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

600

500

400

300

200

100

01950 1960 1970 1980 1990 2000 2010

Year

Nu

mb

er o

f sp

ecie

s

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

NO

T P

OS

T T

O IN

TE

RN

ET

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