Chapter 23 Pesticide Dilemma

Pests Pest- any organism that interferes in some way w/ human welfare or activities Grouped by target organism they kill Grouped by target organism they kill Insecticides- kills insects Herbicides- kills plants Fungicides- kills fungus Rodentcides- kills rodents

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

1 st Generation Pesticides Pre main types (1) Organic compounds (mainly botanicals or plant derived) (1) Organic compounds (mainly botanicals or plant derived) (2) Inorganic compounds (mainly minerals w/ lead, mercury, and arsenic) (2) Inorganic compounds (mainly minerals w/ lead, mercury, and arsenic)

Botanicals Botanicals (plant derived) include nicotine & pyrethin. Problem w/ them is easily degradable but highly toxic to aquatic organisms & beneficial to insects Synthetic botanicals- man-made insecticides produced by chemically modifying the structure of natural botanicals ex. pyrethroids

2 nd Generation Pesticides Synthetic botanicals & other synthetic pests Most famous is DDT

Major Insecticide Groups Chlorinated hydrocarbons- e.g. DDT Broad spectrum Broad spectrum Slow to degrade Slow to degrade Endosulfan, lindane, & methoxychlor still in use Endosulfan, lindane, & methoxychlor still in useOrganophosphates Very poisonous & toxic to birds, bees & aquatic organisms not persistent in the environment Very poisonous & toxic to birds, bees & aquatic organisms not persistent in the environment Methamidophos, dimethoate & malathion are examples Methamidophos, dimethoate & malathion are examples

Major Insecticide Groups Cont. Carbamates Broad spectrum Broad spectrum Generally not as toxic to mammals Generally not as toxic to mammals Examples include carbaryl & aldicarb Examples include carbaryl & aldicarb

Major Kinds of Herbicides Selective herbicides- kill only certain types of plants Broad-leaf herbicide which kill broad-leaf plants but not grasses Broad-leaf herbicide which kill broad-leaf plants but not grasses Grass herbicide- kills grasses but not other plants Grass herbicide- kills grasses but not other plants Non-selective herbicides- kills all vegetation

Major Kinds of Herbicides Cont. Famous example: Agent Orange Mixture of 2 herbicides that also contain dioxins Mixture of 2 herbicides that also contain dioxins Include a variety of health effects including tissue cancers, skin diseases, urological disorders & birth defects Include a variety of health effects including tissue cancers, skin diseases, urological disorders & birth defects

Pros & Cons of Pesticides Benefits: Disease control Disease control Crop protection Crop protectionProblems: Broad toxicity Broad toxicity Genetic resistance (pesticide treadmill) resistance management- using refuge to leave some population untouched to prevent resistance Genetic resistance (pesticide treadmill) resistance management- using refuge to leave some population untouched to prevent resistance Imbalances w/ ecosystem => creating new pesticidess due to loss of natural predators, etc. Imbalances w/ ecosystem => creating new pesticidess due to loss of natural predators, etc. Bioaccumulation => concentration of pesticides in organism’s body Bioaccumulation => concentration of pesticides in organism’s body

Pests and Predators

Pros & Cons of Pesticides Cont. Cons continued: Biomagnification => increase in concentration of pesticides as it moves through successive levels in food web Biomagnification => increase in concentration of pesticides as it moves through successive levels in food web Risks to Human Risks to Human Acute/Short term Chronic/Long term Endocrine desrupters & development Mobility in Environment Mobility in Environment

Actual Pathway

Examples of Risks to Humans Lead => neurological development Mercury => biomagnification/biomagnification via fish/crab from bay

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

Alternatives to Pesticides Reproductive Controls- sterilizing males Pheromones & Hormones- typically used as sexual attractants for lure (e.g. yellow jacket traps & Japanese beetle) Genetic Controls- (GMO) Traditional Selective breeding to develop variety of crops that are genetically resistant to the pest Quarantine- prevent the pest from arriving at all

Integrated Pest Management Combines use of variety of techniques to control the pests using least toxic alternatives first IPM uses 3 fundamental premises: 1.Management rather than eradication of pests 2.Economic injury threshold: Don’t take action w/ pesticides until this point; use non-toxic alternatives first

Integrated Pest Management (cont) 3)Education- educate farmers as to all their options Scout-and-Spray- monitor for pest & only spray when they become a problem Scout-and-Spray- monitor for pest & only spray when they become a problem Calendar Spraying- regular spraying of pesticides whether needed or not

Pesticide Related Laws Food, Drug & Cosmetic Act- recognized need to regulate pesticides but no teeth Pesticide Chemical Amendment (Miller Amendment)- established acceptable levels of pesticides in food Pesticide Chemical Amendment (Miller Amendment)- established acceptable levels of pesticides in food Delaney Clause prohibits cancer-causing substances in food (applies only to pesticides) Delaney Clause prohibits cancer-causing substances in food (applies only to pesticides)

Pesticide Related Laws Cont. Federal Insecticide, Fungicide & Rodenticide Act Regulated pesticide sale to prevent the sale of lemons (pesticides that don’t work) Regulated pesticide sale to prevent the sale of lemons (pesticides that don’t work) Requires disclosure of active ingredients but not inert ingredients Requires disclosure of active ingredients but not inert ingredients Food Quality Protection Act- Established pesticide residue limits in both raw & processed foods Established pesticide residue limits in both raw & processed foods

Problems with Pesticides Key problem w/ pesticide use is it’s not regulated or banned in all places worldwide Stockholm Convention on persistent organic Stockholm Convention on persistent organic Pollutants- UN ban 12 most toxic chemicals in world (persistent organic pollutants or POP) Another problem- stockpiles of banned pesticides, predominantly in developing countries