Jim wrote:
> This adding up of theoretical accumulated exposure
> is thereby inherently invalid, as bees can metabolize
> imidaclopird. Suchail et all (2003, ("Metabolism
> of Imidacloprid in Apis mellifera" Pest Mnmgt Science;
> 60, 291-296)) found that the metabolism half-life of
> imidacloprid in honey bees was 4.5 to 5 hours with no
> detectable residues found in bees 24 hours after exposure
The link that you provided to the paper that I referenced
did not have the reference page for the paper. The apidologie
link does have the reference page (you would have seen that
Seely, who you referred to, and Suchail are both referenced).
Suchail in fact, is the co author of the paper with Guez that
has the lowest sub lethal dose I have seen for imidacloprid in bees.
The following is taken from a government report
(California) quoting Suchail:
"Imidacloprid is highly toxic to honeybees (Apis mellifera),
with a reported LD50 of 8 ng/bee.
Actual toxicity varies widely depending on honeybee
subspecies and type of exposure. Acute oral toxicity LD50
values for both Apis mellifera mellifera and Apis mellifera
caucasica areapproximately 5 ng/bee, while contact LD50
values are 14 ng/bee for A. m. caucasica and 24
ng/bee for A. m. mellifera (Suchail et al., 1999).
Imidacloprid is toxic in smaller doses when
ingested over an extended period: chronic LD50
values range from 0.01-1.0 ng/bee (Suchail et
al., 2001). Low doses of imidacloprid and imidacloprid
metabolites have been found to negatively affect honeybee
foraging and learning behavior (Decourtye et al., 2003, 2004).
So, the author of the paper you represented as showing
that imidacloprid "disappears" from the bee, is one showing
a CHRONIC lethal dose50 down to an incredibly low
0.01ng/bee. Compare that value with the theoretical
values in the paper on systematic insecticide risks and
you will see that it is orders of magnitude lower.
> But imidacloprid DOES NOT bio-accumulate in bees.
>
> This is a crucial point.
> It invalidates the conclusions completely.
Obviously the chronic lethality (many papers
including those of Bayer show that the LD50 for 96
hours is far less than the LD50 for 48 hours) means
that if it is not bio accumulating then it is pretty darn
harmful to the bee in its metabolization. And
that validates the conclusions.
Suchail, S., D. Guez, and L.P. Belzunces. 1999.
Characteristics of imidacloprid toxicity in two
Apis mellifera subspecies. Environ. Toxicol. Chem. 19(7): 1901-1905.
Suchail, S., D. Guez, and L.P. Belzunces. 2001.
Discrepancy between acute and chronic toxicity
induced by imidacloprid and its metabolites in Apis mellifera.
Environ. Toxicol. Chem. 20(11): 2482-2486.
****************************************************
* General Information About BEE-L is available at: *
* http://www.honeybeeworld.com/bee-l/default.htm *
****************************************************
|
