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Lecture
Presentation
Lectures by:
Heidi Marcum, Baylor University
Pests and Pest
Control
CHAPTER 13
© 2017 Pearson Education, Inc.
Assignments
• Read ‘Silent Spring’- Due Friday
• World Food Prize- Due Monday
• Chapter 13- Due Next Thursday 2/8
– Pg. 317-340
– Questions 1-10 pg. 340
© 2017 Pearson Education, Inc.
Pests Introduction
• Fold paper into 3 columns
• Label columns- “Organism,” “Pest,” “Not a Pest”
• As a group, list as many as possible in 5-10
minutes.
© 2017 Pearson Education, Inc.
Organism Pest Not a Pest
© 2017 Pearson Education, Inc.
Lecture
Presentation
Lectures by:
Heidi Marcum, Baylor University
Pests and Pest
Control
CHAPTER 13
© 2017 Pearson Education, Inc.
Bedbugs are a public health problem
• Bedbugs have infested many states in the United States
– They were controlled after WWII, but have resurged to epidemic proportions
– Getting rid of them is extremely difficult
• In 2010, Ohio asked the EPA for permission to use the pesticide Propoxur
– The permit was denied over concerns about the effects on children
– But common foggers don’t work on bedbugs
• Solutions that work include non-chemical controls
– Vacuuming, sealing cracks, heat, removing clutter, monitoring, and diatomaceous earth
© 2017 Pearson Education, Inc.
There are many types of pests
• Pests: organisms that interfere with human activities– Insects, weeds, molds, pathogens, wild animals
– But this is a human-centered definition
• Agricultural pests: feed on crops, plants, or animals– Insects, fungi, viruses, worms, snails, rodents, birds
– Weeds: compete with crops, forests, grasses
– In 2011, mice in Australia cost $300 million in losses
• Veterinary pests affect domestic animals– Fleas, ticks, mites, screwworm flies
• Medical pests attack humans– They may carry diseases (e.g., mosquitoes)
© 2017 Pearson Education, Inc.
Agricultural pests and weeds
© 2017 Pearson Education, Inc.
(a) soybean rust, (b) cotton boll weevil, (c) male medfly,
(d) giant hogweed
Veterinary and medical pests
© 2017 Pearson Education, Inc.
(a) dog ticks, (b) Anopheles mosquito (can transmit
malaria)
Other types of pests
• Forest pests kill trees and wood products
– The emerald ash borer and Asian longhorned
beetle cost $1.7 billion in government spending
• Stored-product pests live in processed foods
– The tiny Khapra beetle, resistant to many
pesticides, is intercepted 200 times a year in the
United States
– Trained agriculture canines can detect such pests
• Biofouling organisms settle in aquatic
environments
– Interfere with shipping, clog pipes and screens
– Pests also live on fabric, paper, etc.
© 2017 Pearson Education, Inc.
Emerald ash borer
© 2017 Pearson Education, Inc.
(a) Borers dig into the bark of ash trees and kill them, (b) Traps
along roads help monitor the borer’s movements
Sniffing out pests
© 2017 Pearson Education, Inc.
A U.S. Customs and Border Protection agriculture specialist
works with an agricultural detector beagle
The cost of controlling pests
• Pesticides and herbicides are costly
– The United States uses 1.1 billion pounds of
herbicides (to kill plants) and other pesticides (to
kill animals) a year
• In 2007, $39 billion was spent on 5.21 billion
pounds of pesticides used worldwide
• Agricultural technology (monocrops, genetically
identical crops) have boosted yields
– But 20–50% of crops are still lost to pests a year
• Pesticide uses have increased drastically
– We have an unsustainable dependency on them
© 2017 Pearson Education, Inc.
Pesticide use in the United States, 1964–2007
© 2017 Pearson Education, Inc.
A change in the way totals were calculated makes it hard to
compare values before and after 1998
Pests and climate change
• It is hard to predict the effects of climate change
on pests
– Insects (medical and agricultural) are increasing
their ranges
– Pathogens will respond to changes in precipitation,
temperature, weather events
– Ticks are increasing in North America
– Crop pests (nematodes, weevils) will increase in
the tropics
– Drought may lower mosquito populations
© 2017 Pearson Education, Inc.
Different philosophies of pest control
• Chemical treatment of pests: eradicates or
decreases pest numbers
– Gives only short-term protection
– Has highly damaging side effects to other
organisms
• Ecological pest control: long-lasting protection
– Based on knowledge of the pest’s life cycle and
ecological relationships
– May be other organisms or chemicals
– May be highly specific to one organism
– May manipulate some aspect of the ecosystem
© 2017 Pearson Education, Inc.
What is IPM?
• Ecological control protects people and plants
– But does not eradicate the pest
– It maintains the ecosystem’s integrity
• Integrated pest management (IPM): combines
chemical and ecological control to control pests
– It uses all suitable methods to bring about long-term
management of pests
– Has minimal environmental impact
– Used in developing countries that can’t afford
pesticides or where they pose a health risk
© 2017 Pearson Education, Inc.
