What is a Pesticide? Why Use Pesticides?What is a Pesticide? Why Use Pesticides?

Photograph from USDA/ARS.

Stephen J. Toth, Jr. Wayne G. BuhlerDepartment of Entomology Department of Horticultural ScienceNorth Carolina State University North Carolina State University

Webster’s Definitions of“Pest” and “Pesticide”

Webster’s Definitions of“Pest” and “Pesticide”

Pesticide: “A chemical substance used to kill pests, as rodents and insects.”

Photograph from USDA/ARS.

Pest: “A plant or animalthat is harmful or injuriousto man.”

Photograph from Mike Stringham.

Regulatory Definition of “Pesticide”Regulatory Definition of “Pesticide”

Code of Federal Regulations, Title 40, Volume 16, Part 152

“A pesticide is any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest, or intended for use as a plant regulator, defoliant, or desiccant.”

Photograph from USDA/ARS.

Common Types of PesticidesCommon Types of PesticidesAlgicides: control algae in lakes, pools and other sitesAntifouling agents: kill or repel organisms on underwater surfacesAntimicrobials: kill microorganisms (bacteria, viruses)Attractants: attract pests (to lure a pest into a trap)Biocides: kill microorganismsDisinfectants: kill or inactivate disease-producing micro- organismsFungicides: kill fungi (cause mildew, molds, etc.)Fumigants: gas or vapor to destroy pests in buildings/soilHerbicides: kill weeds and other unwanted plants

Common Types of PesticidesCommon Types of PesticidesInsecticides: kill insects and other arthropodsMiticides: kill mites that feed on plants and animalsMicrobial pesticides: microorganisms that kill, inhibit or out compete pest organismsMolluscicides: kill mollusks (snails and slugs)Nematicides: kill nematodes (plant-feeding roundworms)Ovicides: kill eggs of insects and mitesPheromones: biochemicals used to disrupt insect mating behaviorRepellents: repel pests such as insects, birds and mammalsRodenticides: control rodents (rats and mice)

Additional Types of PesticidesAdditional Types of PesticidesDefoliants: cause leaves or other foliage to drop from a plant, usually to facilitate harvestDesiccants: promote drying of living plant tissueInsect Growth Regulators: disrupt life processes of insects (molting, pupa maturing to adults, etc.)Plant Growth Regulators: alter the growth, flowering or reproduction of plants (excluding fertilizers)

White flower of cotton plant. Photograph from Jack S. Bacheler.

What is not considered a Pesticide?What is not considered a Pesticide?• Drugs used to control the diseases of humans or

animals, which are regulated by the FDA

• Fertilizers and plant nutrients used to promote plant health and survival

• Biological control organisms except for certain microorganisms (i.e, ladybugs, wasps, etc.)

• Low-risk substances such as cedar chips, garlic and mint oil are exempted from regulation by EPA

• Pest control devices (i.e., mousetraps) are not pesticides, but subject to labeling requirements

What are Biopesticides?What are Biopesticides?• Microbial pesticides: contain a microorganism

(e.g., bacterium, fungus, virus, protozoan) as an active ingredient; example is Bacillus thuringiensis

• Plant-pesticides: pesticide substances that plants produce from genetic material that has been added to the plant; example is Bollgard cotton which contains gene to produce Bacillus thuringiensis

• Biochemical pesticides: naturally occurring substances that control pests by non-toxic means; examples include pheromones

Advantages of BiopesticidesAdvantages of Biopesticides• Usually less harmful than conventional pesticides

• Generally affect only target pests or closely related organisms (conventional pesticides have a more broad spectrum activity which is riskier to non-target organisms)

• Often are effective in very small quantities and decompose quickly in environment

• Can reduce dependence on the use of conventional pesticides (however, users must be knowledgeable of pest management and IPM)

Why Use Pesticides?Why Use Pesticides?“Humans have no divine right to their food supply; they must complete for it with weeds, plant diseases, insects, and other organisms.”

Corn earworm infesting corn.Photograph by Jack Bacheler.

Bacterial spot on pepper fruit.Photograph by David Ritchie.

