1. Chapter 5.1 Human Population Expansion and its Cause
rapid human population expansion is a recent event, occurring mainly over the last 100 years
until the 1800s, population growth was slow
periodic setbacks kept the population relatively small

2. human population totals
1830—1 billion
1930—2 billion
1960—3 billion
1975—4 billion
1987—5 billion
1999—6 billion

3. reasons for patterns of growth
before 1800s, fatal illnesses such as smallpox, diphtheria, measles, and scarlet fever combined to limit population growth
cholera and epidemics such as the black plague eliminated large numbers of adults
high reproductive rates were balanced by high mortality, especially in children

4. breakthroughs
late 1800s, Louis Pasteur and others discovered that diseases were caused by infectious agents
organisms were transmitted via water, food, insects, and rodents
vaccinations were developed against many viruses
communities began treating their sewage and drinking water
penicillin was the first antibiotic discovered in 1930
improvements in nutrition

5. declines
world population growth rate peaked at 2.1% per year in the 1960s after rising steadily for decades
by the 1980s, the number of humans added per year peaked at 87 million
declines are a result of a decrease in total fertility rates
total fertility rate was an average of 5.0 children in the 1960s; it is now 2.7 children per woman

6. Chapter 5.2 Rich Nations, Poor Nations
World Bank divides countries into three main economic categories:
1. high income, highly developed, industrialized countries
Ex. USA, Canada, Australia, western Europe
2. middle-income, moderately developed countries
Ex. Mexico, South Africa, eastern Europe
3. low-income, developing countries
central African countries, central Asian countries

7. human poverty index
long and healthy life: probability at birth of not surviving to age 40
knowledge: adult literacy rate
decent standard of living:
percentage of population not using improved water sources
percentage of children under 5 who are underweight
10-15% of people in developed countries are unable to afford adequate food, shelter, or clothing (compare to 45% in developing countries)

8. population growth in rich and poor nations
developed world (estimated population = 1.2 billion) is growing at rate of 0.1% per year…adds less than 1 million people per year
remaining countries (population = 5.4 billion) are increasing at a rate of 1.5%per year…adds more than 75 million people per year

9. fertility population growth occurs when births outnumber deaths
with lower mortality, major determining factor for population growth is births, measured by the total fertility rate
fertility rates greater than 2.0 lead to a growing population
replacement-level fertility accounts for childhood mortality (fertility rate that will replace population of parents is 2.1 in developed countries)

10. Chapter 5.3 Consequences of Population Growth and Affluence
developing countries
before the Industrial Revolution, most of the human population survived through subsistence agriculture
families lived on the land, raised livestock, and produced enough crops for their own consumption and perhaps some extra for selling and trading

11. impacts of rapid growth on a population that is farming-based:
2. INTENSIFY CULTIVATION
introduction of more highly productive varieties of basic food crops
puts more stress on land and soil (no crop rotation or seasons off for fields)
stress can lead to erosion and desertification

12. impacts of rapid growth on a population that is farming-based:
3. OPEN NEW LAND TO FARM
most good agricultural land is already in production
opening new land means disrupting natural ecosystems, most likely including deforestation
4. ILLICIT ACTIVITIES
shortage of jobs outside of agriculture often drives individuals into theft, corruption, drug-related crop growth, and poaching wildlife

13. impacts of rapid growth on a population that is farming-based:
5. EMIGRATION AND IMMIGRATION
countless number leave poorer countries in hopes of a better life in a more affluent country
related issues: prejudice, disease and hunger in refugee camps, struggles to find work
6. MIGRATION TO CITIES
urban population will likely pass rural population by 2020

14. challenges in rapidly growing cities
cities struggle to provide basic services, such as road maintenance, sanitation, utilities, and law enforcement
many are forced to live in shantytowns and slums where diseases like malaria, malnutrition, and HIV are rampant
jobs that people came to the cities for are in short supply

15. challenges in affluent countries
U.S. leads the world in consumption of many resources
despite adverse effects, increasing average wealth can have a positive affect on the environment—clean water, pollution controls, habitat protection
U.S. still leads the world in the production of many pollutants
Ex. with 5% of the world’s population, the U.S. produces 24% of the carbon dioxide

