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Chapter 22 The Pesticide Dilemma

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Title: Slide 1 Author: Reviewer Last modified by: Leisher, Julie F. Created Date: 5/22/2007 2:17:14 PM Document presentation format: On-screen Show (4:3) – PowerPoint PPT presentation

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Title: Chapter 22 The Pesticide Dilemma


1
Chapter 22The Pesticide Dilemma
2
Overview of Chapter 22
  • What is a Pesticide?
  • Major Kinds of Pesticides
  • Benefits and Problems With Pesticides
  • Alternatives to Pesticides
  • Laws Controlling Pesticides Use

3
What is a Pesticide
  • Types
  • Insecticides
  • Herbicides
  • Fungicides
  • Rodenticides
  • Regulated by the EPA

4
What is a Pesticide
  • Broad spectrum pesticide
  • kills a variety of organisms, not just the
    targeted organisms
  • Doesnt degrade doesnt decompose persist and
    then accumulate in environment or organism.

5
What is a Pesticide
  • First generation pesticide
  • Inorganic compounds
  • Lead and mercury
  • Botanicals- plant derived pesticides
  • Nicotine
  • Second generation pesticide
  • Synthetic poison
  • Ex DDT
  • for mosquitoes
  • used to control
  • malaria

6
What is an herbicide for?
7
What is a fungicide for?
8
What is an insecticide for?
9
Major Groups of Insecticides
  • Chlorinated Hydrocarbons
  • Organic compound containing Chlorine
  • Ex DDT
  • Persist (do not degrade)
  • Rachel Carson Silent Spring problems w/
    pesticides
  • Organophosphates
  • Developed during WWII
  • HIGHLY toxic (bees/humans), but do not persist
  • Currently used in agriculture
  • EX Malathion, diazinon
  • Neurotoxin, especially children
  • Carbamates
  • Not as toxic to mammals
  • Ex household sprays/traps

RACHEL CARSON ENVIRONMENTAL GODDESS
10
  • How are organophosphates different than
    chlorinated hydrocarbons?

11
Major Kinds of Herbicides
  • Selective Herbicides
  • Kill only certain types of plants
  • Can be classified to the type of plant they kill
  • Broad-leaf herbicides
  • Ex 2,4-D (2,4 dichlorophenoxyacetic acid)
  • Ex 2,4,5 T (2,4,5, trichlorophenoxyacetic acid)
  • Used with wheat, corn, rice (cereal grains
    grasses)
  • Grass herbicides
  • Nonselective kill all vegetation

12
  • When would you use a broad-leaf herbicide? A
    grass herbicide

13
Case study Vietnam War and herbicide use
  • Sprayed to kill vegetation Agent White, Blue,
    Orange
  • Ecological damage decades to repair destroyed
    mangroves (habitat for fish and coast protection
    from erosion), forests destroyed
  • Human effects
  • Agent Orange (combination of broad leaf
    herbicides dioxins) ? birth defects,
    stillbirths, cancer
  • Dioxin in breastmilk Vietnamese 1800 ppt, US
    4 ppt

14
Benefits of Pesticides
  • Benefit 1. Disease control
  • Fleas, lice and mosquitoes carry disease
  • Malaria- mosquito born
  • 2.7 million people die each year
  • Few drugs available, so focus is on killing
    mosquitoes
  • DDT

15
Benefits of Pesticides
  • Benefit 2. Crop Protection
  • Pests eat and destroy 1/3 of worlds crops
  • Farmers save 3 to 5 for every 1 they invest in
    pesticides

16
  • Name the 2 reasons why pesticides are used?

