> That equals 5,000 - 50,000 ppb.  Still incredibly high!


Hi Randy and All

Not only did the authors appear to use very high doses (to demonstrate whether an effect was possible I would imagine), they contradict themselves in their paper on the concentrations they did use.

ppm (w/v) is: 1 ug in 1 ml

ppb (w/v) is: 1 ng in 1 ml or 1 pg in 1 ul

Figure 1 in the paper says 0.005 and 0.5 ug/ul imidacloprid (aka 5,000 and 500,000 ppb).

Materials and Methods says 5 and 50 ng/ul (aka 5,000 and 50,000 ppb).

You would think that any scientific journal would make some basic checks on the consistency of the material in the paper before it allowed publication.  For this one, with the provocative 'Killing them with kindness' title and the likely media frenzy given the subject matter, it is really disappointing to see this carelessness on the part of the authors and the journal.

However I completely agree with your basic point.  The lowest value they use is about 1,000 fold higher in concentration than the levels found in European studies of contamination of pollen and nectar.  However the high dosing of trees - which I don't think happens over here - gives much higher levels.

Having said all that the main contribution of the paper may be to make people look harder at the evidence for combined effects in beekeeping systems that pile in the beekeeping chemicals.  OTC plus heavy residues of fluvalinate and coumaphos from past mistreatment of the bees for example.  

Randy - there is the facilty at PLoS One to comment on the paper at the website.  Perhaps that is the best way to ask the authors your questions?

best wishes

Gavin


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