Presentation on theme: "Pesticides. Pesticides -Pros and Cons Kill unwanted pests that carry disease (rats, mosquitoes, Tse-Tse flies) Increase food supplies More food."— Presentation transcript:
Pesticides -Pros and Cons Kill unwanted pests that carry disease (rats, mosquitoes, Tse-Tse flies) Increase food supplies More food means food is less expensive Effective and fast-acting Newer pesticides are safer, more specific Reduces labor costs on farms Food looks better Agriculture is more profitable Accumulate in food chain Pests develop resistance – 500 species so far Resistance creates pesticide treadmill Estimates are $5-10 in damage done for $1 spent on pesticide Pesticide runoff Destroy bees - $200 million Threaten endangered species Affect egg shell of birds 5% actually reach pest ~20,000 human deaths/year
Types of Pesticides Biological – Ladybugs, parasitic wasps, etc. Carbamates effect nervous system of pests more water soluble than chlorinated hydrocarbons –Aldicarb, aminocarb, carbaryl (Sevin), carbofuran, Mirex Chlorinated Hydrocarbons affect nervous system – –Aldrin, Chlordane, DDT, dieldrin, kepone and toxaphene
Fumigants are used to sterilize soil and prevent grain infestation Organophosphates – extremely toxic, rapidly absorbed, low persistence –Malathion, parathion
Types of Pesticides Inorganic – arsenic, copper, lead, mercury –Highly toxic and bioaccumulation Organic or natural – derived from plants such as tobacco and chrysanthemum
Chlorinated Hydrocarbons (organochlorines) DDT, aldrin, dieldrine, chlordane and toxaphene Affect the nervous system of pest Remain in ecosystem 15+ years Highly persistent, fat soluble, and subject to biomagnification Nearly all have been banned
Carbamates Are used as insecticides, herbicides and fungicides effect nervous system of pests More water soluble than chlorinated hydrocarbons – which means greater risks of dissolving in surface water or percolating into groundwater 100 grams has the same effect as 2,000 grams chlorinated hydrocarbons Examples: Aldicarb(Temik), aminocarb, carbaryl (Sevin), carbofuran, Mirex
Aldicarb Potato growers on eastern Long Island used Aldicarb from 1975 – 1979 to control the Colorado potato beetle and the golden nematode. In 1979, Aldicarb residues were detected in well water. Subsequent testing found more than 2,000 wells with very high concentrations. It was banned in New York. In 1984 areas with deep wells were found to have increased levels from 1979 levels wells are still contaminated above state guidelines. Aldicard has been found in groundwater in 26 other states.
Fumigants Gaseous pesticides use to sterilize soil and prevent pest infestation of stored grains. Used on grain weevils, beetles and moth catepillars. Comparable to “mustard gases” used in WWII. Phosphine is the most popular today – others are carbon tetrachloride and methyl bromide Methyl Bromide was banned in 2005 due to it’s damage to the ozone layer.
Inorganic Broad-based pesticides. Includes arsenic, copper, lead, mercury. Highly toxic and accumulates in the environment.
Organic or Natural Pesticides Natural poisons derived from plants such as tobacco or chrysanthemum. Neem Ingredients: Contains 2 ingredients, azadirachtin (AZA0 and liminoids, both from the seed kernels of the neem tree fruit. Application: Sprayed onto plant leaves. How It Works: Upsets the insects hormonal system and prevents it from developing to its mature stage. Most effective on immature insects and species that undergo complete metamorphosis. Pros: Non-toxic to humans Cons: Washes away in rain. Slow acting. Breaks down in sunlight Indiscriminate pesticide Precautions: Keep pets from treated leaves until they dry.
Organic Pesticides Pyrethrins Ingredients: Derived from Chrysanthemum cinerariifolium Application: Generally found in powder form and dusted on leaves. How It Works: Poisons the insect, causing a quick death Pros: Quick acting. Low toxicity to animals. Degrades within a day. Cons: Broad spectrum insecticide. Kills any insect. Very toxic to honeybees Precautions: Use cautiously, only when you have a major problem with hard-to-kill insects.
Organic or Natural Pesticides Rotenone Ingredients: Derived from the roots of tropical legumes (derris plant) Application: Dust onto plant – originally used to kill fish. Kills potato beetles and cabbage worms. Used on chickens to kill mites How It Works: Inhibits a cellular process, depriving insects of oxygen in their tissue cells. Pros: Low residual effect. Breaks down quickly in sunlight. Cons: Broad spectrum pesticide Precautions: Apply in the evening, when bees are less active.
Organophosphates Malathion and Parthion Extremely toxic but only remains in the environment for a brief amount of time. Effects the central nervous system by interfering with the enzyme cholinesterase.
Biological Pest Control A knowledgeable gardener knows that each of those cocoons will hatch into a beneficial parasitic wasp - an organic control for more than just horn worms.
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 Grass herbicides –Ex: 2,4-D Dichlorophenoxyacetic acid common systemic pesticide / herbicide used in the control of broadleaf weeds
Risk of Pesticides to Human Health Short-term Effects of Pesticides –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,
Risk of Pesticides to Human Health Long-term Effects of Pesticides –Cancer- lymphoma –Breast cancer –Sterility –Miscarriage –Birth defects –Decreases body’s ability to fight infection –Potential connection to Parkinson’s disease
Laws Controlling Pesticide Use Food, Drug, and Cosmetics Act (1938) Pesticide Chemicals Amendment (1954) Delaney Clause (1958) (a zero cancer risk standard) Federal Insecticide, Fungicide, and Rodenticide Act (1947) federal control of pesticide distribution, sale, and use Food Quality Protection Act (1996)