Pests and Pest Control

1
Pests and Pest Control

• AP Environmental Science Chapter 16

2

• The Bug That Is Trying To Eat New Orleans
• Originally from East Asia, the Formosan termite
  infests over a dozen southern states, costing an
  estimated 1 billion a year in property damages,
  repairs, and control measures.
• They are believed to have arrived in New Orleans
  as military ships returned from the far East
  after World War II. They were probably
  stowaways, living on the wood that made up crates
  and other packing material.
• These insects are much more invasive than the
  native termites.

3
(No Transcript)
4
(No Transcript)
5

• In addition to wood products used in buildings,
  Formosan termites, unlike native termite, also
  attack trees. Thirty percent of the oldest live
  oaks in New Orleans have been damaged by these
  insects.
• The Formosan termites have expanded their range
  from New Orleans to include 10 states in the
  South and West.
• Rather than rely on chemicals as the sole
  defense, scientists are taking the offensive with
  an integrated pest management approach. One
  avenue of attack will begin in the laboratory as
  researchers look for ways to exploit weaknesses
  in the pest's biology, growth, chemical
  communication, and behavior.

6

• There is work being done to synthesize chemical
  come-hither signals that the termites use to
  attract fellow termites to food sources and other
  locations. These signaling chemicals could be
  used to make toxic baits even more
  irresistible--and deadly.

7

• Currently Formosan termites are being baited at
  bait stations throughout the city. Scientists
  monitoring the insects set out commercial bait
  products around buildings and in parks. The baits
  work by luring foraging termites to bite off food
  laced with an insect growth regulator like
  hexaflumuron, which prevents the pest from
  molting.
• A type of mold that feeds on termites is being
  added to the bait. The spores are eaten along
  with the hexaflumuron and taken to the nest for a
  one two punch.

8
The Need for Pest Control

• Insects are not the only pests that plague humans
  in their attempts to build structures, live a
  life free of disease, and grow crops.
• There are pest plants, molds, slugs, rats, mice,
  birds, and plant pathogens that compete with
  humans for food, attack our animals and invade
  our homes.

9

• Agricultural pests are organisms that feed on
  crops, ornamental plants or agricultural animals
• Weeds are plants that compete with agricultural
  crops, forests and forage grasses for light and
  nutrients.
• The importance of Pest Control
• Insects, plant pathogens and weeds destroy about
  34 of potential agricultural production in the
  US costing 122 billion to consumers and
  producers.

10

• Phythophtora infestans, the fungus that caused
  the blight in potatoes that caused so much death
  in Ireland in the 1800s, is considered to be
  global agricultures worst crop disease. It is
  by no means eradicated and attacked potato crops
  in Russia in the 1990s.
• Striga hermonthica is a parasite weed that causes
  billions of dollars in losses in East Africa.
  When a farm is infested with Striga, the affected
  plants hardly grow more than one foot tall. The
  weed does not grow on its own but grows by
  attaching itself onto the host plants. Each
  Striga plant can produce up to 20,000-50,000
  seeds, which lie dormant in the soil until a
  cereal crop is planted again. This dormancy can
  last for over 15 years. As striga germinates,
  it's roots grow towards the host crop, penetrates
  that crops roots and starts to draw nutrients
  from there. This causes severe stunting of the
  host crop and yield loss.

11
(No Transcript)
12

• The desert locust is still alive and well in
  Africa. It has the potential to migrate
  thousands of miles and destroys food crops
  perpetuating the poverty in already poor African
  nations.

13

• Historically, chemicals have been used to kill
  animals, insects and noxious weeds. In 1999 912
  million pounds of herbicides and pesticides
• The practice of agriculture, using monoculture,
  and genetically identical crops have increased
  crop yields, but have also increased loss of
  crops to pests.
• Crop loss in 1956 was 31. Today 37 of crops
  are lost. This discrepancy was caused by
  herbicide and pesticide use.

14
Ways To Control Pests

• Chemical treatment the magic bullet to
  eradicate or greatly lessen the numbers of the
  pest organism. Unfortunately, the chemicals that
  kill pest insects also kill insects and other
  organisms that are beneficial to man.
• Ecological control based on knowing the pests
  life cycle and ecological relationship. The
  ecological approach protects people and domestic
  plants and animals from pests rather than
  eradicate the pest organism. The pest can be
  controlled while the ecosystem and all its
  components remain stable and intact.

15

• When these two philosophies are combined, the
  approach is called integrated pest management.
• It brings about long term management of the pest
  problem while having a minimal impact on the
  environment.

