Environmental Science: Toward a Sustainable Future Richard T. Wright

1
Environmental Science Toward a Sustainable
Future Richard T. Wright
Chapter 16

• Pests and Pest Control
• PPT by Clark E. Adams

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Pests and Pest Control

• The need for pest control
• Promises and problems of the chemical approach
• Alternative pest control methods
• Socioeconomic issues in pest management
• Pesticides and policy

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Formosan Subterranean Termite Invades the French
Quarter
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The Need for Pest Control

• Any organism that has a negative effect on human
  health or economics
• Any organism that is noxious, destructive, or
  troublesome
• Plants or animals (see Fig. 16-2)
• Formosan termite
• Fire ants
• Aedes mosquito
• Medfly

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Pest Control Purposes

• Protect our food
• Protect our health
• Convenience

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Pesticide Use in the United States
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Philosophies of Pest Control

• Chemical technology
• Use of chemicals to kill large numbers of the
  pest
• Short-term protection
• Environmental and health consequences

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Philosophies of Pest Control

• Ecological pest management
• Control based on pest life cycle and ecology
• Control agent may be an organism or chemical
  (more on next slide)

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Philosophies of Pest Control

• Specific to pest and/or to manipulate a part of
  the ecosystem
• Emphasizes protection from pest

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Promises and Problems of the Chemical Approach

• Development of chemical pesticides and their
  successes
• Problems stemming from chemical pesticide use

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Development of Chemical Pesticides

• First-generation pesticides (inorganic)
• First attempt at chemical technology
• Toxic to humans and agricultural plants
• Pests developed resistance

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Development of Chemical Pesticides

• Second-generation pesticides
• Used after WW II
• Organic chemical
• Toxic to humans and agricultural plants
• Pests developed resistance

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The DDT Story

• DDT the magic bullet
• Extremely toxic to insects seemed nontoxic to
  humans and other mammals
• Cheap
• Broad-spectrum and persistent (more next slide)

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The DDT Story

• DDT the magic bullet
• Effective for disease prevention (typhus fever,
  malaria)
• Expanded agricultural production
• Paul Müller awarded Nobel prize in 1948

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Aerial Spraying
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Problems Stemming from Chemical Pesticide Use

• Development of resistance by pests
• Resurgences and secondary pest outbreaks
• Adverse environmental and human health effects

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Resistance

• Chemical pesticides lose effectiveness
• Resistant pest populations produce next
  generations

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Genetics of Pest Resistance
RR x rr Nonresistant x resistant R nonresistant gene R
r resistant gene Rr nonresistant offspring Rr
r Rr Rr
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Genetics of Pest Resistance
Rr x Rr Heterozygous nonresistant x nonresistant R r
R RR dies Rr dies
r Rr dies rr SURVIVES!
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Pesticide Resistance
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Resurgence and Secondary Outbreaks

• 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.

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The Bugs Are Coming!
Time Magazine, July 12, 1976, page 38
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(No Transcript)
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The Pesticide Treadmill
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Human Health Effects

• Cancer, dermatitis, neurological disorder, birth
  defects, sterility, endocrine system disruption,
  immune system depression.
• Agricultural workers suffer acute poisoning
  during pesticide application.

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Human Health Effects

• 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.

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Environmental Effects

• DDT led to the decline in populations of several
  bird species
• Bald eagle
• Peregrine falcon
• Bioaccumulation
• Biomagnification

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Biomagnification
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Nonpersistent Pesticides

• Substitutes for banned pesticides
• Break down after a few weeks
• Can still be harmful because of
• Toxicity
• Dosage
• Location

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Alternative Pest Control Methods

• Cultural control
• Control by natural enemies
• Genetic control
• Natural chemical control

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Complex Life Cycle of Insects
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Cultural Control
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Genetic Control

• Plants or animals are bred to be resistant to the
  attack of pests.
• Chemical barriers
• Physical barriers

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Genetic Control

• Introduction of genes into crops from other
  species transgenic crops.
• Sterile males are released into pest population.

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Control Using Natural Enemies
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Natural Chemical Control

• 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

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Natural Chemical Control

• Manipulation of pests hormones or pheromones to
  disrupt the life cycle
• Japanese beetle trap (see Fig. 16-18)

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Socioeconomic Issues of Pest Management

• Pressures to use pesticides
• Integrated pest management
• Organically grown food

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The Economic Threshold
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Integrated Pest Management (IPM)

• An approach to controlling pest populations using
  all suitable methodschemical and ecologicalin a
  way that brings about long-term management of
  pest populations and also has minimal
  environmental impact

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(No Transcript)
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Pesticides and Policy

• Fifra Federal Insecticide, Fungicide, and
  Rodenticide Act
• FQPA of 1996 Food Quality Protection Act
• Pesticides in developing countries

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FIFRA or FQPA?

• 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

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End of Chapter 16