FYI MM from http://www.biotech-info.net/sprays.html
"Differences between Bt-Transgenic Corn Varieties and Conventional Bt
Sprays"
Commentary
E. Ann Clark
SANET post
January 12, 2000
GE-Bt is not the same as conventional soil microbe Bt. The key differences
include:
a) GE-Bt is formed in each plant pesticidal cell as an active endotoxin. It
exists in that form in each cell through its lifespan and enters the soil in
that form when the plant dies. Soil microbe Bt exists in each microbe as an
*inactive* precurser which becomes activated only under very specialized
circumstances in the gut of particular organisms.
b) original Bt is rapidly broken down by UV etc. when applied as a foliar
spray. GE-Bt, once it is in the soil, retains insecticidal activity for at
least 6 months, according to a series of articles from the lab of Stotzky at
NY University (e.g. Tapp, H. and G. Stotzky. 1998. Persistence of the
insecticidal toxin from Bt subsp. Kurstaki in soil. Soil Biol. Biochem.
30:471-476). It is true that GE-Bt is a substrate for microbial degradation
and does decay in the soil, but consider the issue of scale (see below).
c) It was this lab that showed in a recent article (Saxena, D., S. Flores,
and G. Stotzky. 1999. Insecticidal toxin in root exudates from Bt corn.
Nature 402:480) another key difference between original and GE Bt. GE Bt
plants actively exude active endotoxin during their lifetime, so the
insecticidal properties of GE Bt need not wait until plant death to exert
their effects, if any, on soil biota.
d) Other studies showing an effect of other transgenic plants (not Bt) on
soil biota include the following: Donegan, K.K., R.J. Seidler, V.J. Fieland,
D.L. Schaller, C.J. Palm, L.M. Ganio, D.M. Cardwell, and Y. Steinberger.
1997. Decomposition of genetically engineered tobacco under field conditions:
persistence of proteinase inhibitor I product and effects on soil microbial
respiration and protozoa, nematode and microarthropod populations. J. Applied
Ecology 34:767-777.
Doyle, J.D., G. Stotzky, G. McClung, and C.W. Hendricks. 1995. Effects of
genetically engineered microorganisms on microbial populations and processes
in natural habitats. Adv. Appl. Micro. 40.
Giovanni, G.D., L.S. Watrud, R.J. Seidler, and F. Widmer. 1999. Comparison of
parental and transgenic alfalfa rhizosphere bacterial communities using
biolog GN metabolic fingerprinting and Enterobacterial Repetitive Intergenic
Consensus Sequence -PRC (ERIC-PCR). Microb. Ecol. 37:129-139.
e) Not only does GE Bt expose humans, fed livestock, soil biota, and
everything else to a completely unprecedented endotoxin (e.g. active, not the
precursor), but it also does so on an inconceivably larger scale - every cell
of every plant on tens of millions of hectares every year.
This is not the same as soil microbe Bt, not by a long shot
** NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is
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