1. Protecting Food Resources: Pesticides and Pest Control
Chapter 20
Protecting Food Resources: Pesticides and Pest Control

2. Rachel Carson was a scientist who wrote Silent Spring in 1962.
It addressed the growing use of pesticides (DDT) and their unpredicted effects on song birds.
Original users of pesticides did not know that the poisons used to kill insects would accumulate in other living things and kill them too. BIOACCUMULATION

3. Pesticides: Types and Uses
What is a Pest?
A pest is any species that competes with us for food, invades lawns and gardens, destroys wood in houses, spreads disease, or is simply a nuisance
Most of the time nature takes care of the pests through natural enemies (predators, parasites, and disease organisms)

4. So what’s a Pesticide?
Pesticides (also known as biocides) are chemicals that are to kill organisms we consider undesirable
Insecticides
Herbicides
Fungicides
Nematocides
Rodenticides

5. Above: Worker prepares his vehicle for a day of pesticide spraying

6. Coevolution
For almost 225 million years, plants have been producing chemicals to ward off or poison herbivores that feed on them…
But, through what is known as coevolution, the predators overcome various plant defenses by natural selection and the plants must develop new defenses

7. First Attempts at Pesticides
Sulfur (early 500 BC)
Toxic compounds of arsenic, lead, and mercury (1400’s)
Abandoned in late 1920’s when the increasing number of human poisonings increased
Nicotine Sulfate (1600’s)
Pyrethrum and Rotenone (mid-1800’s)

8. Paul Mueller and the Second Generation
In 1939 Paul Mueller discovered that DDT, a chemical known since 1874, was in fact a potent insecticide. DDT became the first pesticide of the so- called Second Generation Pesticides. Mueller went on to win the Nobel Prize in 1948 for his discovery.

9. Pesticides Today
Chemists have been developing hundreds of synthetic organic chemicals for use as pesticides
Worldwide about 2.3 million metric tons of pesticides are used yearly
1 lb for each person on earth
75% in developed countries (Latin America, Asia and Africa on the rise)
1996 world sales = $30 billion($11 billion: US)

10. Here in the US
About 630 different biologically active (pest killing) ingredients and about 1,820 inert (inactive) ingredients are mixed to make some 25,000 different pesticide products in the United States

11. Resistance to pesticides
Some individuals are genetically immune to a pesticide.
They survive and pass these genes to their offspring.
Pesticides stop being effective.

12. Pesticide Distribution in US
Cultivation of two crops
Cotton (55%)
Corn (35%)
Used about 90% of the insecticides and 80% of the herbicides applied to crops in the United States in 1995

13. Example of Solid Pesticides

14. More Distribution
25% of the pesticide use in the United States is for ridding houses, gardens, lawns, parks, playing fields, swimming pools, and golf courses of unwanted pests
Average lawn in US = 10x’s more pesticides per hectare than US cropland
Each year = 250,000 residents become ill

15. Biological control
Biological control (Biocontrol): uses a pest’s natural predators to control the pest
Leads to steep reductions in chemical pesticide use
Cactus moths control invasive prickly pear cactus
Bacillus thuringiensis (Bt): soil bacteria that kills many pests

16. Biocontrol involves risks
No one can predict the effects of an introduced species.
The agent may become invasive and harm non-target organisms.
Cactus moths are eating rare Florida cacti.
Removing a biocontrol agent is harder than halting pesticide use.
The harm done by biocontrol agents may be permanent.

17. Some Quick Facts Broad-Spectrum agents : toxic to many species
Selective or Narrow spectrum agents : effective against a narrowly defined group of organisms
Pesticides vary in persistence (length of time they remain deadly in environment)

18. The Pros
Pesticides save human lives: has prevented premature births due to malaria, bubonic plague, typhus, sleeping sickness (all carried by pests)
Pesticides increase food supplies and lower food costs: 55% of crop lost before harvest due to pests
Pesticides increase profits for farmers: every $1 spent on pesticides yields worth approximately $4 (although dropped to $2 if harmful effects)

19. More Pros
Pesticides work faster and better than alternatives: Pesticides can control pests quickly and at a reasonable cost. Long shelf life and easily shipped and applied
Health risks insignificant when compared to their benefits
Safer more effective pesticides are being developed
New pesticides are being used in less rates per unit when compared to older products

20. Ultimate Goal of Pesticides
Kill only the target pest
Harm no other species
Disappear or break down into something harmless after doing its job
Not cause genetic resistance in target
Be cheaper than doing nothing

21. The Cons
Genetic Resistance: pest organisms develop resistance to the pesticide after a short period of being exposed to it
Broad-Spectrum insecticides kill natural predators and parasites that may have been maintaining the population of a pest species at a reasonable level
Ex. Wolf spiders, wasps, predatory beetles…

22. Cons continued…
Because natural predators can be wiped out; this may unleash new pests whose populations the predators had previously held in check

23. In Our Water
Testing in rivers and water reveal that pesticides have strayed away from there targets and found there way into the waters

24. Pesticide Treadmill
As pests become resistant to the pesticides, sales reps for the pesticide recommend larger doses or more frequent application
As a result farmers end up on a pesticide treadmill where they end up paying more and more for a pest control program that often becomes less and less effective

25. Pesticide Treadmill Pesticides become less effective over time
Genetic resistance to pesticides develops in pest species – natural selection
Some individuals have a gene that makes them resistant to a pesticide, they pass the gene onto their offspring so that the entire population becomes resistant
This requires a more frequent sprayings, larger doses or a switch to new pesticides
Yields have decreased because of pesticide resistance since second generation pesticides have come into use

