studio UK su impatto regionale degli OGM

["AlessandroGimona"<agimona@libero.it>]

Cari tutti, 

sotto trovate:

l'abstract di uno studio britannico pubblicato su Science del 1 
settembre 2000, 

un riassunto dello studio 

e la risposta di Monsanto.

Lo studio consiste in un modello matematico ad ampia scala e si occupa 
delle colture di barbabietola. Questo conclude che l'avifauna sarebbe 
negativamente influenzata, a volte in maniera drammatica, 
dall'introduzione del pacchetto colture erbicida-tolleranti e d 
erbicida.  
L'approccio modellistico e' necessario perche' gli esperimenti in campo 
sono limitati ad estensioni modeste, e non possono valutare l'impatto su 
intere regioni.

I risultati confermano,almeno in parte, quel che temeva English Nature, 
quando chiese i 3 anni di moratoria.

Naturalmente, ulteriore ricerca sara' necessaria per valutare gli 
impatti su vasta scala. Questo studio pero' fornisce evidenza che la 
cautela non e' ingiustificata.

Secondo Monsanto (vedi sotto) lo studio non e' conclusivo ed e' 
addirittura irrilevante. Monsanto ritiene che i risultati non siano 
specifici per le biotecnologie ma riguardino il diserbo in generale.

La risposta di Monsanto, comunque non affronta la questione se i 
cambiamenti di pratiche agricole siano associati alla biotecnologia o no 
(cioe' se la tecnologia indurra' cambiamneti che portano a piu' diserbo 
*in pratica*, anche se *in teoria* lo stessa effetto potrebbe essere 
ottenuto con altri mezzi) ed abbiano quindi il potenziale impatto che 
viene modellizzato.


Spero interessi

Saluti

Alessandro Gimona
-----------------------------

Predictions of Biodiversity Response to Genetically Modified
 Herbicide-Tolerant Crops 

 A. R. Watkinson,1* R. P. Freckleton,1  R. A. Robinson,2 W. J. 
Sutherland1 

 We simulated the effects of the introduction of genetically modified 
herbicide-tolerant (GMHT) crops on weed
 populations and the consequences for seed-eating birds. We predict that 
weed populations might be reduced to low
 levels or practically eradicated, depending on the exact form of 
management. Consequent effects on the local use of
 fields by birds might be severe, because such reductions represent a 
major loss of food resources. The regional impacts
 of GMHT crops are shown to depend on whether the adoption of GMHT crops 
by farmers covaries with current weed
 levels. 

---------------------------------------------------
31 AUGUST 2000
Contact: Ginger Pinholster
gpinhols@aaas.org
202-326-6421
American Association for the Advancement of Science

Farmers and GM crops should both impact farmland birds, Science study
predicts

This news release is also available in French.

The use of genetically modified herbicide-tolerant (GMHT) crops may
severely reduce bird populations on a small percentage of farms, while
having little effect on most others, predicts a new study in the 1
September issue of the international journal, Science. Overall, the
consequences should depend upon which farmers adopt the new crop types,
the study's authors conclude.

The possible effects of GMHT crops on wildlife in the countryside has
been the subject of ongoing debate, and the British Government has
introduced a moratorium on the use of these crops until the issue is
resolved.

Lead Science author Andrew Watkinson, from the University of East
Anglia, in Norwich, England, and his colleagues have created a model
that simulates the growth of weed populations within crops. Using the
model, the team investigated the consequences of the changed herbicide
use likely to be associated with GMHT crops. The results showed that
weed seed populations can be expected to decline by at least 90% in some
cases.

An important part of the study links the decline in weed numbers to bird
numbers, predicting that such a decline in seed abundance should
seriously reduce the numbers of skylarks using these fields.

The controversial field trials currently underway in the United Kingdom
are intended to investigate the consequences of GMHT crops for
biodiversity.

"The field trials will be very valuable, but will not tell us what will
happen to bird populations. They are carried out on too small a scale.
One considerable advantage of the methodology we have adopted is that it
enables us to make predictions now rather than having to wait for the
results of a three year trial," Watkinson said.

Several decades of intensified agriculture in Europe have had a
particularly serious effect on birds, whose populations in the United
Kingdom have declined by up to 90 percent in the last 25 years,
according to Watkinson.

"It seems likely that the widespread introduction of herbicide-tolerant
crops will result in further declines for many farmland birds unless
other mitigating measures are taken," Watkinson said.

The model developed by Watkinson's team examines the management of
herbicide-resistant sugar beet and its effects on a major annual weed of
that crop (Chenopodium album, more commonly known as Lamb's Quarters in
North America and Fat Hen in Britain) and the seed-eating skylark Alauda
arvensis.

"These results probably apply widely to other crops, weeds, and seed
eating birds," noted Watkinson.

The study showed that a key issue in predicting the impacts on bird
numbers was the pattern of farmers' uptake of the new GM technology.
Most fields have very low seed densities. It's the smaller proportion of
fields with high seed densities that is particularly important for bird
populations.