16. Chapter 5.4 Dynamics of Population Growth
demography: field of collecting, compiling, and presenting information about populations
age structure: proportion of people in each age group at a given date
can be used as planning tool for future needs (elementary schools, retirement homes, etc.)
Social Security

18. future populations
population projections are based on three variables: births, deaths, and migration
graying populations: indicates proportion of elderly people is increasing in population
population momentum: refers to effect of current age structures on future populations

19. demographic transition
gradual shift in birth and death rates from the primitive to the modern condition
crude birth rate: number of births / 1000 / yr
crude death rate: number of deaths / 1000 / yr
CBR – CDR = natural change  10 = % change
in population in populatio 70
doubling time =
% change in
population

20. epidemiologic transition
throughout most of human history, crude death rates were high (~ 40 / 1000/ yr)
by middle of 19th C., fewer epidemics and improvements in social conditions led to a gradual decrease in CDR (~ 10 / 1000/ yr)
cancer and cardiovascular disease are the main causes of mortality today, meaning many more individuals survive to old age

21. fertility transition
in developed countries, crude birth rates have decreased from / 1000 / yr to 9-12 / 1000 / yr
followed epidemiologic transition

22. phases of demographic transition
phase I: high CBR, high CDR
phase II: high CBR, decreasing CDR
epidemiologic transition
phase III: decreasing CBR, low CDR
fertility transition
phase IV: low CBR, low CDR

23. demographic dividend
as birthrates decline in developing countries, with working-age population increases relative to the younger and older members of the population
dependency ratio: ratio of the nonworking population (under 15 and over 65) to the working-age population
for a time, society can spend less on schools and nursing homes, allowing in investments to alleviate poverty and generate economic growth
countries such as Brazil, Mexico, and South Korea have taken advantage of this window

24. large families or small
fertility transition is the most vital element in the demographic transition
socio-cultural factors cause the poor in developing countries to make different choices regarding large families:
(1.) security in old age
no safety net, such as pension or Social Security, in developing countries

25. large families or small
(2.) infant and childhood mortality
frequency of childhood death (Ex. in Nigeria, 100 infants out of every 1000 do not survive) causes parents to have more children
(3.) helping hands
in subsistence-agriculture societies, women do most of the work relating to child care; children are a productive asset
(4.) importance of education
in subsistence-agriculture societies, education seems unnecessary, especially for women; children who attend school are an economic liability

26. large families or small
(5.) status of women
traditional social structure of many developing countries still discourages women from obtaining education, owning land, and pursuing many careers
(6.) availability of contraceptives
poor women often lack access to reproductive health information

27. conclusions
industrialization and development is usually accompanied by factors leading to smaller families
relatively high cost of raising children
existence of pensions and Social Security
opportunities for women to join the workforce
access to contraceptives and health care
older age at marrying

28. vicious cycle
unfortunately, poverty, environmental degradation, and high fertility drive one another in a vicious cycle
increasing population density leads to depletion of community resources; couples have more children to help gather resources; search for scarcer resources leads to environmental damage…

29. Fertility rates decline as development provides:
(1.) security in old age
(2.) lower infant and childhood mortality
(3.) universal education for children
(4.) opportunities for education and careers for women
(5.) unrestricted access to contraceptives and health care services

30. efforts on behalf of the poor are needed:
1. improving education (especially literacy and education for women)
2. improving health (with a focus on infant mortality)
3. making family planning accessible (available and affordable)
4. enhancing income through employment opportunities
5. improving resource management

31. improving education
basic literacy—reading, writing, and basic math—is what’s needed
literacy rates among women in developing countries ranges from 30-50%
ability to read empowers people with information on countless topics
Ex. Pakistan vs. South Korea
both had similar growth rates and incomes in 1960
however, 30% of children were enrolled in schools in Pakistan compared to 94% in South Korea
now, South Korea has 3x greater economic growth

32. improving health
health care needed by most developing countries is not high-tech
basic nutrition and hygiene will slow the spread of disease
prenatal, postnatal, and child care must be emphasized
boiling water
properly treating infections

33. reproductive health focuses on women and infants: prenatal care
safe childbirth and postnatal care
information and services related to contraception
prevention and treatment of STDs
abortion services (where legal) and care afterwards
prevention and treatment of infertility
elimination of violence against women (rape, sexual trafficking)

