Chapter 1: Pest Management

Learning Objectives

By the end of this chapter you should be able to:

• Define "pest" and name the four main pest groups with examples.
• Explain why pest identification matters and how misidentification causes control failure.
• List the six general pest management methods and tell them apart.
• Define IPM and list five reasons to use it.
• Describe how selectivity and persistence affect chemical controls.
• Explain how pest population levels trigger control (ET, EIL, action threshold).
• Distinguish prevention from suppression from eradication.
• List the common reasons pesticide applications fail.
• Explain why mode of action matters in resistance management and list tactics to delay resistance.

What Is a Pest?

The definition is broader than most people think. It covers anything from a deer eating crops to a fungus rotting stored grain to a clothes moth eating wool. The exam tests whether you recognize this broad scope.

Pests cause harm in several ways:

• Compete with humans for crops and livestock
• Destroy clothing, furniture, and buildings
• Reduce the beauty and recreational value of landscapes
• Invade homes during winter months
• Spread disease to humans and animals

Pest Problems Throughout History

These historical examples show up as background context, but the exam rarely asks about dates. Focus on cause-and-effect relationships:

• Black Plague (14th century Europe): A bacterial disease spread by rat fleas. When rats (the normal host) became unavailable as a food source, fleas fed on humans. Controlled by managing rats and fleas.
• Irish Potato Famine (19th century): Caused by late blight, a fungal disease. Over a million Irish migrated to the U.S. Today managed with resistant cultivars, sanitation, and fungicides.
• Malaria: A parasitic protozoan transmitted by mosquitoes. In 2010, 219 million cases and 660,000 deaths. Managed with antimalarial drugs, insecticides, environmental modification, and bed nets.
• Mountain pine beetle & emerald ash borer (21st century): Destructive beetles; the emerald ash borer was accidentally introduced from Asia. Both managed with preventive insecticidal treatments.

Pest Control Over the Years

Early Methods

Weeds were pulled, rats were clubbed, beetles were plucked from foliage. Ancient nonchemical methods included burning (950 B.C.), Egyptians using fishnets over beds against mosquitoes (440 B.C.), and Romans using rat-proof grain bins (13 B.C.). The first known use of natural enemies — Arabian growers moving predaceous ants to control pest ants on date palms (1000 A.D.).

Early Chemical Use

Sumerians used sulfur for mites and insects (2500 B.C.). Chinese used mercury and arsenic for body lice (500 B.C.). Plant-derived insecticides included hellebore, nicotine, and pyrethrins.

Bordeaux mixture — lime + copper sulfate — was discovered in late 19th-century France. A farmer sprayed it on grapevines to deter thieves and found it also controlled downy mildew. It's still used as a fungicide today.

The Synthetic Era

Until the 1940s, pesticides came from plants and inorganic compounds. During WWII, DDT saved soldiers from insect-borne diseases and launched the synthetic pesticide industry. Pesticides became dominant because they were effective, cheap, provided season-long protection, and worked with other production practices.

The Backlash

Pesticide resistance to DDT was documented as early as 1947. The Colorado potato beetle has developed resistance to every major group of insecticides.

In 1962, Rachel Carson's book Silent Spring focused public attention on DDT and other chlorinated hydrocarbons. These were a problem because of:

The EPA was created in 1970 by Congress. In 1972, EPA banned DDT in the United States.

Pest Recognition

The first step in pest management is always accurate identification. Once identified, you can learn the pest's life cycle, behavior, damage signs, favorable conditions, susceptible life stages, and known control methods. Misidentification causes control failure even when nonchemical methods are used.

How to Identify Pests

• Consult reference materials: ID books, Extension bulletins, field guides, online ID keys.
• If unsure, send specimens to a university diagnostic lab or local specialist. Collect multiple specimens when possible.
• Use a hand lens or microscope for small insects, mites, nematodes, and plant pathogens.
• Note the host (the plant or animal on which the pest lives) and the location — both are major ID clues.
• Note environmental conditions and the time of year of collection.

Pests look different at different life stages. Weed seedlings don't resemble mature plants, and insects change dramatically from egg through immature stages to adult.

Characteristic Damage

Pests leave clues:

• Birds and rodents: Characteristic nests.
• Insects: Feeding damage and excrement.
• Mammals: Burrows, gnaw marks, tracks, trails in grass, feces.
• Weeds: Unique flowers, seeds, fruits, or growth habits.
• Fungi and other pathogens: Specific damage, deformation, or color changes in host tissues.

The Four Main Pest Groups

1. Weeds — undesirable plants.
2. Invertebrates — insects, mites, ticks, spiders, snails, and slugs.
3. Disease agents / pathogens — bacteria, viruses, fungi, nematodes (roundworms), mycoplasmas, and other microorganisms.
4. Vertebrates — birds, reptiles, amphibians, fish, and rodents and other mammals.

