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Pesticides and Pest Control


First Generation Pesticides What Can You Do to Control Common Insect ... of Genetic Resistance to Pesticides ... The Case Against Pesticides Figure 20 ... – PowerPoint PPT presentation

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Title: Pesticides and Pest Control

Pesticides and Pest Control
G. Tyler Millers Living in the Environment 13th
Edition Chapter 20
Dr. Richard Clements Chattanooga State Technical
Community College Modified by Charlotte
Key Concepts
  • Types and characteristics of pesticides
  • Pros and cons of using pesticides
  • Pesticide regulation in the US
  • Alternatives to chemical pesticides

  • Compete with humans for food
  • Invade lawns and gardens
  • Destroy wood in houses
  • Spread disease
  • Are a nuisance

Natural Enemies
  • May be controlled by natural enemies
  • Predator, parasites, and disease organisms
  • Control the populations of 50-90 of pest species
    as part of the earths ecological services
  • Help keep any one species from taking over for
    very long
  • When we replace polyculture with monoculture and
    use pesticides we upset the natural balance
    between plants and natural enemies.

Pesticides Types
  • Chemicals that kill undesirable organisms

See Table 20-1 p. 514
  • Insecticides Kills insects
  • Herbicides Kills weeds
  • Fungicides Kills fungus
  • Rodenticides Kills rodents
  • Nematocides Kills Nematodes (roundworms)

  • We are no the first to develop pesticides.
  • Plants have developed their own natural defenses
    for 225 million years to ward off or poison
    herbivores that feed on them.
  • Herbivores overcome the various plant defenses
    through natural selection and then the plant
    retaliates through their own natural selection to
    develop new defenses.

First Generation Pesticides
  • Primarily natural substances
  • Sulfur, lead, arsenic, mercury Used initially,
    around 500 BC and well into the 15th century.
    These approaches were abandoned as human
    poisoning and fatalities increased.
  • Plant extracts 1600s used nicotine, 1800s
    pyrethrum and rotenone developed
  • Plant extracts are degradable

What Can You Do to Control Common Insect Pests
and Weeds?
  • You can usually persuade ants to leave within
    about 4 days by sprinkling repellents such as red
    or cayenne pepper, crushed mint leaves, or boric
    acid (with an anticaking agent) along their
    trails inside a house and wiping off countertops
    with vinegar. (However, boric acid is poisonous
    and should not be placed in areas accessible to
    small children and pets.)
  • Repel mosquitoes by planting basil outside
    windows and doors and rubbing a bit of vinegar,
    basil oil, lime juice, or mugwort oil on exposed
    skin. You can also reduce mosquito attacks by not
    using scented soaps or wearing perfumes,
    colognes, and other scented products outdoors
    during mosquito season. Researchers have found
    that the 30 million U.S. consumers spend each
    year on electric bug zappers to kill mosquitoes
    is mostly wasted. Only about 3 of the insects
    they kill on an average night are female
    mosquitoes-the kind that bite.
  • Kill cockroaches by sprinkling boric acid under
    sinks and ranges, behind refrigerators, and in
    cabinets, closets, and other dark, warm places
    (but not in areas accessible to children and
    pets) or establishing populations of banana
  • Trap cockroaches by filling much of a bottle or
    large jar with raw potato, stale beer, banana
    skins, or other food scraps (especially fruits),
    greasing the inner neck of the bottle with
    petroleum jelly, and placing a small ramp leading
    into it.
  • Repel flies by planting sweet basil and tansy (a
    common herb) near doorways and patios.

What Can You Do to Control Common Insect Pests
and Weeds?
  • Trap flies by making nontoxic flypaper by
    applying honey to strips of yellow paper (their
    favorite color) and hanging it from the ceiling
    in the center of rooms.
  • Keep fleas off pets by using green dye or
    flea-repellent soaps, feeding them brewer's yeast
    or vitamin B, using flea powders made from
    eucalyptus, sage, tobacco, wormwood, or vetiver,
    or dipping or shampooing pets in a mixture of
    water and essential oils such as citronella,
    cedarwood, eucalyptus, fleabane, sassafras,
    geranium, clove, or mint.
  • Trap fleas by using green-yellow light to attract
    them to an adhesive-coated surface or putting a
    light over a shallow pan of water before going to
    bed at night and turning out all other lights,
    emptying the water every morning, and continuing
    this for a month. (Fleas are attracted to heat
    and light, but they cannot swim.)
  • Rid a house of fleas by sprinkling carpets with
    desiccant powders, such as Dri-Die, Perma-Guard,
    or SG-67 to dry them or diatomaceous earth (or
    diatom powder) to kill them. Diatom powder can be
    purchased in bulk at stores that sell it for use
    in swimming pool filters. It is also found in
    some gardening stores under the name of Permatex.
    Because it contains fine particles of silicate,
    you should wear a dust mask when applying this
    powder to avoid inhaling tiny particles of
  • Control lawn weeds by raising the cutting level
    of your lawn mower so the grass can grow 8-10
    centimeters (3-4 inches) high. This gives it a
    strong root system that can hinder weed growth
    the higher grass also provides habitats for
    spiders and other insects that eat insect pests.
    Pull weeds and douse the hole with soap solution
    or human urine (which is high enough in nitrogen
    to kill the weed).

