I would like to discuss some ideas presented but felt the need to shift the
thread from what seems to me to be a bit fruitless hammering at this paper
and also at the difference between laboratory and field study.
On Tue, Feb 5, 2013 at 1:06 PM, Jerry Bromenshenk <[log in to unmask]>wrote:
>
> >1) For anyone 'musing' about pesticides and how to study, you need to
> start with a proper background concerning variables, interactions,how
> traditional assays have been conducted, as well as the historical and
> yearly
> publications comparing pesticide toxicities, residual effects, field
> weathering,
> etc. which no longer occurs since Universities have gotten out of the
> pesticide testing for label registration and extension services no longer
> have
> easy access to the data needed to provide the comparative data updates.
>
> Not only does the absence of university / government testing make it
difficult to compare data, but as I have found trying to do an access to
information request, the data that companies provide for registration may
be considered proprietary and therefore not publicly available.
But, some of that information is publicly available and so let us look at a
few of Jerry's criteria:
"comparing pesticide toxicities"
2) Laboratory studies are fine, but one must always remember, small
> numbers of bees in a lab or not the same as the superorganism that a
> whole colony
> represents.
>
> I certainly would not dispute this (or your vast experience), Jerry. But
for the purpose of comparing insecticides, which I wish to do, I think we
are going to have to rely on laboratory study, especially since that was
how most of the older pesticides were evaluated. Unless the book you are
referring to has a whole lot of field or tunnel studies, it is my
understanding that most pesticides were evaluated as far as toxicity to
bees on the basis of oral or contact LD50 usually at 24 hours, but
sometimes also at 48 and 96 hours. On the basis of this we can compare the
contact LD50 (24 hr) and the neonicotinoids are almost unexceeded in terms
of the tiny amounts needed for LD50 of bees (and also many other insects
and aquatic invertebrates and larvae) compared with any of the older
insecticides. Now on its own, this may not be particularly bad, but it can
lead to thinks like corn planter dust problems since the amounts that need
to be blown around to become a problem are pretty tiny.
"residual effects"
Few of the older insecticides were systemic. Most degraded quickly, and
the most toxic usually degraded the most quickly in tables that I have
looked at. The older formulations of carbaryl were a big problem in
pollen. But for most of the organophosphates the label did not specify a
very long time period before bees could be placed on or near the field.
But for sytemic neonicotinoids they are purposely formulated to last in the
plant for a considerable time period and so there are definite residual
effects. There is no argument that there is some level in pollen and
nectar of treated crops. Whether the levels are harmful is what the
discussion has been. But with the older insecticides there was usually not
that much uncertainty. After a certain time period beekeepers didn't
usually see colony problems. Most kills were due to improper application
or aerial spraying (for mosquitoes for example). In some cases, as Jerry
noted discussing individual bees vs colony death, with the old pesticides
field bees were killed but colonies soon recovered.
"field weathering"
Not since the old organochlorines and heavy metals have we put such long
lasting pesticides into the environment asthe neonicotinoids. The half
life (aerobic, anaerobic, aqueous....) is something for which data is
available that we can compare. Some of the neonicotinoids have extremely
long half life in some soil types. It is one of their worst features in my
opinion. Fruit growers can get multi year control of pests with soil
injected trees. Foresters can get up to seven years (so one state forestry
service claimed in their submission to EPA asking them to keep imidacloprid
registered. But this means with field crops that we are treating
succeeding non target crops with a pesticide.
I just find it hard to understand why many people on this list keep
bringing up how much better the neonicotinoids are compared with the
organophosphates and pyrethroids. I live on an intensively farmed island
where before neonicotinoids the potatoes were intensively and regularly
sprayed for aphids and colorado potato beetle. But in the almost twenty
years I had bees before imidacloprid came here in 1990 I had almost no
problems with insecticides. The big advantage to the neonicotinoids is to
the farmer's and their worker's and their neighbour's health (almost no
spraying and low mammalian toxicity). But to the bees and to other
insects and for the environment in general (soil, larvae in the water
system.....) I really do not see that these insecticides have
advantages. And in the end, when the farmer's neighbours saw the spraying
going on at least it was visible and people thought about it and maybe
about the alternatives. With the systemics the damage is more insidious.
We should not think just of bees. For one thing, if the neonicotinoids
are eventually withdrawn, I don't think beekeepers should be the scapegoat
for the farmer's having lost a convenient tool. But I do not think Peter
is correct in thinking farmer's will not let us have bee yards. I have
been vocal here since the early 1990's about imidacloprid and still have
little problem finding 80 or more yards each year. And I have the farmers
themselves to thank for ameliorating the problem. They started treating
the potato sets with imidacloprid and vastly reducing the application from
soil injection BEFORE Bayer ever registered that method.
Stan
>
>
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