Transcript WFSC 420 Chapter 17

Environmental Science: Toward a
Sustainable Future
Richard T. Wright
Chapter 16
Pests and Pest Control
PPT by Clark E. Adams
Pests and Pest Control
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The need for pest control
Promises and problems of the chemical
approach
Alternative pest control methods
Socioeconomic issues in pest
management
Pesticides and policy
Formosan Subterranean Termite Invades
the French Quarter
The Need for Pest Control
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Any organism that has a negative effect on
human health or economics
Any organism that is noxious, destructive,
or troublesome
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Plants or animals (see Fig. 16-2)
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Formosan termite
Fire ants
Aedes mosquito
Medfly
Pest Control Purposes
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Protect our food
Protect our health
Convenience
Pesticide Use in the United States
Philosophies of Pest Control
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Chemical technology
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Use of chemicals to kill large numbers of the
pest
Short-term protection
Environmental and health consequences
Philosophies of Pest Control
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Ecological pest management
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Control based on pest life cycle and ecology
Control agent may be an organism or
chemical (more on next slide)
Philosophies of Pest Control
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Specific to pest and/or to manipulate a
part of the ecosystem
Emphasizes protection from pest
Promises and Problems of the Chemical
Approach
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Development of chemical pesticides and
their successes
Problems stemming from chemical
pesticide use
Development of Chemical Pesticides
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First-generation pesticides (inorganic)
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First attempt at chemical technology
Toxic to humans and agricultural plants
Pests developed resistance
Development of Chemical Pesticides
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Second-generation pesticides
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Used after WW II
Organic chemical
Toxic to humans and agricultural plants
Pests developed resistance
The DDT Story
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DDT: the magic bullet
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Extremely toxic to insects; seemed nontoxic to
humans and other mammals
Cheap
Broad-spectrum and persistent (more next
slide)
The DDT Story
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DDT: the magic bullet
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Effective for disease prevention (typhus fever,
malaria)
Expanded agricultural production
Paul Müller awarded Nobel prize in 1948
Aerial Spraying
Problems Stemming from Chemical
Pesticide Use
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Development of resistance by pests
Resurgences and secondary pest
outbreaks
Adverse environmental and human health
effects
Resistance
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Chemical pesticides lose effectiveness
Resistant pest populations produce next
generations
Genetics of Pest Resistance
RR x rr
R
Nonresistant x nonresistant
resistant
gene
R
r
resistant gene
Rr
nonresistant
offspring
Rr
r
Rr
Rr
Genetics of Pest Resistance
Rr x Rr
Heterozygous
nonresistant x
nonresistant
R
r
R
RR
dies
Rr
dies
r
Rr
dies
rr
SURVIVES!
Pesticide Resistance
Resurgence and Secondary Outbreaks
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Resurgences: after “eliminating” a pest, its
population rebounds in even higher
numbers than previous levels.
Secondary outbreaks: outbreaks of
species’ populations that were not
previously at pest levels.
The Bugs Are Coming!
Time Magazine, July 12, 1976, page 38
The Pesticide Treadmill
Human Health Effects
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Cancer, dermatitis, neurological disorder,
birth defects, sterility, endocrine system
disruption, immune system depression.
Agricultural workers suffer acute poisoning
during pesticide application.
Human Health Effects
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Aerial spraying and dumping bring
pesticides in contact with families and
children.
Soldiers exposed to agent orange in
Vietnam suffered high rates of cancer and
other diseases.
Environmental Effects
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DDT led to the decline in populations of
several bird species
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Bald eagle
Peregrine falcon
Bioaccumulation
Biomagnification
Biomagnification
Nonpersistent Pesticides
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Substitutes for banned pesticides
Break down after a few weeks
Can still be harmful because of:
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Toxicity
Dosage
Location
Alternative Pest Control Methods
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Cultural control
Control by natural enemies
Genetic control
Natural chemical control
Complex Life Cycle of Insects
Cultural Control
Genetic Control
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Plants or animals are bred to be resistant
to the attack of pests.
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Chemical barriers
Physical barriers
Genetic Control
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Introduction of genes into crops from other
species: transgenic crops.
Sterile males are released into pest
population.
Control Using
Natural Enemies
Natural Chemical Control
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A volatile chemical produced by the opposite
sex of a species which alters the reproductive
behavior of the opposite sex.
 Perfumes
 Colognes
 After shave
 Natural body odors
Natural Chemical Control
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Manipulation of pests’ hormones or
pheromones to disrupt the life cycle
Japanese beetle trap (see Fig. 16-18)
Socioeconomic Issues of Pest Management
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Pressures to use
pesticides
Integrated pest
management
Organically grown
food
The Economic Threshold
Integrated Pest Management (IPM)
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An approach to controlling pest
populations using all suitable methods—
chemical and ecological—in a way that
brings about long-term management of
pest populations and also has minimal
environmental impact
Pesticides and Policy
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FIFRA: Federal Insecticide, Fungicide, and
Rodenticide Act
FQPA of 1996: Food Quality Protection
Act
Pesticides in developing countries
FIFRA or FQPA?
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Pesticides evaluated on intended use and
potential effects to human health and the
environment
Training and protection of agricultural
workers
Protection of public from risks of pesticides
used on food
End of Chapter 16