34. family planning
agencies enable people to plan their own family size, allowing them to have children only if and when they want them
services include:
counseling and education regarding human reproduction, the hazards of STDs, and the benefits and risks associated with various methods of contraception
counseling and education on achieving the best prenatal and postnatal health for mother and child
counseling and education to avoid high-risk pregnancy
providing contraceptive materials

35. employment and income Grameen Bank
established in 1976 to engage in microlending to the poor
microloans average about $67 and are usually short-term (4-6 months)
loans provide basic things such as
seed and fertilizer for a peasant farmer to start growing tomatoes
pans for a baker
yarn for a weaver
tools for an auto mechanic
loans are secured by having the recipients form credit associations

36. microlending greatest impact is on women
“when women borrow, the beneficiaries are the children and the household”
World Bank recently increased support of microfinancing, investing $1 billion to support institutions that provide microloans

37. Chapter 23.1 Urban Sprawl
sprawl’s signature is a wide urban-suburban network of low-density residential areas, shopping malls, industrial parks, and other facilities connected by multilane highways
“sprawl” is used because boundaries of cities have been extended outward into the countryside, one development after the next
farms and other natural areas are taken over by new developments

38. highways influx of commuters created need for new and larger roads
Congress passed Highway Revenue Act of 1956, which created Highway Trust Fund and took advantage of a gasoline tax to build new roads
ironically, new highways alleviate existing congestion, but spur further development
average commuting distance has doubled since 1960, but average commuting time has remained about the same
increase in commuting distance has provided more revenue for the Highway Trust Fund

39. impacts of urban sprawl
environmental impacts
depletion of energy resources
from 1950 to 2005, U.S. oil consumption doubled
air pollution
despite improvements in pollution control, many cities still fail to meet standards
water pollution
paved areas associated with sprawl lead to substantial increase in runoff, leading to flooding and erosion
increase in runoff also leads to more fertilizer, pesticides, and waste entering the water
loss of agricultural land
due to losses in local land, estimates suggest that food now travels an average of 1000 miles from where it is produced
loss of landscapes and wildlife

40. principles of smart growth
create range of housing opportunities
create walkable neighborhoods
encourage collaboration among citizens, businesses, and municipal leaders
foster distinctive, attractive communities
mix land uses
preserve open space, farmland, natural beauty, and critical habitat
provide variety of transportation choices
strengthen development in existing communities
take advantage of compact building designs

41. Chapter 23.2 Urban Blight
exurban migration is the major factor underlying urban decay, or blight
moving to suburbs requires some degree of affluence, which has excluded the poor, elderly, and handicapped
due to a history of racial discrimination in the U.S., the poor are mostly minorities
historically, discrimination has prevented equal access to education, jobs, and home loans

42. vicious cycle of urban blight
migration to suburbs by more affluent citizens sets into motion a vicious cycle
points to consider:
1. local governments are responsible for services
2. source of revenue for local governments is based on property taxes
3. as home values decrease, property values decrease
4. central city usually has a government separate from the surrounding suburbs
with an increasing tax base, suburbs can improve services and attract more residents

43. urban decay in developing countries
more than half of the 3 million residents of Nairobi live in slums consisting of flimsy shacks made of scrap wood, metal, and plastic
burning trash and charcoal fires cloud the air
people get their water from an array of sources
crime and disease are endemic, and AIDS and tuberculosis spread throughout the slums
despite these conditions, cities like these in developing countries are expected to continue growing

44. What makes cities livable?
common features of “livable” cities:
(1) high population density
(2) heterogeneous mix of residences, businesses, stores, and shops
(3) layout has human dimension so people can meet, conduct business, or stroll in open areas
world’s most livable cities are not those with perfect access for cars
cities have taken measures to reduce sprawl, decrease auto traffic, and improve access by foot, bicycle, and public transportation
examples:
Geneva, Switzerland prohibits auto parking in its city center
Copenhagen bans all on-street parking in its core
Paris has removed 200,000 parking spaces in its downtown

45. Chapter 8.1 Soil and Plants
soil characteristics
soil texture
parent material is mineral base for soil
made of rock or deposited sediments
regardless of origin, parent material is eventually broken down by weathering
as rock weathers, it breaks down into smaller and smaller fragments
fragments of soil
sand: particles from 2.0 to 0.02 mm in size
silt: particles from 0.02 to mm in size
clay: anything finer than mm

