Pesticides

1
Pesticides

• SNC1D

2
Pest

• Pests are living organisms that are not wanted
  around us.
• Examples of pests include unwanted dandelions
  growing in the lawn rodents or insects that eat
  fruits, vegetables or other crop species
  micro-organisms that cause disease in forest,
  fish, or crop resources, etc.

3

• A pest is any organism that man believes is
  undesirable, has a negative impact on the human
  environment, or is in competition with human use
  of a resource, either natural, or cultivated.

4
4 types of Pesticide

• Herbicides kills plants
• Insecticides kills insects
• Fungicides kills fungi
• Bactericides kills bacteria

5
Early Pesticide Use

• First generation pesticides
• the use of toxic inorganic metallic salts such as
  copper sulfate, lead salts, arsenic, or mercury. 
  
• These substances were generally effective against
  the intended pest, but also created some
  environmental problems
• they also killed other beneficial organisms,
• polluted water and soil resources used by man.
• Most early pesticides were non-biodegradable
  (meaning that they were not broken down within
  the ecosystem). Therefore, they began to
  accumulate in the environment, contaminating
  water and soil resources,
• eventually poisoning humans.

6
Modern Pesticides

• Second generation pesticides
• organic pesticides that were designed to be less
  toxic to man and more specific toward the
  intended pests.
• Some of these pesticides were fat soluble. This
  characteristic lead to a problem known as
  bioaccumulation.
• Toxins become more highly concentrated at higher
  trophic levels.

7

• One example of this problem is illustrated by the
  damage done to predatory birds as a result of
  bioaccumulation of DDT. As a result of this
  problem DDT has been banned from use in North
  America.
• DDT dichlorodiphenyltrichloroethane

8
Pesticide Resistance

• When pest become resistant to pesticides which
  means the pesticide no longer effects them.

9
Development of pesticide resistance

• There is a chance that some pest will have genes
  that allow them to survive a first application of
  pesticides.
• They are resistant to the pesticide.

10

• The survivors then have offspring which are
  mostly resistant.
• These individuals survive the next spraying. If a
  similar pesticide is often used, resistant pest
  will soon make up most of the population.

11

• 1. Which statement is generally true regarding
  DDT?
• a. DDT is not a serious problem since it is
  biodegradable.b. DDT will kill all the pests it
  is used against.c. DDT tends to accumulate in
  the tissues of top predators.d. DDT is water
  soluble so it is normally excreted in urine.
• 2.   Which statement best describes the problem
  associated with continued use of the same
  pesticide?
• a. The pests are completely eliminated from the
  ecosystem.b. The pesticide kills a greater
  number of pests with each application.c. The
  pesticide kills fewer of the pests with each
  application.d. Pesticides are generally highly
  specific and rarely harm beneficial organisms.
• 3. Which statement regarding early pesticide use
  is false?
• a. Early pesticides made use of heavy metals such
  as mercury.b. Early pesticides contaminated soil
  and water.c. Early pesticides were
  biodegradable.d. Early pesticides were toxic to
  humans.
• 4. What is the most common problem associated
  with fat soluble pesticides?
• a. They tend to contaminate the ground water
  supply.b. They are highly specific to a single
  pest species.c. They are prone to
  biomagnification.d. They must be sprayed more
  often than water soluble pesticides.
• 5. Which is most likely to contain the highest
  concentration of pesticide in its body tissues?
• a. wheatb. frog eating birdsc. frogsd.
  grasshopppers

