Integrated Pest Management

IPM

Reading Assignment:

Norris et al., Chapter 1. Pests, People, and Integrated Pest Management. Pp. 1 – 14.

Define “Pest”

FIFRA Definition of “Pest”

(1) any organism that interferes with the activities and desires of humans or (2) any other form of terrestrial or aquatic plant or animal life or virus, bacteria, or other micro-organism (except viruses, bacteria, or other micro- organism on or in living man or other living animals) which the Administrator declares to be a pest under section 25(c)(1).

A Working Definition of “Pest”An injurious and noxious or troublesome

living organism [that] does not include a virus, bacteria, fungus or internal parasite that exists on humans or animals (British Columbia Pesticide Control Act,1997)

Includes insects, weeds, plant pathogens, birds, non-human mammals and other organisms which pose non-medical problems to humans and non-veterinary problems to animals

A pest must cause injury

In order for an organism to be considered a pest, a damaging stage of the organism must be present in high enough numbers to cause actual injury to something valued by people.

“Pest” is not a property of a species

Being a pest is not an inherent property of a species but, rather, a species (along with its population and age distribution at a given time and place) and a human valuation of the item being injured or damaged.

Four things required to “make” a pest (Fig. 1-6 from text)

1. Pest species must be present at the right stage

2. Environmental criteria must be met.

3. Crop must be a susceptible variety and growth stage.

4. All of the above must occur at the same time.

This is a pathosystem concept

• Pathogen – host – environnment triad must all be right in order for an outbreak of disease.

• When pest – crop – environment right, leads to “damage”.

Pest damage to crops is significant.

From Fig. 1-9

How do pests become pests?

1. New crop introductions

2. New organism introductions

3. Production system practices

4. Removal of limiting factors

5. Low tolerance

The Pest Complex• The specific collection of pest species

attacking a specific commodity or cropping system at any given time and location.

• A given complex is divisible into different “groups”:– Invertebrates (arthropods, molluscs)– Vertebrates (mammals, fish, birds)– Weeds (perennials, summer/winter annuals)– Plant Pathogens (fungi, bacteria, viruses,

nematodes)

Each pest species has a given status within a complex

• Key pests• Minor pests• Secondary pests• Occasional pests• Potential pests• Chronic pests• Migrants• Accessory Species

– Vectors (Pest status often linked with pathogen)– Alternate Hosts

Pests are often classified by the type of injury that they cause

General Terms

• Direct Pests

• Indirect Pests

• Medical/Veterinary

Pest Injury versus Damage

Injury – The effect that the pest has on the crop or commodity.

Damage – The effect that injury has on man’s valuation of that crop or commodity.

For crops, “Injury” is biological and “Damage” is economic. For non-crops, “Injury” = “Damage”.

Working Concept for DamageV

alu

e

Injury

Maximum Value

{

Mea

sura

ble

Dam

age

} Economic Damage

Loss in value is greatenough to warrantcontrol action.

Organisms that cause economic damage are the ones of interest in

pest management

Introducing “Pest Management”• “Management” -- a process by which

information is collected and used to make good management decisions to reduce pest population impacts in a planned, coordinated way.

• Requires:– Tolerance – Information– Strategy

IPM Defined

IPM – A system that maintains the population of any pest, or pests, at or below the level that causes damage or loss, and which minimizes adverse impacts on society and environment.

Attempts to balance the benefits of pest control actions with the costs when each is considered in the broadest possible terms.

Balancing costs and benefits can be done at various levels

PesticideApplication

Cost

PestDamageAvoided

Cost of UsingAll Available

Tactics

Impact onDamage from

Total Pest Complex

Total Cost toFarmer, Environment,

and Society

Total Benefitto Farmer and

Society

Incr

ea

sin

gly

Co

mp

reh

en

sive

Dec

reas

ingl

y C

ompl

ex

BenefitsCosts

The Pest Management Continuum

Pest Management at the Crossroads

See Handout.

