Presentation on theme: "CHAPTER 20 PESTICIDES & PEST CONTROL -Competes with humans for food -Invades lawns and gardens -Interferes with human activity -Spreads disease -Nuisance."— Presentation transcript:
CHAPTER 20 PESTICIDES & PEST CONTROL
-Competes with humans for food -Invades lawns and gardens -Interferes with human activity -Spreads disease -Nuisance WHAT IS A PEST Any species that does the following:
I. TYPES OF PESTICIDES 1. Insecticides 2. Herbicides 3. Fungicides 4. Nematocides (Round worms) 5. Rodenticides
A. 1 st Generation Pesticides -Generally described as those first used and that were derived from natural sources. Sulfur: Used pre-500B.C. Toxic Chemicals: (1400’s) Arsenic- does not break down, Lead and Mercury -This approach was abandoned as late as the1920’s -Still find measurable levels in tobacco and other crops grown on that soil
Natural Pesticides: (1600’s) Nicotine Sulfate – from tobacco plants 1 st Generation - continued (1800’s) Pyrethrum, Rotenone- from Chrysanthemum flower and tropical legumes
-Generally described as those that are chemically produced -DDT (Dichlorodiphenyl- trichloroethane) *Discovered by Paul Muller (won the Nobel Prize) *1 st used in 1939 *Use in the U.S. stopped in 1972 as a result of adverse effects on the environment and population decreases in unintentional species. - It is still sold to foreign countries B. 2 nd Generation Pesticides
C. 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. 1. TODAY (since 1850)
2. IN THE USA -Around 25,000 pesticide products -25% used for homes, parks, pools, golf courses -The average lawn receives 10x more synthetic pesticide than US cropland -250,000 people become ill each year
D. Broad vs. Narrow 1. Broad Spectrum Agents: -Toxic to many species 2. Selective / Narrow Spectrum: -Specific to a certain species PERSISTANCE -Pesticides vary in their PERSISTANCE (how long they remain in the environment)
II. THE CASE FOR PESTICIDES Those that support the use of pesticides state that the benefits outweigh the potential harmful effects for many reasons.…. A. Save human lives: Protection against diseases like malaria, typhus and sleeping sickness
555% of food is already lost to pests $$65 million / yr HHelps lower food costs B. Increase food supply:
C. Increased Profit to farmers: Every $1 spent on pesticides increases farm profit by $4
D. They work faster and better than alternatives: -Control most pests at reasonable cost -Have a long shelf life -Easily shipped and applied -Relatively safe when handle correctly
E. Relatively Safe: Health risks are insignificant when used properly Many of the new pesticides are used at a lower rate than in the past. Today’s pesticides are actually safer than those of the past.
III. THE CASE AGAINST PESTICIDES A. Can cause Genetic Resistance: Reproduce rapidly and can develop a resistance in 5-10 years Surviving organisms come back stronger. Leads to Pesticide Treadmill- using stronger doses, switching to new chemicals, and an increase in frequency of use Those that oppose the use of pesticides state that they are harmful for many reasons.….
Fig. 20.4, p. 507 600 500 400 300 200 100 0 1950196019701980199020002010 Year Number of species Boll weevil Gypsy moth cateripllar Insects and mites Weeds Plant diseases RISE OF GENETIC RESISTANCE TO PESTICIDES 1945-98
B. Broad Spectrum insecticides kill natural predators & parasites 1/3 of the most destructive pests are secondary pests that became widespread after the use of insecticides
C. 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.
D. 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
E. Threat to Human Health 3 million agricultural workers are harmed each yr (300,000 in USA) Most not reported due to the majority of farm workers being illegal immigrants 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
Bhopal India http://www.bhopal.org/testimony/index.html Bhopal, India, 2-3 Dec. 1984 On the night of 2-3 December 1984, a sudden release of about 30 tons of methyl isocyanate (MIC) occurred at the Union Carbide pesticide plant at Bhopal, India. The accident was a result of poor safety management practices, poor early warning systems, and the lack of community preparedness. The accident led to the death of over 2,800 people living in the vicinity and caused respiratory damage and eye damage to over 20,000 others. At least 200,000 people fled Bhopal during the week after the accident. Estimates of the damage vary widely between US $350 million to as high as US $3 billion.
IV. PESTICIDE REGULATIONS IN THE U.S. A. USE IN THE U.S. (518) All commercial pesticides require EPA approval for general and/or restricted use. (Based on FIFRA) -Evaluated for biologically active ingredients + affects -If approved the EPA sets acceptable tolerance levels
Between 1972-2000, EPA banned or restricted 56 active pesticide ingredients in U.S. – may be used elsewhere. EPA asked to reevaluated 600 pre-1972 active ingredients used in pesticides. (by 2000 less than 10% completed) -weak enforcement -weak laws for pre 1972 toxins
B. OTHER DISTURBING FACTS 165 active ingredients in U.S. approved pesticides are known to be carcinogens Missouri study showed increased childhood brain cancer with use of various pesticides. Also, associated with immune and endocrine disorders Swedish report showed, exposure to glyphosate tripled chances of getting non- Hodgkin’s lymphoma.
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 C. HOW TO IMPROVE PESTICIDE REGULATIONS (519)
D. HOW TO IMPROVE PESTICIDES Kill only target species would be ideal 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
The War Against Insects
A. Goals of Pesticide Control ECONOMIC THRESHOLD. One of the biggest problems with the use of pesticides is in determining the ECONOMIC THRESHOLD. This is point where cost of damage due to not applying pesticides outweighs the cost of application of pesticides. To protect themselves, farmers often practice INSURANCE SPRAYING COSMETIC SPRAYING- Making its appearance more desirable V. 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; B. Alternatives to Pesticides
A Fungus Among Us
3. Biological Pest Control; Pro’s -focus on target -are nontoxic -save money -minimize resistance Con’s -no mass reproduction -slow -must be protected from spraying -can multiply faster than pest -requires a lot of research & development
4. Insect Birth Control ; Sterilization of insects, used with screwworms, fruit flies Involves irradiating males Disadvantages include… -high cost -estimating mating times/behaviors -need large # of males -males must be reintroduced
5. Sex Attractants; The use of pheromone baited traps. Pheromone- is a species-specific chemical sex attractant. 6. Hormones to stunt growth;
7. Spraying with hot water; 8. Exposing food to gamma radiation
C. INTEGRATED PEST MANAGEMENT Approach where crops and pests are examined as part of an ecological system. Overall aim is to reduce crop damage and economic losses but not complete eradication of the pest. Requires more expert knowledge and multiple approaches to pest controlSlower acting than pesticides Only small amounts of pesticide are used at critical times
IPM is ? A chemical program A ecological program A biological program
Ways to Reduce Threat to Pesticides in the Food We Eat. Scrub all food in soapy water Grow own fruits and vegetables using organic gardening methods Purchase organically grown foods
Did you know? Flea collars are linked to brain tumors Pre-1972 pesticides may still have untested chemicals as ingredients Round-Up is linked to Non-Hodgkins type Lymphoma