Bob stated:
In discussions with CCD researchers I have been told the Malpighan tubules
are the area most looked at for chemicals
in the bees body.
I'd like to see any data supporting this claim. If it exists, I want to
know; so I can start using it. I've worked with labs that were thrilled to
have a method and instrumentation a ble to get down to chemical analysis of
one bee, or a few pollen pellets.
It is true that with today's instruments, chemical analysis down to ppb
levels is becoming more common, and the required minimal sample sizes are
much smaller (as one chemist said, even a smear of nectar) but still, the
logistics of obtaining tubules without cross contamination during dissection,
the very tiny size and mass of the resultant sample, and the time it would
take to obtain the samples, all make this statement hard to believe.
Now, if you meant to say that researchers have looked at the tubules for
presence of mites, amoeba, tumors, etc. OR that the genomics folks looked at
DNA from tubules, I'd find that more reasonable.
For chemical analysis, sample size is a critical issue that affects
detection limits. In general, the smaller the sample, the less likely the
instrument will see anything other than a relatively high amount of a given
chemical or category of chemicals. To push detection limits to ppb with any
degree of confidence in broad spectrum pesticide analyses, Roger Simmonds at
Gastonia asks us for at least 5 gm of bee tissue, pollen, or honey.
I know that some labs can use specialized procedures to push this amount
down to less, maybe a gm or even half a gm, but the smaller amount of
tissue, the more difficult the prep, the better the instrument required, and
clearly more work and time. One dodge is to look at a very limited selection
of chemicals - a single chemical analysis is usually more sensitive than
broad spectrum analysis. Usually, the more chemicals, the more compromises,
and the higher the detection limit. Many of us are glad to be able find
labs that can work with as little as one bee or a smear of nectar, a single
pollen pellet. Analysis of individual tubules would present a real
challenge, certainly not cost effective for routine work. Depends on the chemical -
but pesticides would be tough to do.
Jerry
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