In response to Waldemar's questions: The diversity of pesticide residues has
been about the same. The types of chemicals change a bit with the years and
regions. We still see residues of DDT, DDD, and DDE, although these are
very slowly dropping off.
A few weeks ago, I sent the following to our colleagues on the CCD Working
Group:
CCD Working Group: I managed to free up a few minutes and looked up some of
our previous pesticide work, as well as those of some of our colleagues.
We collected hundreds of bee and pollen samples at Aberdeen Proving Grounds
and at off-site areas north of Baltimore in the late 1990s, early 2000s.
We found 4,4'-DDT, 4,4'DDE, 4,4'-DDD, aldrin, gamma-chlorodane dieldrin,
alpha-BHC, beta-BHC, delta-BHC, gamma-BHC (lindane), endosulfan sulfate, endrin,
endrin aldehyde, heptachlor, heptachlor epoxide, and various PCBs (aroclor
1260, 1248, 1254).
I should note: Anderson, J.F.; Wojtas, M.A. (1986) also found PCBs in bees,
as well as lots of other pesticides in samples from Connecticut counties.
More often than not, in the Aberdeen/Baltimore area, we found detectable
levels of pesticides in most bee samples, and sometimes in pollen. Heptachlor
was seen in both bees and pollen and was often the highest concentration
(ug/kg dry weight). 299+ 360. PCB concentrations often exceeded those of
pesticides. In fact, over the last 20 years, we have been unable to find a bee
sample that does not contain readily detectable levels of PCBs. Not
surprisingly, DDT and its breakdown products remain readily detectable in many soils.
In Europe, the Italians have conducted some long-term and wide area sampling
for pesticides. Porrini et al., in a four-year pesticide monitoring study
(1983-86), found 70.8% of the samples tested positive for Dithiocarbamates,
15.3% for dimethoate, 14.7% for parathion, 11.9% for azinphos-methyl, 11% for
carbaryl, 10.4% for methyl parathion, 7.2% for endosulfan, 7.2% for omethoate,
and 2.4% for methamidophos. The Italians noted that the dithocarbamates,
used as fungicides, are considered to be of low toxicity to bees, however, they
were the most widespread chemicals in dead bees in cultivated fields.
In recent litigation concerning pesticides and bees in the U.S., for which
we consulted to several different beekeepers, sevin xlr and furadan were
allegedly involved in several severe bee kills. The residue levels that we've
seen would indicate poisoning events by these chemicals in the cases that we
saw. Finally, we've had some recent correspondence with USGS that indicates
that pyrethroid usage is on the increase in California, and is showing up in
more and more water samples.
Finally, whereas pesticide residues are common in bees, our work has shown
that other environmental chemicals occur in bee colonies, sometimes at toxic
levels. For example, heavy metals and fluoride in industrial regions. Among
the volatile and semi-volatile organics, chemicals like benzene and styrene
stand out in terms of concentrations and/or prevalence.
We look forward to learning how the PSU/USDA results compare with these
studies.
Jerry
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