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Mon, 25 Dec 2006 10:40:32 +0000 |
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Chris Slade wrote:
> Is this proven fact or supposition?
>
I have seen so many references to it that at the time of posting I
thought it was fact. However, I think the French beekeepers managed to
get the chemical banned for use with sunflowers and the BBKA article
(snippet below) by Graham White indicates that imidacloprid does have an
effect in the right concentrations.
“Klaus Wallner confirmed in his study of Imidacloprid prepared Phacelia
with a burden of 50 g/hectare, that the bee’s honey-sac average
contamination was 5ppb and the pollen taken from the 'pollen baskets' of
the bees contained 7ppb. The centrifuged honey contamination level could
not (yet) be ascertained. The level was less than the 3ppb trace ability
level for honey.
* Clarification in ** France**: *
In a report issued by the French Agriculture Ministry it was stated:
According to the sunflower variety the residues in the flower on the
65th day (at start of blossom period) varied between 2.5ppb (Pharon) and
8.7ppb (Natil). These values could possibly be higher at point of
harvest. The sunflower pollen is contaminated at an average level of
3ppb (up to 11 ppb max.). In untreated plantings (sunflower, rape and
corn), which were planted in Imidacloprid-contaminated-soil, up to
7.4ppb was detected in the flowers.
“The Bayer study produced a mortality rate due to Imidacloprid for bees
as follows: The LD 50 (the lethal dose which kills 50% of test organisms
within 48 hours) lay between 3.7 and 40.9 Nanogrammes of Imidacloprid
per bee. Long term injury was investigated by Bonmatin. He achieved an
LD 50 after 8 days by feeding individual bees an Imidacloprid/ sugar
solution of 0.1 ppb. The substance showed itself to be highly toxic when
delivered over time.”
The complete article can be found here :
www.bbka.org.uk/articles/imidacloprid.php
It also includes some useful references.
All the best
Steve Rose
-- Visit www.honeybeeworld.com/bee-l for rules, FAQ and other info ---
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