Thanks Randy for your comments. You said
“Perhaps you could ask Dr. Lu for us why, if the typical measured levels
were less than 1 ppb, that he tested for effects at 135 ppb? “
The study was done before these recent measurements were made. The recent measurements of mine are part of an as yet unpublished study. Your comment about the cumulative effect of drinking beer brings up the question in my mind of cumulative toxicity effects of neonicotinoids:
The Dutch Toxicologist Tennekes has argued that Bayer’s own scientists have pointed out that the damage done to the central nervous system by imidacloprid is irreversible. Tennekes says somewhere in his writings that neonic exposure is cumulative for bees and that there probably is no safe level level of application of this poison. (see, for instance
Tennekes, H.A., The significance of the Druckrey–Küpfmüller equation for risk assessment—The toxicity of neonicotinoid insecticides to arthropods is reinforced by exposure time: http://www.boerenlandvogels.nl/sites/default/files/Tennekes_2010b.pdf )
I haven’t seen any serious attempt to by other scientists to follow up and prove or disprove Tennekes claims. It seems to be an extremely important point.
You also said
“Another question (not rhetorical, I'd really like an answer) is that if you
observed a drastic reduction in the quality of bee health at 0.64 ppb, why
was Lu unable to observe that effect when feeding a much higher dose during
the summer?”
That seems like a really good question that deserves some follow up research. Could it be that Lu et al were breeding imidacloprid resistant bees ? There is a huge spread in the published LD50 values for acute oral toxicity to imidacliprid. One publication lists values between 3.7 ng and 40.9 ng (Schmuck et al in Risk posed to honeybees (Apis mellifera L, Hymenoptera) by an imidacloprid seed dressing of sunflowers at http://www.ncbi.nlm.nih.gov/pubmed/11455652 ) And Lu et al found a publication that claimed an LD50 value of 118.7 ng per bee which helps him bolster his claim that their doses were sub lethal. Bayer uses a value of 5ng per bee (http://bee-quick.com/reprints/imd/BayerFAQ.pdf ) . It seems likely that at least some of this wide range of values could be attributed to genetic differences and that repeated treatments of imidacloprid are going to select the most resistant bee. Maybe Lu et al were growing the super bees for the next century.! Apparently the young larvae are not going to be killed by these high doses because they apparently have a much greater LD50 value according to Yang et al (Yang E-C, Chang H-C, Wu W-Y, Chen Y-W (2012) Impaired Olfactory Associative Behavior of Honeybee Workers Due to Contamination of Imidacloprid in the Larval Stage. PLoS ONE 7(11): e49472. doi:10.1371/journal.pone.0049472) This last publication also seems very important because, while finding they could still raise brood up to doses as large as 8000 ng per bee, that sub lethal doses as low as 0.04 ng per larva will affect the olfactory associative behavior of the maturing adult larva to such an extent that it
“may affect the survival condition of the entire colony, even though the larvae survive to adulthood” A level of 0.04 ng per larva corresponds to 0.25 ppB imidacloprid contamination of the pollen coming into the hive.
In another post Cam Bishop said
“No one I know submitted samples. Since I have a yard close to a corn field it would have been instructive to have my pollen tested.”
The study is over. I, and others, learned of it through a public solicitation through the Middlesex County Beekeepers web site. I understood the study was for the whole state of Massachusetts, but I could be wrong. Others in the club have submitted samples.
In still another post Richard Cryberg said
“Feeding under 0.005% of a lethal dose daily is very seldom going to have health or survivability issues that a bee keeper is going to be able to see.”
You’re right !! But see the above referenced publication by Yang et al.
And James Fisher said
“these kinds of
articles do nothing but divert funds and attention to problems that do not
exist, rather than to problems that do exist.”
Nobody has commented on the observation by Lu et al that
“One of the defining symptomatic observations of
CCD colonies is the emptiness of hives in which the
amount of dead bees found inside the hives do not account
for the total numbers of bees present prior to winter
when they were alive”
The authors claim that a symptom to look for in a winter dead-out is a bottom board that has far fewer bees on it as compared to a normal colony- and they have two pictures for comparison. The beekeepers who are co authors on this paper are highly regarded beekeepers. Can anyone else corroborate this observation? I think that seems to be valuable contribution if it is a diagnostic tool recognized and verified by others. As to the funds involved, I doubt that there was much of that stuff.
You also said
“0.3 ng/g LOD and 1 ng/g LOQ for
Imidacloprid for decades, which is more than good enough, as what is
commonly found in pollen of Imidacloprid-treated plants is 2-3 ng/g which
is 2 to 3 ppb.”
The order-of-magnitude higher accuracy of 0.1 LOQ ng/g being claimed by Lu’s lab seems crucial for evaluating the low levels found in a place like Carlisle and in light of the long term chronic effects that apparently are occurring at contamination levels as low as 0.25 ppB as reported in the above referenced study by Yang et al.
Ernie Huber
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