17
Problems with PesticidesPesticide Resistance
  • Problem Evolution of Genetic Resistance
  • Pest populations are evolving resistance to
    pesticides (right)
  • Pesticide Treadmill
  • Cost of applying pesticide increases
  • Because they must be applied more frequently or
    in larger doses
  • While their effectiveness decreases
  • Because of increased genetic resistance in pests
  • Resistance Management
  • Refuge of untreated plants allows mating of
    treated/untreated pests to delay resistance
  • Remove surviving weeds after herbicide application

18
Problems with Pesticides
  • Problem Kills non-target organisms
  • Spraying to kill insects can kill birds, fish,
    bees
  • Despite 33-fold increase in pesticides since the
    1940s, crop loss has not really changed

19
Problems with Pesticides
  • Problem Creation of New Pests
  • Pesticide kills predator or competitor of minor
    pest

20
Problems with Pesticides
  • Problem Persistence, Bioaccumulation, and
    Biological Magnification
  • Bioaccumulation
  • The buildup of a persistent pesticide or
  • other toxic substance in an organisms body
  • Biological magnification
  • Increased concentration
  • of toxic chemicals in tissues of
  • organisms at higher trophic
  • levels, stored in fat
  • Ex Peregrine falcons (right),
  • Bald Eagles

21
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22
Problems with Pesticides
  • Problem Mobility in the Environment
  • Do not stay where they are applied ? harm
    non-target organisms.
  • Move through soil, water (run-off) and air

23
Risk of Pesticides to Human Health
  • Effects of Pesticides
  • Handling food with pesticide residue
  • Mild case nausea, vomiting, headaches
  • Severe case damage to nervous system
    (neurotoxin!!!)

24
Risk of Pesticides to Human Health
  • Long-term Effects of Pesticides
  • Cancer- lymphoma and breast
  • Sterility
  • Miscarriage
  • Birth defects
  • Harms immune system

25
Case Study Bhopal Disaster
  • 1984 Bhopal, India
  • Explosion at pesticide plant released toxic gas
    (cyanide)
  • Many died immediately
  • Others problems to respiratory, reproductive,
    nervous systems

26
Alternatives to Pesticides
  • Using cultivation methods to control pests
  • Interplant mixtures of plants (alternating rows)
    polyculture !!
  • Crop rotation
  • Biological Control
  • Use of naturally occurring disease organisms,
    parasites or predators to control pests
  • Must take care that introduced agent does not
    attack unintended hosts

CANE TOADS
27
Alternatives to Pesticides
  • Pheromones and Hormones
  • Can use pheromones to lure pests to traps
  • Reproductive Controls
  • Sterilizing some of the members
  • Sterile male technique sterilize in lab and then
    release

28
Systems Approach- Integrated Pest Management (IPM)
  • IPM
  • Combination of pest control methods that keeps
    pest population low without economic loss
  • Controls pests, not eradicate
  • Cons requires a lot of knowledge
  • Conventional pesticides are used sparingly when
    other methods fail

HOW DOES IPM DIFFER FROM ORGANIC FARMING?
29
  • Farmers MONITOR pests and act when injury
    threshold is reached.
  • EX Cotton 1 of land 50 of pesticide use in
    US. WOW!! Organic cotton helps reduce
    pesticide use.

30
Systems Approach- Integrated Pest Management (IPM)
  • Rice Production in Indonesia
  • Predators of pests normally kept in check by
    pesticides

31
Laws Controlling Pesticide Use
  • Food, Drug, and Cosmetics Act (1938) FDCA
    determined pesticides need regulation!
  • Delaney Clause (1958) no cancer causing
    substances not cover raw foods.
  • Federal Insecticide, Fungicide, and Rodenticide
    Act (1947) FIFRA regulates what pesticides
    are sold based on safety.
  • Food Quality Protection Act (1996) stricter
    guidelines on pesticide limits, covers raw food,
    reduce time to ban harmful pesticide.

32
Manufacture and Use of Banned Pesticides
  • Some US companies still make banned or seriously
    restricted pesticides
  • Product is exported
  • Importation of food tainted with banned
    pesticides from other countries
  • Global ban of persistent organic pollutants
  • Stockholm Convention on Persistent Organic
    Pollutants (2004) requires countries to
    eliminate usage of the 12 most toxic chemicals.

33
Manufacture and Use of Banned Pesticides
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