Farmers can spray crops with less herbicide to kill weeds Ex

I.
Genetic Engineering


C.
Advantages

1.
Greater agricultural yields

•
More food production per acre could

•
Reduce area needed to support existing population

•
Support future population growth

•
Ex

–

European corn borer destroys 7% of annual corn harvest worldwide

•
Modified corn resistant to ECB could eliminate this loss

•
Extra corn =

7
-
10 mmt (enough to feed 60 million people)

2.
Reduced herbicide use

•
Wheat, corn, soybeans, cotton, sugar beets, alfalfa, etc. engineered to be
resistant to certain herbicides (e.g. Roundup)

•
Farmers can spray crops with less herbicide to kill weeds

•
Ex

–

Soybeans
–

Reduction of pesticide use by 10
-
40% from 1996
-
1997

3.
Reduced pesticide use

•
Crop plants can be engineered for resistance to certain pesticides

•
Ex

–

Insect resistant cotton planted in Alabama led to an 80% reduction in
use of insecticides on cotton from 1996
-
1997

4.
Environmentally beneficial tasks

•
Ex

–

Bacteria engineered to degrade petroleum rapidly can be used to
clean up oil spills

5.
Novel properties

•
Ex

–

Phytase maize (approved in China, 2009)

•
Enzyme makes phosphorus more available to livestock

•
Enhances animal growth, reduces P content of waste (up to 60%)

I.
Genetic Engineering


D.
Drawbacks

•
Opponents emphasize failures of
technology, potential environmental harm

•
“Frankenfood”

•
“Farmageddon”

1.
Harm to native species through competition

•
Transgenic organisms could be superior competitors

•
Potential route to extinction for native species

2.
Damage to beneficial insects

•
Ex

–

Evidence that ladybugs and lacewings suffer (shorter lifespan,
reduced reproduction) when fed aphids and caterpillars that had fed on
GM potatoes and corn, respectively

3.
Damage to soil community

•
Certain GM crops could reduce activity of soil fungi and microbes

•
Negative impact on nutrient cycling in the soil

4.
Release of resistance genes

•
Could potentially lead to “super weeds” if resistance genes get
transferred to weedy species

•
Could harm non
-
GM agriculture, including organic farming through pollen
drift

5.
Upset natural balance of ecosystems

•
Could result from release of GMOs or hybridization between GMOs and
native species

•
Ex

–

GM rape can crossbreed with wild turnips, passing herbicide
tolerance to offspring

•
Potential solution = “
Terminator technology
”

I.
Genetic Engineering


E.
Trends

•
125 GM agricultural plants approved for
growth in the U.S. (ISAAA)

•
Most designed to

1)
Reduce pest damage

2)
Confer resistance to herbicides, pesticides,
viruses, other pathogens

3)
Reduce crop spoilage

Huang et al. 2002

Nature

418
, 678
-
684


Genetically modified crop traits tested

in developed countries, 1987
–
2000

I.
Genetic Engineering


E.
Trends

•
US grows ~48% of GM crops worldwide
(acreage basis)

•
2011: corn 88%, cotton 90%, soy 94% GM

•
Other major growers of GM crops

1)
Brazil

2)
Argentina

3)
India

4)
Canada

5)
China

http://www.ers.usda.gov/Data/BiotechCrops/genengcrops.gif

I.
Genetic Engineering


F.
Examples

1.
Bollgard
®

and Bollgard II
®

Cotton

•
Both strains express insecticidal protein isolated from
Bacillus thuringiensis

(Bt)

•
Safe
–

Farmers can spray with Bt toxin and still label
produce as organic

•
Low toxicity to most non
-
target organism types

•
Low persistence
–

breaks down readily

•
Bollgard II
®

has
stacked traits

to enhance effectiveness

•
Controls bollworms, budworm

•
Year 2000
–

United States averages

•
Cotton fields planted with Bollgard
®

sprayed 3.9
times less often
vs.

conventional fields

•
Reduced total pesticide use by 2.7 million pounds

•
Pest control cost less
-

$15.43/acre

•
Higher production
-

37 pounds/acre

•
Higher profit
-

$39.86/acre

•
Concern

–

Development of resistance by insect pests

I.
Genetic Engineering


F.
Examples

2.
Golden Rice

•
GM rice containing genes that produce beta
-
carotene

•
Can be converted to vitamin A

•
Vitamin A deficiency (VAD) may cause weakened immune
systems, partial to total blindness, and increased chance of
death

•
VAD causes 350,000 cases of blindness and has been
linked to 1 million+ deaths each year

•
Highly controversial

a.
Proponents

•
Reduce incidence of blindness and other VAD related
health disorders

•
1/2 lb of rice/day will keep VAD symptoms away

b.
Opponents

•
Nutritional deficiencies will prevent people from absorbing
beta
-
carotene from rice

•
Concentrations of beta
-
carotene in rice are low, and an
average woman would need to eat 16 lbs of golden rice a
day to get 100% of daily requirement

•
Alternatives like leafy green vegetables or unpolished rice
are better, cheaper sources of vitamin A

•
Western corporations are trying to control rice production

I.
Genetic Engineering


F.
Examples

3.
Future GM crops

•
SmartStax
TM

corn

•
Pest resistant, herbicide tolerant

•
Bt rice

•
Pest resistant

•
High omega
-
3 soybeans

•
Enhanced nutrition

•
RR Sugarbeets*

•
Herbicide tolerant

•
2007: <10% of US

•
2009: 95% of US

•
Blue roses

•
Ornamental

I.
Genetic Engineering


G.
Benefits and Risks

1.
Benefits

•
Accelerated improvement of crop strains

a.
Elevated yields, either per plant or per acre

•
Usually involves inserting growth factor

•
Plants grow larger, faster or both

•
Con

–

Accelerated growth may alter chemical
composition


A汬敲杩敳Ⱐ摩来g瑩t攠灲潢汥浳Ⱐ整e.

戮
A捣敬e牡瑥搠浡瑵牡瑩潮 灲潣p獳

•
Increased yield per acre, more crops per year

•
Con

–

Plants produce different compounds at
different life stages

•
Young plants tend to produce more irritants and
toxins (self defense)

•
Potential to cause digestive or allergic problems