26. Example of Pesticide Treadmill
In Central America, cotton growers increased the frequency of insecticide applications from 10 to 40 times per growing season. Still, declining yields and falling profits forced many of the farmers into bankruptcy

27. Chromosome with gene conferring resistance to insecticide
application
Chromosome with gene conferring resistance to insecticide
Survivors
Additional applications of the same insecticide will be less effective, and the frequency of resistant insects in the population will grow
Figure 13.1

28. Where does it all go?
Only about 2% of the sprayed insecticide by air reaches target pests
Less than 5% of herbicides applied reach target weed
Pesticides that don’t reach there target end up in the air, surface water, groundwater, bottom sediments, food and other non- target organisms

29. Continued
Still, pesticide waste can be reduced by using re- circulating sprayers, covering spray booms, and using rope-wick applicators

30. DDT
Banned in 1972 by US
1980 high levels in peregrine falcon and the osprey
EPA found DDT in 99% of the freshwater fish it tested
DDT drifts from other countries still using it

31. DDT accumulates in fat body tissues of animals
DDT was not used for handling weeds
DDT is, persistent, synthetic organic compound and a subject to biomagnifications in food chains

32. World’s Worst Industrial Accident
Bhopal, India
Occurred December 2, 1984
Union Carbide (a pesticide manufacturer)
MIC (methyl isocyanate) gas leaked
the cooling system malfunctioned and the tank exploded
Gas affected 30 square miles and an estimated 600,000 people were exposed

33. Bhopal
Officially 5,100 people were killed (probably anywhere from 7,000 – 15,000 died)
50,000 – 60,000 sustained permanent injuries, blindness or lung injuries

34. The Cause?
Indian government claims it was caused by company negligence
The company claims sabotage by a disgruntled former worker

35. Regulation in the US All commercial pesticides must be approved by EPA
EPA reviews each pesticide
EPA sets tolerance levels : amount of toxic pesticide residue that can legally remain on crop
No longer has to test on birds and fish
55 active pesticides banned in US, but may be used and shipped elsewhere

36. More Regulations
National Academy of Sciences says that the federal laws are not adequate
98% of potential risk of cancer would be eliminated if pesticide residue on food eliminated by government
Approximately $1 Billion spent on regulating pesticides each year

37. FIFRA and the EPA Federal Insecticide, Fungicide, Rodenticide Act
All commercial pesticides must be approved for use
The pesticide companies evaluate the biologically active ingredients in their products and the EPA reviews the data
When a pesticide is approved for use on fruits or vegetables, a tolerance level is set that can legally remain on a crop when a consumer eats it

38. 1996 Food Quality Protection Act
Requires food to have only reasonable levels of pesticide tolerance
It requires manufacturers to demonstrate that the active ingredients in there products are safe for infants and children
Requires EPA to consider exposure to more thatn one pesticide when setting pesticide tolerance levels
EPA develops program to screen ingredients

39. From Above
Just one of the many ways that pesticides are being applied are through aerial drops of the chemicals

40. Other Solutions Crop rotations Planting times can be adjusted
Plowing at night (reduces weeds)
Plant where major pests do not exist
Switch away from monoculture to intercropping, agroforestry, and polyculture

41. More Solutions
Plants and animals that are genetically resistant to certain pest insects, fungi and diseases can be developed
- downside: costly
Biological control: predators and pathogens
300 biological pest control successful in China and Cuba
Biological Control: non-toxic to humans
Downside: timely

42. We depend on insects to pollinate crops
Most insects do not harm agriculture, and some are absolutely vital.
800 cultivated plant species rely on insect pollinators.
Pollination: male plant sex cells (pollen) fertilize female sex cells
By wind or animals
Pollinators include:
Hummingbirds
Bats
Insects

43. Colony Collapse Disorder
Populations of native pollinators have plummeted.
Honeybees pollinate more than 100 crops — 1/3 of the U.S. diet.
Recently, introduced parasitic mites have devastated hives.
To conserve pollinators:
Reduce or eliminate pesticide use
Plant gardens of flowering plants

44. Even more Solutions… Plant toxins
Bt toxin used to kill thousands of strain of common soil bacterium
Insect Birth Control (sterile male approach)
Aqua heat: spray boiling water on crops

45. Fish or frankenfish? FDA weighs altered salmon

46. Yes… more solutions
Some crops can be exposed to gamma rays after harvest
Extends shelf life
Critics say irradiating food destroys vitamins and other nutrients
Increases death from botulism poisoning
Picowaved stickers on food that has been

47. Integrated Pest Management (IPM)
IPM uses multiple techniques to suppress pests.
Biocontrol
Chemicals, when necessary
Population monitoring
Habitat alteration
Crop rotation and transgenic crops
Alternative tillage methods
Mechanical pest removal

48. Integrated Pest Management (IPM)
Each specific crop and its pest(s) are evaluated
It requires a mix of biological, cultivation and chemical practices
Pests populations are not eradicated, but carefully managed so that crop destruction is minimized

49. IPM
Biological methods – predators, parasites, disease organisms, sterilization, sex attractants, hormones
Cultivation – vacuuming, planting times, trap crops, polyculture, intercropping, agroforestry
Development of genetically resistant plants, genetically engineered plants
Chemical pesticides in small amounts are used as a last resort

50. IPM Integrated Pest Management
Goal is reduction of crop damage to an economically tolerable level
Carefully monitor damage levels of pests
When reached, farmers first use biological methods
Small amounts of insecticides are used as a last resort

52. Pesticides in Politics
Pesticides have been a big issue with environmentally safe activists. It is a big topic the EPA has to deal with