Distribution of US Cropland Over the IPM Continuum

Tot

al U

S C

rop

Acr

eage

Source: Benbrook Consulting Services Analysis of Data in Adoption of IPM in U.S. Agriculture, ERS/USDA, 1994

Limitation on IPM is Macro vs. Micro Economics

Cos

t to

Far

mer

(M

icro

)

Cos

t to

Soc

iety

(M

acro

)

No IPM

Low Medium High

(Biointensive)

Farmer Cost

Social Cost

IPM Continuum

Proponents of one flavor often attack other flavors

As an example, read the paper by Ehler & Bottrell in the Reading Assignments for Jan 14.

Come Prepared to Discuss

Two Basic Decision Categories in IPM

Most Control Decisions Combine One of Each of the Following:

1. Tactical vs. Strategic• Tactics – Individual control options• Strategies – Combinations of Tactics

2. Preventative (Prophylactic) vs. Curative (Therapeutic)

• Preventative – Before pest is a threat• Curative – When pest is threatening

Hypothetical Strategy

Tactics

Preventative

Preventative

Rescue

IPM Strategies are Implemented Via Programs

• Programs include pest monitoring and decision tools

• Monitoring & decision tools tie into the strategy.

Strategy vs. Program (Strategic Plan)

Strategy Pest Management Program

The Evolution of IPM

• Pest management is at least as old as agriculture.

• It has evolved along with agriculture and technology

• Generally, when technology as advanced, so has pest management (and vice versa).

• Read Chapter 3 in text: Historical Development of Pest Management. Pp. 47 - 64

Four Logical Periods

• Before WWI

• Between WWI & WWII

• Between WWII & 1962 (Silent Spring)

• 1962 onward

Before WWI

• Periods of great advancement followed by decline.

• Advancing periods characterized by:– Scientific inquiry into the nature of crops and

pest biologies– Agricultural production for profit, specifically,

for well-developed export markets.

Early Examples

4,000 – 5,000 BC Early China

2,500 BC Summerians

1,000 BC Egyptians

400 – 200 BC Greeks

200 BC – 100 AD Romans

1500 – 1700 AD Baconism

Major Events in Baconism

• Voyages of Discovery

• Printing & Woodcuts

• Perspective in Art

• Microscope Invented

• First Naturalists

• Agricultural Markets Develop

• Scientific Method

During the 19th Century

• Great strides in biological knowledge (e.g. germ theory, evolution, genetics).

• Industrial revolution leads to large scale farming and commercial markets

• Modern pest groups are recognized (insects, weeds, pathogens)

• Potato famine creates incentive for government funding of pest controls.

19th Century Pest Control Advances

• Pressurized spray equipment nozzles invented

• First modern success in biological control

• First modern success in host plant resistance

• Modern cultural tools developed

• Most key pests’ biologies understood

By WWI

• Modern pest tactics were available but only a few were practical.

• Developed countries were being invaded by major foreign pests.

Between WWI & WWII

Pest Control Depended on Relative Crop Value

• High Value Crops – Became pesticide-oriented: Improved equipment and chemicals

• Low Value Crops – Management-oriented. Emphasis on plant breeding, cultural methods, basic science & ecology

During the 1940’s

• 1940 – DDT patented as an insecticide

• 1942 – BHC found insecticidal

• 1943 – 2,4-D found effective as a herbicide

• 1946 – Gerhard Schrader hired by Bayer

• 1946 – Houseflies found resistant to DDT

During 1950’s

Organic chemical pesticides become routine on all crops

• Viewed as “modern” farming

• Low risk, “cost of business”

• Few/no regulations

• High prices/demand for US exports

• Problems would not be addressed until 1962

Problems Arising During the 1950’s

• Pest Resistance

• Bird/Fish Kills

• Human Poisonings

• Secondary Pests

• Biomagnification

“Pesticide Treadmill”

1. Spray, kill pest & natural controls. Pest comes back. Repeat until…

2. Resistance in primary pest. Increase application rates. Kill broader range of natural controls.

3. Induce secondary pest4. Begin spraying for secondary pest until…5. Resistance in secondary pest6. Change chemicals. Repeat sequence.

IPM Evolution Continued

Reading Assignment

Norris et al. Chapter 2. Pests and Their Impacts. Pp. 15 - 45

Silent Spring in Context of its Time

In the 10 years before Silent Spring…• Many new innovations were introduced.