46. proportions
soil texture refers to the relative proportions of each type of particle in a given soil
if one type of particle predominates, soil is said to be sandy, silty, or clayey
a common proportion, known as loam, is 40% sand, 40% silt, and 20% clay

47. properties
three basic considerations determine how several important properties of soil are influenced by its texture:
1. larger particles have larger spaces separating them than smaller particles
2. smaller particles have more surface area relative to their volume than larger particles
3. nutrient ions and water molecules tend to cling to surfaces
soil texture also affects workability—the ease with which a soil can be cultivated

48. soil profiles
processes of soil formation create a vertical gradient of layers that are often quite distinct
horizontal layers are known as horizons
vertical slice through different horizons is known as soil profile

49. soil profiles
O horizon: topmost layer; consists of dead organic matter (detritus) deposited by plants (leaves, stems, seeds, etc.)
high in organic content
primary source of energy for soil community
decomposition is ongoing in lower portions of O horizon, producing rich, dark material known as humus
A horizon: mixture of mineral soil from below and humus from above; also called topsoil
usually dark due to humus
filled with fine roots; thickness varies

50. soil profiles
E horizon: E stands for eluviation—process of leaching (dissolving away) of many minerals due to downward movement of water
B horizon: characterized by deposition of minerals that have leached from the A and E horizons
referred to as subsoil; often is high in clay and is yellowish or reddish in color
often high in Fe, Al, and Ca
C horizon: parent mineral material that originally occupied the site

51. soil fertility—soil’s ability to support plant growth
for best growth, plants need root environment that supplies conditions:
proper amounts of mineral nutrients, water, and air
pH and salinity are also important
soil fertility—soil’s ability to support plant growth

52. fertilizer
in agriculture, there is an unavoidable removal of nutrients by crops
fertilizer replenishes the soil
organic fertilizer includes plant or animal wastes
inorganic fertilizers are chemical formulations of required nutrients
much more prone to leaching

53. water and water-holding capacity
water is constantly being absorbed by the roots of plants
however, water is continuously exiting as vapor through small pores in the leaves called stomata
inadequate water leads plants to wilt, which conserves water
by closing the stomata, wilting also shuts off photosynthesis

54. water and water-holding capacity
three properties of soil regulate a plant’s water supply:
1. infiltration: soil’s ability to let water soak in
2. water-holding capacity: ability to hold water like a sponge, providing a reservoir for plants to draw from between rains
sandy soils have poor water-holding capacity, while clayey soils are good at holding water
3. evaporative water loss: water returns to the atmosphere before serving the needs of plants (a well-developed O horizon helps retain water)

55. aeration
land plants depend on the soil being loose and porous enough to allow the diffusion of oxygen into the soil and carbon dioxide out of the soil
compaction closes the spaces between soil particles, preventing adequate aeration
also reduces infiltration and increases runoff

56. other properties relative acidity salt and water uptake
different plants are adapted to different pH levels
most plants do best with a pH near 7
salt and water uptake
buildup of salts in the soil makes it impossible for roots of a plant to take in water
only plants with special adaptations can survive saline soils (and none of these are crop plants)

57. soil community
to supply good growing conditions for a crop, the soil must
1. have a good supply of nutrients and good nutrient-holding capacity
2. allow infiltration, have a good water-holding capacity, and resist evaporative water loss
3. have a porous structure that permits good aeration
4. have a pH near 7
5. have a low salt content

58. detritus, soil organisms, humus
detritus in soil supports a complex food web
most numerous and important organisms are bacteria
humus—residue of partly decomposed organic matter found in the bottom of the O horizon
composting fosters the decay of organic waste under somewhat controlled conditions
soil structure—refers to the arrangement of soil particles
loose soil structure is ideal for infiltration, aeration, and workability
humus has extraordinary ability to hold water and nutrients

59. interactions
mycorrhizae—symbiotic relationship between the roots of some plants and certain fungi
drawing some nourishment from the roots, mycorrhizae penetrate the detritus, absorb nutrients, and transfer them directly to plants
prevents loss of nutrients from leaching

