CHAPTER 20PESTICIDES &

PEST CONTROL

-Competes with humans for food

-Invades lawns and gardens-Interferes with human activity -Spreads disease-Nuisance

WHAT IS A PESTAny species that does the following:

I. TYPES OF PESTICIDES1. Insecticides 2. Herbicides3. Fungicides4. Nematocides

(Round worms)5. Rodenticides

A. 1st Generation Pesticides-Generally described as those first used and

that were derived from natural sources.Sulfur: Used pre-500B.C.Toxic Chemicals: (1400’s) Arsenic- does not

break down, 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

Natural Pesticides: (1600’s) Nicotine Sulfate – from tobacco plants

1st Generation - continued

(1800’s) Pyrethrum, Rotenone- from Chrysanthemum flower and tropical legumes

-Generally described as those that are chemically produced

-DDT (Dichlorodiphenyl-trichloroethane)*Discovered by Paul Muller (won

the Nobel Prize)*1st used in 1939*Use in the U.S. stopped in 1972

as a result of adverse effects on the environment and population decreases in unintentional species.

- It is still sold to foreign countries

B. 2nd Generation Pesticides

Biological Magnification

C. Pesticide Use Today

-50 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.

1. TODAY(since 1850)

2. IN THE USA-Around 25,000 pesticide products-25% used for homes, parks, pools, golf courses-The average lawn receives 10x more synthetic pesticide than US cropland-250,000 people become ill each year

D. Broad vs. Narrow1. Broad Spectrum Agents:

-Toxic to many species

2. Selective / Narrow Spectrum:-Specific to a certain species-Pesticides vary in their

PERSISTANCE

(how long they remain in the environment)

II. THE CASE FOR PESTICIDES

Those that support the use of pesticides state that the benefits outweigh the potential harmful effects for many reasons.….

A. Save human lives: Protection against diseases like malaria,

typhus and sleeping sickness

55% of food is already lost to pests

$65 million / yr Helps lower food costs

B. Increase food supply:

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 weevilPink bollworm

ranges overlap

C. Increased Profit to farmers:

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

D. They work faster and better than alternatives:-Control most pests at reasonable cost

-Have a long shelf life-Easily shipped and applied

-Relatively safe when handle correctly

E. Relatively Safe: Health risks are insignificant when

used properly

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

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

III. THE CASE AGAINST PESTICIDES

A. Can cause Genetic Resistance: Reproduce rapidly and can develop a

resistance in 5-10 years Surviving organisms come back stronger. Leads to Pesticide Treadmill- using stronger doses, switching to

new chemicals, and an increase in frequency of use

Those that oppose the use of pesticides state that they are harmful for many reasons.….

Fig. 20.4, p. 507

600

500

400

300

200

100

01950 1960 1970 1980 1990 2000 2010

Year

Num

ber o

f spe

cies

Boll weevilGypsy moth cateripllar

Insects and mites

Weeds

Plant diseases

RISE OF GENETIC RESISTANCE TO PESTICIDES 1945-98

B. Broad Spectrum insecticides kill natural predators & parasites

1/3 of the most destructive pests are secondary pests that became widespread after the use of insecticides

C. 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.

D. Some Pesticides Harm Wildlife

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

in lost pollination

Kills 67 million birds Kills 6-14 million fish Hurt 20% endangered species

E. Threat to Human Health 3 million agricultural workers are

harmed each yr (300,000 in USA) Most not reported due to the majority

of farm workers being illegal immigrants

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 tons 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.

IV. PESTICIDE REGULATIONS IN THE U.S.

A. USE IN THE U.S. (518) All commercial pesticides require

EPA approval for general and/or restricted use. (Based on FIFRA)

-Evaluated for biologically active ingredients + affects

-If approved the EPA sets acceptable tolerance levels

Between 1972-2000, EPA banned or restricted 56 active pesticide ingredients in U.S. – may be used elsewhere.

EPA asked to reevaluated 600 pre-1972 active ingredients used in pesticides. (by 2000 less than 10% completed)

-weak enforcement -weak laws for pre 1972

toxins

B. OTHER DISTURBING FACTS 165 active ingredients in U.S.

approved pesticides are known to be carcinogens

Missouri study showed increased childhood brain cancer with use of various pesticides.

Also, associated with immune and endocrine disorders

Swedish report showed, exposure to glyphosate tripled chances of getting non-Hodgkin’s lymphoma.

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

New tests for evaluating toxicity of pesticides

Consider the cumulative exposures of all Pesticides

C. HOW TO IMPROVE PESTICIDE REGULATIONS (519)

D. HOW TO IMPROVE PESTICIDES Kill only target species would be

ideal Harm no other species Break down into something

harmless after doing its job Not cause genetic resistance in

target organisms Be more cost effective than doing

nothing

The War Against Insects

A. Goals of Pesticide Control One of the biggest problems with the use of

pesticides is in determining the ECONOMIC THRESHOLD.

This is point where cost of damage due to not applying pesticides outweighs the cost of application of pesticides.

To protect themselves, farmers often practice

INSURANCE SPRAYING COSMETIC SPRAYING- Making its appearance

more desirable

V. OTHER WAYS TO CONTROL PESTS

1. Cultivation Practices; crop rotation changing planting times planting trap crops increasing habitat for natural

predators

2. Create Genetically Resistant Plants;

B. Alternatives to Pesticides

A Fungus Among Us

3. Biological Pest Control;

Pro’s-focus on target-are nontoxic-save money-minimize resistance

Con’s-no mass reproduction-slow-must be protected from spraying-can multiply faster than pest-requires a lot of research & development

4. Insect Birth Control; Sterilization of insects, used with screwworms,

fruit flies Involves irradiating males Disadvantages include…

-high cost-estimating mating times/behaviors

-need large # of males -males must be reintroduced

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

Pheromone- is a species-specific chemical sex attractant.

6. Hormones to stunt growth;

7. Spraying with hot water;

8. Exposing food to gamma radiation

C. INTEGRATED PEST MANAGEMENT Approach where crops and pests

are examined as part of an ecological system.

Overall aim is to reduce crop damage and economic losses but not complete eradication of the pest.

Requires more expert knowledge and multiple approaches to pest controlSlower acting than pesticides

Only small amounts of pesticide are used at critical times

IPM is ? A chemical program

A ecological program

A biological program

Ways to Reduce Threat to Pesticides in the Food We Eat.

Scrub all food in soapy water

Grow own fruits and vegetables using organic gardening methods

Purchase organically grown foods

Did you know? Flea collars are linked to brain tumors

Pre-1972 pesticides may still have untested chemicals as ingredients

Round-Up is linked to Non-Hodgkins type Lymphoma