(Grodner 1996)

Johnsongrass. Photograph by Dale Monks.

Numbers of Pest SpeciesNumbers of Pest Species• About 10,000 insects classified

as pests; these insects destroy our crops, attack livestock and transmit diseases

• At least 600 species of plants are classified as weeds; these weeds compete with crops for sunlight, nutrients and water

• Approximately 1,500 different fungi can cause plant diseases

Boll weevil on cotton boll.Photograph by Jack Bacheler.

Fruit rot of blueberries.Photograph by Bill Cline.

Green mold (Pencillium) on orange.Photograph by Turner Sutton.

San Jose scale damage to apple.Photograph by Marvin Williams.

Pests Damage FruitPests Damage Fruit

Fruit rot of blueberries. Photograph by Bill Cline.

Corn earworm on cotton. Photograph from USDA/ARS.

Sooty mold caused by insect honeydew. Photograph by Steve Bambara.

Japanese beetles feeding on blueberry foliage. Photograph by John Meyer.

Pests Damage FoliagePests Damage FoliageLeafminer damage. Photograph by Steve Bambara.

Tobacco mosiac virus. Photograph from NCSU Plant Pathology Dept.

Pests Damage Stems Pests Damage Stems and Branchesand Branches

Terrapin scales on blueberry stems. Photographs from John Meyer. Nectria canker on apple tree caused by

fungi. Photograph by Marvin Williams.

Pests Damage RootsPests Damage Roots

Black rot rot (CBR) of peanut. Photograph by Marvin Beute.

Damage to peanut crop caused by sting nematodes. Photograph from NCSU Plant Pathology Department.

Root knot nematode damage to the roots of okra plants. Photograph from NCSU Plant Disease and Insect Clinic.

Pests DamagePests DamageSeed and SeedlingsSeed and Seedlings

Black cutworm damage to seedling. Photograph by James Baker.

Western flower thrips damage to seedling. Photograph by James Baker.

Damping-off caused by soil-borne fungi. Photograph from Turner Sutton.

Pests Attack Humans and Animals,Pests Attack Humans and Animals,Damage StructuresDamage Structures

Norway rat. Photograph from Mike Stringham.

Asian tiger mosquito. Photograph courtesy of P. Koehler, University of Florida.

Economic Impacts of the Lossof Pesticides and Fertilizers

• Weekly food bills of middle-income consumers would increase 12%; 44% increase for low-income consumers

• The volume of grain and cotton exported from the U. S. would drop nearly 50%

• Cultivated acreage in the U. S. would increase by 10%; erosion would rise

• Crop production in the Southern U. S. would fall more than in other regions

Pesticide application to trees. Photograph by Ken Hammond.

Pest Outbreaks of Historic Proportions• From 1845-1851, potato famine in Ireland resulted from

fungal disease Phytophora infestans (late blight)

• Stem rust destroyed 30% of wheat crop in U. S. in 1930 and 3 million tons of wheat in Western Canada in 1954

Late blight of potato. Photograph by Turner Sutton. Wheat harvest. Photograph by Tim McCabe.

Pest Outbreaks of Historic Proportions

• Construction of the Panama Canal abandoned by French after 30,000 workers died of yellow fever (transmitted by mosquitoes)

• In 1853, 12,000 persons died from yellow fever in New Orleans; 23 epidemics in the city from 1718-1860

Asian tiger mosquito. Photograph courtesy of P. Koehler, University of Florida.

Pest Outbreaks of Historic Proportions• 65 million persons have died

of bubonic plague since the first recorded epidemic of the disease (caused by rat flea)

Norway rat. Photographfrom Mike Stringham.

References

• U. S. EPA, Office of Pesticide Programs. What is a Pesticide? (http://www.epa.gov/pesticides/whatis.htm)

• U. S. EPA, Office of Pesticide Programs. What is a Biopesticide? (http://www.epa.gov/biopesticides/ what_are_biopesticides.htm)

• Grodner, M. L.. 1996. Why Use Pesticides? SERA-IEG 1 Pesticide Fact Sheets. (http://ipmwww.ncsu.edu/ safety/Southern_region/pestwhy.pdf)