60. Chapter 8.2 Soil Degradation
erosion—process of soil and humus particles being carried away by water or wind
occurs any time soil is bared and exposed to the elements
may be slow and subtle, like soil blown gradually by wind
may be dramatic, as when gullies are washed out in a single storm
in ecosystems other than deserts, vegetation protects against erosion
grass is particularly good for erosion control
with increased runoff volume and velocity, grass lies down to form a smooth mat over which the water can flow without disturbing the soil

61. 1. overcultivation
although plowing helps remove weeds and loosens the soil to improve infiltration, it also exposes the soil to wind and water erosion
soil may remain bare ad time passes before crops are planted
runoff and erosion are especially bad on slopes
despite harmful impacts of cultivation, rotating crops (corn  hay  clover) has been proven to be sustainable
clover fixes nitrogen and adds organic matter to the soil

62. no-till
no-till agriculture allows continuous crops, yet minimizes soil erosion
field is first sprayed with herbicide to kill weeds
planting apparatus pulled behind tractor (a) cuts furrow through dead weeds, (b) drops seed and fertilizer into the furrow, and (c) closes the furrow
at harvest, process is repeated, with the waste from the previous crop becoming detritus and mulch for the next crop
no-till farming is a variation in which only one pass is made with a tractor to plant wheat after a rice crop (previously, farmers would plow 6-12x)

63. fertilizer optimal nutrients can be supplied by inorganic fertilizers
however, inorganic fertilizers do not supply organic matter to support soil organisms and build soil structure
in overcultivation, nutrients content may remain high thanks to fertilizer, but mineralization proceeds
with soil’s loss of nutrient-holding capacity, fertilizer leaches into waterways, causing pollution

64. US Natural Resource Conservation Service
established in response to Dust Bowl of 1930s
provides information to farmers regarding soil or water conservation practices
Ex. contour strip cropping
Ex. shelterbelts

65. 2. overgrazing
grasslands that traditionally receive too little rain to support crops have traditionally been used for grazing livestock
too often, these lands are overgrazed
overgrazing kills grass plants, causing erosion and encroachment by desert plants such as sagebrush, mesquite, and juniper (which are not palatable to cattle)
besides damaging the land, overgrazing reduces biodiversity and alters feeding and breeding patterns of native species

66. 3. deforestation
forest ecosystems are extremely efficient systems for holding and recycling nutrients and for absorbing and holding water
maintain a very porous, humus-rich soil
when forests are cut and left exposed, topsoil becomes saturated with water and slides down slopes, leaving barren subsoil
problem is most acute in developing countries where tropical regions are cut
thin layer of humus washes away very quickly, leaving behind nutrient-poor clayey soil which is poor for agriculture

67. irrigation and salinization
irrigation—supplying water to croplands by artificial means
traditionally, water has been diverted from rivers to flood furrows in fields
center-pivot irrigation has become much more popular (gigantic sprinkler slowly pivots around well)
salinization—accumulation of salts in and on the soil to the point where plant growth is suppressed

68. Green Revolution
spread of technologies to the developing world that led to the agricultural revolution in industrialized countries
agriculture expert Norman Borlaug sent to Mexico to deliver agricultural technology
bred dwarf hybrid wheat crop with a large head and thick stalk (crop did well in warm weather when it was given water and fertilizer)
similar techniques were taken to other countries around the world, leading to tremendous increases in food production

69. Green Revolution
because technology raises yields without requiring new agricultural land, significant amounts of deforestation have been prevented
irrigation requirement for high-yield crops means that water shortages are becoming more common in dry regions
crops also require fertilizer, pesticides, and energy-intensive machines—all of which can be in short supply

70. subsistence agriculture
problems
pressures of population and conversion of better land to industrialized agriculture often leads to unsustainable practices
woodlands and forests removed for agriculture or firewood, leaving soil susceptible to erosion
lack of firewood leads residents to burn animal dung for cooking and heat, which diverts nutrients from the land
erosion-prone land is used to grow annual crops
good agricultural land is used for multiple crops and never has a chance to recover nutrients
all of these factors tend to increase poverty, which then puts more pressure on the land

