Chapter 22 The Pesticide Dilemma

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

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

Second-Generation Pesticides Synthetic botanicals (DDT) - persistent & stable DDT - https://www.youtube.com/watch?v=v2EtxYxEKww

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

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

Lawn Care

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

Benefit - Disease Control

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

Problem: Imbalances in the Ecosystem Lemons

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.

Biomagnification

Biomagnification Example: Effect of DDT on bald eagles

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

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

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: http://www.youtube.com/watch?v=vMG-LWyNcAs

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

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 - 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.

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