Pesticides and Pest Control

1. Pesticides and Pest Control G. Tyler Miller’s Living in the Environment 13th Edition Chapter 20 Dr. Richard Clements Chattanooga State Technical Community College Modified by Charlotte Kirkpatrick

2. Key Concepts • Types and characteristics of pesticides • Pros and cons of using pesticides • Pesticide regulation in the US • Alternatives to chemical pesticides

3. Pests • Compete with humans for food • Invade lawns and gardens • Destroy wood in houses • Spread disease • Are a nuisance

4. Natural Enemies May be controlled by natural enemies Predator, parasites, and disease organisms Control the populations of 50-90% of pest species as part of the earth’s ecological services Help keep any one species from taking over for very long • When we replace polyculture with monoculture and use pesticides we upset the natural balance between plants and natural enemies.

5. Pesticides: Types • Chemicals that kill undesirable organisms See Table 20-1 p. 514 • Insecticides: Kills insects • Herbicides: Kills weeds • Fungicides: Kills fungus • Rodenticides: Kills rodents • Nematocides: Kills Nematodes (roundworms)

6. Coevolution We are no the first to develop pesticides. Plants have developed their own natural defenses for 225 million years to ward off or poison herbivores that feed on them. Herbivores overcome the various plant defenses through natural selection and then the plant retaliates through their own natural selection to develop new defenses.

7. First Generation Pesticides • Primarily natural substances • Sulfur, lead, arsenic, mercury: Used initially, around 500 BC and well into the 15th century. These approaches were abandoned as human poisoning and fatalities increased. • Plant extracts: 1600’s used nicotine, 1800’s pyrethrum and rotenone developed • Plant extracts are degradable

8. What Can You Do to Control Common Insect Pests and Weeds? You can usually persuade ants to leave within about 4 days by sprinkling repellents such as red or cayenne pepper, crushed mint leaves, or boric acid (with an anticaking agent) along their trails inside a house and wiping off countertops with vinegar. (However, boric acid is poisonous and should not be placed in areas accessible to small children and pets.) Repel mosquitoes by planting basil outside windows and doors and rubbing a bit of vinegar, basil oil, lime juice, or mugwort oil on exposed skin. You can also reduce mosquito attacks by not using scented soaps or wearing perfumes, colognes, and other scented products outdoors during mosquito season. Researchers have found that the $30 million U.S. consumers spend each year on electric bug zappers to kill mosquitoes is mostly wasted. Only about 3% of the insects they kill on an average night are female mosquitoes-the kind that bite. Kill cockroaches by sprinkling boric acid under sinks and ranges, behind refrigerators, and in cabinets, closets, and other dark, warm places (but not in areas accessible to children and pets) or establishing populations of banana spiders. Trap cockroaches by filling much of a bottle or large jar with raw potato, stale beer, banana skins, or other food scraps (especially fruits), greasing the inner neck of the bottle with petroleum jelly, and placing a small ramp leading into it. Repel flies by planting sweet basil and tansy (a common herb) near doorways and patios.

9. What Can You Do to Control Common Insect Pests and Weeds? Trap flies by making nontoxic flypaper by applying honey to strips of yellow paper (their favorite color) and hanging it from the ceiling in the center of rooms. Keep fleas off pets by using green dye or flea-repellent soaps, feeding them brewer's yeast or vitamin B, using flea powders made from eucalyptus, sage, tobacco, wormwood, or vetiver, or dipping or shampooing pets in a mixture of water and essential oils such as citronella, cedarwood, eucalyptus, fleabane, sassafras, geranium, clove, or mint. Trap fleas by using green-yellow light to attract them to an adhesive-coated surface or putting a light over a shallow pan of water before going to bed at night and turning out all other lights, emptying the water every morning, and continuing this for a month. (Fleas are attracted to heat and light, but they cannot swim.) Rid a house of fleas by sprinkling carpets with desiccant powders, such as Dri-Die, Perma-Guard, or SG-67 to dry them or diatomaceous earth (or diatom powder) to kill them. Diatom powder can be purchased in bulk at stores that sell it for use in swimming pool filters. It is also found in some gardening stores under the name of Permatex. Because it contains fine particles of silicate, you should wear a dust mask when applying this powder to avoid inhaling tiny particles of silicate. Control lawn weeds by raising the cutting level of your lawn mower so the grass can grow 8-10 centimeters (3-4 inches) high. This gives it a strong root system that can hinder weed growth; the higher grass also provides habitats for spiders and other insects that eat insect pests. Pull weeds and douse the hole with soap solution or human urine (which is high enough in nitrogen to kill the weed).

