Agriculture Reference
In-Depth Information
detritivores that are exposed to
Bt
plant material, which appears to be widely dispersed
throughout aquatic ecosystems.
on nontarget Lepidopteran larvae and aquatic insects
Although it has been demonstrated that some nontarget insects (e.g., Lepidoptera) can be
negatively impacted by certain
Bt
cultivars, particularly those that express high levels of
the Cry proteins
in pollen, root exudates, and plant biomass, further studies are needed
to determine the long-term health and reproductive success of nontarget insect larvae
that feed on naturally deposited
Bt
pollen and other plant residues in the field. Because
most
Bt
crops developed thus far are not wind pollinated and would therefore have
minimal impacts of pollen drift on nontarget insect larvae, in future studies, it will be
important to evaluate the impact of
Bt
plants that are wind pollinated or are cultivated
in close proximity to the primary food sources of nontarget insects. Moreover, the scope
of future biotech risk assessment research should be broadened to assess the impacts of
Bt
crops on a variety of insect species in different parts of the world, as many risk assess-
ment studies to date have focused primarily on effects on nontarget insect larvae in the
United States.
Continuing to monitor and test for effects of the cultivation of
Bt
crops on nontarget
aquatic insects is also important, particularly as the deposition of
Bt
plant biomass into
streams and rivers is common throughout
Bt
crop-growing regions of the United States.
Because Cry proteins from
Bt
maize have been detected in streams at least up to 82 km
downstream, nontarget insects such as caddisfly larvae and other aquatic invertebrates
that serve as an important food source for fish should be monitored for nontarget effects
of different types of
Bt
proteins and over multiple distances away from the source. In
some cases, there may even be a continual source of
Bt
residue deposition into aquatic
ecosystems, as more and different types of
Bt
crops are cultivated near waterways and
Bt
plant debris enters aquatic ecosystems at different times throughout the growing season.
If further research demonstrates negative effects of
Bt
proteins, the cultivation of
Bt
crops,
or
Bt
biomass on nontarget insect larvae in aquatic or terrestrial ecosystems, it may be pos-
sible to use these data to develop new conditions that can be imposed on registration of
Bt
products and to establish new scientific evaluation protocols that would minimize the
environmental impacts of different types of
Bt
crops in both types of systems.
Gene flow and introgression of
Bt
crops has been a concern in both the agriculture and
scientific communities since transgenic crops were commercially released, so much so
that the planting of GM PIP crops in close proximity to SCWR in the United States is
regulated by the EPA (for more details, see the section on how
Bt
and other GM plants
are regulated in the United States in this chapter). Although the regulatory agencies
in the United States have a fairly rigorous oversight role in protecting the interests of
farmers, consumers, seed companies, and the environment, other countries, particu-
larly those with small economies, may not be able to enforce the types of regulations
that the United States has designed to minimize environmental impact, especially with
regard to containment or separation of GM products (produce, grain, seed), setting aside
refuge areas to minimize the development of pest resistance, creating buffers to limit
gene flow, or monitoring for nontarget effects in the environment. This potential lack of
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