attention away
from these other chemicals.  But that doesn't mean that the problem of
exposure and potential for bee kills from inorganics doesn't still exist --
with the caveats:

that we don't use as many or as much of the metal-based insecticides
anymore (but I should note that a common defoliant used on cotton contains
arsenic),

and wholesale releases of metals into the atmosphere by industries, has
been reduced, but not eliminated.

8.  Remember also that not all inorganic insecticides are composed of
metals - sulfur was and is a common component.

9.  All of these elements vary in toxicity depending on the form, route and
duration of exposure, etc.

10. Now, back to copper.

In Europe, beekeepers in the early 1900's tried to offset industrial
poisoning by feeding bees copper in water.  Some also argued that gradually
moving colonies into the area next to a source such as a smelter would help
offset kills (in other words, they thought that the bees developed some
resistance from gradual exposure)

We have found that elevated levels of copper in the environment surrounding
a beehive does not necessarily result in elevated levels of copper in bees
- they probably excrete some of the excess.  And the same can be said for
zinc.  Note however, that both copper and zinc are essential elements,
vital to the overall health of the bee.  On occasion, we have seen elevated
levels of zinc in bees in areas where environmental zinc levels are high.

Whether zinc levels tend to accumulate above certain thresholds seems to
depend on what else is in the area around the beehive.  If zinc is the only
elevated element (or, if there is no exposure to elements known to be
harmful to bees), then we see accumulation in bees.

In areas where the air, soils, etc. are elevated in chemicals such as
arsenic, lead, and copper (such as around many smelters), we often see
REDUCED LEVELS of COPPER AND ZINC, even if these two elements are also
elevated in the surroundings.

The explanation may lie with a protein called metallothionein.  Richard
Cronn, one of my students, did his M.S. thesis on this.  This protein
appears in a variety of organisms, from plants to insects to mammals to
humans.  It appears to be important to animals in regulating some of the
divalent elements and binds copper, zinc, and cadmium.  Richard
demonstrated that bees can produce this protein, that exposure to cadmium
increases its production in a bee, and that the protein sequesters (binds)
preferentially with cadmium.  We and others suspect that this affords some
protection from cadmium poisoning.  In those bees with elevated
concentrations of metallothionein, we often see reduced levels of copper
and zinc.  Its probable that all three interact physiologically within the
bee.

So, we seldom see elevated levels of copper, we sometimes see elevated
levels of zinc; and in highly polluted areas, we see reduced levels of
copper and zinc in bees (which may point to a deficiency).  So, we have
bees with copper poor blood.

So, whether copper or zinc is toxic to bees is a complex issue - and I'd
say that like any essential element, too little and you are in trouble,
some excess can be tolerated, too much and its going to be harmful.

Finally, I can't say the same for arsenic, lead, cadmium, etc. which, if
the initial exposure doesn't kill the bees outright, will accumulate and
eventually can kill off entire hives and apiaries - all depending on
exposure levels, duration, forms, etc.  AND WEATHER -- usually exposure
levels to bees in industrial areas are reduced during wet weather (assuming
that the exposure routes are mainly from air, dust, soils) and increase
during dry periods when these elements tend to disperse in the air or be
re-entrained among or on dust particles AND pollen.

In general, exposure to these substances from plants is more a factor of
what is deposited on the surface of the plant or pollen, and less of a
factor of what is taken up by the plant or in the nectar (but there are
exceptions to this general rule of thumb).

Again, Whew!!!  This is a very superficial coverage of this topic.

Jerry J. Bromenshenk
[log in to unmask]
http://www.umt.edu/biology/bees