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Objectives
By the end of today’s lesson, you will
be able to…
• Explain why pest control is so
important in corn/crop production.
• Describe the European Corn Borer
(ECB) and the damage it causes.
• Describe how bacteria are used to
create insect resistance in plants.
• List the advantages of plants that
have been genetically modified.
• Identify some concerns of Bt crops.
Introduction
• Selective breeding has been
used for thousands of years to
change and improve plants
that are grown for food,
shelter, and clothing.
• This technology has made
tremendous progress in the
past; however, nothing has
come close to improving plants
as much as genetic
engineering.
History of Insect Damage
• Historically, one of the greatest
problems associated with crop
production has been the control
of insects.
• A common practice used to be to
plant twice as much as needed
because you could count on bugs
devouring at least half the crop.
• Even today with effective
pesticides and management
techniques, its estimated that 40%
of the world’s food supply is lost
to pests, disease, and spoilage.
European Corn Borer (ECB)
• ECB (Ostrinia nubilalis) is a pest of
grain, particularly maize (corn).
• Native to Europe.
• First reported in North American
in 1917.
• Since its discovery, the insect has
spread into Canada and westward
across the United States to the
Rocky Mountains.
ECB Damage
European corn borer caterpillars damage:
1. The ears of corn.
2. The stalks, chewing tunnels causing the plants to fall over.
Development of Insect-Resistant Plants
• Genetic material is introduced
from different species and often
different kingdoms of organisms.
• Bacillus thuringiensis (Bt), a soilborne bacteria discovered in
1911, is used in GM crops to
disrupt the digestive process of
insects, thus making the crop
insect-resistant.
• This bacteria is nontoxic to
mammals and other warmblooded animals, such as birds.
Insect-Resistant Plants (cont.)
• Currently, millions of acres of Bt
crops are produced all over the
world and the amount is
increasing.
• Bt crops include: corn,
soybeans, potatoes, tomatoes,
apples, rice, and several
vegetables.
• Bt crops aren’t always widely
accepted by the public.
Problems With Pesticides
1.
2.
3.
4.
5.
6.
Plants not absorbing enough pesticide to be effective.
Withdrawal periods may be required before harvest
and processing.
Pesticides are very expensive and timing is important.
Sprays cannot reach all areas of the leaves/plants .
Trips though the field cost time and money.
Chemical pollution.
Bt Benefits
• Labor costs, fuel expenses, and
machinery operating costs are
greatly reduced when plants
have built-in resistance to
insects.
• Bt prevents feeding of insects on
the plant, which cause damage
and produce openings for
fungus spores to grow.
• Less insect damage equals fewer
openings and less fungus
damage.
Benefits (cont.)
• In addition, Bt toxins actually
kill the fungus which reduces
damage in stored crops such
as grain and silage.
• Saves millions of dollars in
pesticides costs and safer for
the environment.
• Reduced mycotoxins, which
are potent poisons produced
by fungi.
• Most dramatic effects may
be in third world countries.
Bt & Monarch Caterpillars
Scientific research backs data:
1. Monarch caterpillars are not
very sensitive to pollen from
most types of Bt corn - the
exposure is too low to be
significant.
2. Other data shows no ill
effects for black swallowtail
butterfly.
How To Prevent Resistance In ECB
• The EPA sets standards and requires
“buffer zones” and the use of
“refuges.”
• Use Bt corn hybrids in fields where
the risk of severe ECB infestations
warrants the price premium for
seed.
• Carefully record and mark where Bt
and non-Bt corn hybrids are
planted, so Bt corn performance can
be monitored and non-Bt corn can
be scouted, and if needed, treated
with a non-Bt insecticides.
Resistance Prevention (cont.)
• Plant non-Bt corn refuge(s) to
protect 20-30% of the ECB larval
populations from exposure to Bt Cry
proteins.
• Plant non-Bt corn at a similar time
and in close proximity to Bt corn. In
corn-soybean production areas,
where corn is the primary refuge, at
least 20-30% of the corn acreage
should be non-Bt corn.
• Where spraying of non-Bt corn is
anticipated, increase the refuge size
to 40%.
Common Concerns Of The Bt Trait
• Genetic pollution
• Creation of a “super bug”
• Possible negative impacts to
wildlife
• Allergen risk
• Not all countries are accepting
GMO’s
• The fear of the unknown
Summary
• Humans have genetically
altered plants for thousands
of years.
• The invention of genetic
engineering has greatly
accelerated the process of
plant improvements.
• Scientists can select specific
desirable genes, insert them
into conventional plants, and
produce super plants that
have capabilities far
exceeding any produced by
convention means.