Agriculture Reference
In-Depth Information
detritivores that are exposed to Bt plant material, which appears to be widely dispersed
throughout aquatic ecosystems.
8.4.6.1 Research recommendations: Effects of the cultivation of Bt crops
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.
8.5 Gene escape/introgression
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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