Losey (and colleagues) data??

1_iron 1_iron at msn.com
Mon Dec 3 17:19:41 EST 2001


Running gives you smart brains.

Jim Taylor
----- Original Message -----
From: "Martha Rosett Lutz" <lutzrun at AVALON.NET>
To: <leps-l at lists.yale.edu>
Sent: Monday, December 03, 2001 2:41 PM
Subject: Losey (and colleagues) data??

> I received the following post to the list:
> "When John Losey and colleagues in Cornell University published their
> that Bt-corn pollen harmed monarch butterflies, the concern raised was not
> just over monarch butterflies, but on all other (non-target) species in
> environment."
> I acknowledge the broader context, and do not wish to diminish that
> but would like to comment specifically on the Losey et al. paper in
> Please, correct me if I am somehow mistaken, but their actual data (as
> published in Nature) did not establish that Bt-corn pollen harms Monarchs.
> They failed to distinguish between antibiosis and antixenosis, and the
> which had statistical significance showed that both Bt and non-Bt corn
> pollen resulted in significantly decreased feeding by Monarch larvae.
> Their study ended at four days, with both the pollen-fed groups (Bt and
> non-Bt) showing significant failure to gain weight compared to the control
> group fed on pollen-less leaves.
> There was no information presented concerning ultimate survival of any of
> the larvae, so I do not know whether both Bt and non-Bt pollen treatment
> reduced fitness to zero (i.e. no information about whether the individual
> larvae were unable to develop to reproductive maturity and successfully
> reproduce).  Without seeing data relevant to the survival and reproduction
> of all the groups, I cannot accept the published conclusion that Bt pollen
> is toxic to Monarch larvae, as it also seems possible that they died of
> starvation due to reduced feeding.  All the non-tachinid-infested Monarch
> larvae I have raised (since about 1971) have taken ten days from egg to
> chrysalis, and it seems likely that significantly reduced feeding for four
> of these ten days would have an impact on health and fitness.  Any
> conclusions drawn from the data that were actually presented must account
> for the significantly reduced feeding (and failure to gain weight at a
> normal rate) in both the pollen-fed groups, rather than ignoring the
> pollen data and assuming that death was due to antibiosis from Bt toxin.
> Personally, I can neither accept nor reject the conclusions published by
> Losey et al., without seeing more information.  I also cannot accept a
> blanket statement that their findings are transferable to field
> I have lived in Iowa since 1987, spend time most summers hunting for
> Monarch eggs and larvae to raise, and have never yet seen a milkweed plant
> whose leaves were dusted with corn pollen.  For one thing, there is this
> funny ritual of de-tasseling that goes on every summer . . . oak pollen we
> have in buckets-full, but not a lot of corn pollen wandering around the
> landscape.  The ditches near cornfields are, however, often clear-cut,
> nothing much above four to six inches in height growing there.  Otherwise
> the ditches mostly contain Pastinaca sativa.  Things may be different in
> the Finger Lakes region of NY--I have not lived there since I got my B.S.
> in entomology from Cornell in 1978, so I can't say what conditions prevail
> in cornfields there these days.  But here in Iowa I just don't see much
> milkweed near cornfields and not much corn pollen lying around anywhere.
> Just my $0.02 worth, and certainly open to critique from people who have
> more information or more up-to-date information!
> In Stride,
> Martha Rosett Lutz
> a.k.a. the old lady sprinter in Iowa
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