The promises of chemical pesticides
• Pesticides are categorized by the organisms
they kill
– Insecticides (insects), rodenticides (rats, mice), fungicides (fungi), herbicides (plants)
– All can pose hazards to others, including humans
• First-generation pesticides: first substances to
control pests
– Toxic heavy metals: lead, arsenic, mercury, cyanide
– Build up in soils, inhibit plant growth, poison organisms, lose effectiveness, pests gain resistance
• Second-generation pesticides: developed through
synthetic organic chemistry
© 2017 Pearson Education, Inc.
The DDT story
• DDT is a second-generation pesticide
• Chemist Paul Müller studied DDT in the 1930s
– Dichlorodiphenyltrichloroethane
– First synthesized 50 years earlier
• As a pesticide, it was extremely successful
– Extremely toxic to insects, not humans or mammals
– Very cheap
– Broad spectrum: effective against many insect
pests
– Persistent: provided long-lasting protection so
repeated treatments were not necessary
© 2017 Pearson Education, Inc.
DDT in war and in peace
• DDT saved millions of lives
– The military used it to control lice (cause typhus fever)
– It also controlled dengue fever, mosquitoes (malaria)
– Müller was awarded the 1948 Nobel Prize
• After World War II, DDT was used to control spruce budworms, mosquitoes, Dutch elm disease
• Farmers could ignore other pest control methods (crop rotation and destruction of crop residues)
– They grew less resistant crops in more areas
• Now, the EPA regulates over 18,000 pesticide products
© 2017 Pearson Education, Inc.
DDT in war
© 2017 Pearson Education, Inc.
This 1945 image shows a U.S. soldier spraying DDT
directly on a fellow soldier
Pesticide problems: acute health effects
• In 2012, 86,690 people in the United States
were affected
– Farm workers and employees of pesticide
companies
• Pesticides cause:
– Nausea, abdominal pain, shock, respiratory failure,
allergic reactions, seizures, pneumonia, coma
• Over 1 million people/yr. suffer serious poisoning
• Most acute cases occur in developing countries
– Untrained users have little information on pesticides
– People get sprayed, incorrectly store pesticides, or
drink water from contaminated containers
© 2017 Pearson Education, Inc.
Pesticides are used unsafely
© 2017 Pearson Education, Inc.
This farmer in Thailand is spraying pesticides on soybeans
without using protective gear
Pesticide problems: chronic health effects
• Pesticides are applied to fields and orchards
– They are also used to protect harvested food
• Consumers and farmers are exposed to low levels
of pesticides and pesticide residues
– Which may have chronic effects
• Pesticides may cause:
– Cancer (lymphoma, breast cancer)
– Dermatitis, nerve damage, birth defects, infertility
– Disruption of the immune and endocrine systems
– Parkinson’s disease, low white blood cell counts
© 2017 Pearson Education, Inc.
Pesticides are endocrine disrupters
• Many pesticides affect reproductive hormones
– Increased breast cancer in humans
– Abnormal sexual development in alligators,
fish, etc.
• Very low levels mimic or disrupt estrogenic
hormones (potent sexual chemicals)
• The Endocrine Disruptor Screening Program
– This EPA program has developed procedures for
testing chemicals for endocrine disruption
© 2017 Pearson Education, Inc.
Adverse environmental effects
• Many bird species declined in the 1950s and 1960s
– DDE and DDT caused eggs of birds at the top of the food chain (e.g., bald eagle, osprey) to break
• Bioaccumulation: over time, small amounts of chemicals build up to toxic levels in organisms
– Many synthetic organic chemicals are soluble and are stored in lipids (fats)
– Organisms can’t metabolize or excrete the chemicals
• Biomagnification: the multiplying effect of bioaccumulation in organisms up the food chain
– Top-level organisms have high levels of contaminants
© 2017 Pearson Education, Inc.
DDT decimated ospreys
© 2017 Pearson Education, Inc.
Ospreys and other fish-eating birds were decimated by DDT
but recovered when DDT was banned
Biomagnification of DDT
© 2017 Pearson Education, Inc.
Organisms absorb pesticides from lower levels, bioaccumulating
and magnifying the concentration of the pesticide
Bedbugs are a public health problem
• Bedbugs have infested many states in the United States (Watch: HP Cities 19:40)
• Solutions that work include non-chemical controls
– Vacuuming, sealing cracks, heat, removing clutter, monitoring, and diatomaceous earth
© 2017 Pearson Education, Inc.
There are many types of pests
• Pests: organisms that interfere with human activities– Insects, weeds, molds, pathogens, wild animals
– But this is a human-centered definition
© 2017 Pearson Education, Inc.
• Agricultural pests: feed on crops, plants, or animals
• Veterinary pests affect domestic animals
• Medical pests attack humans
© 2017 Pearson Education, Inc.
Agricultural pests and weeds
© 2017 Pearson Education, Inc.
(a) soybean rust, (b) cotton boll weevil, (c) male medfly,
(d) giant hogweed
Veterinary and medical pests
© 2017 Pearson Education, Inc.
(a) dog ticks, (b) Anopheles mosquito (can transmit
malaria)
Other types of pests
• Forest pests kill trees and wood products
– The emerald ash borer and Asian longhorned
beetle cost $1.7 billion in government spending
© 2017 Pearson Education, Inc.
• Stored-product pests live in processed foods
• Biofouling organisms settle in aquatic
environments
© 2017 Pearson Education, Inc.
