Transcript Pesticides
Pesticides Pesticides Pro and Con 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% or less 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, lindane and paradichlorobenzene Fumigants are used to sterilize soil and prevent grain infestation Types of Pesticides Inorganic mercury – arsenic, copper, lead, – Highly toxic and bioaccumulation Organic or natural – derived from plants such as tobacco and chrysanthemum Organophosphates – extremely toxic, low persistence – Malathion, parthion, chlophyrifos, acepate, propetamphos and trichlofon Chlorinated Hydrocarbons DDT Affect the nervous system of pest Remain in ecosystem 15+ years Prevent malaria Carbamates Carbamates 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, 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. 1400 wells are still contaminated above state guidelines. Aldicard has been found in groundwater in 26 other states. Fumigants Methyl Bromide was banned in 2005 due to it’s damage to the ozone layer. 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 were tied to contaminated (toxic) bread and grain products. 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 Application: Dust onto plant 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.