CHAPTER 20 PESTICIDES & PEST CONTROL

1. CHAPTER 20PESTICIDES & PEST CONTROL

2. Beneficial Spiders • Hibernating spiders in China help in rice and cotton fields • Wolf spiders in undergrowth help protect cotton and soybeans • Banana spiders in warmer climates consume household cockroaches

3. Wolf spider

4. Banana spider

5. Chapter Objectives • Define Pesticides • Discusses the Pro’s and Con’s chemical Pesticide Use • Discusses the Pro’s and Con’s of biological and ecological alternatives for controlling pests • Understanding of Regulations • Alternatives

6. 20.1 Types and Uses WHAT IS A PEST- • Any species that does the following: • Competes with humans for food • Invades lawns and gardens • Destroys wood in a home • Spreads disease • Nuisance

7. TYPES OF PESTICIDES(biocides) Chemicals to kill Organisms undesirerable • Insecticides • Herbicides • Fungicides • Nematocides (Round worms) • Rodenticides

8. 1st Generation Pesticides • Natural substances, derived from plants • Sulfur: Used pre-500B.C. • Natural Pesticides: (1600’s)Nicotine Sulfate, (1800’s) Pyrethrum, Rotenone • Toxic Chemicals: Arsenic, Lead and Mercury • This approach was abandoned as late as the1920’s • Still find measurable levels in tobacco and other crops grown today on that soil

9. 2nd Generation Pesticides • DDT (Dichlorodiphenyl-trichloroethane) • 1st used in 1939 • Discovered by Paul Muller who won the Nobel Prize • WWII materials by-products

10. OUTCOMES OF DDT

11. Pesticide Use Today • 50 fold increase in the use of pesticides since the 1950’s • 10x stronger than the original pesticides • 2.5 million tons used per year, worldwide.

12. Pesticides in the USA • Around 25,000 pesticide products • 25% used for homes, parks, pools, golf courses • Insecticides, herbicides, fungicides, fumigants all have a known persistence in the environment

13. Broad vs. Narrow • Broad Spectrum Agents: • Toxic to many species • Selective / Narrow Spectrum: • Specific to a certain species • Pesticides vary in their persistence: • How long they remain in the environment (Usually recorded as half life) ( see table page 514)

14. The Case for Pesticides “Benefits outweigh the potential harmful effects” 1.) Save human lives: • Protection against diseases like malaria, typhus and sleeping sickness

15. 2. Increase food supply: • 55% of food is already lost to pests • $65 million / yr

16. IncreasedProfit to farmers: Every $1 spent on pesticides increases farm profit by $4

17. 4. They work faster and better than alternatives: -Control most pests at reasonable cost -Have a long shelf life -Easily shipped and applied

18. 5.Relatively Safe: • Health risks are insignificant when used properly • Today’s pesticides are actually safer than those of the past. • Many of the new pesticides are used at a lower rate than in the past.

19. THE CASE AGAINST PESTICIDES 1. Can cause Genetic Resistance: • Insects reproduce rapidly and can develop a resistance in 5-10years • Surviving organisms come back stronger. Directional natural selection due to changing conditions • Leads to Pesticide Treadmill: pay more and more for less and less protection

20. 600 500 400 Number of species 300 200 100 0 1950 1960 1970 1980 1990 2000 2010 Year RISE OF GENETIC RESISTANCE TO PESTICIDES 1945-98 Gypsy moth cateripllar Boll weevil Insects and mites Plant diseases Weeds Fig. 20.4, p. 507

21. 2. Broad Spectrum insecticides kill natural predators • 1/3 of the most destructive pests are secondary pests that became widespread after the use of insecticides

22. Pesticides Do Not Stay Put • Less than 2% of the pesticides used actually reach the target pests • Less than 5% of herbicide reaches the appropriate weeds • Pesticides may end up in the air, water, bottom sediments, food or non-target organisms.