Sniffing out pests
© 2017 Pearson Education, Inc.
A U.S. Customs and Border Protection agriculture specialist
works with an agricultural detector beagle
© 2017 Pearson Education, Inc.
The cost of controlling pests
• Pesticides and herbicides are costly
– The United States uses 1.1 billion pounds of
herbicides (to kill plants) and other pesticides (to
kill animals) a year
© 2017 Pearson Education, Inc.
Pests and climate change
• It is hard to predict the effects of climate change
on pests
© 2017 Pearson Education, Inc.
Different philosophies of pest control
• Chemical treatment of pests: eradicates or
decreases pest numbers
• Ecological pest control: long-lasting protection
© 2017 Pearson Education, Inc.
• Integrated pest management (IPM): combines
chemical and ecological control to control pests
• (Watch HP Cities 14:00)
What is IPM?
• Ecological control protects people and plants
– But does not eradicate the pest
– It maintains the ecosystem’s integrity
• Integrated pest management (IPM): combines
chemical and ecological control to control pests
– It uses all suitable methods to bring about long-term
management of pests
– Has minimal environmental impact
– Used in developing countries that can’t afford
pesticides or where they pose a health risk
© 2017 Pearson Education, Inc.
The promises of chemical pesticides
• Pesticides are categorized by the organisms
they kill
– Insecticides (insects), rodenticides (rats, mice), fungicides (fungi), herbicides (plants)
© 2017 Pearson Education, Inc.
• First-generation pesticides: first substances to
control pests
• Second-generation pesticides: developed through
synthetic organic chemistry
© 2017 Pearson Education, Inc.
The DDT story
• DDT is a second-generation pesticide
• Chemist Paul Müller studied DDT in the 1930s
– Dichlorodiphenyltrichloroethane
– First synthesized 50 years earlier
© 2017 Pearson Education, Inc.
DDT in war and in peace
• DDT saved millions of lives
– The military used it to control lice (cause typhus fever)
– It also controlled dengue fever, mosquitoes (malaria)
– Müller was awarded the 1948 Nobel Prize
© 2017 Pearson Education, Inc.
• After World War II, DDT was used to control spruce budworms, mosquitoes, Dutch elm disease
• Farmers could ignore other pest control methods (crop rotation and destruction of crop residues)
© 2017 Pearson Education, Inc.
DDT in war
© 2017 Pearson Education, Inc.
This 1945 image shows a U.S. soldier spraying DDT
directly on a fellow soldier
Pesticide problems: acute health effects
• In 2012, 86,690 people in the United States
were affected
• Pesticides cause:
– Nausea, abdominal pain, shock, respiratory failure,
allergic reactions, seizures, pneumonia, coma
© 2017 Pearson Education, Inc.
Pesticide problems: chronic health effects
• Pesticides may cause:
– Cancer (lymphoma, breast cancer)
– Dermatitis, nerve damage, birth defects, infertility
– Disruption of the immune and endocrine systems
– Parkinson’s disease, low white blood cell counts
© 2017 Pearson Education, Inc.
DDT sprayed from a TIFA (Todd
Insecticidal Fog Applicator)
around model Kay Heffernon to
© 2017 Pearson Education, Inc.
• Pesticides are applied to fields and orchards
– They are also used to protect harvested food
• Consumers and farmers are exposed to low levels of
pesticides and pesticide residues
– Which may have chronic effects
Pesticides are endocrine disrupters
• Many pesticides affect reproductive hormones
– Increased breast cancer in humans
– Abnormal sexual development in alligators,
fish, etc.
• Very low levels mimic or disrupt estrogenic
hormones (potent sexual chemicals)
• The Endocrine Disruptor Screening Program
© 2017 Pearson Education, Inc.
Adverse environmental effects
• Many bird species declined in the 1950s and 1960s
– DDE and DDT caused eggs of birds at the top of the food chain (e.g., bald eagle, osprey) to break
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
• Bioaccumulation: over time, small amounts of chemicals build up to toxic levels in organisms
– Many synthetic organic chemicals are soluble and are stored in lipids (fats)
– Organisms can’t metabolize or excrete the chemicals
© 2017 Pearson Education, Inc.
• Biomagnification: the multiplying effect of bioaccumulation in organisms up the food chain
– Top-level organisms have high levels of contaminants
DDT decimated ospreys
© 2017 Pearson Education, Inc.
Ospreys and other fish-eating birds were decimated by DDT
but recovered when DDT was banned
Biomagnification of DDT
© 2017 Pearson Education, Inc.
Organisms absorb pesticides from lower levels, bioaccumulating
and magnifying the concentration of the pesticide
Silent Spring
• Rachel Carson’s Silent Spring (1962) documented
the effects of uncontrolled use of pesticides in the
United States
What did Carson believe?
What was the purpose of writing Silent Spring?
© 2017 Pearson Education, Inc.
Pesticide problems: resistance
• Chemical pesticides lose their effectiveness
– More and more quantities must be used
– Newer, more potent pesticides must be developed
• It takes more pesticide to get the same results
– In 1946, 2.2 lb. of pesticide resulted in 60,000
bushels of corn; in 1971, it took 141 lb.
