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Chapter 23 The Pesticide Dilemma. Overview of Chapter 23 o What is a Pesticide? Major Kinds of Pesticides Major Kinds of Pesticides o Benefits and Problems.

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Presentation on theme: "Chapter 23 The Pesticide Dilemma. Overview of Chapter 23 o What is a Pesticide? Major Kinds of Pesticides Major Kinds of Pesticides o Benefits and Problems."— Presentation transcript:

1 Chapter 23 The Pesticide Dilemma

2 Overview of Chapter 23 o What is a Pesticide? Major Kinds of Pesticides Major Kinds of Pesticides o Benefits and Problems With Pesticides o Risks of Pesticides to Human Health o Alternatives to Pesticides o Laws Controlling Pesticides Use o The Manufacture and Use of Banned Pesticides

3 What is a Pesticide o Broad spectrum pesticide A pesticide that kills a variety of organisms, not just the targeted organisms A pesticide that kills a variety of organisms, not just the targeted organisms o First generation pesticide Inorganic compounds Inorganic compounds Lead and mercury Lead and mercury Botanicals- plant derived pesticides Botanicals- plant derived pesticides Nicotine and pyrethrin Nicotine and pyrethrin

4 What is a Pesticide o Second generation pesticide Synthetic poison Synthetic poison Ex: DDT Ex: DDT

5 Major Groups of Insecticides o Chlorinated Hydrocarbons Organic compound containing Chlorine Organic compound containing Chlorine Ex: DDT Ex: DDT Slow to degrade and persist in the environment Slow to degrade and persist in the environment Banned or largely restricted Banned or largely restricted o Organophosphates Organic compounds that contain phosphorus Organic compounds that contain phosphorus Most poisonous insecticide Most poisonous insecticide Do not persist as long as chlorinated hydrocarbons Do not persist as long as chlorinated hydrocarbons o Cabamates Derived from cabamic acid Derived from cabamic acid

6 Major Kinds of Herbicides o Selective Herbicides Kill only certain types of plants Kill only certain types of plants Can be classified to the type of plant they kill Can be classified to the type of plant they kill Broad-leaf herbicides Broad-leaf herbicides Grass herbicides Grass herbicides Ex: 2,4-D Ex: 2,4-D

7 Benefits and Problems with Pesticides o Benefit: Disease control Fleas, lice and mosquitoes carry disease Fleas, lice and mosquitoes carry disease Malaria- mosquito born Malaria- mosquito born 2.7 million people die each year 2.7 million people die each year Few drugs available, so focus is on killing mosquitoes Few drugs available, so focus is on killing mosquitoes DDT DDT

8 Benefits and Problems with Pesticides o Benefit: Crop Protection Pests eat and destroy 1/3 of world’s crops Pests eat and destroy 1/3 of world’s crops Farmers save $3 to $5 for every $1 they invest in pesticides Farmers save $3 to $5 for every $1 they invest in pesticides o Problem: Evolution of Genetic Resistance Pest populations are evolving resistance to pesticides (right) Pest populations are evolving resistance to pesticides (right)

9 o Pesticide Treadmill Cost of applying pesticide increases Cost of applying pesticide increases Because they must be applied more frequently or in larger doses Because they must be applied more frequently or in larger doses While their effectiveness decreases While their effectiveness decreases Because of increased genetic resistance in pests Because of increased genetic resistance in pests o Resistance Management Strategies for managing genetic resistance in order to maximize the period in which a pesticide is useful Strategies for managing genetic resistance in order to maximize the period in which a pesticide is useful Delays the evolution of genetic resistance Delays the evolution of genetic resistance Refuge of untreated plants Refuge of untreated plants Pesticide Resistance

10 Benefits and Problems with Pesticides o Problem: Imbalances the Ecosystem Spraying to kill insects can affect birds, rabbits, etc. Spraying to kill insects can affect birds, rabbits, etc. Despite 33-fold increase in pesticides since the 1940s, crop loss has not really changed Despite 33-fold increase in pesticides since the 1940s, crop loss has not really changed

11 Benefits and Problems with Pesticides o Problem: Creation of New Pests Infestation of red scale insects on lemons after DDT sprayed to control another pest Infestation of red scale insects on lemons after DDT sprayed to control another pest