16
The Chemical Approach

• Classes of pesticides
• Insecticides for insects
• Rotenticides for mice and rats
• Herbicides for weeds
• Fungicides for fungi
• All of these have an effect on organisms other
  than the target species.
• Pesticides and their development and successes.
• First generation pesticides included heavy metals
  that were toxic to certain organisms.

17

• These chemicals were effective (example scale
  insects on fruit trees)
• The problem with these is that they accumulated
  in the soil.
• In 1900 90 of target insects were killed. By
  1930, the same chemical killed as few as 3 of
  the target insects.
• Second generation pesticides developed as a
  result of organic chemistry.
• In 1938, a Swiss chemist, Paul Müller developed
  a chemical, dichlorodiphenyltrichloroethane
  (DDT). It was and still is an effective
  insecticide. It was considered the magic
  bullet. It seemed nontoxic to humans and other
  mammals. It was cheap. It was broad spectrum.
  It was also persistent and provided lasting
  protection.

18

• During WWII, the military used DDTA to control
  body lice which spread typhus . Historically,
  typhus killed more soldiers in any other war,
  because of filthy living conditions, than of
  battle wounds.
• DDT was used against the Aedes ageypti mosquito,
  which is the vector carrying the virus that
  causes dengue fever. It was effectively used to
  control Anopholes mosquitoes, and thus to control
  malaria.
• There is no question that DDT has saved millions
  of lives.
• Müller was awarded the Nobel prize for medicine
  in 1948 for his discovery of DDT.

19

• After the war
• DDT was used to control the spruce budworm,
• It was sprayed on salt marshes to kill
  mosquitoes.
• It was sprayed in the suburbs to control the
  beetle that spread Dutch elm disease
• It was the bomb diggity in insect control in
  agriculture.
• It was so effective that many crop yields
  increased dramatically.
• Growers could ignore good agricultural management
  such as crop rotation and destroying previous
  years crop residues. They could grow crops in
  areas that, previously were too wet, too warm, or
  too moist, lending crop growth there impossible.

20

• The success of DDT led chemists to develop more
  synthetic chemical pesticides./
• Problems associated with Chemical Pesticide Use.
• Development of resistance by pests.
• This is the most common problem with chemical
  pesticides.
• In 1946 it took 1.1 lbs of pesticide to provide
  protection to produce 60,000 bu of corn. By 1971
  it took 141 lbs to produce the same amount.
  Losses due to pests increased during the
  intervening years.
• This is due to resistance buildup. Insects have
  an incredible potential to reproduce. They
  produce thousands of times the number of
  individuals to replace the original parents.

21

• Repeated pesticide use results in the selection
  of genetic lines that are highly or totally
  resistant to the chemicals that were designed to
  kill them.
• Natural selection is a powerful force to reckon
  with!
• The last Roundup.
• The herbicide glyphosate is used widely on
  genetically modified Roundup Ready corn,
  soybeans, and cotton. The crops contain a gene
  that makes them resistant to glyphosate.
• Several weeds have now developed a resistance to
  glyphosate giving concern to the agriculture
  world so heavily dependent on Roundup Ready
  crops.

22
Number of species resistant to pesticides
1908-1998.
23

• Resurgences And Secondary Outbreaks
• Resurgence is the tendency for a pest that has
  been virtually eliminated, to recover and explode
  to higher and more severe levels.
• Secondary pest outbreaks -Small populations of
  insects, previously of low or no concern start to
  explode creating new problems.

24

• Recently in California, a study of pest outbreaks
  listed 25 major incidences causing more than 21
  million in damage. All but one of these pests
  involved resurgences or secondary-pest outbreaks.
  
• To make matters worse, the secondary pest
  outbreak species became resistant to pesticides.
• The chemical approach fails because it ignores
  basic ecological principles. It assumes that the
  ecosystem is static and that one species can be
  eliminated.

25

• In the natural world, plant eating insects, while
  not totally eliminated, are often held in check
  by other organisms that prey or parasitize them.
  
• Using chemical pesticides often have more impact
  on the natural enemies than on the target pest.
• The treadmill this describes attempts to
  eradicate pests with synthetic organic chemicals,
  leading to more resistance and more secondary
  pest outbreaks.

