Chapter 23Chapter 23

Pesticide DilemmaPesticide Dilemma

PestsPests

Pest- any organism that interferes in some Pest- any organism that interferes in some way w/ human welfare or activitiesway w/ human welfare or activities Grouped by target organism they killGrouped by target organism they kill

Insecticides- kills insectsInsecticides- kills insects

Herbicides- kills plantsHerbicides- kills plants

Fungicides- kills fungusFungicides- kills fungus

Rodentcides- kills rodentsRodentcides- kills rodents

AgricultureAgriculture

Sector that uses the most pesticides Sector that uses the most pesticides (85%) worldwide(85%) worldwideNarrow spectrum pesticides- pesticides Narrow spectrum pesticides- pesticides that kills only the organism for which it was that kills only the organism for which it was intendedintendedBroad spectrum pesticides- pesticides that Broad spectrum pesticides- pesticides that kills a wide variety of organismskills a wide variety of organismsAdditional Problems w/ pesticides- more in Additional Problems w/ pesticides- more in environment, don’t degradeenvironment, don’t degrade

11stst Generation Pesticides Generation Pesticides

Pre-1940Pre-1940

2 main types2 main types

(1) Organic compounds (mainly botanicals (1) Organic compounds (mainly botanicals or plant derived)or plant derived)

(2) Inorganic compounds (mainly minerals (2) Inorganic compounds (mainly minerals w/ lead, mercury, and arsenic)w/ lead, mercury, and arsenic)

BotanicalsBotanicals

Botanicals (plant derived) include nicotine Botanicals (plant derived) include nicotine & pyrethin. Problem w/ them is easily & pyrethin. Problem w/ them is easily degradable but highly toxic to aquatic degradable but highly toxic to aquatic organisms & beneficial to insectsorganisms & beneficial to insects

Synthetic botanicals- man-made Synthetic botanicals- man-made insecticides produced by chemically insecticides produced by chemically modifying the structure of natural modifying the structure of natural botanicals ex. pyrethroidsbotanicals ex. pyrethroids

22ndnd Generation Pesticides Generation Pesticides

Synthetic botanicals & other synthetic Synthetic botanicals & other synthetic pestspests

Most famous is DDTMost famous is DDT

Major Insecticide GroupsMajor Insecticide Groups

Chlorinated hydrocarbons- e.g. DDTChlorinated hydrocarbons- e.g. DDT Broad spectrum Broad spectrum Slow to degradeSlow to degrade Endosulfan, lindane, & methoxychlor still in useEndosulfan, lindane, & methoxychlor still in use

OrganophosphatesOrganophosphates Very poisonous & toxic to birds, bees & aquatic Very poisonous & toxic to birds, bees & aquatic

organisms not persistent in the environmentorganisms not persistent in the environment Methamidophos, dimethoate & malathion are Methamidophos, dimethoate & malathion are

examplesexamples

Major Insecticide Groups Cont.Major Insecticide Groups Cont.

CarbamatesCarbamates Broad spectrumBroad spectrum Generally not as toxic to mammalsGenerally not as toxic to mammals Examples include carbaryl & aldicarbExamples include carbaryl & aldicarb

Major Kinds of HerbicidesMajor Kinds of Herbicides

Selective herbicides- kill only certain types Selective herbicides- kill only certain types of plantsof plants Broad-leaf herbicide which kill broad-leaf Broad-leaf herbicide which kill broad-leaf

plants but not grassesplants but not grasses Grass herbicide- kills grasses but not other Grass herbicide- kills grasses but not other

plantsplants

Non-selective herbicides- kills all Non-selective herbicides- kills all vegetationvegetation

Major Kinds of Herbicides Cont.Major Kinds of Herbicides Cont.

Famous example: Agent OrangeFamous example: Agent Orange Mixture of 2 herbicides that also contain Mixture of 2 herbicides that also contain

dioxinsdioxins Include a variety of health effects including Include a variety of health effects including

tissue cancers, skin diseases, urological tissue cancers, skin diseases, urological disorders & birth defectsdisorders & birth defects

Pros & Cons of PesticidesPros & Cons of Pesticides

Benefits:Benefits: Disease controlDisease control Crop protectionCrop protection

Problems:Problems: Broad toxicityBroad toxicity Genetic resistance (pesticide treadmill) resistance Genetic resistance (pesticide treadmill) resistance

management- using refuge to leave some population management- using refuge to leave some population untouched to prevent resistance untouched to prevent resistance

Imbalances w/ ecosystem => creating new Imbalances w/ ecosystem => creating new pesticidess due to loss of natural predators, etc.pesticidess due to loss of natural predators, etc.