Pest Management Methods: Natural vs. Applied

Abiotic factors are natural (non-living) controls — climate (wind, temperature, sunshine, rain), air or water pollution, and topography (rivers, lakes, mountains). When these don't hold pests in check, humans apply control.

There are six applied control methods. Memorize all six:

1. Biological
2. Chemical
3. Cultural
4. Genetic
5. Mechanical/Physical
6. Regulatory

1. Biological Control

In an undisturbed ecosystem, most organisms are kept in check by natural enemies. When an organism moves to a new area without those enemies, it can explode into pest status. Biological control reunites pests with their natural enemies.

Three approaches:

• Classical biological control (importation): Finding the pest's native enemies in its home country, extensive testing to make sure THEY won't become pests, then importing, rearing, and releasing them. Once established, they provide long-term control with no further human intervention. Importation of biological control agents is strictly regulated.
• Mass release (augmentation): Releasing large numbers of natural enemies periodically into fields, orchards, or greenhouses. Does NOT yield long-term results — releases must be repeated. Examples: predatory mites for spider mites; parasitic wasps; praying mantids, lady beetles, and lacewings as general predators.
• Conservation: Maintaining healthy populations of native natural enemies. Plant diverse pollen and nectar sources. Choose pesticides less toxic to beneficial insects. Apply pesticides at lower-than-label rates when recommended and effective.

2. Chemical Control

Chemical control uses naturally derived and/or synthetic chemicals. Benefits: effectiveness, speed, ease, reasonable cost.

Pesticide Types by Pest Group

• Avicides — pest birds
• Bactericides — bacteria
• Chemosterilants — sterilize insects or pest vertebrates
• Defoliants — cause leaves to drop
• Desiccants — promote drying/moisture loss
• Disinfectants (antimicrobials) — microorganisms
• Fungicides — fungi
• Growth regulators — alter plant/animal growth
• Herbicides — weeds
• Insecticides — insects and related arthropods
• Miticides (acaricides) — mites
• Molluscicides — snails and slugs
• Nematicides — nematodes (roundworms)
• Ovicides — eggs
• Pheromones — attract insects
• Piscicides — pest fish
• Predacides — predatory vertebrates (e.g., coyotes)
• Repellents — repel a wide range of pests
• Rodenticides — rodents

Pesticide Classes

Each pesticide type contains several classes (families). For example, insecticide classes include organophosphates, organochlorines, carbamates, pyrethroids, botanicals, insecticidal soaps, and microbials. Pesticides within a class share similar chemistry, mode of action (how they kill), or site of action (the biological system affected).

Selectivity

Movement in/on the Host

Persistence

Persistence = how long the pesticide stays active. Residual pesticides last weeks, months, or years. Short-lived pesticides may only last a few hours.

3. Cultural Control

Two big sub-categories: cultural practices and sanitation.

Cultural Practices

• Mowing, irrigation, aeration, and fertilization for healthy turf.
• Cultivation (plows, disks, cultivators) — one of the most important weed controls.
• Selection of crop plant varieties.
• Timing of planting and harvesting.
• Irrigation management and timing.
• Crop rotation.
• Trap crops.
• Mulching (plastic, straw, shredded bark, wood chips).
• Cover crops.

Sanitation

Eliminating food, water, or shelter that pests need. Examples:

• Removing weeds that harbor pest insects or rodents.
• Destroying diseased plant material and crop residues.
• Managing manure to reduce flies in livestock operations.
• Draining standing water for mosquitoes.
• Closed garbage containers and frequent pickup.
• Removing soil, trash, and wood debris from around buildings (reduces termite and fungal rot damage).

4. Genetic Control

Examples:

• Livestock breeds selected for physical traits that resist pests, or for physiological disease resistance.
• Plant varieties naturally resistant to insects, pathogens, or nematodes.
• Plants that repel pests or contain toxic substances.
• Genetically modified crops: Bt corn and potatoes (produce a protein that kills caterpillars), Roundup Ready corn/cotton/soybean (herbicide tolerance), Liberty Link corn (herbicide tolerance).

5. Mechanical/Physical Control

Controls that kill the pest directly or make its environment unsuitable.

Mechanical Examples

• Rodent traps — snap traps, sticky traps, pheromone-baited traps.
• Traps can kill or snare-and-release.

Physical Examples

• Mulches for weed management.
• Steam soil sterilization for disease control.
• Deer fences, window screens, cloth mesh over fruit trees.
• Sealing cracks, crevices, and small openings in buildings to exclude insects, rodents, bats, birds, and squirrels.
• Sticky bands painted around tree trunks to stop crawling insects.