Pesticides were viewed as one of them.• Widespread attitude was that man could

control nature. Pesticides were a manifestation of that view.

• After the depression & war, people wanted to believe that the govt & corporations could be trusted.

Silent Spring Coincided with Other Events

• 1962 – John Glen’s first orbital flight.• 1962 – Thalidomide taken off market

(problem identified 11/61, public outrage throughout 1962).

• 1962 – Cuban Missile Crisis• 1961 – 1963 – MLK’s movement climaxes• 1961 – 1963 – US increased presence

from 900 to 16,000 in Viet Nam• 1963 – JFK assassinated

Silent Spring Aftermath

• 1963 – President’s Science Advisory Committee issues report calling for reducing pesticides’ effects.

• 1963 – Senate calls for creation of Environmental Protection Commission

• Early – mid ’60’s – Increased sensitivity in analytical equipment enables detection of ppb’s. Including other chemicals.

• 1965 – First pesticide food tolerances

As the Effects Spread …

• Public became increasingly negative toward chemical companies.

• 1970 – EPA established.

• 1972 – DDT banned (biomagnification)

• 1973 – IBP project started– Emphasized pest control as a system– Introduced pest modeling/decision tools– Only for insects

IPM Concept Solidifies in the 1970’s

• 1975 – First textbook, Metcalf & Luckman (former had been criticized in SS)

• 1978 – CIPM project replaces IBP– Included weeds & plant pathogens– Included economic analyses

• 1978 – KY statewide IPM program began

IPM Becomes Ingrained

• 1984 – IPM becomes an annual federal budget item

• Large-scale scouting programs rise, decline, and stabilize in the 1980’s

• 1993 – National IPM Initiative: 75 % of US cropland to have IPM by 2000

• 2000 – National effort to develop “Crop Profiles” and “IPM Strategic Plans”

Current Status

• IPM widely recognized as the proper approach to dealing with pests in production agriculture.

• Implementation is up to individual farmers so it varies considerably

• Concepts are well established but the technology continues to improve.

Significance of Pests in IPM

By Wednesday, Read Norris et al. Chapter 5, Comparative Biology of Pests

Impact Related to Direct & Indirect Effects

Comparison of Direct and Indirect Pests

Characteristic Direct IndirectCommodity Marketable Non-Marketable

Yield-Pest Relationship

Simple Complex

Pest Status Usually Key Pest Any

Pest GroupInsects & Pathogens

Any

Farmer Tolerance Low Higher

General Impact of Pests -- Injury

• Consumption of plant parts

• Chemical toxins, elicitors, and signals

• Physical damage

• Loss of harvest quality

• Cosmetic damage

• Vectoring of pathogens

• Direct contamination

General Impact of Pests – Non-injury

• Costs incurred to implement controls

• Environmental and social costs

• Regulatory costs (embargoes, quarantines, shipment costs, etc.)

Crop Injury in More Detail

• Crop Injury– Tissue Injury

• Leaves • Structural • Roots • Flowers and Fruiting/Reproductive Tissues• General Systemic Injury

– Weed Effects• Competition for Water, Light, Nutrients• Allelopathy• Other Economic Effects

Tissue Injury to LeavesAbscission -- Leaf prematurely dropped by the plant, often while still green.

Tissue Injury to LeavesBleaching Leaf turns white or nearly so. Usually caused by using the wrong herbicide.

Tissue Injury to LeavesChlorosis Leaf tissue loses its chlorophyll and turns yellow. May occur in spots.

Chlorosis in soybeans. Individual leaves (left) and at the field level (right).

Tissue Injury to LeavesCrinkling Leaf takes on a crinkled texture. Usually associated with viruses or toxic effects of saliva from homopterous insects.

Crinkling may occur throughout the leaf (left) or may be confined to edges (right).

Tissue Injury to LeavesCupping and Curling Leaves cup up or down or they curl inward from the edges.

Downward cupping along main vein of each leaflet in soybeans caused by Bean Common Mosaic Potyvirus

Tissue Injury to LeavesEdge Feeding Leaves chewed and eaten from the edges. Feeding lesions can have smooth or jagged edges. Usually caused by insects w/chewing mouthparts.

