Environmental Science: Toward a Sustainable Future Richard T. Wright Pests and Pest Control PPT by Clark E. Adams Chapter 16

Pests and Pest Control The need for pest control Promises and problems of the chemical approach Alternative pest control methods Socioeconomic issues in pest management Pesticides and policy

Formosan Subterranean Termite Invades the French Quarter

The Need for Pest Control Any organism that has a negative effect on human health or economics Any organism that is noxious, destructive, or troublesome  Plants or animals (see Fig. 16-2) Formosan termite Fire ants Aedes mosquito Medfly

Pest Control Purposes Protect our food Protect our health Convenience

Pesticide Use in the United States

Philosophies of Pest Control Chemical technology  Use of chemicals to kill large numbers of the pest  Short-term protection  Environmental and health consequences

Philosophies of Pest Control Ecological pest management  Control based on pest life cycle and ecology  Control agent may be an organism or chemical (more on next slide)

Philosophies of Pest Control Specific to pest and/or to manipulate a part of the ecosystem Emphasizes protection from pest

Promises and Problems of the Chemical Approach Development of chemical pesticides and their successes Problems stemming from chemical pesticide use

Development of Chemical Pesticides First-generation pesticides (inorganic)  First attempt at chemical technology  Toxic to humans and agricultural plants  Pests developed resistance

Development of Chemical Pesticides Second-generation pesticides  Used after WW II  Organic chemical  Toxic to humans and agricultural plants  Pests developed resistance

The DDT Story DDT: the magic bullet  Extremely toxic to insects; seemed nontoxic to humans and other mammals  Cheap  Broad-spectrum and persistent (more next slide)

The DDT Story DDT: the magic bullet  Effective for disease prevention (typhus fever, malaria)  Expanded agricultural production  Paul Müller awarded Nobel prize in 1948

Aerial Spraying

Problems Stemming from Chemical Pesticide Use Development of resistance by pests Resurgences and secondary pest outbreaks Adverse environmental and human health effects

Resistance Chemical pesticides lose effectiveness Resistant pest populations produce next generations

Genetics of Pest Resistance RR x rr Nonresistant x resistant R nonresistant gene R r resistant gene Rr nonresistant offspring Rr r

Genetics of Pest Resistance Rr x Rr Heterozygous nonresistant x nonresistant Rr RRR dies Rr dies rRr dies rr SURVIVES!

Pesticide Resistance

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 Bugs Are Coming! Time Magazine, July 12, 1976, page 38

The Pesticide Treadmill

Human Health Effects Cancer, dermatitis, neurological disorder, birth defects, sterility, endocrine system disruption, immune system depression. Agricultural workers suffer acute poisoning during pesticide application.

Human Health Effects Aerial spraying and dumping bring pesticides in contact with families and children. Soldiers exposed to agent orange in Vietnam suffered high rates of cancer and other diseases.

Environmental Effects DDT led to the decline in populations of several bird species  Bald eagle  Peregrine falcon Bioaccumulation Biomagnification

Nonpersistent Pesticides Substitutes for banned pesticides Break down after a few weeks Can still be harmful because of:  Toxicity  Dosage  Location

Alternative Pest Control Methods Cultural control Control by natural enemies Genetic control Natural chemical control

Complex Life Cycle of Insects

Cultural Control

Genetic Control Plants or animals are bred to be resistant to the attack of pests.  Chemical barriers  Physical barriers

Genetic Control Introduction of genes into crops from other species: transgenic crops. Sterile males are released into pest population.

Control Using Natural Enemies

Natural Chemical Control A volatile chemical produced by the opposite sex of a species which alters the reproductive behavior of the opposite sex.  Perfumes  Colognes  After shave  Natural body odors

Natural Chemical Control Manipulation of pests’ hormones or pheromones to disrupt the life cycle Japanese beetle trap (see Fig )

Socioeconomic Issues of Pest Management Pressures to use pesticides Integrated pest management Organically grown food

The Economic Threshold

Integrated Pest Management (IPM) An approach to controlling pest populations using all suitable methods— chemical and ecological—in a way that brings about long-term management of pest populations and also has minimal environmental impact

Pesticides and Policy Fifra: Federal Insecticide, Fungicide, and Rodenticide Act FQPA of 1996: Food Quality Protection Act Pesticides in developing countries

FIFRA or FQPA? Pesticides evaluated on intended use and potential effects to human health and the environment Training and protection of agricultural workers Protection of public from risks of pesticides used on food

End of Chapter 16