71. animal farming
raising livestock (sheep, goats, cattle, buffalo, poultry) has many connections to raising crops
Ex. 70% of U.S. grain crop goes to feed animals
As with crop farming, two general patterns:
(1) in developed world, animals are raised in large numbers, often under confinement
(2) in developing world, livestock and poultry are raised on family farms

72. factory animals
industrial-style animal farming can be damaging to the environment
rangelands are susceptible to overgrazing
animal manure is mismanaged
according to EPA, animal-based agriculture is the most widespread source of pollution in the U.S. rivers
factory farms can also impact human health
crowded farms are perfect conditions for diseases to incubate and spread among animals
in Asia, more than 140 million birds have been killed as a result of avian flu

73. factory animals—other concerns
loss of rain forest
in Latin America, over 58 million acres of tropical rain forest have been converted to cattle pasture
climate change
deforestation and other changes in land use in the tropics release 1.6 million tons of carbon into the atmosphere each year
cows and other ruminant animals release 100 million tons of methane through belching and flatulence
anaerobic decomposition of manure leads to another 30 million tons of methane (~3% of GHG)
groups such as Heifer International provide animals for rural families for sustainable development

74. prospects for increasing food production
currently, food production is keeping up with (and meat production is exceeding) population growth
concern is whether trend can continue
in 2020, there will be 1.5 billion more people on Earth, and there is already a significant portion that suffers from hunger or malnutrition
International Food Policy Research Institute expects demand for grain to remain constant, slightly ahead of population growth
by 2020, meat consumption is likely to increase by 50%, with shift from red meat to poultry
outlook for developing countries attempting to keep pace is not good (degrading land, limited water and resources)

75. prospects of increased food production
two main options:
(1) continue to increase crop yields
(2) grow food crops on land that is now used for feed crops or cash crops
while yields have increased for many crops throughout the 20th C., much of the productivity of plants depends on the soil and water available
possible impact of climate change on rainfall patterns is difficult to predict

76. less meat?
70% of grain in U.S. goes to feed livestock, while only 2% is used in Sub-Saharan Africa and India
feed grain can be seen as a buffer against world hunger (people can eat lower on the food chain)
current trend shows an increase in meat consumption

77. Chapter 9.2 Genetic Engineering
genetic engineering makes it possible to:
crossbreed different plants
incorporate desired traits into crops and animals
has potential to help developing world to make more food
most widely adopted genetically engineered products to this point:
cotton plants with built-in insect resistance
corn and soybean plants resistant to Roundup to allow no-till farming techniques

78. new products of genetic engineering
sorghum (African crop) resistant to witchweed (parasitic plant)
corn and potatoes resistant to insects
rice resistant to bacterial blight disease
trees and salmon that grow rapidly

79. biotech crop research to benefit developing countries is proceeding at a rapid pace
researchers in China have sequenced the rice genome
other objectives:
incorporate resistance to diseases and pests that attack important tropical plants
increase tolerance to environmental conditions, such as drought and high salt levels
improve the nutritional value of commonly eaten crops
produce pharmaceutical products in ordinary plants
Ex. bananas and tomatoes with antidiarrheal vaccine

80. environmental concerns related to genetic engineering
broad exposure to toxins such as pesticides can lead the pests to develop resistance, causing the transgenic crop to lose its advantage
pollen from pest-resistant crops may damage beneficial insects that carry pollen
pollen of transgenic species can spread to wild relatives, leading to “super” weeds

81. safety concerns related to genetic engineering
transgenic crops contain proteins from different organisms and might trigger an unexpected allergic response in people who consume the food
antibiotic-resistance genes are sometimes used to track cells that have been transformed
product could then transfer antibiotic resistance to humans
plants could produce new toxins or allergens in their tissues in response to the presence of foreign genes
to date, no evidence of these concerns have appeared in countries growing transgenic crops

82. policies
in the U.S., the EPA, USDA, and FDA have all had regulatory oversight of different aspects of biotechnology
Cartagena Protocol
U.N. Convention on Biodiversity sponsored conference in 2000 to deal with trade of genetically modified organisms
puts right to deny entry of any of transgenic organism in the hands of the importing country
however, decision must be based on sound science (involving an assessment of the risks involved) and a broad sharing of information about the products

83. policies Cartagena Protocol is based on the precautionary principal
where there are threats of serious or irreversible damage, lack of scientific certainty should not be used as a reason for failing to take measures to prevent potential damage
according to agreement, shipments containing food made with genetically modified organisms must be labeled to indicate that they may contain bioengineered products
the European Union has lifted a ban on genetically modified foods, but is requiring labels on any food that contains more than 0.9% of genetically modified ingredients

84. terms
hunger: lack of basic food required for energy and meeting nutritional needs, resulting in an inability to lead a normal, healthy life
malnutrition: lack of essential nutrients (amino acid, vitamin, mineral)
undernourishment: lack of adequate food energy (usually measured in calories)

85. extent of hunger
almost 2/3 o f the worlds undernourished (519 million) live in Asia and the Pacific (China, Bangladesh, Pakistan, and India are most seriously affected)
sub-Saharan Africa has the highest percentage of undernourished people, where 1/3 of the population (204 million) do not get enough food

86. famine
famine: severe shortage of food accompanied by a significant increase in the death rate
usually a sign that a society is either unable or unwilling to distribute food to all segments of its population
drought and conflict are the two prominent causes of recent famines

87. Chapter 16.1 The Need for Pest Control
pest: any organism that is noxious, destructive, or troublesome
includes pathogens, nuisance wild animals, annoying insects, molds
agricultural pest: organism that feeds on ornamental plants or agricultural crops or animals
includes insects, fungi, viruses, worms, snails, slugs, rats, mice, birds
weeds: compete with agricultural crops, forests, and grasses for lights and nutrients

88. pest management
efforts to control pests in the U.S. in 2001 involved 888 million pounds of:
herbicides—chemicals that kill plants
pesticides—chemicals that kill animals and insects
many of the changes to agriculture, such as monocultures and the use of genetically identical crops, have increased the portion of crops lost to pests

89. different philosophies of pest control
1. chemical treatment
like antibiotics in medicine, seeks “magic bullet” to eradicate or greatly decrease pest numbers
method is very successful, but success is often short-lived
chemicals may have damaging side-effects

90. different philosophies of pest control
2. ecological control
similar to stimulating the body’s immune system
attempts long-lasting protection by developing controls based on the pest’s life cycle and ecological relationships
may be organisms or chemicals
work in one of two ways:
highly specific for best that is being fought
manipulate one or more aspects of the ecosystem

91. different philosophies of pest control
chemical treatment and ecological control are combined in approach called integrated pest management (IRM)
approach to controlling pest populations using all suitable methods—chemical and ecological—to bring about long-term management of pest populations with minimal environmental impact

92. problems with chemical pesticides
problems fit into three categories:
1. development of resistance
2. resurgences and secondary pest outbreaks
3. adverse effects
human health
environment

93. 1. development of resistance
over the years, farmers have to use larger and larger quantities, try new and more potent pesticides, or both
resistance builds up because pesticides destroy the sensitive individuals in a population
few that are left behind already have some resistance
resistance spreads rapidly due to insects’ ability to reproduce quickly

94. 2. resurgences and secondary outbreaks
resurgence: after a pest has been eliminated by a pesticide, the pest population generally recovers and explodes to higher and more severe levels
secondary outbreak: explosion of insect populations that were small before the application of the pesticide
in a recent study of 25 major pest outbreaks (each caused more than $1 million worth of damage) in California showed, all but one were followed by a resurgence or secondary outbreak

95. 3a. human health effects
pesticides can be responsible for both acute and chronic effects
acute cases are most often farm workers or employees poisoned by direct contact with the chemicals
chronic effects are likely to be seen in consumers exposed to residues on food or farmers exposed to subacute levels

96. 3a. human health effects one likely chronic outcome is cancer
at least 20 pesticides have some carcinogenic properties
other chronic effects include dermatitis, neurological disorders, birth defects, and infertility
studies have linked pesticide exposure to suppression of the immune and endocrine systems, as well as Parkinson’s disease
evidence of some pesticides interfering with reproductive hormones

97. 3b. environmental effects
impact of DDT
ornithologists observed drastic declines in bird species at the top of food chains during the 1950s and 1960s
fish-eating birds such as eagles and osprey were on the brink of extinction
problem was reproductive failure—eggs were breaking in the nest before hatching
investigators found that the eggs contained high concentrations of DDE, a compound that forms when DDT is partially broken down
DDE interferes with calcium metabolism, leading to thin-shelled eggs
studies show that birds were acquiring high levels of DDT and DDE through bioaccumulation and biomagnification

98. 3b. environmental effects
bioaccumulation
many synthetic organic compounds (man-made) are soluble in lipids, but not in water
as they pass through cell membranes, they leave the water solution to become part of the lipid bilayer
as a result, traces of synthetic organic compounds become trapped in the body’s lipids
because synthetics are unnatural compounds, the body cannot fully metabolize them and has no mechanism to excrete them
over time, trace levels accumulate in the body and can build to toxic levels

99. 4. environmental effects
biomagnification
each individual organism accumulates contamination
over time, the concentration of the contaminant becomes much higher in the organism than in its food
the next organism on the food chain then consumes food that already has a high concentration of contaminant
the contaminant eventually becomes concentrated into the smaller biomass of the organisms at the top of the food chain
both bioaccumulation and biomagnification often go unrecognized until serious problems arise

100. four general categories of natural control:
1. cultural control
2. control by natural enemies
3. genetic control
4. natural chemical control

101. 1. cultural control
nonchemical alteration of one or more environmental factors in a way that leads the pest to find the environment unsuitable
human examples include brushing hair, changing bed linens, disposing of garbage
major disasters can compromise practices of hygiene and sanitation

102. 1. cultural control
Example 1: maintaining grass on lawn at a height of at least 3 inches keeps out most weeds
Example 2: marigolds and chrysanthemums act as insect repellants (while roses act as attractants)
Example 3: shelterbelts can provide refuge for natural enemies of pests (birds, amphibians, etc.)
Example 4: rotating crops eliminates pest that may only have a source of food every few years; likewise, a mixture of crops in an area can help prevent a pest outbreak

103. 2. control by natural enemies
Example 1: gypsy moth controlled by imported parasitic wasp
Example 2: rabbits in Australia controlled by infectious virus
guidelines:
protect native species
first step should be conservation of natural enemies
avoid broad-spectrum pesticides
import aliens as last resort

104. 3. genetic control
most plant-eating insects and plant pathogens attack only one species or a few closely related species
implies genetic incompatibility between pest and species that are not attacked
most genetic strategies are aimed at providing this incompatibility

105. 3. genetic control A. control with chemical barriers
chemical barrier is chemical produced by plant that is vulnerable to pest
chemical is lethal, or at least repulsive to pests
B. control with physical barriers
physical barriers are structural traits that impede the attack of a pest
Ex. hooked hairs on leaf surfaces trap leafhopper insects that damage relatively smooth leaves

106. 3. genetic control C. control with sterile males
involves flooding population with sterile males that have been raised in laboratories
Ex. screwworm fly has been controlled using this method (aided by fact that females mate just once, lay their eggs, then die)
Ex. used to eradicate the tsetse fly from island of Zanzibar, eliminating sleeping sickness

107. 3. genetic control D. strategies using biotechnology
one promising strategy is to incorporate the protein coat of a plant virus into the plant
when the plant expresses the viruses protein coat, the plant becomes resistant to infection by the real virus
many strategies involving biotechnology have the potential to reduce the use of pesticides
Bt = incorporation of important protein produced by Bacillus thuringiensis
widespread use of Bt crops means that resistance is likely to develop
EPA anticipated this problem and required seed companies to verify that farmers planted at least 20% of their fields with non-Bt crops

108. 4. natural chemical control
hormones: chemicals produced by animals to provide signals for the control of developmental processes and metabolic functions
pheromones: chemicals secreted by one individual that influence the behavior of another individual of the same species
both of these types of chemicals may be used to disrupt the life cycle of pests
advantages:
nontoxic
highly specific

109. 4. natural chemical control
Ex. use of juvenile hormone to prevent pupation in caterpillars
larvae continue to feed and grow until they become grossly oversized and die
Ex. synthetic version of ecdysone, the hormone that controls molting in insects, prevents insects from completing molting process
larva is trapped in its old skin and eventually starves to death
Ex. pheromones used in trapping technique lead pests to traps full of poison bait
Ex. pheromones used in confusion technique prevent males from finding mate