Leaf edge feeding on rhododendron leaves by adult black vine root weevils.

Tissue Injury to LeavesHole Feeding Leaves have holes chewed through them. Caused by insects w/chewing mouthparts.

Yellow poplar weevil adult feeding on yellow poplar

Tissue Injury to LeavesMines Caused by small, immature beetles or flies that live in-between the upper and lower leaf surfaces. The shape of the mine, along with the plant species being attacked, is useful in identifying the pest species involved.

Frass-linear leaf mine on birch leaf. Mines come in many shapes.

Tissue Injury to LeavesMottling Leaf is not uniform in color but is, instead, a mottled mixture of different shades of green to yellow.

Soybean leaf mottling caused by the Bean Pod Mottle Virus.

Tissue Injury to LeavesNecrosis Areas of dead tissue which usually sloughs off over time.

Necrosis simply means dead tissue and may occur in any pattern. Necrosis may be in spots (top left), on leaf margins (above), or follow leaf veins (bottom left). Other patterns are possible as well.

Tissue Injury to LeavesRolling Leaf is rolled up like a cigar. Usually caused by caterpillars that use the rolled leaf as a pupation chamber.

Leaves may be rolled entirely (above) or only partially (left).

Tissue Injury to LeavesShothole Small holes in a straight line across the leaf. Usually caused by insects that bore through the developing leaf when the un-emerged leaf is still rolled up in the plant’s whorl.

Tissue Injury to LeavesSkeletonization Leaf tissue between the veins is removed but the veins remain intact leaving a skeleton-like appearance.

Lindin leaf skeletonized by Japanese beetle. Note that the distal leaf tissue is relatively normal looking indicating that the leaf veins are fully functional.

Tissue Injury to LeavesSpots Caused by fungal, bacterial, and viral diseases. Spots vary in size, shape and number and may be solid or only peripheral (e.g. ring spot, frog-eye spot).

Bacterial leaf spot on pepper

Fungal leaf spot on soybean

Viral ring spot on purple cone flower

Tissue Injury to LeavesStippling Large numbers of tiny pin-prick feeding lesions cause by mites or other minute herbivores with piercing-sucking mouthparts.

Leaf stippling by leaf hoppers (sucking insect). Non-uniform pattern. Stippling = dead cells surrounding feeding puncture.

Tissue Injury to LeavesWindowpaning One side of the leaf is scrapped off leaving the other side intact and translucent. This gives the feeding lesion a window-like appearance. Primarily caused by some young beetle and moth larvae.

Cereal leaf beetle windowpaning on wheat (left); European corn borer windowpaning on corn (right).

Structural Tissue Injury

• Galls (may be on any tissue)

• Interference with transport– Xylem injury– Phloem injury

• Interference with structural support

• Shape/appearance impact– Abnormal growth– Shoot dieback

Galls

Western gall rust on Ponderosa pine branch

Soybean roots with galls from root knot nematode (right) vs. healthy root (left).

Galls on oak leaves from cynipid wasps

Olive knot gall (caused by Pseudmomonas bacteria) on olive main trunk

Can occur on all tissues; leaves, stems/trunks, branches, roots, etc.

Ash flower galls caused by a mite

Structural Tissue Injury -- Xylem

Many insects, such as the squash vine borer feed on xylem tissue.

Tomato wilt is caused by fungi in the genus Fusarium which plugs xylem tissue preventing water/mineral transport.

Structural Tissue Injury -- Phloem

Phloem discoloration and necrosis caused by spiroplasma infection.

Bark beetle gallery (right): The adult Beetle lays a line of eggs along a gallery. The grubs hatch, eat phloem tissue until they mature.

Phloem discoloration by San Jose scale on apple.

Structural Tissue Injury – Interference with Structural Integrity

Stalk breakage (lodging) caused by fungal stalk rot (left) and European corn borer (right)

Structural Injury – Abnormal Growth

Many plant pathogens and some insects cause abnormal growth in plants. Common forms are called rosettes (above) and witch’s brooms (right).

