Transcript Silent Spring By Rachel Carson Chapters 16&17 in comparison to

Silent Spring By Rachel Carson
Chapters 16&17 in comparison to
Biology: 7th edition
By: Vanie Mangal, Lisa Lee &
Jordan Monfort
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.
• 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.
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.
• 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.
• 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.
• 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.
• 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.
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.
• 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.
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.
• 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.
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.
• A wasp imported from Japan gained
complete control of an insect attacking
eastern apple orchards.
• Japanese beetle was controlled by Tiphia
wasp.
“It is more than clear we are
traveling a dangerous road.”
- Dr. Briejér