Environmental Modifications

• Refrigeration protects stored food from insects (lowered temp kills insects, stops feeding, prevents egg hatch).
• Bright lights in attics discourage roosting bats.
• Lowering humidity of stored grain reduces mold and insect damage.
• Increasing air movement in greenhouses prevents fungal disease.

6. Regulatory Control

Government-directed programs for pests that seriously endanger public health or threaten widespread damage to crops, livestock, forests, or ornamentals. Too big for individuals to handle.

Government agencies are also authorized to destroy:

• Weeds causing fire hazards.
• Plants harboring harmful pathogens or animals.
• Plants noxious to people or livestock.
• Diseased or infected livestock or poultry.
• Weeds in residential, commercial, and industrial areas.

Mosquito abatement is a key regulatory control function. Mosquito abatement laws allow state agencies to drain or treat standing water.

Integrated Pest Management (IPM)

IPM is NOT "no pesticides." Pesticides are still a tool — just one of many. IPM balances control with environmental and health protection.

Five Reasons to Practice IPM

1. Preserves a balanced ecosystem. Chemicals kill beneficial organisms, disrupt food chains, and let other pests dominate.
2. Pesticides can be ineffective. Resistance develops. Pests survive if the chemical doesn't reach them, washes off, or is applied wrong.
3. Saves money. Prevents damage; avoids unnecessary pesticide purchases; may even reduce medical costs (e.g., asthma triggered by cockroach/rodent allergens).
4. Promotes a healthy environment. Fewer pesticides = less risk to groundwater and wildlife; less container and waste disposal.
5. Maintains a good public image. IPM is respected and requested in food, turf, homes, schools, and public health.

Five Components (Steps) of IPM

1. Identify the pest and understand its biology.
2. Monitor the target pest.
3. Develop the pest management goal (prevention, suppression, or — rarely — eradication).
4. Implement the IPM program.
5. Record and evaluate results.

Pest Types Within IPM

• Key pests — cause major damage regularly unless controlled. Many weeds, cockroaches, and rodents are key pests (cockroach skins and rodent hairs trigger asthma).
• Secondary pests — only become a problem AFTER a key pest is controlled or absent. Some weeds only show up once dominant weeds are gone. Some fleas/ticks only target humans when pet hosts are removed.
• Occasional pests — only troublesome once in a while, due to life cycles, environmental changes, or human activities. Example: ants moving indoors after a rainstorm destroys an outdoor food source.

Monitoring

Regular monitoring measures pest populations and resulting damage. Techniques include:

• Scouting — carefully looking at plants/animals over time.
• Trapping.
• Weather and temperature data for life cycle tracking.
• Predictive models for specific insects and plant diseases.

Pest Population Thresholds

Not every pest requires control. Thresholds tell you when to act.

Economic Threshold vs. Economic Injury Level

The ET must be set BELOW the EIL. If you wait until the pest reaches the EIL, you've already lost money equal to your control cost — plus now you're paying for the control. Setting ET below EIL triggers control before economic damage occurs.

Action Threshold

For pest managers NOT in commodity production (urban, structural, school, public health), the action threshold is used instead of the ET. It's a predetermined, unacceptable pest level — often expressed as pests per unit area.

• Below threshold: No control measures, but continue monitoring and sanitation inspections.
• At or above threshold: Implement IPM strategies.

The action threshold can be ZERO for:

• Pests that transmit human pathogens (mosquitoes + West Nile virus).
• Pests creating a public health emergency (cockroaches, rodents).
• Wood-boring insects that will destroy a tree.

Action thresholds vary by pest (stinging insect in a classroom vs. a foraging ant), by site (storage room vs. school infirmary), and by season. In urban landscapes, thresholds consider economic value, ecology, AND aesthetics — not just economics.

Prevention, Suppression & Eradication

These are the three possible goals of an IPM program. Know which fits each scenario.

Prevention

Stop pest damage BEFORE it occurs. Includes:

• Planting weed- and disease-free seed.
• Growing resistant plant varieties.
• Cultural controls to prevent weed seeding.
• Timing plantings and harvests to avoid pest pressure.
• Sanitation to reduce pest buildup.
• Exclusion from the target area.
• Conserving natural enemies.
• Proper water/nutrition to reduce plant stress.
• Preventive pesticide uses: Preplant or preemergence herbicides (weed seeds known to be present). Fungicides applied BEFORE infection when conditions favor infection. Pesticides applied to lumber before construction.

Suppression

Reduce pest populations to tolerable levels or below the EIL. Does NOT eliminate all pests. Suppression is the goal of most pesticide applications. Other suppressive tactics: cultivation, mowing, releasing biological control agents.