23. 4. Some Pesticides Harm Wildlife • Destruction of more than 20% of honeybee colonies • Costing farmers $200 million in lost pollination • Kills 67 million birds • Kills 6-14 million fish • Hurt 20% endangered species

24. 5. Threat to Human Health • 3 million agricultural workers are harmed each yr (300,000 in USA) • 18,000 deaths (probably underestimated) • 165 of the approved active ingredients are carcinogenic • Exposure in food is related to 4-20,000 cases of cancer / year • Birth defects, genetic mutations, nervous system disorders, immune system problems

25. PESTICIDE REGULATIONS IN THE USA • All commercial pesticides require EPA approval for general and/or restricted use.

26. Federal Insecticide, Fungicide and RodentcideAct (FIFRA) -Pesticides are evaluated for biologically active ingredients & their affects -If approved the EPA sets acceptable tolerance levels • The amount of toxic residue that can legally remain on the crop when a consumer eats it

27. The Good News about Pesticides • Between 1972-2000, EPA banned or restricted 56 active pesticide ingredients in U.S. • EPA asked to reevaluated 600 pre-1972 active ingredients used in pesticides.

28. The Bad News: As of 2010 less than 10% of the pesticide evaluations have been completed • Weak enforcement • Weak laws for pre 1972 toxins

29. OTHER DISTURBING FACTS • Many active ingredients are known to be carcinogens • Missouri study showed increased childhood brain cancer with use of various pesticides. • Swedish report showed, exposure to glyphosate (Key agent in ROUND-UP)tripled chances of getting non-Hodgkin’s lymphoma.

30. The Circle of Poison • US Companies can make and export banned chemicals to other countries • 26 tons per day • Many of the crops the pesticides are used on return to the USA

31. HOW TO IMPROVE PESTICIDE REGULATIONS • Need to make human health the primary consideration for setting pesticide limits. • New tests for evaluating toxicity of pesticides • Consider the cumulative exposures of all Pesticides

32. HOW TO IMPROVE PESTICIDES • Kill only target species • Harm no other species • Break down into something harmless after doing its job • Not cause genetic resistance in target organisms • Be more cost effective than doing nothing

33. OTHER WAYS TO CONTROL PESTS • One of the biggest problems with the use of pesticides is in determining the ECONOMIC THRESHOLD. • The point where economic damage due to the pest outweighs the cost of the pesticide

34. Excessive Pesticide Use • To protect themselves, farmers often practice INSURANCE SPRAYING and/or COSMETIC SPRAYING

35. Other Ways to Control Pests 1.Cultivation Practices; • crop rotation • changing planting times • planting trap crops • increasing habitat for natural predators • 2. Create Genetically Resistant Plants;

36. Biological Pest Controls • Natural predators, parasites, and disease-causing bacteria and viruses imported to regulate pest populations

37. Con’s -no mass reproduction -slow -must be protected from spraying -can become a pest Pro’s -focuses on target -are nontoxic to other species -saves money -minimizes genetic resistance 3. Biological Pest Control;

38. Ladybugs and the Praying Mantis

39. 4. Insect Birth Control; Sterilization of male insects – used with screwworms,fruit flies Disadvantages include… -high cost -estimating mating times/behaviors -need large # of males -males must be reintroduced

40. Screw Worm Maggots

41. 5. Sex Attractants; The use of pheromone baited traps 6. Hormones to stunt growth;

42. 7. Spraying with hot water; 8. Exposing food to gamma radiation

43. INTEGRATED PEST MANAGEMENT • Strategy to use natural interactions rather than chemical interactions CONTROL OPTIONS: • Cultural: Crop Rotation and Sanitation • Physical: Manipulation of water, temperature and humidity • Mechanical: Release of natural predators and use screens and other covers

44. Basic Principles of IPM • Know the target • Learn what, where and how for the organism • Monitor and evaluate pest populations • Establish a threshold(what level you can tolerate) • Chose a tactic • Evaluate results The goal is not total elimination but reduce crop damage and economic losses

45. Rachael Carson’s Silent Spring Rachael Carson • Born: May 27, 1907in Springdale, Pennsylvania • Graduate of Chatham College • Died: April 14, 1964 in Silver Spring, Maryland

46. Her Scientific Impact • Her 1962 book, Silent Spring, put forth bold accusations against the use over-use of pesticides, such as DDT, which had become common practice after WWII • The well-researched scientific book showed how the use of such deadly chemicals were harming the entire environment, unnecessarily destroying life and could potentially affect the human race as well. • The Department of Agriculture, as well as the pesticide community, attacked Carson and her book saying that her accusations were wildly overdramatic, made the public aware for the first time of the harmful substances and basically began the modern environmental movement. • After the truth about the harmful chemicals was revealed in, Silent Spring, theses dangerous pesticides’ were limited and, probably, many lives were saved. • This book also started the public questioning of science because before this, people had also viewed science and its works as a positive force, but after these startling discoveries, many people became much more skeptic of science and new technology.