Root Injury – Fibrous Roots

Varying degrees of corn rootworm injury (left) and resulting lodged plants (right)

Phytophthora root rot on alfalfa (left); Fusarium root rot on soybean (right)

Root Injury – Storage Organs

Black rot on carrot (left), nematode injury to carrots (middle), carrot weevil injury (right)

Flower & Fruit Injury

Codling moth in apple

Apple scab on apple (right)

Left: Western flower thrips feeding injury on impatiens.

Above: Bean pod mottle virus in soybeans (left) vs. uninfected beans (right)

Weed Effects

Weed Groups• Algae (aquatic systems)• Mosses/liverworts (turf & nurseries)• Ferns/horsetails (pastureland, horticultural

crops)• Gymnosperms (rangeland, forests, long-term no-

till systems)• Angiosperms [monocotyledon & dicotyledon]

(annuals, biennials, perennials)

Weed Impacts

• Competitive -- yield loss (quantity and quality)

• Parasitic effects (cf Norris et al., p 23 – 24)• Mechanical interference with farm

implements• Other incidental

– Seed contamination– Land valuation– Health & safety (hay fever, toxins, fire hazard)

Comparative Biology of Pests

Chapter 5 is divided into 3 principal segments

1. Concepts in Pest Population Regulation

2. Dissemination, Invasion, and Colonization Processes

3. Pest Genetics

Comparative Biology of Pests

• Concepts in Pest Population Regulation1. Reproduction

2. Fecundity & Fertility

3. Population Generation Time

4. Longevity & Mortality

5. Quiescence and Dormancy

6. Heat Summation & Degree Days

7. Molting & Metamorphosis

8. Life Tables

9. Basic Life Cycle Models

1. Reproduction -- “Vivipary”

Flowers are replaced by tiny plantlets which detach and grow into new plants. A form of asexual reproduction. These plants grow where there is a short growing season or where it is shady with few pollinators. This example is a wild onion Allium, where the flowers in the umbel inflorescence are replaced by vegetatively produced bulblets (little bulbs), and these bulblets sprout on the parent plant.

In Plants

1. Insect Reproduction

Oviparity -- Eggs deposited shortly after fertilization

Ovoviviparity -- Female deposits a larva or nymph instead of an egg

Viviparity -- Female feeds embryo after development has begun

Paedogenesis -- Larvae give birth without becoming an adult

Parthenogenesis -- Development without fertilization

Polyembryony -- A single egg results in more than one individual

1. Reproduction

Good for IPM Bad for IPM

Sexual 1. Can manage resistance

2. Mating disrupt. possible

More plastic, better able to overcome tactics

Asexual 1. Strain/race geographically specific

2. Can’t overcome effective controls

1. More inoc. (path & weed)

2. Faster popn. growth (all are reproductive)

Note: Many serious species have both sexual & asexual periods or stages.

Individual and Population Development Time

• Includes:2. Fecundity & Fertility

3. Population Generation Time

4. Cycles per Season – note terms in Norris et al., p. 99.

5. Longevity and Mortality

• Affects management response time

Understand Generic Life CyclesMany insects, some pathogens & nematodes, many mammals, summer annual weeds

Some insects, some mammals, most winter annual weeds

Many nematodes, multivoltine arthropods, polycyclic pathogens, small mammals.

Weed seedbanks, some pathogens, cyst nematodes

Ecological Basis for Pest Management

Part I. Ecosystems and Pest Organisms

Ecological Basis for Pest Management

• Part I -- Ecosystems & Pest Organisms

• Part II -- Ecology of Interactions of Pests

• Part III -- Ecosystem Biodiversity and IPM

• Part IV -- Applying Ecological Principles to Managing Pest Populations

This is a 4-part unit:

Assignment for Friday, Feb. 6

Find an article (preferably online) that applies an ecological principle to pest management. Hand in one page containing a copy of the abstract of the article (with title and reference) and a brief description of the article and how an ecological principle was applied to a pest management problem. Identify which of the three ecological chapters from the text (Chap. 4, 6, or 7) your article most closely relates. We will group the articles by chapter and everyone will make a 2-3 minute presentation on his or her article.

Why Study Ecology in IPM?

• History of IPM is a history of applied ecology

• