Transcript Pest Control - APESspring09

Pest Control
Chapter 12 APES
2008
What are pesticides?
 Chemicals that kill
pests
 Biocides- kill wide
range of pests
 Herbicides- kill plants
 Insecticides- kill
insects
 Fungicides- kill fungi
History of Pesticides
 Every culture has used pesticides
 Modern era of pesticides began in
1934 with development of DDT
(Dichloro-DiphenylTrichloroethane)
 Used in WWII to control parasites
& tropical disease
 Was cheap, stable, soluble in oil,
easily spread over wide areas.
 High toxicity for target organismskills 90% of target organisms in
single application
 It was the “magic bullet”- the
answer to our prayers… or was it?
History of Pesticides
 Indiscriminate & excessive
use of pesticides has caused
 Damage to ecosystems
 Harm to human health
 Creation of “superbugs”
 ¾ of all pesticides are used in
Most Developed Countries
(MDC) but rates in LDC are
on the rise by 7-8%.
 DDT was banned in US in the
1970’s. We can now only use
it in emergencies.
 DDT is still used in many
Children playing in DDT clouds at
other countries- especially for beach.
control of mosquitoes.
History of Pesticides
classified based on chemical structure
1st stage included
Inorganic Pesticides
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Arsenic, copper,
lead, mercury
Highly toxic &
indestructable
Arsenic poisoning from
infected water sources in
Bangladesh
History of Pesticides
2nd stage included
petroleum based
sprays and natural
organic pesticides
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Nicotine, rotenone
Botanicals
From plants
History of Pesticides
3rd stage included chlorinated
hydrocarbons
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DDT, chlordane, aldrin,
dieldrin, toxaphene
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Block nerve signals
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Fast & toxic,
carcinogenic
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Biomagnify- stay in
ecosystem
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Dieldrin 50X as toxic to
people as DDT
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Toxaphene kills goldfish
at 5 ppb- one of the
highest toxicities for any
compound
History of Pesticides
4th stage: Biological
controls•
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using live
organisms or their
toxins instead of
pesticides
Bacillus thuingiensis
(Bt)- kills beetles,
caterpillars by
destroying their
digestive tract
Parasitic wasps
Ladybugs eat
Alternatives to Pesticides
 Biological controls- natural
predator
 Bacillus thuringiensis (Bt)kills beetles & caterpillars
 Ladybugs, praying mantises,
wasps
 Ducks & geese in fields will
eat insects & weed seed.
 Planting garlic or marigolds
can deter pests.
 Release of artificial
hormones can disrupt life
cycles (sex phermones)
Alternatives
to Pesticides
 Integrated Pest Management
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(IPM)- use a combination of
methods, including biological
control, chemical pesticides, and
methods of crop planting.
Vacuuming bugs off crops
Move away from monoculturegrow several crops to confuse the
pest.
No till or low till agriculture- helps
natural enemies to build up in the
soil
 Trap crops- mature before rest
of field to attract pests, then
sprayed heavily, destroy trap
crop to prevent spread to
people or “real” crop.
IPM continued
 Crop rotation keeps
pest population low.
 Using cover crops
keeps weeds down
 Provide habitat for
natural predators
(plant trees along
edge of farm for birds
which will eat bugs &
provide windbreak
which prevents
erosion)
Benefits of Pesticides
 Reduce disease transmission by insect vectors (DDT
sprayed to kill mosquitoes & prevent malaria, when
stopped in 1964, malaria reappeared immediately)
 Which is more important? Protecting people or the
environment?
 If you had to choose between contracting masses of worms
that will make you go blind before the age of 30 or a small
chance of cancer due to pesticide exposure it you live to 50 or
60, which would you choose?
 Reduce crop losses by two-thirds.
 Farmers save $3-$5 for every $1 they spend on pesticides.
 Lowers costs and increases crop quality
Problems with Pesticides
 Non-target organisms affected
 Potato aphid spraying killed
migrating robins
 Insecticide spraying in CA killed
salmon
 Honeybees disappearing
 Resistant individuals will develop due
to natural selection
 Pesticide is killing off natural
predators that help control bad
populations
 Limited useful lifespan- can move far
from original application spot (next
slide)
 Persistant organic pollutants (POP’s)
are very long lasting and dangerous.
Banned in most countries but
persistent in soil & water
 Affect Human Health
 Acute- poisoning & illness
 Chronic- cancer, birth defects,
degenerative diseases
Pest resurgence leads to the use
of higher doses or more toxic
chemical use
The Grasshopper Effect
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Many chemicals like chlorinated
hydrocarbons evaporate from
water & soil in warm areas &
condense & precipitate in colder
regions.
This happens over & over,
“hopping” northward until it
collects in polar regions.
Affecting top predators (polar
bears, whales, & humans)
Some carcasses have to be
treated as toxic waste they are
so “infected” with pesticide.
Be familiar with “The Dirty
Dozen”- from toxicity handout
About Human Health…
 Yaqui children in Mexico tested…
 Foothills children age 4-5 not exposed to
much pesticide
 Valley children age 4-5 repeatedly exposed
Who regulates pesticide
usage?
 Environmental Protection Agency (EPA)
 Regulates sale & usage under Federal Insecticide, Fungicide,
& Rodenticide Act (FIFRA) which mandates the “registration”
of all pesticide products.
 Determines which pesticides are safe to use for humans &
environment
 Sets tolerance levels for residues that may remain in or on
foods marked in U.S. This falls under the Federal Food, Drug,
and Cosmetic Act (FFDCA).
 Department of Agriculture (USDA) & Food & Drug
Administration (FDA) enforce pesticide use & tolerance
limits set by EPA. Can seize & destroy food shipments
that violate.