12 Benefits and Problems with Pesticides o Problem: Persistence, Bioaccumulation, and Biological Magnification Bioaccumulation Bioaccumulation The buildup of a persistent pesticide or other toxic substance in an organisms body The buildup of a persistent pesticide or other toxic substance in an organisms body Biological magnification Biological magnification Increased concentration of toxic chemicals in tissues of organisms at higher trophic levels Increased concentration of toxic chemicals in tissues of organisms at higher trophic levels Ex: Peregrine falcons (right) Ex: Peregrine falcons (right)

13 Benefits and Problems with Pesticides o Problem: Mobility in the Environment Do not stay where they are applied Do not stay where they are applied Move through soil, water and air Move through soil, water and air

14 Risk of Pesticides to Human Health o Short-term Effects of Pesticides Handling food with pesticide residue Handling food with pesticide residue Mild case: nausea, vomiting, headaches Mild case: nausea, vomiting, headaches Severe case: damage to nervous system, Severe case: damage to nervous system,

15 Risk of Pesticides to Human Health o Long-term Effects of Pesticides Cancer- lymphoma Cancer- lymphoma Breast cancer Breast cancer Sterility Sterility Miscarriage Miscarriage Birth defects Birth defects Decreases body’s ability to fight infection Decreases body’s ability to fight infection Potential connection to Parkinson’s disease Potential connection to Parkinson’s disease

16 Alternatives to Pesticides o Using cultivation methods to control pests Interplant mixtures of plants (alternating rows) Interplant mixtures of plants (alternating rows) Strip cutting Strip cutting Proper timing of planting, fertilizing, and irrigating Proper timing of planting, fertilizing, and irrigating Crop rotation Crop rotation o Biological Control Use of naturally occurring disease organisms, parasites or predators to control pests Use of naturally occurring disease organisms, parasites or predators to control pests Must take care that introduced agent does not attack unintended hosts Must take care that introduced agent does not attack unintended hosts

17 Alternatives to Pesticides o Pheromones and Hormones Can use pheromones to lure pests to traps Can use pheromones to lure pests to traps By applying insect hormones at wrong time in life cycle, insects can be killed off By applying insect hormones at wrong time in life cycle, insects can be killed off o Reproductive Controls Sterilizing some of the members Sterilizing some of the members Sterile male technique Sterile male technique

18 Alternatives to Pesticides o Genetic Controls Genetically Modified plants (GMOs) Genetically Modified plants (GMOs) Bt toxin Bt toxin Potential problem: may affect non-target species (monarch butterfly) Potential problem: may affect non-target species (monarch butterfly) o Quarantine Restriction of the importation of exotic plant and animal material that might harbor pests Restriction of the importation of exotic plant and animal material that might harbor pests Effective, but not foolproof Effective, but not foolproof

19 Systems Approach- Integrated Pest Management (IPM) o IPM Combination of pest control methods that keeps pest population low without economic loss Combination of pest control methods that keeps pest population low without economic loss o Conventional pesticides are used sparingly when other methods fail

20 o Rice Production in Indonesia Systems Approach- Integrated Pest Management (IPM) IPM Introduced

21 Alternatives to Pesticides o Irradiating Food Harvested food is expose to ionizing radiation, which kills many microorganisms Harvested food is expose to ionizing radiation, which kills many microorganisms Predominantly used on meats Predominantly used on meats Somewhat controversial due to potential for free radicals Somewhat controversial due to potential for free radicals

22 Laws Controlling Pesticide Use o Food, Drug, and Cosmetics Act (1938) o Pesticide Chemicals Amendment (1954) o Delaney Cause (1958) o Federal Insecticide, Fungicide, and Rodenticide Act (1947) o Food Quality Protection Act (1996)

23 Manufacture and Use of Banned Pesticides o Some US companies still make banned or seriously restricted pesticides Product is exported Product is exported o May lead to the importation of food tainted with banned pesticides o Global ban of persistent organic pollutants Stockholm Convention on Persistent Organic Pollutants (2004) Stockholm Convention on Persistent Organic Pollutants (2004)

24 Manufacture and Use of Banned Pesticides


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