Bioaccumulation => concentration of pesticides in Bioaccumulation => concentration of pesticides in organism’s bodyorganism’s body

Pests and PredatorsPests and Predators

Pros & Cons of Pesticides Cont.Pros & Cons of Pesticides Cont.Cons continued:Cons continued:

Biomagnification => increase Biomagnification => increase in concentration of pesticides in concentration of pesticides as it moves through as it moves through successive levels in food websuccessive levels in food web

Risks to Human Risks to Human

Acute/Short termAcute/Short term

Chronic/Long termChronic/Long term

Endocrine desrupters & Endocrine desrupters & development development

Mobility in EnvironmentMobility in Environment

Actual PathwayActual Pathway

Examples of Risks to HumansExamples of Risks to Humans

Lead => neurological developmentLead => neurological development

Mercury => Mercury => biomagnification/biomagnification via biomagnification/biomagnification via fish/crab from bayfish/crab from bay

Alternatives to PesticidesAlternatives to Pesticides

Alt. Cultivation methods-Alt. Cultivation methods- such as such as interplanting (alternating rows of different interplanting (alternating rows of different plants) & strip cutting (leaving strips of plants) & strip cutting (leaving strips of unharvested crop) & proper timing for unharvested crop) & proper timing for planting, fertilizing & irrigationplanting, fertilizing & irrigationBiological Controls-Biological Controls- using naturally using naturally occurring disease organisms, parasites or occurring disease organisms, parasites or predators to control pests e.g. lady bugs, predators to control pests e.g. lady bugs, praying mantisespraying mantises

Alternatives to PesticidesAlternatives to Pesticides

Reproductive Controls-Reproductive Controls- sterilizing males sterilizing males

Pheromones & Pheromones & Hormones- typically used as Hormones- typically used as sexual attractants for lure (e.g. yellow jacket sexual attractants for lure (e.g. yellow jacket traps & Japanese beetle)traps & Japanese beetle)

Genetic Controls-Genetic Controls- (GMO) Traditional Selective (GMO) Traditional Selective breeding to develop variety of crops that are breeding to develop variety of crops that are genetically resistant to the pestgenetically resistant to the pest

Quarantine-Quarantine- prevent the pest from arriving at all prevent the pest from arriving at all

Integrated Pest Management Integrated Pest Management

Combines use of variety of Combines use of variety of techniques to control the techniques to control the pests using least toxic pests using least toxic alternatives firstalternatives firstIPM uses 3 fundamental IPM uses 3 fundamental premises:premises:

1.1. Management rather than Management rather than eradication of pestseradication of pests

2.2. Economic injury threshold:Economic injury threshold:• Don’t take action w/ Don’t take action w/

pesticides until this point; pesticides until this point; use non-toxic use non-toxic alternatives firstalternatives first

Integrated Pest Management (cont)Integrated Pest Management (cont)

3)Education- educate farmers as to all their 3)Education- educate farmers as to all their optionsoptions

Scout-and-Spray- monitor for pest & only Scout-and-Spray- monitor for pest & only spray when they become a problemspray when they become a problem

Calendar Spraying- regular spraying of Calendar Spraying- regular spraying of pesticides whether needed or notpesticides whether needed or not

Pesticide Related LawsPesticide Related Laws

Food, Drug & Cosmetic Act- recognized Food, Drug & Cosmetic Act- recognized need to regulate pesticides but no teethneed to regulate pesticides but no teeth Pesticide Chemical Amendment (Miller Pesticide Chemical Amendment (Miller

Amendment)- established acceptable levels of Amendment)- established acceptable levels of pesticides in foodpesticides in food

Delaney Clause prohibits cancer-causing Delaney Clause prohibits cancer-causing substances in food (applies only to pesticides)substances in food (applies only to pesticides)

Pesticide Related Laws Cont.Pesticide Related Laws Cont.

Federal Insecticide, Fungicide & Federal Insecticide, Fungicide & Rodenticide ActRodenticide Act Regulated pesticide sale to prevent the sale Regulated pesticide sale to prevent the sale

of lemons (pesticides that don’t work)of lemons (pesticides that don’t work) Requires disclosure of active ingredients but Requires disclosure of active ingredients but

not inert ingredientsnot inert ingredients

Food Quality Protection Act-Food Quality Protection Act- Established pesticide residue limits in both Established pesticide residue limits in both

raw & processed foodsraw & processed foods

Problems with PesticidesProblems with Pesticides

Key problem w/ pesticide use is it’s not Key problem w/ pesticide use is it’s not regulated or banned in all places worldwideregulated or banned in all places worldwide Stockholm Convention on persistent organicStockholm Convention on persistent organic

Pollutants- UN ban 12 most toxic chemicals Pollutants- UN ban 12 most toxic chemicals in world (persistent organic pollutants or in world (persistent organic pollutants or POP)POP)

Another problem- stockpiles of banned Another problem- stockpiles of banned pesticides, predominantly in developing pesticides, predominantly in developing countries countries