10. Second Generation Pesticides • Began in 1939 with discovery of DDT by Paul Muller:Nobel prize in 1948 • Primarily synthetic organic compounds • 630 biologically-active (pest killing) compounds with 1820 inert ingredients combine to make 25,000 pesticides See Table 20-1 p. 514

11. Second Generation Pesticides • Broad-spectrum agents: Toxic to many species • Narrow-spectrum agents: toxic to narrow group of organisms • Target species: species pesticide is to act on. • Nontarget species: species that is effected as a result of pesticide use and is not inteded to be such as beneficial insects

12. The Case for Pesticides • Save human lives • Increase supplies and lower cost of food • Increase profits for farmers • Work better and faster than alternatives • Health risks may be insignificant compared to benefits • Newer pesticides are becoming safer • New pesticides are used at lower rates

13. Characteristics of an Ideal Pesticide • Kill only target pests • Harm no other species • Break down quickly • Not cause genetic resistance • Be more cost-effective than doing nothing

14. The Case Against Pesticides • Genetic resistance • Can kill nontarget and natural control species • Can cause an increase in other pest species • The pesticide treadmill • Pesticides do not stay put • Can harm wildlife • Potential human health threats

15. Figure 20-4Page 516 Rise of Genetic Resistance to Pesticides 600 500 400 Number of species 300 200 100 0 1950 1960 1970 1980 1990 2000 2010 Year Gypsy moth caterpillar Boll weevil Insects and mites Plant diseases Weeds

16. Pesticide Regulation in the United States • Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA):established by Congress in 1947 and amended in 1972 it requires the EPA to approve all use of commercial pesticides. • All pesticide companies must test their products for toxicity to animals and extrapolate to humans before they can be registered for use. • Tolerance levels:level of pesticide residue allowable on fruits and vegetables when a consumer eats it.

17. Pesticide Regulation in the United States • EPA Evaluation of chemicals: more than 600 active ingredients approved for use in pre 1972 pesticide products are to be reevaluated for cancer, birth defects, or other heath risks. They have only evaluated 10% in over 30 years. • Inadequate and poorly enforced: Blame difficulty and expense of determining the health effects of chemicals. Also the falsification of data from a pesticide company that allowed more than 200 pesticide active ingredients to be registered.

18. Food Quality Protection Act (FQPA) • Established in 1996 • Requires pesticide companies to verify safety of active ingredients in children and infants • Allows 10 fold pesticide tolerance level for infants and children • Requires the EPA to consider exposure to more than one pesticide when setting tolerance levels • Requires the EPA to develop rules for program to screen for estrogenic and endocrine effects by 1999 (still not accomplished by 2002)

19. Why Control Pests? In most cases the primary goal of pesticides is to eradicate pests in the area affected However many believe it should be to keep the crop damage to an economically tolerable level. Economic threshold is the point at which the economic losses outweigh the cost of applying more pesticides. Tough to determine. Concern is with insurance spraying to be on the safe side. May purchase pest loss insurance Another concern is with cosmetic spraying

20. Economic Threshold Fig. 20-6 p. 520

21. Other Ways to Control Pests • Adjusting cultivation practices • Use genetically-resistant plants: pest and disease resistance • Biological pest control • Insect birth control • Hormones and pheromones • Ionizing radiation • Spraying with hot water • Irradiate foods

22. Variety of alternative pest control methods Biological pest control Synthetic hormones

23. Integrated Pest Management • Ecological system approach • Reduce pest populations to economic threshold • Field monitoring of pest populations • Use of biological agents • Chemical pesticides are last resort