– Losses to pests actually increased
• Many pest species have developed resistance
– Stored product, medical, and veterinary pests
© 2017 Pearson Education, Inc.
Pesticides are involved in synergistic effects
• Synergistic effects: multiple factors work together
to create an unexpected outcome
• What is causing the decline of bees?
– Colony collapse disorder is not caused by one thing
– It could be a mixture of pests, pathogens, parasites,
viruses, poor nutrition, and stress
– Pesticides can interact with these factors
• Bees exposed to pesticides:
– Had low growth rates, ate less, and had trouble
finding their way back to the hive
– They produced fewer queens and danced less
© 2017 Pearson Education, Inc.
Pollinators in decline
© 2017 Pearson Education, Inc.
Colony collapse disorder (CCD) killed these bees in Florida.
CCD has caused a massive world die off of bees.
Evolution at work
• Pesticides destroy sensitive individuals
– The resistant ones survive
• Resistance develops rapidly in r-selected species
– They have high reproductive capacity
• Repeated pesticide applications select for genetic
lines that are highly, or totally, resistant to
pesticides
– The Colorado potato beetle developed resistance to
52 compounds (including cyanide) in 50 years
• Many major pest species are resistant to all of the
principal pesticides
© 2017 Pearson Education, Inc.
Invertebrate food chains
© 2017 Pearson Education, Inc.
(a) Food chains exist among insects; (b) This ant lion is using
its powerful jaws to capture an ant; (c) This huntsman spider
is eating a grasshopper
Pesticide problems: resurgence
• Resurgence: occurs after a pest has almost been
eliminated
– The population recovers and even explodes
• Secondary pest outbreak: insects that were
originally of no concern create new problems
– They quickly become resistant to pesticides
© 2017 Pearson Education, Inc.
• Pesticide treadmill: use of pesticides increases
resistance and secondary-pest outbreaks
– New and larger amounts of pesticides are used
– Resistance and secondary-pest outbreaks occur
© 2017 Pearson Education, Inc.
Trapping technique
© 2017 Pearson Education, Inc.
Pheromones lure adult Japanese beetles into traps
Alternatives to using pesticides
• A species becomes a pest only when it causes
significant damage
• Economic threshold: the point where:
– Economic losses of pest damage outweigh the cost
of applying a pesticide
© 2017 Pearson Education, Inc.
What if pest damage is not significant?
• Insurance spraying: use of pesticides to prevent
losses to pests
• Cosmetic spraying: using pesticides to control
pests that harm only the item’s appearance
– Does not increase yields or nutritional value
– Results in increased use and residues on the
produce
© 2017 Pearson Education, Inc.
The four approaches of IPM
• Set action thresholds: Monitor and identify
pests: Prevent pests: Control pests:
© 2017 Pearson Education, Inc.
Why do farmers still use pesticides?
• Farmers need to understand the economic
benefits of natural control through IPM
• At first, pesticides increase yield and profits
• Pest-loss insurance: pays the farmer if crops are
lost due to pests
© 2017 Pearson Education, Inc.
Integrated pest management
© 2017 Pearson Education, Inc.
IPM has helped Indonesian rice farmers control
the brown plant hopper
Organically grown food
• Organic farms are small and use traditional
farming methods to grow diverse crops
– They are tied to local economies
• Organic crops have lower yields and cost more
• Organic foods in the United States bring in
$33 billion/year
© 2017 Pearson Education, Inc.
Catching pests early
© 2017 Pearson Education, Inc.
On December 23, 2013, one coconut rhinoceros beetle, an
invasive pest on palms, was caught in a trap in Honolulu,
Hawaii. After discovering others, APHIS is coordinating a
response to eradicate it before it can spread.
Regulation of pesticides
• The Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA) (1947)
– Administered by the EPA
– The EPA has total jurisdiction over the
manufacture, use, sale, and testing of pesticides
– Manufacturers must register and test pesticides
– The EPA can ban or restrict a product that causes
unreasonable adverse effects on the environment
© 2017 Pearson Education, Inc.
The EPA’s Pesticide Program
• It puts high priority on registering “reduced risk”
pesticides that replace more toxic ones
• Biopesticides: naturally occurring substances that
control pests
– Microbial pesticides (Bt), plant-incorporated
protectants in GM crops, and pheromones
– Can be registered faster than other pesticides
• The EPA has come under fire for giving provisional
registration to hundreds of pesticides
– Without requiring them to be fully tracked or tested
© 2017 Pearson Education, Inc.
Federal Food, Drug, and Cosmetic Act (1938)
(FFDCA)
• Three agencies are involved in protecting
consumers from pesticides on food:
– EPA: sets allowable tolerances for residues
– FDA: monitors and enforces tolerances on
most foods
– USDA: monitors and enforces tolerances on meat,
poultry, and eggs
© 2017 Pearson Education, Inc.
• The Delaney clause of the FFDCA says that:
– No detectable residue of a pesticide may be on
food if it presents any risk of cancer
– More sensitive analytical techniques banned more
and more pesticides from use on food
© 2017 Pearson Education, Inc.
