Environmental Engineering Reference
In-Depth Information
with genes from silkworms to make the vines resistant to a disease spread
by insects. A strawberry can be given a fl ounder gene that makes it frost
resistant. The body of a fi sh might be turned into rows of corn kernels.
The visible divisions between species can be overcome if the researcher
wishes it.
Use of Genetic Modifi cation in Agriculture
The chief use of genetic engineering in agriculture has been to make
crops resistant to herbicides and insecticides. This enables a farmer to
blanket-spray the crops with herbicides and insecticides produced by
the agrobiotech companies without harming his crops, which have been
engineered to be resistant to these chemicals. Weeds and insects will die
but the crops are unaffected. The appeal of this to the farmer is obvious
in the farm labor it saves.
Adoption of genetically engineered soybeans and corn by farmers in
the United States has been rapid, although they still form only 9 percent
of global crop production.
31
Genetically modifi ed crops were introduced
in 1996, and by 2009, 63 percent of America's corn was GM, as were
93 percent of soybeans. Both of these crops are used mostly for animal
feed. Wheat is consumed largely by humans, and resistance to GM foods
around the world halted Monsanto's plans to develop GM wheat. As of
2008, Europe's supermarket shelves contain almost no biotech produce,
and top retailers shun GM foods. Most food sold in American stores
contains GM ingredients. There is no evidence that the public's health
has been harmed by eating GM food, although several animal studies
have resulted in harm or death to the animals.
32
The Downside of Genetically Modifi ed Crops
Hybridization of GM crops with nearby weeds can transfer herbicide
resistance or other benefi cial crop traits to weeds. This has already
occurred in fi fteen weed species.
33
In addition, weeds and insects develop
resistance to certain pesticides through evolution. Although this phenom-
enon can and has affected both conventional and GM varieties, the
evolutionary pressure to develop resistance is stronger in GM crops
because of greater reliance on a single gene or herbicide.
Studies over the past decade have revealed that early results with GM
crops were as the agrobiotech companies predicted: a decreased need for
pesticides and better crop yields as weed and insect problems declined.
However, the pattern reverses within a few years as superweeds appear
and insect resistance evolves. Reports of weeds resistant to the herbicide
