1. Chapter 22
The Pesticide Dilemma

2. Perfect Pesticide Easily biodegrade into safe elements
Narrow Spectrum - kill target species only
Remain put in applied location in environment

3. Prior to the 1940’s 1st generation Inorganic - lead, mercury, arsenic
Persistent and stable
Toxic to animals
2. Organic (botanicals) - nicotine, pyrethrin, rotenone
Biodegradable
Toxic to bees and fish
3. Synthetic Botanicals = second generation
Persistent and stable (DDT)
Toxic and nonpolar

4. Second-Generation Pesticides
Synthetic botanicals (DDT) - persistent & stable
DDT -

5. The Major Pesticide Groups
Chlorinated hydrocarbon (DDT)
Broad-Spectrum persistent – nonpolar
Organophosphates
Broad-spectrum: very toxic to mammals, birds, fish
Nerve agent
Biodegradable
Carbamates
Broad-spectrum similar to organophosphates but less toxic to mammals - degrades rapidly

6. Major Herbicides Nonselective herbicides glyphosate, aka: Round-UpTM
Selective herbicides - 2,4,5-T & 2,4-D kills broad-leaved plants
Nonselective herbicides
glyphosate, aka: Round-UpTM

7. Lawn Care

8. Malaria Snapshot
247 million cases of malaria in 2006, causing about 880,000 deaths, mostly among African children.
Approximately half of the world's population is at risk of malaria – mostly low income countries
Control:
1. DDT
2. Insecticide-treated nets
3. Increasing mosquito resistance to insecticides and drugs

9. Benefit - Disease Control

10. Big Business Problem: Evolution of genetic resistance
creates a pesticide treadmill
Kills most pests
Resistant survive
Numbers increase
INCREASE
Pesticide application
EVEN MORE
New population genetically resistant

11. Problem: Imbalances in the Ecosystem
Lemons

12. Pull on a star and you find the universe attached
Problems:
Mobility
Persistence
Bioaccumulation
Biological Magnification
Fat soluble (lipophilic - nonpolar) substances cannot be excreted in urine, a water-based medium, and so accumulate in fatty tissues. Metabolized polar molecules are excreted.

13. Biomagnification

14. Biomagnification
Example: Effect of DDT on bald eagles

15. Laws Controlling Pesticide Use
Food, Drug, and Cosmetics Act (1938) - recognized need to regulate pesticides in food
Federal Insecticide, Fungicide, and Rodenticide Act (1947) - regulated effectiveness of pesticides
Pesticide Chemicals Amendment (1954) - set standards & testing for pesticides in food
Delaney Clause (1958) - no cancer causing agent may be used
Food Quality Protection Act (1996) - amended Delaney and reduced time to ban pesticide from 10 years to 14 months
Estimates of Risk of Cancer from Pesticide Residue 8.8 deaths per 10,000 people

16. The Manufacture and Use of Banned Pesticides
The Global Ban of Persistent Organic Pollutants - Stockholm Convention

17. Alternatives to Pesticides
Integrated Pest Management
Management of pest not eradication
Education of farmers

18. Alternatives to Pesticides
Biological Controls
Naturally occurring diseases, parasites, & predators
Pheromone and Hormone Traps
Reproductive Controls - Sterile-male technique
Quarantine - if foreign pest detected
Parasitic Wasp:

19. Using Cultivation Methods to Control Pests
Crop rotation
Interplant mixtures of plants
Planting, fertilizing, and irrigating at proper time
Strip cutting or leaving margins
Refuge Planting

20. Strip Cutting / Border Cutting
Strip cutting was developed as a management tool to reduce the migration of lygus bugs from forage alfalfa into cotton. It consisted of harvesting alternate strips (250 to 300 ft wide) of alfalfa at two-week intervals throughout the summer to assure that some alfalfa was always available to attract lygus bugs. This system worked well as an insect management strategy, it created operational constraints, since the strips had to be managed as separate fields within a field thus complicating irrigation and harvesting operations. An alternative strategy called border cutting. Narrow (10-ft) strips of uncut alfalfa were left. At the following harvest, these strips ("old hay") were cut. The old hay was blended with new growth alfalfa. There were concerns about the nutritional quality of the blended bales, so border cutting was not readily adopted.

21. Alternatives - GMO’s Bacillus thuringiensis (Bt)
Corn & Cotton (roundup ready)
non-target species monarch butterfly
Soil accumulation of Bt
1. Growers plant 80% corn acres with Bt corn - 20% planted with non-Bt corn (refuge area).
2. Refuge area must be within 1/2 mile of Bt field.

22. Resistance Management
Create a “refuge” (no pesticide applied)
Avoid repeated use of same pesticide
Mechanically pull resistant weeds or vacuum bugs: non-chemical methods
IPM