Pesticides and Pest ControlPesticides and Pest Control

Grasshopper

Gypsy mothcaterpillar

Key ConceptsKey Concepts

Types and characteristics of pesticides Types and characteristics of pesticides

Pros and cons of using pesticides Pros and cons of using pesticides

Pesticide regulation in the US Pesticide regulation in the US

Alternatives to chemical pesticides Alternatives to chemical pesticides

PestsPests

Compete with humans for food Compete with humans for food

Invade lawns and gardens Invade lawns and gardens

Destroy wood in houses Destroy wood in houses

Spread disease Spread disease

Are a nuisance Are a nuisance

May be controlled by natural enemies May be controlled by natural enemies

Types of PesticidesTypes of Pesticides

Pesticides are chemicals that kill undesirable organisms.

Pesticides are chemicals that kill undesirable organisms.

Insecticides Insecticides

Herbicides Herbicides

Fungicides Fungicides

Rodenticides Rodenticides

Major Types of PesticidesType

Insecticides

Chlorinatedhydrocarbons

Organophosphates

Carbamates

Botanicals

Microbotanicals

Examples

DDT, aldrin, dieldrin, toxaphene, lindane, chlordane, methoxychlor, mirex

Malathion, parathion, diazinon, TEPP, DDVP, mevinphos

Aldicarb, Carbaryl (Sevin), propoxur,maneb, zineb

Rotenone, pyrethrum, and camphorextracted from plants, synthetic pyrethroids (variations of pyrethrum), rotenoids (variations of rotenone), and neonicotinoids(variations of nicotine)

Various bacteria, fungi, protozoa

Persistence

High (2–15 years)

Low to moderate (1–2 weeks), but some can last several years

Low (days to weeks)

Low (days to weeks)

Low (days to weeks)

Biologically Magnified?

Yes

No

No

No

No

Major Types of Pesticides

Type

Herbicides

Contact chemicals

Systemic chemicals

Soil sterilants

Fungicides

Various chemicals

Fumigants

Various chemicals

Examples

Atrazine, simazine, paraquat

2,4-D, 2,4,5-T, Silvex, diuron,daminozide (Alar), alachlor (Lasso),glyphosate (Roundup)

Tribulan, diphenamid, dalapon, butylate

Captan, pentachlorophenol, zeneb, methyl bromide, carbon bisulfide

Carbon tetrachloride, ethylene dibromide, methyl bromide

Persistence

Low (days to weeks)

Mostly low(days to weeks)

Low (days)

Most low (days)

Mostly high

Biologically Magnified?

No

No

No

No

Yes (for most)

First Generation PesticidesFirst Generation Pesticides

Primarily natural substances Primarily natural substances

Sulfur, lead, arsenic, mercury Sulfur, lead, arsenic, mercury

Plant extracts: nicotine, pyrethrum Plant extracts: nicotine, pyrethrum

Second Generation PesticidesSecond Generation Pesticides

Primarily synthetic organic compounds Primarily synthetic organic compounds

Broad-spectrum agents Broad-spectrum agents

Narrow-spectrum agents Narrow-spectrum agents

Persistence in the environment Persistence in the environment

Targets specific organism

Ideally, it would break down fast and turn into benign products.

It would stay in the area it was applied and not move around in the environment.

Narrow Spectrum PesticidesNarrow Spectrum Pesticides

Broad Spectrum Pesticides

Kills a variety of organisms, not just the target species.

Many are persistent in the environment.

Many decompose into harmful byproducts.

Many move through the environment and bioaccumulate.

Inorganic Pesticides

Extremely toxic to birds and fish, do not decompose, accumulate in soil and water

Chlorinated Hydrocarbons

Highly toxic to birds and fish, high persistence, most bioaccumulate

Types of PesticidesTypes of Pesticides

Types of PesticidesTypes of Pesticides

OrganophosphatesVarying toxicity to birds and fish,

low persistence, doesn’t bioaccumulate.

CarbamatesHighly toxic to birds, mild toxicity

to fish, low persistence.

Types of PesticidesTypes of Pesticides

BotanicalsHighly toxic to aquatic life and

bees, low persistence, doesn’t bioaccumulate.

