Silent Spring By Rachel Carson Chapters 16

1
Silent Spring By Rachel CarsonChapters 1617 in
comparison to Biology 7th edition

• By Vanie Mangal, Lisa Lee Jordan Monfort

2
Insects Fight Back

• Organismal ecology is concerned with
  morphological physiology behavioral ways in which
  individual organisms meet the challenges posed by
  their biotic and abiotic environments.

3

• In 1945 there were 12 known insect species that
  had grown resistant. By 1960 the number reached a
  peek of 137 species.
• The Blue Tick in South Africa killed 600 cattle .
  They had gained resistance to arsenical dipst
  Benzene hexaechloride (1949).
• By 1950, houseflies and the Culex mosquitoe
  became resistant to chlorodane.
• Body lice caused typhus. By 1957, 15 cuntries had
  confirmed that the lice had grown resistant to
  DDT.

4
Insect Resistance, Public Health the Role We
Play

• Stability is the tendency of community to reach
  and maintain anequilibium or relatively constant
  composition of species, in the face of
  dissturbances.

5

• Throughout much of the Midwest, thousands of
  acres were destroyed by insects now impervious to
  spraying.
• Another insect to learn the profitable way of
  resistance was the codling moth or appleworm, in
  the 1920s, although lead arsenate had been used
  successfully against it for some 40 years.

6

• Before 1945, only about a dozen species were know
  to have developed resistance to any of the
  pre-DDT insecticides with the new methods for
  their intensive application, resistance began a
  meteoric rise that reached the alarming level of
  137 species in 1960.
• The oriental rat flea, the principal vector of
  the plague, has recently demonstrated resistance
  to DDT, a most serious development.

7

• Both houseflies and mosquitoes of the genus Culex
  began to show resistance to the sprays. In 1948 a
  new chemical, chlordane, was tried as a
  supplement to DDT. This time good control was
  obtained for two years, but by August of 1950
  chlordane-resistant flies appeared, and by the
  end of that year all of the houseflies as well as
  the Culex mosquitoes seemed to be resistant to
  chlordane.
• As rapidly as new chemicals were brought into
  use, resistance developed.

8

• In an army camp in southern Taiwan samples of
  resistant bedbugs were found actually carrying a
  deposit of DDT power on their bodies.
• Resistant houseflies may have the stable fly
  habit of sitting still in one place, thus greatly
  reducing the frequency of their contact with
  residues of poison.

9

• Cultural Eutrophication is human intrusion that
  disrupts freshwater ecosystem.

• A biological attempt using sound as an agent of
  direct destruction of insect. Ultrasonic sound
  will kill all mosquito larvae, but it also kills
  other aquatic organisms.

Relationship between insect and disease

• Mosquito malaria, yelow fever, encephalitis.
• Bodylice typhus
• Ratfleas plague
• Housefly contamination of food to transmit eye
  diseases.

10

• Because of human actions of spraying and dusting
  to annihilate insect species, the insects have
  actually grown stronger the population number
  has actually increased resulting in more
  potential harm for humans.

11

• The interactions between organisms and their
  environments determine the distribution and
  abundance of organisms.

• By the end of 1951, DDT, mexthoxychlor,
  chlordane, heptachlor, and benzene Hexachoride
  had joined the list of chemicals no longer
  effective. The flies, meanwhile, had become
  fantastically abundant.
• When the Taiwanese bedbugs were experimentally
  placed in cloth impregnated with DDT, the live as
  long as a month they proceeded to lay their
  eggs and the resuling young grew and thrived.

12

• Flies in Canada have been slower to develop
  resistance than those in southern United States,
  where long hot summers favor a rapid rate of
  reproduction.

13
Predator vs Prey
Insects vs Insects

• Predation an interaction between species in
  which one species, the predation, eats the other,
  the prey.

• Erasmus Darwin was the 1st to practice the method
  of Biological control- insect vs insect.
• In 1988, Albert Koebele found natural enemies of
  the cottony cushion that was detrimental to the
  California citrus industry. It was highly
  successful.

14

• A wasp imported from Japan gained complete
  control of an insect attacking eastern apple
  orchards.
• Japanese beetle was controlled by Tiphia wasp.

15
It is more than clear we are traveling a
dangerous road.

• - Dr. Briejér