26

• Human Health Effects
• Pesticides can be the agent for acute and chronic
  health problems
• Numbers indicate over 90,000 persons were
  poisoned by pesticides in 2001 with 17 deaths.
• WHO of the United Nations estimated between 3.5
  and 5 million cases of acute occupational
  pesticide poisoning each year in developing
  countries with at least 20,000 resulting in
  death.
• This is because untrained people are using and
  applying the pesticide.
• Children and families come in contact with the
  pesticides through aerial spraying, dumping of
  wastes and use of pesticide containers to store
  drinking water. Organophosphates and carbamates
  were the causative agents for most of the
  poisonings

27

• It is inevitable that consumers are exposed to
  pesticides.
• Pesticides are used not only on the crops during
  the growth phase of production, but also on the
  harvested food as it goes to market.
• There is a potential of causing cancer including
  lymphoma and breast cancer.
• Chronic effects include dermatitis, neurological
  disorders, birth defects, and infertility.
• Depression of the immune system is a danger as
  well as disruption of the endocrine system.
• This evidence comes from lab animal testing and
  epidemiological studies. Factory workers exposed
  to pesticides in India led to abnormally low
  white blood cell counts.

28

• Atrazine, alachlor, (weed killers)DDT,
  endosulfan, diazinon and methoxychlor
  (insecticides) interfere with reproductive
  hormones, and are implicated in a rise in the
  indcidence of breast cancer among humans.
• Abnormal sexual development in alligators and
  other animals in the wild have suggested that low
  levels of a number of chemicals mimic or disrupt
  the effects of estrogenic hormones.
• Farm workers and herbicide sprayers have
  defective sperm counts.

29

• Environmental Effects
• In the 1950s and 1960s ornithologists observed
  drastic declines in fish eating birds.
  Extinction of the bald eagle seemed imminent.
• It was observed that the eggs were breaking
  before they were hatching.
• The eggs contained dichlorodiphenyldichloroethylen
  e (DDE) which is a product of the partial
  breakdown of DDT by the animals body
• DDE interferes with calcium metabolism, causing
  birds to lay thin-shelled eggs.
• The birds were acquiring high levels of DDT and
  DDE by bioaccumulation and biomagnification.

30

• Because of accumulation, small amounts received
  over a long period of time may reach toxic
  levels. (bioaccumulation)
• These chemicals concentrate themselves in fatty
  tissues of the body. Because they are synthetic,
  the body cannot fully metabolize them and has no
  way to excrete them.
• Each organism accumulates contaminated food and
  accumulates a concentration of contaminant in its
  body that is many times higher than found in its
  food.
• The next organism has a more contaminated food
  and accumulates the contaminant even more.
• There is no warning or indication that this is
  occurring until concentrations of contaminant are
  high enough to cause problems.

31

• Silent Spring
• Written in 1962 by Rachel Carson, documenting the
  almost uncontrolled use of insecticides across
  the US.
• Made a big impact on the public
• Proponents of the agriculture and chemical
  industries decried the book as unreasonable and
  that halting the use of insecticides would halt
  human progress.
• The book and its impact, along with concerns
  about the long term health risks due to
  pesticides led to banning DDT in the US and most
  other industrialized countries.

32

• The result has been that the bird species that
  were adversely affected have recovered.
• The debate centers on the continued use of DDT
  against malaria in developing countries.
• Rachel Carson is credited for stimulating the
  start of the modern environmental movement and
  the creation of the EPA. Rachel Carson died of
  cancer 2 years after her book was published.
• Nonpersistent Pesticides
• Because of their nature, chlorinated hydrocarbons
  remain in the environment for many years.
  Microbes are unable to break them down. The
  halflife for DDT is 20 years.
• Organophosphates and carbamates have been
  substituted for chlorinated hydrocarbons.
• These compounds are inhibitors for the enzyme
  cholinesterase, necessary for proper functioning
  of the nervous system in all animals.

33

• These chemicals break down into simple nontoxic
  products within a few weeks after their
  application.
• They are not as environmentally sound as they
  might appear. Many are more toxic than DDT and
  are a very real hazard to agricultural workers.
  Organophosphates are responsible for 70 of all
  pesticide poisonings.
• The Food Quality Protection Act of 1996 requires
  the EPA to develop new health-based standards
  that address the risk of childrens exposure to
  such pesticides. Chemicals that are banned
  include parathion on produce, chlorpyrifos on
  flea collars, tomatoes and on apples once bloom
  has ceased. Diazinon has been banned for may
  agricultural and all indoor residential uses.
  Outdoor uses are being phased out.

