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
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
Different Philosophies of Pest Control
Integrated pest management:
“using all suitable methods – chemical and ecological – in a way that brings about long- term 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
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
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)
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
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
nonresistant gene
R
r
resistant gene
Rr
nonresistant offspring
Rr
r Rr Rr
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.
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
Biomagnification
Aerial Spraying
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.
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
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.
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