Food Quality Protection Act (FQPA) (1996)
• Eliminated the Delaney clause
• It also amended FIFRA and FFDCA
• The FQPA’s new safety standard sets “a
reasonable certainty of no harm” and requires:
– Special consideration for children exposed to
pesticide residues
– Prohibition of pesticides that carry a risk of cancer
more than one in a million
– All sources of a pesticide must be considered
– All products over 10 years old must be reassessed
– Raw and processed foods have the same standard
© 2017 Pearson Education, Inc.
Care for kids
• The FQPA requires the EPA to add a 10-fold
safety factor in assessing children’s risks from
pesticides
– Children eat more fruits and vegetables per unit of
body weight
– They are more susceptible to carcinogens and
neurotoxins
© 2017 Pearson Education, Inc.
Pesticides in developing countries
• The United States exports thousands of tons of
pesticides/yr.
– Some have been banned in the United States
• People in developing nations can be exposed to
toxic pesticides
– Low literacy, weak laws, unfamiliarity with
equipment
• FIFRA requires “informed permission” before
shipping any pesticide banned in the United States
– Permission comes from the purchaser
– The EPA must notify the government of the
importing company’s identity
© 2017 Pearson Education, Inc.
An international framework for pesticides
• The Rotterdam Convention: an international
treaty that promoted open exchange of information
– About hazardous chemicals (including pesticides)
• Prior informed consent (PIC): exporting
countries inform all potential importing countries:
– About actions they have taken to ban or restrict a
chemical, and label them clearly
• The International Code of Conduct on the
Distribution and Use of Pesticides
– A worldwide guidance document about pesticides
© 2017 Pearson Education, Inc.
The International Code of Conduct
• Addresses conditions of safe pesticide use
– Both private companies and governments are
responsible for safe pesticide use
• The Stockholm convention (2004) eliminates or
restricts persistent organic pollutants
– Nations will ban 9 of the 12 most dangerous
chemicals
– DDT will only be used for malaria control
– Limits accidental releases of dioxins and furans
– 178 countries and the EU—but not the United
States—were parties to the convention
© 2017 Pearson Education, Inc.
What about the future?
• Pesticide use illustrates two trends in
environmental science issues:
– The problems of cumulative impacts
– The problems of unintended consequences
• Grassroots action and pressure from public-
interest groups and NGOs are pressuring for:
– Safe and sustainable pest prevention and
management
• We must care for the welfare of all creatures to
solve pest problems in a sustainable manner
© 2017 Pearson Education, Inc.
Nonpersistent pesticides: the answer?
• Persistent chlorinated hydrocarbons can remain
in the environment for decades
– Many have been banned
• Nonpersistent pesticides are extensively used
– Organic phosphates (malathion, parathion,
chlorpyrifos)
– Carbamates (aldicarb, carbaryl)
– They break down into nontoxic products in a
few weeks
– They do not migrate long distances
© 2017 Pearson Education, Inc.
Nonpersistent pesticides are dangerous
• They harm non-target organisms
• Nonpersistent pesticides are highly toxic
– The EPA must develop health-based standards to
address the risk of children’s exposure to pesticides
• Carbofuran killed 2 million U.S. birds/year
– The EPA revoked all uses in 2008
• Beneficial insects (bees, butterflies) are highly
sensitive
– Predatory insects and spiders are also harmed
• Resurgences, secondary-pest outbreaks, and
resistance to nonpersistent pesticides occur
© 2017 Pearson Education, Inc.
Alternative pest control methods
• Ecological control: manipulates natural factors
without damaging the environment or human
health
– Depends on understanding the pest and its
relationship with its host and ecosystem
• Insects have complex life cycles
– Each stage may be vulnerable to abiotic factors,
predators, or parasites
• Four categories of ecological pest control are:
– Cultural control, natural enemies, genetic control,
and natural chemical control
© 2017 Pearson Education, Inc.
Insects have complex life cycles
© 2017 Pearson Education, Inc.
Biological control recognizes different life stages and attacks
the insect using this knowledge
Cultural control
• A nonchemical change of environmental factors
– The pest finds the area unsuitable or can’t access
its target
• Cutting lawns too short results in weeds
– Keep grass at least 3 inches long
• Mulch discourages weeds and protects the soil
• Avoid plants that attract pests (e.g., roses)
• Plant plants that repel pests (marigolds)
• Hedgerows, fencerows, and shelterbelts
– Provide refuge for pest predators (birds,
amphibians, praying mantises)
© 2017 Pearson Education, Inc.
Cultural control of wheat rust
© 2017 Pearson Education, Inc.
Wheat rust must infest barberry―eliminating this plant
controls the wheat rust
More cultural controls of pests
• Plowing or burning crop residues lowers the chance of diseases
• By rotating crops (changing crops each year), pests of the first crop can’t feed on the second crop
• Mixed plantings lowers crop losses to any one pest
• Trap cropping lures a pest to its favorite plant
• Refuge plants are untreated, and predators survive
• Imported pests are the hardest pests to control
– The U.S. Customs and Border Protection and agriculture departments keep pests out of the United States
– Biological materials are prohibited, quarantined, and so on.
© 2017 Pearson Education, Inc.
Tomato wilt devastates tomato plants
© 2017 Pearson Education, Inc.
