Hi All,
I've been busy moving bees to almonds, so am behind in following posts to
the List. Perhaps you have discussed the recent paper from Yamato
(2012)--Influence of dinotefuran and clothianidin on a bee colony. This
paper is making the rounds on the web.
From the abstract, it sounded like someone had finally produced
experimental evidence supporting a neonic/CCD causal effect!
However, upon reading the details, that was hardly the case. At even the
lowest doses used, the syrup exceeded the acutely toxic level of the active
ingredients. If you do some quick math, you can see that at even the
lowest applied dose of clothianidin consumed by a colony (roughly 4mg),
then divided by the total number of bees (sum of populations taken each
brood cycle = 27,500 bees), that the actual dose per bee was 145ng--nearly
4x the acute toxic dose per bee (of course, this calc does not allow for
degradation). All other dilutions were much higher doses. Even the lowest
dose of clothianidin was 0.4ppm, which equals 400ppb--a dose that will
normally quickly kill any adult bee!
These researchers simply poisoned the hives.
Of interest, look at the populations in Table 2 for the two extremely high
doses, which killed most of the colony populations in the first weeks,
which then scared the researchers to the extent that they stopped giving
the colonies any more treatment (the trial was run during the nectar
dearth). Both of those colonies started to rally again to rebuild their
population, but were simply too small (covering a fraction of one side of a
frame) to survive the winter.
This study ranks right there with that by Lu from Harvard.
--
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com
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