CHAPTER 20 PESTICIDES & PEST CONTROL

Chapter Objectives  Define Pesticides  Discuss the Pro’s and Con’s of Pesticide Use  Understanding of Regulations  Alternatives

20.1 Types and Uses WHAT IS A PEST- AAny species that does the following: 1. Competes with humans for food 2. Invades lawns and gardens 3. Destroys wood in a home 4. Spreads disease 5. Nuisance

TYPES OF PESTICIDES 1. Insecticides 2. Herbicides 3. Fungicides 4. Nematocides (Round worms) 5. Rodenticides

1 st Generation Pesticides  Sulfur: Used pre-500B.C.  Natural Pesticides: Nicotine Sulfate, 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 on that soil

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

Pesticide Use Today 550 fold increase in the use of pesticides since the 1950’s 110x stronger than the original pesticides 22.5 million tons used per year, worldwide.

Pesticides in the USA  Around 25,000 pesticide products  25% used for homes, parks, pools, golf courses

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)

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

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

555% of food is already lost to pests $$65 million / yr 2. Increase food supply:

3.Increased Profit to farmers: Every $1 spent on pesticides increases farm profit by $4

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

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.

20.3 THE CASE AGAINST PESTICIDES 1. Can cause Genetic Resistance:  Reproduce rapidly and can develop a resistance in 5-10 years  Surviving organisms come back stronger.  Leads to Pesticide Treadmill

Fig. 20.4, p Year Number of species Boll weevil Gypsy moth cateripllar Insects and mites Weeds Plant diseases RISE OF GENETIC RESISTANCE TO PESTICIDES

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

3.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.

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

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

Bhopal India Bhopal, India, 2-3 Dec On the night of 2-3 December 1984, a sudden release of about 30 tonnes 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.

20.4 PESTICIDE REGULATIONS IN THE USA  All commercial pesticides require EPA approval for general and/or restricted use. (Based on FIFRA)

Federal Insecticide, Fungicide and Rodentcide Act -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

LABEL SIGNAL WORDS  DANGER & POISON (PELIGRO) –Skull and Crossbones –Highly Toxic  DANGER – No Skull/Crossbones –Significant Skin or Eye effects  WARNING / AVISO –Moderately Toxic  CAUTION –Slightly Toxic or relatively non-toxic –Page 52 Pesticide Manual

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

The Bad News: As of 2000 less than 10% of the pesticide evaluations have been completed  Weak enforcement  Weak laws for pre 1972 toxins

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.

 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

1. Need to make human health the primary consideration for setting pesticide limits. 2. New tests for evaluating toxicity of pesticides 3. Consider the cumulative exposures of all Pesticides HOW TO IMPROVE PESTICIDE REGULATIONS

HOW TO IMPROVE PESTICIDES 1. Kill only target species 2. Harm no other species 3. Break down into something harmless after doing its job 4. Not cause genetic resistance in target organisms 5. Be more cost effective than doing nothing

The War Against Insects

 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 20.5 OTHER WAYS TO CONTROL PESTS

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

1. Cultivation Practices;  crop rotation  changing planting times  planting trap crops  increasing habitat for natural predators 2. Create Genetically Resistant Plants;

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 become a pest

Using Parasitic Wasps

Ladybugs and the Praying Mantis

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

Screw Worm Maggots

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

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

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

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