Title: Chapter 16 Pests and Pest Control
1Chapter 16Pests and Pest Control
2Learning Objectives
- Define pest
- Why do we control pests?
- What are the methods to control pests and the
philosophies of pest control? - What are the problems with pesticides?
- Define Integrated Pest Management, is it
successful? - Any current revisions?
- How are exportations to developing countries
regulated? - How are importations of food to our country
regulated?
3Vocabulary
- Pest any organism that is noxious, destructive,
or troublesome - Agricultural pests
- Insecticide toxin aimed at killing insects
- Herbicide toxin aimed at killing plant or
fungus - Pesticide toxin aimed at killing all pests
4PHILOSOPHIES OF PEST CONTROL
- Chemical Treatment
- Ecological Control long-lasting protection
- Against pest or ecosystem
- Integrated Pest Management
- First generation pesticides toxic heavy metals
- Second-generation pesticides synthetic organic
chemistry
5DDT PART 1 1940s 1950s
- General Consensus at the time
- Toxic to insects and NOT to humans
- Broad spectrum, kills all types of insects, but
relatively low risk to mammals - Persistent (sticks around without degradation)
- Saved many lives during WWII to prevent spread of
body lice and death from typhus fever (sores, ab
pain,deliria) also used in tropics to stop the
spread of malaria by mosquitoes - Used to increase crop production by controlling
insect pests in agriculture
6DDT Part 1 (continued)
- History of DDT
- DDT (dichlorodiphenyltrichloroethane) is one of
the most well-known synthetic pesticides - 1874 - synthesized
- 1939 - DDT's insecticidal properties discovered,
where it kills by opening sodium ion channels in
the neurons, causing them to fire spontaneously
leading to spasms and eventual death - used with great success in the second half of
World War II to control malaria and typhus among
civilians and troops - after the war, DDT was made available for use as
an agricultural insecticide, and soon its
production and use skyrocketed. - 1948 - Swiss chemist Paul Hermann Müller was
awarded the Nobel Prize in Physiology or Medicine
"for his discovery of the high efficiency of DDT
as a contact poison against several arthropods.
7Pg. 418
8DDT Part 2
- Decline of birds on top of food chain (osprey,
eagles) - Eggs breaking before hatched
- Bioaccumulation synthetic organics and breakdown
products trapped in bodys lipids - Biomagnification multiplying affect of
bioaccumulation as you move up food chain,
negative in this case
Pg. 423
9DDT Part 2 (continued) 1960s - today
- 1962, Silent Spring by American biologist Rachel
Carson was published, cataloguing the
environmental impacts of the indiscriminate
spraying of DDT in the US and questioned the
logic of releasing large amounts of chemicals
into the environment without fully understanding
their effects on ecology or human health. - The book suggested that DDT and other pesticides
may cause cancer and that their agricultural use
was a threat to wildlife, particularly birds. - Its publication was one of the signature events
in the birth of the environmental movement, and
resulted in a large public outcry that eventually
led to DDT being banned in the US in 1972.
- DDT was subsequently banned for agricultural use
worldwide under the Stockholm Convention, but its
limited use in disease vector control (like
malaria) continues to this day and remains
controversial. - the US ban on DDT (and Endangerd Species Act of
1973) is cited by scientists as a major factor in
the comeback of the bald eagle from
near-extinction in the contiguous US.
10Problems with chemical pesticides
- Since the plant eating insects (the pests) are
part of a dynamic ecosystem, Chemical treatments
of crops can lead to pesticide treadmill as seen
on page 418 - Pest problem surpasses economic threshold ? use
chemical pesticides ? surviving pests develop
resistance to that dosage leading to resurgence
of stronger pests - Thru biomagnification of pesticide effects the
predator insects are killed off more than actual
pest ? allowing for resurgence AND secondary
outbreaks (when other plant eating insects
previously not pests become pests due to having
no predators ? higher and more severe pest
problem ? leads to ever-increasing dosages of
pesticides and dependence on them ? more
contamination of food stuffs and ecosystem.YUCK - Human Health Effects
- Poisoning (toxin)?
- Cancer (carcinogenic)?
- Birth Defects (teratogen)
- Endocrine Disruptors like atrazine and alachor
weed killers. (increased breast cancer and
defective or low sperm counts, other sexual
abnormalities)
11Solution nonpersistent pesticides or IPM
Environmental Effects of Chemical Pesticides
- Toxicity through biomagnification up food chain
- Broad effect on unintended organisms (like us)
- Location of application (in a riparian
environmental, a watershed or upwind) - Effect on beneficial insects
- Persistent take a long time to break down esp.