Inorganic PesticidesInorganic Pesticides

Used before 1940’sContained lead, mercury and arsenicExtreme toxicityNatural processes do not decomposeAccumulate in soil and water Threat to most life.

Endosulfan: Highly toxic, restricted use

Chlorinated HydrocarbonsChlorinated Hydrocarbons

General Form:

Malathion:

OrganophosphatesOrganophosphates

Diazinon (Spectracide)

Nerve Agents:

Sarin

Tabrun

Broad spectrum pesticide family

Derived from carbamic acid

Usually not toxic to mammals

Usually low persistence

Usually does not bioaccumulate

CarbamatesCarbamates

AldicarbCommon Carbamates

Carbaryl

Natural organic compounds, from plants natural defense systems

Easily degraded by microorganisms in the soil; not very persistent

Toxic to aquatic organisms and bees.

BotanicalsBotanicals

BotanicalsPyrethrin I

Rotenone

Selective herbicides- specific target weeds

Nonselective, broad spectrum herbicides. Kill all vegetation

Broad leaf herbicides, kill all but grasses

Grass herbicides, other plants are generally safe.

HerbicidesHerbicides

2,4 D 2,4,5 T

Two forms of chlorophenoxyacetic acid

Common Broad Leaf HerbicidesCommon Broad Leaf Herbicides

2, 4 D and 2,4,5 T are similar to plants natural growth hormone, therefore they disrupt growth processes.

Most food grains are grasses. These herbicides are used extensively to kill weeds that compete with these crops.

2,4,5 T is now banned, because it is probably harmful to humans.

Common Broad Leaf HerbicidesCommon Broad Leaf Herbicides

The Case for PesticidesThe Case for Pesticides

Save human lives Save human lives

Increase food supplies and lower costs Increase food supplies and lower costs

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

Ideal PesticidesIdeal Pesticides

Affects only target pests Affects only target pests

Harms no other species Harms no other species

Breaks down quickly in the environment Breaks down quickly in the environment

No genetic resistance No genetic resistance

Be more cost-effective than doing nothing Be more cost-effective than doing nothing

Grasshopper

Gypsy mothcaterpillar

European red mite

The Case Against PesticidesThe Case Against Pesticides

Genetic resistance Genetic resistance

Can kill non-target and natural control species Can kill non-target 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 Can harm wildlife

Potential human health threats Potential human health threats

600

500

400

300

200

100

1940 1950 1960 1970 1980 1990

Nu

mb

er o

f g

enet

ical

ly r

esis

tan

t in

sect

sp

ecie

s

Year

Neonicotinoids(1995)

Pyrethroids (1978)

Carbamates (1972)

Organophosphates (1965)

DDT/cyclodienes (1946)

MH

MH

JH

MH

JH

JH

MH

Pupa

Eggs

Larva

Black

Boll weevil

Pink bollworm

ranges overlap

Pesticide Regulation in the United StatesPesticide Regulation in the United States

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)

Tolerance levels Tolerance levels

EPA Evaluation of chemicals EPA Evaluation of chemicals

Inadequate and poorly enforced Inadequate and poorly enforced

Food Quality Protection Act (FQPA) Food Quality Protection Act (FQPA)

Alternate Ways to Control PestsAlternate Ways to Control Pests

Economic threshold Economic threshold

Adjusting cultivation practices Adjusting cultivation practices

Use genetically-resistant plants Use genetically-resistant plants

Biological pest control Biological pest control

Insect birth control Insect birth control

Hormones and pheromones Hormones and pheromones

Ionizing radiation Ionizing radiation

Hot water Hot water

Integrated Pest ManagementIntegrated Pest Management

Ecological system approach Ecological system approach

Reduce pest populations to economic threshold

Reduce pest populations to economic threshold

Field monitoring of pest populations Field monitoring of pest populations

Use of biological agents Use of biological agents

Chemical pesticides are last resort Chemical pesticides are last resort

Why is Integrated Pest Management not more widely used?Why is Integrated Pest Management not more widely used?

Requires expert knowledgeSlower than conventional pesticidesInitial costs may be highHindered by government subsidies

Requires expert knowledgeSlower than conventional pesticidesInitial costs may be highHindered by government subsidies