Eradication

Complete elimination of a pest from a designated area.

• Works well in: Buildings and confined spaces where pests can be excluded after elimination. E.g., eliminating cockroaches, rats, and mice from commercial food establishments.
• Rarely works at scale: Large areas are expensive and often fail. Regulatory eradication targets exotic/introduced pests with area-wide threats.

Why Pesticide Applications Fail

Memorize these seven reasons — each one is a potential exam question.

1. Pest misidentification. Example: Bt controls caterpillars but NOT sawflies. Look-alikes matter.
2. Wrong dosage. Not applied at the correct rate per label.
3. Wrong product for the pest. Some herbicides kill grasses only, others broadleaves only, others both. Always check the label for the target pest.
4. Bad application timing. Pest not present, or in a life stage not susceptible. Insects are most vulnerable when IMMATURE. Weeds are easiest to kill BEFORE flowering and seeding. Or — the current pest may be a new infestation that arrived AFTER treatment.
5. Wrong application equipment. Concealed pests (under leaves, in soil, in stems/fruits) need specific equipment. Air-blast sprayer for pests under apple leaves. Granular applicator during planting for soil-dwelling pests.
6. Environmental conditions. Rain washes pesticide off. Temperature extremes and wind move it off target. Don't apply just before a storm.
7. Pesticide degradation in storage. Old product. Granular pesticides stored in humid conditions absorb moisture, clump, and deactivate.

Pesticide Resistance

How it develops: heavy use kills susceptible individuals in a population. The resistant ones survive and reproduce. Over generations, the resistant population grows until the pesticide stops working.

Initially you can compensate with higher labeled rates and more frequent applications. Eventually even that fails.

Types of Resistance

Resistance can develop to:

• A single pesticide.
• An entire chemical class (more common).
• Two or more classes with DIFFERENT modes of action (cross-resistance).

What INCREASES the Likelihood of Resistance

• Continual use of the same chemical class (e.g., only pyrethroids, only growth regulator herbicides).
• Frequent applications.
• Greater persistence of the chemical (more exposure time).
• Many generations per year + many offspring per generation — insects, mites, fungi, rodents are especially prone.

Tactics to Prevent or Delay Resistance

1. Use new pesticides with different modes of action. The label has a mode-of-action code number at the top (e.g., Group 4A Insecticides — Neonicotinoids; Group 2 Herbicides — ALS Inhibitors). Know that new products are costly, complex, and can breed resistance quickly too.
2. Reduce dosages when possible — fewer pests killed means less selection pressure.
3. Apply over limited areas (spot treatments). Leaves a large pool of susceptible individuals to interbreed with resistant ones, diluting resistance genes.
4. Rotate modes of action between generations. Treating alternate generations with different-MOA products decreases selection pressure.
5. Monitor and treat only when necessary — not on a calendar schedule.
6. Keep good application records so treatment history is known.
7. Use all available pest management techniques (IPM) to extend the useful life of current pesticides.

Key Terms Cheat Sheet

Quick glossary of every definition you're expected to know:

• Pest: Undesirable organism injuring humans, plants, animals, products, or substances.
• Abiotic factors: Natural non-living controls (climate, topography, pollution).
• Bioaccumulation: Buildup of a chemical within one organism's fatty tissue.
• Biomagnification: Increased concentrations at each higher level of the food chain.
• Host: The plant or animal on which an organism lives.
• Mode of action: HOW a pesticide kills the pest.
• Site of action: The specific biological system affected within the pest.
• Selective pesticide: Toxic to some pests but not others.
• Nonselective pesticide: Toxic to a wide variety of pests.
• Systemic pesticide: Absorbed and moved within the treated plant or animal.
• Contact pesticide: Not absorbed; must directly touch the pest.
• Persistence: How long a pesticide remains active.
• Residual pesticide: A long-persisting pesticide.
• IPM: Strategy using a wide range of methods to keep pests below damaging levels with least environmental risk.
• Key pest: Causes regular major damage unless controlled.
• Secondary pest: Only a problem when a key pest is absent.
• Occasional pest: Only a problem once in a while.
• Economic threshold (ET): Pest density needing control to prevent reaching EIL.
• Economic injury level (EIL): Pest density where losses = cost of control.
• Action threshold: Predetermined unacceptable pest level (non-commodity settings).
• Quarantine: Preventing entry of pests into pest-free areas.
• Eradication: Eliminating a pest from a designated area.
• Mosquito abatement: Public-health mosquito control; laws allow agencies to drain or treat standing water.
• Pesticide resistance: Ability of a pest to tolerate a pesticide that once controlled it.