Second Generation Pesticides
  • Began in 1939 with discovery of DDT by Paul
    MullerNobel prize in 1948
  • Primarily synthetic organic compounds
  • 630 biologically-active (pest killing) compounds
    with 1820 inert ingredients combine to make
    25,000 pesticides

See Table 20-1 p. 514
Second Generation Pesticides
  • Broad-spectrum agents Toxic to many species
  • Narrow-spectrum agents toxic to narrow group of
  • Target species species pesticide is to act on.
  • Nontarget species species that is effected as a
    result of pesticide use and is not inteded to be
    such as beneficial insects

The Case for Pesticides
  • Save human lives
  • Increase supplies and lower cost of food
  • Increase profits for farmers
  • Work better and faster than alternatives
  • Health risks may be insignificant compared to
  • Newer pesticides are becoming safer
  • New pesticides are used at lower rates

Characteristics of an Ideal Pesticide
  • Kill only target pests
  • Harm no other species
  • Break down quickly
  • Not cause genetic resistance
  • Be more cost-effective than doing nothing

The Case Against Pesticides
  • Genetic resistance
  • Can kill nontarget and natural control species
  • Can cause an increase in other pest species
  • The pesticide treadmill
  • Pesticides do not stay put
  • Can harm wildlife
  • Potential human health threats

Figure 20-4Page 516
Rise of Genetic Resistance to Pesticides
Gypsy moth caterpillar
Boll weevil
Insects and mites
Plant diseases
Pesticide Regulation in the United States
  • Federal Insecticide, Fungicide, and Rodenticide
    Act (FIFRA) established by Congress in 1947 and
    amended in 1972 it requires the EPA to approve
    all use of commercial pesticides.
  • All pesticide companies must test their products
    for toxicity to animals and extrapolate to humans
    before they can be registered for use.
  • Tolerance levels level of pesticide residue
    allowable on fruits and vegetables when a
    consumer eats it.

Pesticide Regulation in the United States
  • EPA Evaluation of chemicals more than 600 active
    ingredients approved for use in pre 1972
    pesticide products are to be reevaluated for
    cancer, birth defects, or other heath risks.
    They have only evaluated 10 in over 30 years.
  • Inadequate and poorly enforced Blame difficulty
    and expense of determining the health effects of
    chemicals. Also the falsification of data from a
    pesticide company that allowed more than 200
    pesticide active ingredients to be registered.

Food Quality Protection Act (FQPA)
  • Established in 1996
  • Requires pesticide companies to verify safety of
    active ingredients in children and infants
  • Allows 10 fold pesticide tolerance level for
    infants and children
  • Requires the EPA to consider exposure to more
    than one pesticide when setting tolerance levels
  • Requires the EPA to develop rules for program to
    screen for estrogenic and endocrine effects by
    1999 (still not accomplished by 2002)

Why Control Pests?
  • In most cases the primary goal of pesticides is
    to eradicate pests in the area affected
  • However many believe it should be to keep the
    crop damage to an economically tolerable level.
  • Economic threshold is the point at which the
    economic losses outweigh the cost of applying
    more pesticides. Tough to determine.
  • Concern is with insurance spraying to be on the
    safe side.
  • May purchase pest loss insurance
  • Another concern is with cosmetic spraying

Economic Threshold
Fig. 20-6 p. 520
Other Ways to Control Pests
  • Adjusting cultivation practices
  • Use genetically-resistant plants pest and
    disease resistance
  • Biological pest control
  • Insect birth control
  • Hormones and pheromones
  • Ionizing radiation
  • Spraying with hot water
  • Irradiate foods

Variety of alternative pest control methods
Biological pest control
Synthetic hormones
Integrated Pest Management
  • Ecological system approach
  • Reduce pest populations to economic threshold
  • Field monitoring of pest populations
  • Use of biological agents
  • Chemical pesticides are last resort