34

• Monocrotophos is an organophosphate used in
  Argentina to control grasshoppers. 20,000 hawks
  died in one year. In response, the Argentine
  government banned the use of monocrotophos in
  1996. It was banned in the US in 1988.
• Desirable insects are just as sensitive as pest
  insects to nonpersistent pesticides/
• Bees are highly susceptible.
• Nonpersistent chemicals are just as likely to
  cause resurgence and secondary-pest outbreaks as
  well as force insect populations to become
  resistant.

35
Alternate Pest Control Methods

• Ecological control involves
• Working with natural factors instead of synthetic
  chemicals
• Biological controls
• Understand the life cycle of the pest
• Find out where in the life cycle the pest is
  vulnerable
• Could be a parasite or a predator
• Interfere with finding food or finding a mate
• Four categories
• Cultural control
• Control by natural enemies
• Genetic control
• Natural chemical control

36

• Cultural control
• Nonchemical alteration of one or more
  environmental factors in such a way that the pest
  finds the environment unsuitable or is unable to
  gain access to its target.
• Disposing of sewage
• Avoiding unsafe drinking water
• Personal hygiene
• Window screens
• Sanitation in handling and preparing food

37

• Cultural control of Pests affecting Lawns,
  Gardens and Crops
• Good cultural practices, not mowing grass too
  short
• The right plant in the right place
• Eliminate plants that are attractants (roses)
  and grow plants that are repellants (marigolds
  and chrysanthemums)
• Provide habitat for natural enemies of pests.
• Shelterbelts, nesting sites, fencerows,
• Plow under or burn crop residue
• Crop rotation
• Border control

38

• Control by Natural Enemies
• Find predators for pest insects, parasitic wasps
• Rabbits in Australia are controlled by a virus
• Green muscle, a mixture of spores that attacks
  desert locusts.
• Protect the natives
• Import aliens as a last resort

39

• Genetic Control
• Grow resistant varieties resistant potatoes to
  prevent late blight
• Grow with Chemical barriers
• Some plants naturally produce chemicals that are
  toxic to insect pests.
• A wheat variety was developed that has a chemical
  that is toxic to the Hessian fly.

40

• Control with physical barriers
• Hooked hairs on plant surfaces trap and hold
  immature leafhoppers until they die.
• Enhance these aspects
• Control with sterile males
• Flood the population with sterile males
• Combating the screwworm

They look like any other fly. But, the little bug
looks for an open wound, lays her eggs quickly,
then those eggs slowly screw their way into the
flesh looking for blood serum. Scientists
realized that the female only mated one time and
if they could produce enough sterile flies to
overcome the population then they might be able
to decrease the population of screw flies.
41

• Tsetse fly -
• the sterile male technique has also been used on
  Zanzibar, eliminating trypanosomiasis (sleeping
  sickness).
• Efforts are being made to continue this effort on
  other parts of the African continent.
• Biotechnology
• genetic engineering makes it possible to
  introduce genes into crop plants from other
  species.
• Transplant the gene for the protein that makes a
  virus protein coat. The plant becomes resistant
  to infection by the real virus. This has been
  done for more than 12 plant viruses

42

• Bt
• Plants are bioengineered to incorporate a protein
  normally produced by Bacillus thuringiensis. The
  protein kills the larvae of quite a few plant
  eating pests. It, however, is harmless to
  mammals, birds and most other insects. It has
  been used in corn, potatoes and corn.
• Roundup Ready ?
• these are plants engineered with a gene that
  makes them resistant to glyphosate.
• Biotechnical crops are not well suited to
  developing countries.

43

• The seed is expensive
• a definite possibility of developing super weeds
• Natural Chemical Control
• hormones - a signaling chemical
• pheromones - chemicals secreted by an individual
  to control behavior of another individual of the
  same species.
• There are juvenile hormones that prevent
  pupation.
• Mimic - a synthetic variation of ecdysone., the
  molting hormone. Mimic begins the molting
  process but doesnt complete it.

44

• Pheromones - used by insects to attract mates.
  Pheromones can be used in traps. They can also
  be sprayed over fields to confuse males who dont
  find the females and fail to mate.
• Socioeconomic issues in Pest Management
• natural controls are aimed at keeping pest
  populations below damaging levels
• what is the economic threshhold? (economic losses
  are greater than the cost o applying a pesticide)
• people like their fruit to be unblemished so we
  are willing to accept pesticide residue on fruit
  so that we can buy pretty fruit. Cosmetic
  spraying

45

• IPM the Four Tiered Approach
• Set action thresholds - an assignment is made to
  a point where action must take place.
• Monitor and identify pests - field scouts are
  trained in identifying and monitoring pest
  populations.
• They help determine when the population exceeds
  the economic threshold
• Prevention - polyculture instead of monoculture,
  destruction of crop residues. Maintenance of
  predator populations, trap crops are used.
• Control - if the preceding steps indicate that a
  pest control is needed in spite of the preventive
  methods, then pesticides may b used.

