Pests and Pest Control The need for pest control Philosophies of control Development of Chemical Pesticides Promises and problems of the chemical approach Some of the more commonly used icides Alternative pest control methods Pesticides and policy The Need for Pest Control: Defining Pests Any organism that has a negative effect on human health or economics Any organism that is noxious, destructive, or troublesome Plants or animals termites Fire ants Medfly Kudzu Dandelions Purpose for pest control Protect food sources Protect health Convenience Monetary gains 1
Pests and Pest Control The need for pest control Philosophies of control Development of Chemical Pesticides Promises and problems of the chemical approach Some of the more commonly used icides Alternative pest control methods Pesticides and policy Different Philosophies of Pest Control Chemical technology Use of chemicals to kill large numbers of the pest Short-term protection Environmental and health consequences Ecological pest management Control based on pest life cycle and ecology Control agent may be an organism or chemical Specific to pest and/or manipulate a part of the ecosystem Emphasizes protection from pest 2
Different Philosophies of Pest Control Integrated pest management: using all suitable methods chemical and ecological in a way that brings about longterm management of pest populations and minimal environmental impact. Pests and Pest Control The need for pest control Philosophies of control Development of Chemical Pesticides Promises and problems of the chemical approach Some of the more commonly used icides Alternative pest control methods Pesticides and policy 3
Development of Chemical Pesticides First-generation pesticides (inorganic) First attempt at chemical technology Toxic to humans and agricultural plants Pests developed resistance Second-generation pesticides Used after WW II Organic chemical Toxic to humans and agricultural plants Pests developed resistance Pesticides & Types Pesticides general term for substance used to eradicate/remove harmful organisms Herbicides most not terribly harmful as soil bacteria break them down Trinitrophenol (agent orange) very toxic and implicated in birth defects/disorders Fungicides kills fungus Use copper and mercury as the active ingredients Acts as a toxin in animals Copper can be limiting nutrient for algae causing blooms and resulting ecosystem damage 4
Pesticides & Types Insecticides Organochlorines ddt - banned due to environmental effects on biota - peak use 72,000 tonnes in 1970 - banned for use in Britain and America, but still sold worldwide to developing countries with less strict environmental laws! aldrin metabolized in insects to form a neurotoxin - banned due to classification as a persistent organic pollutant, a carcinogenic and mutagenic. - last farm to use it was in Covina, CA in 1973 Organophosphates parathion & melathion - The later is newer and less toxic Pesticides & Types Rodenticides Usually involve anticoagulants or compounds that interact with normal rat chemistry to produce toxic substances May also include nuerotoxic compounds, fat soluble vitamins,. The list is long!!! (and pretty nasty for the rats) 5
Pests and Pest Control The need for pest control Philosophies of control Development of Chemical Pesticides Promises and problems of the chemical approach Some of the more commonly used icides Alternative pest control methods Pesticides and policy Promises and Problems of the Chemical Approach Promises? Problems stemming from chemical pesticide use 6
Problems Stemming from Chemical Pesticide Use Development of resistance by pests Chemical pesticides lose effectiveness Resistant pest populations produce next generations Resurgences and secondary pest outbreaks Adverse environmental and human health effects Genetics of Pest Resistance RR x rr Nonresistant x resistant r resistant gene R nonresistant gene Rr nonresistant offspring R Rr r Rr Rr 7
Crossing of Second Generation Rr x Rr Heterozygous nonresistant x nonresistant R r R RR dies Rr dies r Rr dies rr SURVIVES! Resurgence and Secondary Outbreaks Resurgences: after eliminating a pest, its population rebounds in even higher numbers than previous levels. Secondary outbreaks: outbreaks of species populations that were not previously at pest levels. 8
The Pesticide Treadmill Pest Problem Use of Chemical Pesticides resistance, resurgence, secondary outbreaks More Pest Problems Environmental effects Negative impact on human health Environmental Effects Bioaccumulation Occurs in individuals Biomagnification Occurs across trophic levels 9
Biomagnification Aerial Spraying 10
The DDT Story DDT: the magic bullet Extremely toxic to insects; seemed nontoxic to humans and other mammals Cheap Broad-spectrum and persistent Effective for disease prevention (typhus fever, malaria) Expanded agricultural production Paul Muller awarded Nobel prize in 1948 The reality? Human Health Effects of Pesticides Cancer, dermatitis, neurological disorder, birth defects, sterility, endocrine system disruption, immune system depression. Agricultural workers suffer acute poisoning during pesticide application. Aerial spraying and dumping bring pesticides in contact with families and children. 11
Pests and Pest Control The need for pest control Philosophies of control Development of Chemical Pesticides Promises and problems of the chemical approach Some of the more commonly used icides Alternative pest control methods Pesticides and policy Alternative Pest Control Methods Cultural control Control by natural enemies Genetic control Natural chemical control 12
Pests and Pest Control The need for pest control Philosophies of control Development of Chemical Pesticides Promises and problems of the chemical approach Some of the more commonly used icides Alternative pest control methods Pesticides and policy Pesticides and Policy FIFRA (Federal Insecticide, Fungicide, and Rodenticide Act) Requires that pesticides be evaluated for intended use and impacts on human health and the environment Requires the protection and proper training of those who work with pesticides FFDCA (Federal Food, Drug, and Cosmetic Act) & FQPA (Food Quality Protection Act) address the public protection from risks of pesticide residues on products for human consumption. 13
Pesticides in Developing Countries U.S. exports > 200,000 tons of pesticides each year = $1.6 billion (25% banned in this country). PIC: prior informed consent = exporting countries inform all potential importing countries on bans to restrict pesticide or other toxic chemicals. Back to Environmental Pollutions 14