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
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