The researchers predict that the severity of the bird declines will
depend upon which farmers are most likely to adopt the GMHT crops. If
their use is restricted to intensive farms with low seed densities then
the effect will be minor. However, if the herbicide-hardy crops are
adopted by a wide range of farmers--especially farmers with very weedy
fields--then the bird declines are likely to be more severe, according
to the study.

In their Science paper, Watkinson and his colleagues emphasize that
their findings don't just apply to the effects of genetic engineering.
The same approach could be used to predict the consequences of other
changes in farming practice, they say.

A commentary by Les Firbank, of the Centre for Ecology and Hydrology, in
Cumbria, England, and Frank Forcella at the USDA Agricultural Research
Station, in Morris, Minnesota, and the University of Minnesota, in St.
Paul, Minnesota, accompanies the Science paper.

Firbank and Forcella write that the model provides a "welcome conceptual
framework," but that further work will be necessary to resolve some of
the model's simplifications. According to the commentary, some data from
the United States, where GMHT crops are currently growing, suggest that
weed control with GMHT crops may not be as effective as some of the
model results indicate.

Such differences emphasize the need for field trials to complement
theoretical studies like this one, Firbank and Forcella point out.

----------------------------------------------------


31 AUGUST 2000 AT 14:00 ET US
Contact: Scarlett L Foster
scarlett.l.foster@monsanto.com
314-694-2883
Monsanto Company

Monsanto Company response to European study in Science magazine

To interested media parties:

European researchers will publish an article in the Sept. 1 edition of
Science magazine using a theoretical model to suggest that the planting
of herbicide-tolerant sugar beets could reduce the production of weed
seed and ultimately decrease bird populations. The article claims that
herbicide-tolerant crops reduce weeds that provide important sources of
food for birds, including skylarks.

It is important to understand that this is not an issue of
biotechnology. It is an issue of weed control, whether through
biotechnology or other methods. This mathematical model, and any
conclusions drawn from it, must be viewed with caution, because it does
not reflect real farming conditions. Most importantly, the study ignores
the value of weed control to farmers who can lose valuable yields and
the ability to effectively grow their crops.

When reviewing this model, the following facts should be considered:


This report describes predictions that are not specifically related to
biotechnology, but are equally applicable to any agricultural practice
designed to manage weeds. The use of biotechnology as a basis for
modeling is irrelevant. It is possible to achieve the same level of weed
control, and hence the same impact, using traditional pesticides,
tilling and other methods.

This report is based on a theoretical model that uses basic assumptions
that are inconsistent with real agricultural practices. It is
inappropriate and misleading to draw conclusions about the natural
environment based on a single, non-validated theoretical model that
employs untested assumptions.

Contrary to this theoretical report, data from other scientists who have
conducted field studies on herbicide-tolerant sugar beets has shown that
herbicide-tolerant plants allow farmers to maintain weeds longer in
sugar beet fields, which could offer greater resources at a time of year
when for birds is scarce.

Agricultural practices that improve the yield per acre actually prevent
additional land from coming under cultivation, preserving the best
wildlife environments in their natural state and protecting indigenous
habitats for birds and other wildlife.

Furthermore, biotechnology crops like herbicide-tolerant crops, promote
reduced tillage systems which have been proven to improve wildlife
habitat for species ranging from birds to soil invertebrates. By using
reduced tillage, there is less soil disturbance and increased food
supplies that encourage higher densities of bird species in farmersą
fields.

Herbicide tolerant crops can reduce the number of herbicide applications
for weed control, often replacing herbicides that can have negative
environmental effects. In a 2000 study by the National Center for Food
and Agricultural Policy, researchers showed that U.S. soybean growers,
for example, had decreased the number of applications of active
ingredient herbicides by 16 million applications, or roughly 20 percent.

Weed control is especially important in growing sugar beets, as
scientists have proven that uncontrolled weeds can reduce sugar beet
yields by more than 90 percent.

Finally, sugar beets are grown on a minor percentage of agricultural
acres. In terms of wildlife habitats, sugar beet fields represent an
inconsequential amount of habitat compared to more natural environments
and feeding grounds for birds, including undisturbed fields, natural
forests and waterways.

###
The following experts can help provide a field context and perspective
to the impact of biotech crops on wildlife.

Bill Palmer, Ph.D.
Adjunct Professor/Research Scientist
Tall Timbers Research Station - University of Georgia, Mississippi State
University, North Carolina State University
850/893-4153 ext. 226

Richard E. Warner, Ph.D.
Assistant Dean of Research
College of Agriculture, Consumer and Environmental Studies
University of Illinois
217/333-0240

Monsanto Company urges those who cover this to be careful in how the
study and its subject are treated. The study leaves many questions
unanswered, and it does not reflect how farmers truly grow their crops
and protect wildlife.

Please contact me with any questions or for additional comments. I can
be reached at 314/694-2883.

Sincerely,

Scarlett Foster
Director, Public Affairs
Monsanto Company

 http://www.eurekalert.org/releases/mc-mcr083000.html