Pest ManagementChapter 23

APESAaron WilleySpring 2013

Essential Questions

Types and characteristics of pesticidesPros and cons of using pesticidesPesticide regulation in the USAlternatives to chemical pesticides

Your teacher’s obsession with spiders

Nature’s PESTicide

What is a Pest anyway?• A pest is any species that…– Competes with humans for food– Invades lawns and gardens– Destroys wood in houses– Spreads disease– Are a nuisance

• Worldwide, only about 100 species of plants (weeds), animals (insects), fungi, and microbes cause about 90% of the damage

Polyculture Monoculture

• Natural “checks and balances”–Natural enemies (predators, parasites, and

disease organisms) control most pest species

• Monoculture crops –Now WE are forced to control pests nature

once took care of (for free)

Pesticides (aka Biocides)

• Chemicals used to control pests–Insecticides (insects)–Herbicides (plants)–Fungicides (fungi)–Rodenticides (rats and mice)

Coevolution

First-Generation Pesticides

• Prior to 1940’s• Inorganic compounds–As, Hg, Pb

• Organic compounds–Nicotine sulfate (tobacco)–Pyrethrum (chrysanthemum)–Rotenone (tropical forest legumes)

Second-Generation Pesticides

• Synthetic organic compounds• Ranges from broad to narrow-

spectrum agents and persistence levels

DDT• 1939• Paul Müller–Entomologist–Nobel prize

Life after DDT

• Since 1970, chemists have returned to natural chemicals (neem tree) to produce pesticides

• 2003 natural pesticide in Knapweed discovered

Pesticide use today

• Pesticide use on crops have leveled off since 1980

• Use on homes, lawns, parks, golf courses, etc have risen 50-fold since 1950–Most of these are 10

times as toxic

Table 23-1 Major Types of Pesticides

• Know:–Major classes–Broad or narrow-spectrum–Degree of persistence–Example of each–Does it undergo bioaccumulation–Difference between contact and systemic

herbicides(See p. 520)

Concept Check

• Briefly describe the history of the development of pesticides

The Good….

1. They save human livesDDT and other chlorinated hydrocarbon and

organophosphate insecticides have prevented many deaths

– Malaria (mosquitoes)– Bubonic plague (rat fleas)– Typhus (body lice, fleas)

The Good....

2. They increase food supplies55% of the world’s potential human food supply is lost to pests (37% of US)

The Good….

3. They increase profits for farmers*4. They work faster and better than alternatives5. When used properly, their health risks are

very low compared to their benefits*

*Pesticide companies and American Council on Science and Health (ACSH) http://www.acsh.org/about/

Encouraging facts about Pesticides

• Newer pesticides are safer and more effective• Many new pesticides are used at lower rates• Genetically engineered crops could reduce

the need for pesticides

What would an IDEAL pesticide look like?

1. Affect only target organism

2. Not cause genetic resistance

3. Break down/disappear in environment

4. More cost effective than doing nothing

The Bad….1. Insects can rapidly become

genetically resistant to widely used pesticides

• Main problem with synthetic pesticides-It accelerates genetic resistance– Since 1945, several hundred species

have become resistant– Reemergence of diseases (malaria)– Pesticide treadmill

The Bad….

2. Pesticides kill natural enemies of pests and create new pests

• Of the 300 most destructive insect pests in the US……

…..100 were once minor pests

The Bad….

3. Pesticides do NOT stay put!

The Bad….

4. Some harm wildlife (bees, birds, fish endangered species)

20% loss of honeybee colonies every year = 200 million cost to farmers

The Bad….

5. Harm to humans• Agricultural workers– 3 million/yr (developing countries)– 300,000/yr US

• 4,000-20,000 cancer cases/yr• Childhood leukemia, Parkinson’s, immune

disorders, prostate cancer, breast cancer, behavioral disorders

Do they even make a difference?

• David Pimentel, insect ecologist– In the 1940’s, 31% of US crops lost to pests• So pesticide use increased 33-fold.

– Today about 37% of US crops lost to pests

Do they even make a difference?

• David Pimentel, insect ecologist– Estimated environmental, health, and social

costs of pesticides has been estimated up to $100-200 billion/yr

Do they even make a difference?

• David Pimentel, insect ecologist–Alternative practices could cut the pesticide

use in HALF on 40 major US crops WITHOUT reducing yields

All My Pesticide Regulations

• Organophosphates• Persistent Organic

Pollutants (POPs) “Dirty Dozen”

• President Kennedy• 56 Active ingredients• Tolerance level• 43 out of 165• Pesticide Industry• Environmentalists

• Federal Insecticide, fungicide and Rodenticide Act (FIFRA)

• Environmental Protection Agency

• DDT• Food Quality Protection Act

(FQPA)• Missouri children• National Academy of Science• India and Africa• Rachel Carson’s Silent Spring

What should be the primary goal of pest control efforts?

• Reduce crop damage to an economically tolerable level– Economic threshold: the point at which the economic

losses outweigh the cost of applying pesticide• How do you determine when this threshold has

been met?– Insurance spraying– Pest-loss insurance– Cosmetic spraying

Alternative Methods

1. Cultivation practices– Crop rotation,

switch planting seasons, polyculture, etc.

– Grass height, plant selection

Alternative Methods

2. GMO– Pest and disease-

resistant– Controversial

Alternative Methods

3. Biological pest control– Introducing

natural enemies

– What pros and cons can you think of?

Alternative Methods

4. Insect birth control– Sterilization from

radiation and chemicals

– Screwworm fly

Alternative Methods

5. Hormones– Pheromones– Interrupt life cycle

Alternative Methods

6. Hot water– Cotton, alfalfa,

potato, citrus

7. Gamma radiation- Trace chemicals?- Long-term effects?

When to go organic

Nectarines – 97.3% of nectarines sampled were found to contain pesticides.Celery – 94.5%Pears – 94.4%Peaches – 93.7%Apples – 91%Cherries – 91%Strawberries – 90%Imported Grapes – 86%Spinach – 83.4%Potatoes – 79.3%Bell Peppers – 68%Red Raspberries – 59%