Dave Green added to the discussion by saying "Another example is that of
using frames with pollen from winter deadouts, and seeing vigorous young
queens immediately take on a spotty brood pattern.
This is why I have asserted that more of our winter losses are pesticide
related than most of us realize. Bees can cover contaminated pollen with
uncontaminated, only to uncover it in winter, when they are much more
vulnerable."

I have always wondered why there is not more discussion and articles about
bees or larvae dying as a result of feeding contaminated pollen from dead
hives.  Whether from winter losses or hives that die during the summer, it
is only logical that some hives die from pollen contamination.  Yet I can't
remember seeing any university-type research or studies on the subject.
While I have seen many articles cautioning to not use frames from AFB or
even EFB-infected hives, I have not seen similar cautions concerning hives
that perish from no known reason...meaning they might have contaminated
pollen.

Beekeepers who maintain "a hive will never collect any appreciable amount of
contaminated pollen (before dying)", would say there are no such warnings
because unsafe levels of contaminated pollen have not been found in frames
of dead hives.  Is that the case, or has no one looked?  I dunno.

Like Dave, I know of a beekeeper who daily consumed a tablespoon of pollen
on his cereal, and became very sick.  His doctor suggested he stop taking
the pollen, and he promptly got better!  His doctor thought his illness was
most likely an allergic reaction, the beekeeper thinks it was most likely
because the pollen was contaminated.  Yet, he says he is unaware of any
decline or losses from hives used for trapping.  Who knows?

BeeCrofter wonders about the residual pesticide levels on pollen compared
with, say, such levels on apples or spinach.  Again, who knows?

I sell trapped pollen (as well as pollen traps).  One customer who purchases
well over 100 pounds a year says he only wants spring pollen from maple
through wild cherry bloom as he figures those blooms are over well before
pesticide use starts.  In this climate he is probably right.  I have another
who wants only goldenrod and aster pollen as it is extremely attractive and
"is never sprayed".   I have pointed out to him that farmers are still
spraying cole crops (cabbage, brussel sprouts, etc.) but he apparently isn't
worried about any drift.

Personally, I don't trap pollen during June-August as corn pollen really
messes up the traps.  I also avoid the bulk of pesticide use.  I generously
feed pollen patties to nucs.  While I have certainly had the occasional nuc
fail, I have never had whole groups of nucs fail, which should have happened
if I had fed contaminated pollen.  As the bee tolerance level of pesticides
is far lower than that for humans, perhaps feeding pollen to nucs and
observing the results is an inexpensive (and inexact) method of determining
whether any contamination levels are acceptable.

Lloyd
Lloyd Spear, Owner, Ross Rounds, Inc.  The finest in comb honey production.
www.rossrounds.com