chlorinated hydrocarbons, long-range danger and
long term
12NONPERSISTENT PESTICIDES
- Since persisent pesticides are banned now,
Agrochemical industry has created nonpersistent
organic phosphates (malathion, parathion,
chlorpyrifos) and carbamates (aldicarb and
carbaryl) - Typically inhibit enzyme cholinesterase essential
for proper functioning of nervous system in
insects, and all animals (us too) - Dangers
- Persistent enough to ride the food supply from
farmer to consumer (few weeks to break down) - Many are more toxic to mammals than older
chlorinated hydrocarbons varieties like DDT
(higher LD50) and require more applications
(higher dosage) - Still kill beneficial insects and have
biomagnification effect see Argentina Hawk
problem pg 421
Dupont Agrosciences
134 Categories of natural or biological PEST CONTROL
- 1. Cultural nonchemical alteration of
environmental factors (import restrictions, grass
lawn of at least 3 inches high keeps away most
crabgrass noxious weeds, crop rotation) - 2. Control by natural enemies/predators
(parasitic wasp uses gypsy moth pupa - or tomato hornworms, or less pesticide
- spraying to allow natural return predators
- to control brown planthoppers on rice)
- 3. Genetic Control
- Chemical Barriers (crossbreeding of plants to
enhance toxic chemical production by plant like
with Hessian fly and wheat leaves) - Physical Barriers (hooked sticky hairs on stems
to trap small larva)
144 Categories of natural or biological PEST CONTROL
- 3. Genetic Control (cont.)
- Sterile Males so no successful offspring
- Biotechnology to introduce genes from bacteria,
virus or other plant species (GMOs like
engineering Bt, a bacillus thuringienis protein,
into plants which kills larva of plant eating
insects,but harmless to mammals birds) (Roundup
herbicide resistant gene in crops, 90 of US
soybean crop is Roundup Ready) - 4. Natural Chemical Controls
- Use of hormones (chemical signals) like
pheromones to cause physiological issues or stunt
development cycle (Juvenile hormone prevents
pupation, or Mimic emulates ecdysone hormone
causing molting to begin but not finish
15Integrated Pest Management (IPM)
- Coordinated use of pest environmental
information to develop the best feasible control
methods, often using natural pathways to promote
sustainable control when possible - In a way that is the least harmful to people,
property and environment and still cost effective - Emphasis is on pest control not eradication
- Targeted, finely tuned common-sense methods as
opposed to indiscreminate toxification of
EVERYTHING - A return to old-school, pre-chemical industry
methods of pest management - 4 Tiered Approach Pest Action Threshold,
Information Building, Prevention First, Control
and Reduction (biological first, then narrow
range synthetic, then broad spectrum synthetic
(see IPM Notes ppt for more details)
16SOCIOECONOMIC ISSUESbalancing crop yield,
nutrition, cosmetics and cash
- Economic
- Threshold
- Insurance
- Spraying
- Cosmetic
- Spraying
- Snow white
- syndrome
- Organic
- growing
17Pg. 433
18Concerns when regulating pesticide
- Evaluated for intended use and impacts on
environmental health - Proper training and safety of agricultural
workers using it - Risk of pesticide residue on our food
19PUBLIC POLICY (pg 432 433)
- FFDCA 1938 (Federal Food, Drug, and Cosmetic Act)
is a piece of legislation that first started the
control pesticide residues left on food eaten in
the US the Delaney Clause was controversial
because it prevented any trace of a pesticide
that had evidence of being carcinogenic in lab
animal tests (too restrictive?) - 3 agencies involved EPA sets allowable
tolerances ? FDA monitors and enforces all food
except meat while USDA (US Dept of Ag) enforces
meat, poultry and eggs - FIFRA 1947 1972 (Federal Insecticide,
Fungicide, and Rodenticide Act) - Must register pesticide, label lists active
ingredients - FQPA 1996 (Food Quality Protection Act)
- The new law regulating safe amounts of pesticide
residue on food, requiring reasonable certainty
of no harm, especially in chronic cause of cancer
or exposure to children - Developing Countries and Importing Foods
- Prior informed consent (PIC) managed by FAO
importers and exporters inform each other of
practices
20New Policy Needs
- Reduction of pesticide use
- Develop methods that rely on biological control
and use of natural processes - Adopt IPM practices
- Adopt precautionary principle (like European
Union has) of requiring burden of proof on
manufacturers not consumers, meaning a new
chemical must be proven safe rather than assumed
safe until long term problems develop
21DDT
- DDT was not used for handling weeds but has saved
millions of lives by controlling disease-causing
pests - The 1948 Nobel prize was awarded to Paul Muller
for discovering DDT - DDT is a cheap, persistent, synthetic, organic,
compound is subject to biomagnifications in
food chains
22Diseases
- Lyme disease can be transferred to humans through
a bite from an infected tick (vector) - Mosquitoes are the vector for Malaria
- The protozoan of the genus Plasmodium is the
causative agent of malaria - DDT is great at killing mosquitoes should we use
it? - Lack of access to safe drinking water is a major
cause of disease transmission in developing
countries.