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 DDT - DDT -

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

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

Lawn Care

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

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

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

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

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

Problem: Imbalances in the Ecosystem Creation of New Pests Lemons

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

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.

Biomagnification

Example: Effect of DDT on bald eagles

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

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.

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

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.

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

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 Estimates of Risk of Cancer from Pesticide Residue 8.8 deaths per 10,000 people

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