CHAPTER 20CHAPTER 20PESTICIDES & PEST PESTICIDES & PEST

CONTROLCONTROL

Chapter ObjectivesDefine PesticidesDiscuss the Pro’s and

Con’s of Pesticide UseUnderstanding of

RegulationsAlternatives

20.1 Types and UsesWHAT IS A PEST-Any species that does the

following:1. Competes with humans for food2. Invades lawns and gardens3. Destroys wood in a home4. Spreads disease5. Nuisance

TYPES OF PESTICIDES1. Insecticides

2. Herbicides

3. Fungicides

4. Nematocides (Round worms)

5. Rodenticides

1st Generation Pesticides Sulfur: Used pre-500B.C. Natural Pesticides: Nicotine

Sulfate, Pyrethrum, Rotenone Toxic Chemicals: Arsenic, Lead

and Mercury This approach was abandoned

as late as the1920’s Still find measurable levels in

tobacco and other crops grown on that soil

2nd Generation PesticidesDDT

(Dichlorodiphenyl-trichloroethane)

1st used in 1939Discovered by Paul

Muller who won the Nobel Prize

WWII materials by-products

Pesticide Use Today50 fold increase in

the use of pesticides since the 1950’s

10x stronger than the original pesticides

2.5 million tons used per year, worldwide.

Pesticides in the USAAround 25,000 pesticide

products25% used for homes, parks,

pools, golf courses

Broad vs. Narrow Broad Spectrum Agents: Toxic to many species

Selective / Narrow Spectrum: Specific to a certain species

Pesticides vary in their persistence:How long they remain in the

environment (Usually recorded as half life)

20.2 The Case for Pesticides

“Benefits outweigh the potential harmful effects”

1.) Save human lives:Protection against diseases

like malaria, typhus and sleeping sickness

Rachael Carson’s Silent Spring

Rachael CarsonRachael Carson

• Born: May 27, 1907in Springdale, Pennsylvania

• Graduate of Chatham College• Died: April 14, 1964 in Silver Spring, Maryland

55% of food is already lost to pests

$65 million / yr

2. Increase food supply:

3.Increased Profit to farmers:

Every $1 spent on pesticides increases farm profit by $4

4. They work faster and better than

alternatives:

-Control most pests at reasonable cost

-Have a long shelf life

-Easily shipped and applied

5. Relatively Safe:Health risks are insignificant

when used properly

Today’s pesticides are actually safer than those of the past.

Many of the new pesticides are used at a lower rate than in the past.

20.3 THE CASE AGAINST PESTICIDES

1. Can cause Genetic Resistance:

Reproduce rapidly and can develop a resistance in 5-10 years

Surviving organisms come back stronger.

Leads to Pesticide Treadmill

Fig. 20.4, p. 507

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 cateripllar

Insects and mites

Weeds

Plant diseases

RISE OF GENETIC RESISTANCE TO PESTICIDES RISE OF GENETIC RESISTANCE TO PESTICIDES 1945-981945-98

2. Broad Spectrum insecticides kill natural

predators• 1/3 of the most destructive

pests are secondary pests that became widespread after the use of insecticides

3. Pesticides Do Not Stay Put

Less than 2% of the pesticides used actually reach the target pests

Less than 5% of herbicide reaches the appropriate weeds

Pesticides may end up in the air, water, bottom sediments, food or non-target organisms.

4. Some Pesticides Harm Wildlife

Destruction of more than 20% of honeybee colonies –Costing farmers $200 million

in lost pollination

Kills 67 million birdsKills 6-14 million fishHurt 20% endangered species

5. Threat to Human Health 3 million agricultural workers are

harmed each yr (300,000 in USA) 18,000 deaths (probably

underestimated) 165 of the approved active

ingredients are carcinogenic Exposure in food is related to 4-

20,000 cases of cancer / year Birth defects, genetic mutations,

nervous system disorders, immune system problems

Bhopal India

http://www.bhopal.org/testimony/index.html

Bhopal, India, 2-3 Dec. 1984On the night of 2-3 December 1984, a sudden release of about 30 tonnes of methyl isocyanate (MIC) occurred at the Union Carbide pesticide plant at Bhopal, India. The accident was a result of poor safety management practices, poor early warning systems, and the lack of community preparedness. The accident led to the death of over 2,800 people living in the vicinity and caused respiratory damage and eye damage to over 20,000 others. At least 200,000 people fled Bhopal during the week after the accident. Estimates of the damage vary widely between US $350 million to as high as US $3 billion.

