Pesticides - Mrs. Marosy`s Science Page

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Transcript Pesticides - Mrs. Marosy`s Science Page

Pesticides
Mrs. Marosy APES
Food and Agriculture
Pesticides Pro and Con
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Kill unwanted pests
that carry disease
(rats, mosquitoes, TseTse flies)
Increase food supplies
More food means food
is less expensive
Effective and fastacting
Newer pesticides are
safer, more specific
Reduces labor costs on
farms
Food looks better
Agriculture is more
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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
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
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
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.