Contents - Faperta

13
Transgenic Resistance to Insects: Gene Flow
Introduction
There is a need for planned introduction of genetically modifi ed organisms into the environment.
There are concerns that the deployment of transgenic plants will lead to development
of resistance in insects and gene fl ow between closely related species and the
unrelated species in the ecosystem. While some of these concerns may be real, others seem
to be highly exaggerated. Therefore, careful thought should be given to the production and
release of transgenic crops in different agroecosystems. A number of ecological issues,
including gene fl ow, need to be addressed while considering the production and deployment
of transgenic crops for insect control. The greatest risk of a transgenic plant released
into the environment is its potential spread to other areas to become a weed. Genes from
unrelated sources may change the fi tness and population dynamics of the hybrids between
native plants and the wild species. However, there are no records of a plant becoming a
weed as a result of plant breeding (Cook, 2000). This is mainly because of:
• Low risk of crop plants to the environment;
• Extensive testing of the crop varieties before release; and
• Adequate management practices to mitigate risks inherent in crop plants.
Plant breeding efforts have tended to decrease rather than increase the toxic substances,
as a result making the improved varieties more susceptible to insect pests. However, there
is a feeling that genes introduced from outside the range of sexual compatibility might
present new risks to the environment and human beings. However, many such apprehensions
are not supported by data. A study conducted by the National Academy of Sciences
(NAS, 1987) has concluded that:
• There is no evidence of hazards associated with DNA techniques.
• The risks, if any, are similar to those with conventional breeding techniques.
•
The risks involved are related to the nature of the organism rather than the process.