pesticides and pest control g. tyler miller’s living in the environment 13 th edition chapter 20...
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Pesticides and Pest ControlPesticides and Pest Control
G. Tyler Miller’sLiving in the Environment
13th Edition
Chapter 20
G. Tyler Miller’sLiving in the Environment
13th Edition
Chapter 20
wolf spider crab spider
Key ConceptsKey Concepts
Types and characteristics of pesticidesTypes and characteristics of pesticides
Pros and cons of using pesticidesPros and cons of using pesticides
Pesticide regulation in the USPesticide regulation in the US
Alternatives to chemical pesticidesAlternatives to chemical pesticides
What is a Pest?What is a Pest?
Compete with humans for foodCompete with humans for food
Invade lawns and gardensInvade lawns and gardens
Destroy wood in housesDestroy wood in houses
Spread diseaseSpread disease
Are a nuisanceAre a nuisance
May be controlled by natural enemiesMay be controlled by natural enemies
Natural Ecosystem (Polyculture)Natural Ecosystem (Polyculture)
• Natural enemies of pests control 50 – 90% of pest species (Earth’s ecological services)
• Natural enemies of pests prevent any one pest species from taking control for very long
Pesticides: TypesPesticides: Types
Chemicals that kill undesirable organisms
Chemicals that kill undesirable organisms
Insecticides Insecticides
Herbicides Herbicides
Fungicides Fungicides
Rodenticides Rodenticides
First Generation PesticidesFirst Generation Pesticides
Primarily natural substances Primarily natural substances
Sulfur, lead, arsenic, mercury Sulfur, lead, arsenic, mercury
Plant extracts: nicotine, pyrethrum, rotenone (from tobacco,
chrysanthemums, and tropical forest legume roots, respectively.)
Plant extracts: nicotine, pyrethrum, rotenone (from tobacco,
chrysanthemums, and tropical forest legume roots, respectively.)
Plant extracts are degradable Plant extracts are degradable
Second Generation PesticidesSecond Generation Pesticides
Primarily synthetic organic compounds Primarily synthetic organic compounds
630 biologically-active compounds 630 biologically-active compounds
Broad-spectrum agents Broad-spectrum agents
Narrow-spectrum agents Narrow-spectrum agents
Target species Target species
Nontarget species Nontarget species
Major Types of InsecticidesMajor Types of Insecticides
• Chlorinated Hydrocarbons– DDT– Highly Persistent (2-15 years)
• Organophosphates– Malathion– Moderately Persistent (1-2 weeks)
• Carbamates– Sevin– Low Persistence (days-weeks)
• Botanicals– Rotenone, pyrethrum– Low Persistence (days-weeks)
The Case for PesticidesThe Case for Pesticides
Save human livesMalaria (mosquito)Bubonic plague (rat fleas)Typhus (body lice and fleas)Sleeping sickness (tsetse fly)
Save human livesMalaria (mosquito)Bubonic plague (rat fleas)Typhus (body lice and fleas)Sleeping sickness (tsetse fly)
Increase supplies and lower cost of food55% of world’s potential food supply
is lost to pestsWithout pesticides it would be worse
Increase supplies and lower cost of food55% of world’s potential food supply
is lost to pestsWithout pesticides it would be worse
The Case for PesticidesThe Case for Pesticides
Work better and faster than alternatives Work better and faster than alternatives
Health risks may be insignificant compared to benefits
Health risks may be insignificant compared to benefits
Newer pesticides are becoming safer Newer pesticides are becoming safer
New pesticides are used at lower rates New pesticides are used at lower rates
Grasshopper
Gypsy mothcaterpillar
MAJOR PESTS
European red mite
MAJOR PESTS
Boll weevil
Pink bollworm
ranges overlap
MAJOR PESTS
BOLL WEEVIL
Boll WeevilBoll Weevil
• Lay thousands of eggs every 21 days
• 6 generations per growing season
• 25% of pesticide use in US to control the cotton boll weevil
• Approximately 0.24 pounds of pesticides to make one cotton T-shirt
Characteristics of an Ideal PesticideCharacteristics of an Ideal Pesticide
Kill only target pests Kill only target pests
Harm no other species Harm no other species
Break down quickly Break down quickly
Not cause genetic resistance Not cause genetic resistance
Be more cost-effective than doing nothing Be more cost-effective than doing nothing
The Case Against PesticidesThe Case Against Pesticides
Genetic resistance (directional natural selection) Genetic resistance (directional natural selection)
Can kill nontarget and natural control species Can kill nontarget and natural control species
Can cause an increase in other pest species Can cause an increase in other pest species
The pesticide treadmill The pesticide treadmill
Pesticides do not stay put Pesticides do not stay put
Can harm wildlife (pollinators and insect eaters) Can harm wildlife (pollinators and insect eaters)
Potential human health threats Potential human health threats
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01950 1960 1970 1980 1990 2000 2010
Year
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Boll weevilGypsy moth caterpillar
Insects and mites
Weeds
Plant diseases
Rise of Genetic Resistance to Pesticides
Pesticide Regulation in the United StatesPesticide Regulation in the United States
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (1947, 1972)
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (1947, 1972)
Tolerance levels: specify the amount of pesticide residue that can legally remain on a crop when the consumer eats it
Tolerance levels: specify the amount of pesticide residue that can legally remain on a crop when the consumer eats it
EPA Evaluation of chemicals for toxicity EPA Evaluation of chemicals for toxicity
Good NewsGood News
• Between 1972 and 2001, the EPA banned or severely restricted the use of 56 active pesticide ingredients– Most chlorinated hydrocarbon insecticides– Several carbamates and organophosphates
–HOWEVER: they may still be manufactured in US and exported to other countries…..Circle of Poison
Bad NewsBad News
• Less than 10% of the 600 active ingredients used in pesticides have been evaluated fully.– 165 are suspected human carcinogens– Missouri study showed a connection between
childhood brain cancer and pesticide use in home
– Multiple studies have shown connections between pesticide use and various types of cancers
Good NewsGood News
• 1996 Food Quality Protection Act (FQPA)– Requires new standards for pesticide tolerance
levels– Requires manufacturers to demonstrate safety
for infants and children– Allows EPA to apply an additional 10-fold
safety factor– Requires EPA to consider exposure to more
than one pesticide when setting tolerance levels
Other Ways to Control PestsOther Ways to Control Pests Economic threshold: reduce crop damage to an economically tolerable level
Economic threshold: reduce crop damage to an economically tolerable level
Adjusting cultivation practices Adjusting cultivation practices Use genetically-resistant plants Use genetically-resistant plants
Biological pest control Biological pest control
Biopesticides Biopesticides
Insect birth control Insect birth control
Hormones and pheromones Hormones and pheromones
Ionizing radiation (gamma) Ionizing radiation (gamma)
Figure 20-8Page 521Figure 20-8Page 521
DO
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T T
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Integrated Pest Management (IPM)
Integrated Pest Management (IPM)
Ecological system approachEcological system approach
Reduce pest populations to economic threshold
Reduce pest populations to economic threshold
Field monitoring of pest populationsField monitoring of pest populations
Use of biological agentsUse of biological agents
Chemical pesticides are last resortChemical pesticides are last resort
Effects of IPMEffects of IPM