The Pesticide Dilemma Chapter 23

Perfect Pesticide 1.Easily biodegrade into safe elements 1.Narrow Spectrum - kill target species only 1.Remain put in applied location in environment

Prior to the 1940’s 1st generation 1.Inorganic - lead, mercury, arsenic Persistent and stable Toxic to animals 2. Organic (botanicals) - nicotine, pyrethrin, rotenone Easily biodegrade Do not persist Toxic to bees and fish 3. Synthetic Botanicals = second generation

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

Benefit - Disease Control

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 – most low income countries Economic toll Insecticide-treated nets Increasing mosquito resistance to insecticides

The Major Pesticide Groups Chlorinated hydrocarbon (DDT) Broad-Spectrum persistent – nonpolar Organophosphates Broad-spectrum: very toxic to mammals, birds, fish Nerve agent Degrades rapidly More toxic than Chlorinated Hydrocarbons Carbamates Broad-spectrum similar function to organophosphates but reversible and less toxic to mammals - degrades rapidly

Bioaccumulation Synthetic substances typically not metabolized - accumulate in fat Fat soluble (lipophilic) substances cannot be excreted in urine, a water- based medium, and so accumulate in fatty tissues.

Pull on a star and you find the universe attached Problems: 1.Mobility 2.Persistence 3.Bioaccumulation 4.Biological Magnification

Biomagnification

Example: Effect of DDT on bald eagles

Major Herbicides Selective herbicides - (2,4,5-T & 2,4-D – kills broad-leaved plants) Nonselective herbicides (glyphosate, aka: Round-Up TM )

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.

Lawn Care

Benefits - Initial Returns Crop production Savings of 3-5$ in crops for every $1 invested in pesticides

Big Business Problem: Evolution of Genetic Resistance Creates a pesticide treadmill Pesticide application Kills most pests Resistant survive Numbers increase New population genetically resistant EVEN MORE INCREASE

Benefits - Longterm? Problem: Evolution of Genetic Resistance # of species exhibiting genetic resistance to pesticides 30 fold increase in insecticide use since 1940

Problem: Imbalances in the Ecosystem Creation of New Pests Lemons

Alternatives to Pesticides Integrated Pest Management 1.Management of pest not eradication 2.Education of farmers

1. Using Cultivation Methods Interplant mixtures of plants Planting, fertilizing, and irrigating at proper time Crop rotation Refuge Planting Strip or border cutting (see next slide)

Strip Cutting / Border Cutting 1.Lygus bugs love alfalfa like cotton and hay as well 2.Strips ’ wide 3.Alfalfa harvested in two week intervals 4.Drawback - Complicated irrigation and harvesting due to mix

2. Resistant Crop Varieties 1.Plants have many natural mechanisms to keep insects at bay: repellent or toxic chemicals, thorns, hairs, and tough roots and stems. 2. May reduce need for various “cides” 3. Yields may drop since the plant puts its resources towards its defense. 4. Evolutionary arms race continues and insects may counter plants defense.

3. Natural Enemies (Biological Controls) Wasp Invaders 4 Min. 1.Predators 2.Disease 3.Parasites

4. Pheromone Traps

5. Other:Alternatives to Pesticides 1.Avoid repeated use of same pesticide 1.Reproductive Controls - Sterile-male technique 1.Quarantine - if foreign pest detected 1.Create a “refuge” (no pesticide applied) 1.Mechanically pull resistant weeds or vacuum bugs: non-chemical methods

Alternatives to Pesticides Integrated Pest Management Rice Production in Indonesia IPM introduced

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

Stockholm Convention The Global Ban of Persistent Organic Pollutants