Growing plants in the same place lets spores in the
soil re-infect plants
Cultural controls decrease disease
• Sewage treatment prevents waterborne diseases
• Proper hygiene prevents lice, fleas, and bedbugs
– Combing hair, bathing, cleaning clothing and
bedding
• Bed nets and mattress covers protect against
mosquitoes, bedbugs, and mites
• Garbage disposal and sealing household cracks
and screens prevent roaches, mice, mosquitoes
• Safe food handling, refrigeration, freezing, and
canning prevent spread of disease and rotting
• Catastrophes increase diseases, sickness, death
© 2017 Pearson Education, Inc.
Control by natural enemies
• There are four types of natural enemies:
– Predators, parasitoids, pathogens, herbivores
• Predator beetles prevent the non-native wooly
adelgid from killing hemlock trees
• Mealy bugs and caterpillars in Africa are controlled
by parasitic wasps
• “Green muscle” (a fungus) controls desert locusts
• Brazilian weevils control water hyacinth in lakes
• Over 30 weed species are limited by insects
© 2017 Pearson Education, Inc.
Parasitic wasps
© 2017 Pearson Education, Inc.
Parasitic wasps use moth caterpillars as their hosts
Protect the natives
• Natural enemies must control the target species
without attacking desirable species
• 1% of 50,000 plant-eating insect species are pests
– The other 99% are controlled by natural enemies
• Conservation: protect natural enemies already
here
– The first step in using natural enemies for control
– Avoid or restrict broad-spectrum chemical
insecticides
– These natural enemies control secondary pests
(which become pests only after using pesticides)
© 2017 Pearson Education, Inc.
Import aliens as a last resort
• Effective natural enemies are not always available
– We import pests, but not their enemies
• Natural enemies are found in the pest’s native land
– They must be carefully tested before being released
• Introduced species can be a success or failure
– Cane toads, imported to control beetles, overran
Australia’s natives instead
– But a parasitoid wasp has successfully controlled
the cassava mealybug in Africa
• Better science and controls help releases succeed
© 2017 Pearson Education, Inc.
Cane toads and Hessian flies
© 2017 Pearson Education, Inc.
Cane toads, introduced to Australia to control beetles in sugar
cane fields, became pests themselves
Plant breeding
• Most insects and plant pathogens attack only one
or a few closely related species
– Incompatible plants are not attacked
• Genetic control strategies: develop genetic traits in
the host species that provide incompatibility
– The hosts are resistant to attack by the pest
• But scientists and disease continue to battle
– Scientists developed wheat resistant to wheat stem
rust, a parasitic fungus
– A new fungus is now spreading to Asia, devastating
wheat
© 2017 Pearson Education, Inc.
Control with chemical and physical barriers
• Plants can produce substances that are lethal or
repulsive to the pest
– A wheat variety produces a chemical that kills the
larvae of the Hessian fly
– Losses to this pest are less than 1% of the non-
resistant wheat varieties
• Plants can have physical traits that trap pests
– Leaves with hooked hairs trap and hold immature
leafhoppers until they die
– Glandular hairs that secrete a sticky substance trap
other pests
© 2017 Pearson Education, Inc.
Chemical and physical control of plants
© 2017 Pearson Education, Inc.
This wheat plant produces a chemical toxic to Hessian flies,
while sticky hairs on this alfalfa plant trap an
immature leafhopper
Biotechnology and Bacillus thuringiensis
• Incorporating the protein coat of a virus into the plant
– The plant becomes resistant to the viral infection
• A gene-silencing chemical that interferes with an insect’s normal molting can be put into pests
• A protein from the bacteria Bt can be put into plants
– Kills larvae from plant-eating insects
– But it is harmless to mammals, birds, other insects
• Resistance to Bt and secondary pests are increasing
– Farmers must plant 20% of their fields in non-Btcrops to provide a refuge for susceptible pests
– The resistance genes are diluted© 2017 Pearson Education, Inc.
Bioengineered potatoes
© 2017 Pearson Education, Inc.
The plant on the left is not genetically modified, while the one
on the right is resistant to a plant pest
Genetic control with sterile males
• Sterile-insect technique: a natural population is
flooded with sterile males that were raised in a
laboratory
• Screwworm flies lay eggs in wounds of animals
– Causing pain, infection, and death
• Screwworm females mate only once
– Males raised in the lab are sterilized with radiation
– If 100 males are released, there is a 99% chance
the female will mate with a sterile male
• Tsetse flies and others have been eradicated
– Eliminating sleeping sickness in Zanzibar
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Natural chemical control is nontoxic and
highly specific
• It can be used as biocides, pesticides from plants,
or in communication or immunity
• Pheromones: influence the behavior of others of
the same species
– Lures pests into traps or eating poisoned bait
– Males become confused and can’t find females
• Hormones: chemicals produced in organisms that
control development and metabolic functions
– They can be used to disrupt a pest’s life cycle
– Mimic: a synthetic hormone that starts, but does
not continue, molting in moths and butterflies
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Natural chemical control on crops
• Natural chemicals used on crops can boost
defenses
– Seeds dipped in jasmonic acid (which occurs
naturally) have lower aphid attacks and caterpillar
damage
• Bt can be sprayed into water or crops
– Instead of being incorporated into genetically
modified plants
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Trapping technique
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Pheromones lure adult Japanese beetles into traps
Alternatives to using pesticides
• There is a growing movement to avoid pesticides
– Availability of alternative pest controls
– Evidence of the failures of chemical treatment
• A species becomes a pest only when it causes
significant damage
• Natural controls keep pests below damaging levels
– They do not try to eradicate the pest
• Economic threshold: the point where:
– Economic losses of pest damage outweigh the cost
of applying a pesticide
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The economic threshold
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Pest control is not about eradication―the population just
needs to be kept below the economic threshold
What if pest damage is not significant?