20.4 PESTICIDE REGULATIONS IN THE USA

All commercial pesticides require EPA approval for general and/or restricted use.

(Based on FIFRA)

Federal Insecticide, Fungicide and Rodentcide

Act-Pesticides are evaluated for

biologically active ingredients & their affects

-If approved the EPA sets acceptable tolerance levels

The amount of toxic residue that can legally remain on the crop when a consumer eats it

LABEL SIGNAL WORDS DANGER & POISON (PELIGRO)

– Skull and Crossbones– Highly Toxic

DANGER – No Skull/Crossbones– Significant Skin or Eye effects

WARNING / AVISO– Moderately Toxic

CAUTION– Slightly Toxic or relatively non-toxic

– Page 52 Pesticide Manual

The Good News about Pesticides

Between 1972-2000, EPA banned or restricted 56 active pesticide ingredients in U.S.

EPA asked to reevaluated 600 pre-1972 active ingredients used in pesticides.

The Bad News:As of 2000 less than 10% of the

pesticide evaluations have been completed

Weak enforcement

Weak laws for pre 1972 toxins

OTHER DISTURBING FACTS Many active ingredients are

known to be carcinogens Missouri study showed increased

childhood brain cancer with use of various pesticides.

Swedish report showed, exposure to glyphosate (Key agent in ROUND-UP) tripled chances of getting non-Hodgkin’s lymphoma.

US Companies can make and export banned chemicals to other countries

26 tons per dayMany of the crops the

pesticides are used on return to the USA

1. Need to make human health the primary consideration for setting pesticide limits.

2. New tests for evaluating toxicity of pesticides

3. Consider the cumulative exposures of all Pesticides

HOW TO IMPROVE PESTICIDE REGULATIONS

HOW TO IMPROVE PESTICIDES

1. Kill only target species

2. Harm no other species

3. Break down into something harmless after doing its job

4. Not cause genetic resistance in target organisms

5. Be more cost effective than doing nothing

The War Against Insects

The War Against Insects

One of the biggest problems with the use of pesticides is in determining the ECONOMIC THRESHOLD.

The point where economic damage due to the pest outweighs the cost of the pesticide

20.5 OTHER WAYS TO CONTROL PESTS

Excessive Pesticide Use

To protect themselves, farmers often practice INSURANCE SPRAYING and/or COSMETIC SPRAYING

1.1. Cultivation PracticesCultivation Practices;; crop rotation changing planting times planting trap crops increasing habitat for natural predators

2. 2. Create Genetically Resistant PlantsCreate Genetically Resistant Plants;;

A Fungus Among Us

3. Biological Pest Control;3. Biological Pest Control;

Pro’sPro’s

-focus on target-focus on target

-are nontoxic-are nontoxic

-save money-save money

-minimize -minimize resistanceresistance

Con’sCon’s

-no mass -no mass reproductionreproduction

-slow-slow

-must be -must be protected from protected from sprayingspraying

-can become a -can become a pestpest

Using Parasitic Wasps

Ladybugs and the Praying Mantis

4. 4. Insect Birth ControlInsect Birth Control;;

Sterilization of insects – used with screwworms,fruit flies

Disadvantages include…-high cost-estimating mating

times/behaviors-need large # of males-males must be reintroduced

Screw Worm Maggots

5. Sex Attractants;5. Sex Attractants;The use of pheromone baited traps

6. Hormones to stunt growth;6. Hormones to stunt growth;

7. Spraying with hot water;7. Spraying with hot water;

8. Exposing food to 8. Exposing food to gamma radiationgamma radiation

INTEGRATED PEST MANAGEMENT

Strategy to use natural interactions rather than chemical interactions

CONTROL OPTIONSCONTROL OPTIONS:: Cultural: Crop Rotation and Sanitation Physical: Manipulation of water, temperature and

humidity Mechanical: Release of natural predators and use screens

and other covers

Basic Principles of IPM Know the target Learn what, where and how for the

organism Monitor and evaluate pest populations Establish a threshold (what level you

can tolerate) Chose a tactic Evaluate resultsThe goal is not total elimination but

reduce crop damage and economic losses

Slide 2

Grasshopper

Gypsy mothcaterpillar

Fig. 20.2a, p. 505

Slide 3

Fig. 20.2b, p. 505

European red mite

Slide 4

Fig. 20.2c, p. 505

Boll weevil

Pink bollworm

ranges overlap