12

• 1. Which statement is generally true regarding
  DDT?
• a. DDT is not a serious problem since it is
  biodegradable.b. DDT will kill all the pests it
  is used against.c. DDT tends to accumulate in
  the tissues of top predators.d. DDT is water
  soluble so it is normally excreted in urine.
• 2.   Which statement best describes the problem
  associated with continued use of the same
  pesticide?
• a. The pests are completely eliminated from the
  ecosystem.b. The pesticide kills a greater
  number of pests with each application.c. The
  pesticide kills fewer of the pests with each
  application.d. Pesticides are generally highly
  specific and rarely harm beneficial organisms.
• 3. Which statement regarding early pesticide use
  is false?
• a. Early pesticides made use of heavy metals such
  as mercury.b. Early pesticides contaminated soil
  and water.c. Early pesticides were
  biodegradable.d. Early pesticides were toxic to
  humans.
• 4. What is the most common problem associated
  with fat soluble pesticides?
• a. They tend to contaminate the ground water
  supply.b. They are highly specific to a single
  pest species.c. They are prone to
  biomagnification.d. They must be sprayed more
  often than water soluble pesticides.
• 5. Which is most likely to contain the highest
  concentration of pesticide in its body tissues?
• a. wheatb. frog eating birdsc. frogsd.
  grasshopppers

13
Bioaccumulation
14
Effect of Bioaccumulation on Ecosystems

• Amphibians are valuable indicators of
  environmental health because theyre sensitive to
  chemical changes.
• Since the 80s the world amphibian population has
  declined birth deformities have increased.
• This may be due to drought, increased UV rays,
  pollution, habitat loss, parasites diseases.

Amphibians, like this frog, have exhibited
drastic changes since the 1980s.
15
Bioaccumulation

• Bioaccumulation a slow build up of chemicals in
  the bodies of organisms.
• If bioaccumulation occurs in a keystone species,
  it can affect every other organism
• in its far reaching niches.
• Eg. bioaccumulation of PCBs in the
• B.C. Orcas.
• PCBs will affect the reproductive
• cycles of Orcas until at least 2030,
• even though they were banned in 77.

16

• Chemicals like PCBs and DDT other insecticides
  are called persistent organic pollutants (POPs).
• POPs contain carbon, remain in water soil for
  many years (like all organic comp)
• DDT, even at low levels (5 ppm) causes nervous,
• immune reproductive system disorders in
  animals.
• ppm parts per million

Spraying DDT, 1958
17
Videos

• PCBs
• http//video.nationalgeographic.com/video/player/n
  ews/culture-places-news/norway-bear-apvin.html
• Pesticides and heavy metals

18
Biomagnification

• Biomagnification the consumers in each trophic
  level receive larger doses of accumulated
  chemicals than the one before it.

The bioaccumulation of PCBs begins with the
absorption of the chemicals by microscopic
plants and algae.
See page 94
19

• Heavy metals also bioaccumulate.
• Lead, cadmium mercury are the most dangerous.
• Lead is not considered safe at any level, it can
  cause anemia, nervous reproductive system
  damage.
• Cadmium is toxic to earthworms causes many
  health problems in fish.
• Cadmium causes lung diseases,
• cancer, nervous immune
• system damage in humans
• (exposure to cigarette smoke).

20

• Mercury enters ecosystems through burning of
  fossil fuels, waste incineration, mining the
  manufacture of batteries.
• Coal burning adds 40 of the mercury released.
• Mercury bioaccumulates in the brain, heart
  kidneys of many animals (Fish bioaccumulate
  mercury, adding risk for any organisms eating
  fish).

21
Reducing the effects of chemical pollution

• If chemicals are trapped in the soil, they cannot
  enter the food chains as easily.
• Bioremediation micro-organisms or plants are
  used to help clean up, and are then removed from
  the ecosystem.
• Eg. The oil industry will often use bacteria to
  eat oil spills.

22

• Biomagnification
• http//www.youtube.com/watch?vE5P-UoKLxlA
• Bioaccumulation
• http//www.youtube.com/watch?vwkpFIW6ke5Efeature
  PlayListpD35F0BB0E6936BB3playnext1index2
• Bioremediation
• http//www.youtube.com/watch?vpSpjRPWYJPg
• http//www.youtube.com/watch?vzmSaNqMpfCs