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The term "genetically modified organisms" for the purpose of
this position statement includes a wide range of transgenic (GM)
crops, trees, insects, fish, livestock and microorganisms that are
currently under development and either have been or could be
released into the environment within the foreseeable future.
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Genetic (transgenic) engineering is a more radical form of
plant and animal breeding, by which genes from other species (or
even phyla) can be inserted into the recipient genome. These genes
have never been, and in many cases could never naturally be, part
of the recipient species' gene pool. Due to the often subtle nature
of interactions between transgenes and native genes, it is
impossible to predict accurately their behaviour if they should
out-cross to native species without carrying out detailed studies
of fitness parameters in a range of environments. It is likely that
some genes are inherently more risky than others. For example,
genes conferring resistance to insects, viruses and fungi in GM
crops such as oilseed rape, if transferred to native species, have
the potential to increase fitness of the resulting hybrids. These
could then become ecological weeds, with the potential to invade
native ecosystems and cause adverse impacts on biodiversity.
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BN3
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Recent research and survey has revealed severe declines in UK
farmland bird populations, especially in those species associated
with lowland arable and mixed farmland. Because of these declines,
farmland bird populations have been included as one of the
Government's 'Quality of Life Counts' headline indicators of
sustainable development. Long-term research in southern England has
identified increased pesticide efficacy as a major factor
contributing to declines of skylarks, partridges and corn buntings.
Herbicide efficacy is very important in determining the breeding
success of these species; low breeding success is strongly
associated with highly efficient weed control programmes. One of
the factors involved in this effect is the reduction in
invertebrate density caused by lack of weeds in arable fields. It
has been demonstrated that bird chicks fail to thrive when
invertebrate densities are low.
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BN4
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There is little doubt that biotechnology has great potential
to be able to alleviate some of the problems associated with
conventional intensive agriculture, especially if out-crossing from
GM crops to native species can be prevented. Reductions in, or even
elimination of, pesticides by using pest- and disease-resistant
varieties, coupled with the prospect of nitrogen fixation and
perennial crops, are attractive goals for genetic engineering. They
could contribute towards more sustainable agriculture, as long as
there were no reductions in biodiversity by diminishing
invertebrate food sources, or through toxin transfer through the
food chain. Present trends in GM crop engineering are, however, in
the opposite direction, with herbicide tolerance being widely used
to increase herbicide efficacy, exacerbating the adverse effects of
agricultural intensification.
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BN5
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Pest and disease resistances are currently being engineered
into a wide range of crops, although none are currently close to
commercial growing in the UK. Insect resistance has been achieved
mainly by expressing various types of toxic proteins (for example,
Bt proteins and lectins) into GM plants. Although some instances of
toxicity to non-target invertebrates have been demonstrated in the
laboratory, the limited amount of fieldwork that has been carried
out so far (mainly in the USA) suggests that these impacts are not
translated into significant population-level effects when compared
to using pesticides on conventionally grown crops. Pest- and
disease-resistant crops could also have effects on soil ecosystems,
which are extraordinarily complex and difficult to study. We
recommend further research in this area.
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BN6
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Recent research has shown that gene flow from some GM crops to
native plants and to non-GM crops is inevitable, but there is
little research on the impact of such crossbreeding on the genetic
fitness of any resulting hybrids. Risks associated with gene flow
can be minimised in experimental plots, but may increase if GM
crops are grown commercially. The JNCC is especially concerned
about the transfer of insect, fungal and viral resistance to native
plant populations, causing possible disruption to the population
dynamics of the plants themselves and their parasites and
predators. However, transgenes that increase fitness of crops or
wild relatives in agricultural environments may also pose risks to
biodiversity. For example, the presence of one or more herbicide
tolerance genes in volunteer oilseed rape plants could cause
farmers to instigate changes in weed management that have an
adverse impact on arable plant communities in crops and field
margins. The technology for preventing gene transfer (by male
sterility, pollen incompatibility and changing flowering times)
already exists, but has not yet been incorporated into commercially
available GM crops. The ACRE report on best practice in the design of
GM crops outlines these technologies in more detail. Any adverse
impacts resulting from gene flow from transgenic animals, such as
fish and insects, into wild populations might be especially
difficult to control or reverse, since these species are highly
mobile. Technologies for producing sterile transgenic fish are
already commercially available, but none of these are currently 100
per cent reliable. It may be hard to predict the impacts of
transgenes on fitness of wild animals without conducting
experiments in the open environment, especially since transgenes
may affect animal behaviour in complex ways. Important
uncertainties about rates and patterns of gene flow, and the
practical difficulties of preventing escape of transgenic animals,
may make it hard to construct valid risk assessments for such
deliberate experimental releases.
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Besides the need to demonstrate that any changes in land use
and management associated with the use of individual GMOs are at
least benign and preferably beneficial to wildlife, there is a need
for strategic thinking within government as a whole about the
likely impacts of biotechnology on agricultural sustainability in
the UK and worldwide. We value the continuing role of the
Agriculture and Environment Biotechnology Commission in promoting
strategic thinking and debate on these issues.
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Constructing 'designer' genes is now routine in medical
biotechnology and may be an attractive option for the farming
industry when more advanced GM crops are formulated. There is
already considerable interest and research into inserting genes
coding for industrial raw materials, pharmaceuticals and nutrient
supplements ('nutraceutical' crops) into various crop plants, some
of which are capable of out-crossing to native species. We believe
that this could have serious effects on ecosystems if such genes
were to become incorporated into native plants.
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BN9
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If coexistence between GM cropping and other farming systems
is possible, mechanisms are likely to differ between crop species.
These may include management practices and/or the use of
genetically isolated varieties. Management practices could include
minimum separation distances, rotations, volunteer control and
cleaning of machinery. The JNCC believes that management practices
alone are unlikely to be sufficient to ensure long-lasting
coexistence for UK crops that have high rates of outcrossing and/or
sexually compatible wild relatives – for example, oilseed rape,
sugar beet and fodder beet. The JNCC is also concerned that some
changes in farming practices designed to enable coexistence could
harm non-crop biodiversity in and around fields.
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BN10
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Genetically modified bacteria and fungi are already being used
experimentally to deal with oil spills and heavy metal
contamination. There is considerable potential in extending this to
other types of bioremediation, dealing with other types of
pollution and contamination. Even if the risks to biodiversity from
such GMOs are demonstrated to be relatively low, we are concerned
that the existence of these GMOs should not reduce pressure to
prevent pollution.
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