• If significant crop damage is not occurring and
natural controls are working?
– Leave the situation alone because chemicals upset
the natural balance and are not cost-effective
• Insurance spraying: use of pesticides to prevent
losses to pests
• Cosmetic spraying: using pesticides to control
pests that harm only the item’s appearance
– Does not increase yields or nutritional value
– Results in increased use and residues on the
produce
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Integrated pest management
• IPM aims to minimize use of synthetic organic
pesticides without jeopardizing crops
– Includes all factors in crop protection
– Crop and pests are seen as parts of a dynamic
system
• The goal is not pest eradication, but keeping crop
damage below the economic threshold
• The EPA’s four-tiered approach to IPM:
– Set action thresholds, monitor and identify pests,
prevent pests, and control pests
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The four approaches of IPM
• Set action thresholds: identify the point where
conditions indicate that some control is needed
• Monitor and identify pests: experts determine if
pests exceed the economic threshold
– Extension services, farm cooperatives, consultants
– Field scouts: trained to identify and monitor pests
• Prevent pests: use cultural and biological controls
– Crop rotation, predators, fertilizing, “trap crops”
• Control pests: select pesticides that do the least
damage to natural enemies of the pest
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Why do farmers still use pesticides?
• Farmers need to understand the economic
benefits of natural control through IPM
• At first, pesticides increase yield and profits
– Farmers think they are the only option for profit
– Rising pesticide costs and harm eliminated
pesticides’ economic advantage
• Pest-loss insurance: pays the farmer if crops are
lost due to pests
– Growers don’t do unnecessary and costly
“insurance spraying”
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IPM can control malarial mosquitoes
• Cultural controls are used on mosquitoes
– Pesticide-impregnated nets, removal of breeding
sites
– Bt, natural enemies (birds, insects)
– A fungus kills larvae, while bacteria prevent
mosquitoes from passing the malarial parasite on
– The sterile male technique is being tested
– A virus kills the older adults that pass on the
disease
© 2017 Pearson Education, Inc.
The Indonesian IPM program
• Government policies determine if IPM is used
– Governments and agencies subsidize pesticides
– Encourage growers to step on the pesticide
treadmill
• The Indonesian government used IPM to control
the brown plant hopper
– Rice growers switched from heavy pesticide use to
light spraying
– Preserves the enemies of the insect
• FAO workers trained farmers
– Who in turn trained others
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Brown plant hoppers
© 2017 Pearson Education, Inc.
These immature brown plant hoppers are shown on the stem
of a rice plant
The Indonesian IPM program succeeded
• The economic and environmental benefits have
been remarkable
– The government saved millions by not buying
pesticides
– Farmers have not had to buy pesticides and
equipment
– Thousands of tons of pesticides did not enter the
environment
– Fish are thriving in the rice paddies
– Farmers, consumers, and wildlife have increased
health benefits from reduced pesticide use
© 2017 Pearson Education, Inc.
Integrated pest management
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IPM has helped Indonesian rice farmers control
the brown plant hopper
Organically grown food
• Many farmers are turning away from pesticides,
chemical fertilizers, antibiotics, and hormones
– For grains, vegetables, and livestock
• Organic farms are small and use traditional
farming methods to grow diverse crops
– They are tied to local economies
• Organic crops have lower yields and cost more
– But also incur lower expenses
– Crops lack, or have much smaller, pesticide
residues
• Organic foods in the United States bring in
$33 billion/year
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Organic foods
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This symbol on food signals that the food or crop was
produced on a certified organic farm
USDA certifies organic food
• Organic Foods Protection Act (1990)
– Established the National Organic Standards Board
(NOSB) under the USDA
• Standards for certifying organic foods prohibits:
– Genetically engineered or irradiated food
– Fertilizing with sludge or chemicals
– Conventional pesticides, antibiotics, growth
hormones, chemical fertilizers
• Farmers must be inspected to use the organic seal
• If food is at least 95% organic, they can use the
seal—but cannot claim to be 100% organic
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Regulation of pests
• The United States has many guidelines for federal
and state agencies to protect food safety
– To monitor, eradicate, and prevent pests
• International treaties exist to lower the impact of
pests and prevent misuse of dangerous pesticides
• The USDA’s Animal and Plant Health Inspection
Service (APHIS) monitors and controls pests
– It consolidated multiple agencies involved with
animals and plants
– It regulates animals used in research and exhibition
and by dealers
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The APHIS
• APHIS monitors potential pests to prevent
outbreaks
• For example, soybean rust devastated crops
in Brazil
– Hurricane Irene blew this fungus into the
United States
– APHIS set up a Web-based tracking system
– Governmental agencies, universities, and farmers
used rigorously surveyed “sentinel plots”
– These actions successfully prevented an epidemic
in the United States
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Plant Protection Act
• Plants in the United States have been regulated
since 1912
– The 2000 Plant Protection Act consolidated all acts
• Duties of the Plant Protection Act include:
– Noxious weeds cannot be moved across state lines,
imported, or exported
• APHIS regulates imports and exports to prevent
movement of pests
– In 2012 ash tree products and firewood were
regulated to stop the emerald ash borer
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APHIS’ role has expanded
• It monitors pests that might attack wildlife and monitors bioengineered species
• It regulates the welfare of domestic animals
• It protects plant and animal agriculture from disease
– It tracks efforts to eradicate animal and plant diseases
– After detecting a bacterial disease that had come from Kenya, it temporarily stopped imports of geraniums
• The Agricultural Bioterrorism Protection Act (2002)
– Regulates labs and vaccine companies
• APHIS assessments are open to public review
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Catching pests early
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On December 23, 2013, one coconut rhinoceros beetle, an
invasive pest on palms, was caught in a trap in Honolulu,
Hawaii. After discovering others, APHIS is coordinating a
response to eradicate it before it can spread.