46

• Many farmers still want to continue to use
  pesticides because they worked for them in the
  past. To encourage farmers to try IPM there is
  Pest Loss insurance - this pay farmers in the
  event of loss due to pests. This has eliminated
  costly and dangerous insurance spraying.
• Governments stabilize the costs of pesticides,
  making it easy for farmers to stay on the
  pesticide treadmill. An Indonesian experience has
  provided a viable IPM model for other rice
  growing countries. Instead of heavy pesticide
  spraying to control the brown plant hopper, a
  light spraying is used that preserves the natural
  enemies of the brown plant hopper. This hs
  eliminated the costly spraying of tons of
  pesticides. Fish are now thriving on rice
  paddies.

47

• Organically Grown Food
• Organically grown food have increased 20 per
  year for the last decade. It I now an 11
  billion enterprise in the US and 25 billion
  worldwide.
• In 1990, Congress passed the Organic Foods
  Protection Act. This established the National
  Organic Standards Board, NOSB, under the USDA
  auspices.
• No product can be genetically engineered
• No irradiation
• No foods that have been fertilized with sewage
  sludge.
• No chemical pesticides, antibiotics, growth
  hormone, no chemical fertilizers.

48

• Pesticides and Policy
• Pesticides must be evaluated both for their
  intended uses and for their impacts on human
  health and the environment.
• Those who use the pesticides must be
  appropriately trained and protected from the
  risks of close contact
• because most of the agricultural applications
  involve food, the public must be protected from
  the risks of pesticide residues on food products.
• FIFRA - The Federal Insecticide, Fungicide, and
  Rodenticide Act. This law addresses the first two
  above concerns. FIFRA is administered by the
  EPA.
• Places high priority on registering reduced
  risk pesticides. These are pesticides that
  promise to replace more toxic chemicals. Most
  are biopesticides
• examples include Bt
• these pesticides often clear the registration
  process within a year compared to 3 years for
  conventional pesticide

49

• Pesticide workers must be trained under a program
  controlled by the EPA. The states must
  demonstrate to the EPA that on the basis of the
  federal regulations, they have adequate
  regulation and enforcement mechanisms.
• FQPA of 1996 -
• The Delaney Clause - No food additive shall be
  deemed to be safe if it is found to induce cancer
  when ingested by man or animal.
• This clause was applied in prohibiting many
  pesticides from being used on food when those
  pesticides had been found to cause cancer in lab
  tests with animals

50

• The law states that if a given pesticide presents
  any risk of cancer, no detectable residue may
  remain on the food.
• As testing became more sensitive, extremely low
  traces could be measured.
• After years of debate, congress passed the Food
  Quality Protection Act
• reasonable certainty of no harm for substances
  applied to food.
• Special consideration to exposure of young
  children to pesticide residues
• pesticides can be prohibited if shown to carry a
  risk of more than one case of cancer per million
  people
• all sources of exposure to a pesticide evaluated
• older products (before1996) must be reassessed.
• Special attempt to evaluate potential harm on
  hormone disrupters
• same standards applied to raw and proceed foods

51

• Care for children -
• they consume more fruits and vegetables per unit
  of body weight.
• More susceptible to carcinogens and neurotoxins
• limits set on the amounts of a pesticide that
  remain in or on foods.

52

• Pesticides in Developing Countries
• 35,000 tons of pesticides imported each year.
• 25 of these are chemicals banned in the US
• FIFRA requires informed permission from the
  purchaser .
• EPA notifies the government as to the identity of
  the importing country.
• PIC
• Two UN agencies. The FAO and the UNEP require a
  prior informed consent (PIC) where exporting
  countries inform all potential importing
  countries of actions they have taken to ban or
  restrict the use of pesticides or other toxic
  chemicals.

53

• The importing country responds to the
  notification via the UN agencies, which then
  disseminate all the information they receive to
  the exporting countries.
• The UN is also addressing the unsafe use of
  pesticides in developing countries. The code
  determined by the FAO (Food and Agriculture
  Organization of the United Nations) in Nov. of
  2002, makes clear the responsibilities of both
  private companies and countries receiving
  pesticide in promoting their safe use. All this
  is voluntary and not legally binding but it does
  help in holding private industry and importing
  countries to standards of safe use.