The United States collaborates with other
nations
• U.S. agencies collaborate with other nations to
prevent the spread of pest organisms
• The International Plant Protection Convention
– The IPPC set up an international system to
quarantine products to prevent pest spread
• The 1995 United Nations Convention on the Law
of the Sea (UNCLOS)
– Prevents the introduction of marine species to
new areas
• Other international agreements also help prevent
the spread of plant diseases and other pests
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Regulation of pesticides
• Pesticide regulation focuses on three main areas:
– Safety and testing of pesticides, and protection of
pesticide workers and consumers
• The Federal Insecticide, Fungicide, and
Rodenticide Act (FIFRA) (1947)
– Administered by the EPA
– The EPA has total jurisdiction over the
manufacture, use, sale, and testing of pesticides
– Manufacturers must register and test pesticides
– The EPA can ban or restrict a product that causes
unreasonable adverse effects on the environment
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The EPA’s Pesticide Program
• It puts high priority on registering “reduced risk”
pesticides that replace more toxic ones
• Biopesticides: naturally occurring substances that
control pests
– Microbial pesticides (Bt), plant-incorporated
protectants in GM crops, and pheromones
– Can be registered faster than other pesticides
• The EPA has come under fire for giving provisional
registration to hundreds of pesticides
– Without requiring them to be fully tracked or tested
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Federal Food, Drug, and Cosmetic Act (1938)
(FFDCA)
• Three agencies are involved in protecting
consumers from pesticides on food:
– EPA: sets allowable tolerances for residues
– FDA: monitors and enforces tolerances on
most foods
– USDA: monitors and enforces tolerances on meat,
poultry, and eggs
• The Delaney clause of the FFDCA says that:
– No detectable residue of a pesticide may be on
food if it presents any risk of cancer
– More sensitive analytical techniques banned more
and more pesticides from use on food© 2017 Pearson Education, Inc.
Food Quality Protection Act (FQPA) (1996)
• Eliminated the Delaney clause
• It also amended FIFRA and FFDCA
• The FQPA’s new safety standard sets “a
reasonable certainty of no harm” and requires:
– Special consideration for children exposed to
pesticide residues
– Prohibition of pesticides that carry a risk of cancer
more than one in a million
– All sources of a pesticide must be considered
– All products over 10 years old must be reassessed
– Raw and processed foods have the same standard
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Care for kids
• The FQPA requires the EPA to add a 10-fold
safety factor in assessing children’s risks from
pesticides
– Children eat more fruits and vegetables per unit of
body weight
– They are more susceptible to carcinogens and
neurotoxins
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Pesticides in developing countries
• The United States exports thousands of tons of
pesticides/yr.
– Some have been banned in the United States
• People in developing nations can be exposed to
toxic pesticides
– Low literacy, weak laws, unfamiliarity with
equipment
• FIFRA requires “informed permission” before
shipping any pesticide banned in the United States
– Permission comes from the purchaser
– The EPA must notify the government of the
importing company’s identity
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An international framework for pesticides
• The Rotterdam Convention: an international
treaty that promoted open exchange of information
– About hazardous chemicals (including pesticides)
• Prior informed consent (PIC): exporting
countries inform all potential importing countries:
– About actions they have taken to ban or restrict a
chemical, and label them clearly
• The International Code of Conduct on the
Distribution and Use of Pesticides
– A worldwide guidance document about pesticides
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The International Code of Conduct
• Addresses conditions of safe pesticide use
– Both private companies and governments are
responsible for safe pesticide use
• The Stockholm convention (2004) eliminates or
restricts persistent organic pollutants
– Nations will ban 9 of the 12 most dangerous
chemicals
– DDT will only be used for malaria control
– Limits accidental releases of dioxins and furans
– 178 countries and the EU—but not the United
States—were parties to the convention
© 2017 Pearson Education, Inc.
What about the future?
• Pesticide use illustrates two trends in
environmental science issues:
– The problems of cumulative impacts
– The problems of unintended consequences
• Grassroots action and pressure from public-
interest groups and NGOs are pressuring for:
– Safe and sustainable pest prevention and
management
• We must care for the welfare of all creatures to
solve pest problems in a sustainable manner
© 2017 Pearson Education, Inc.
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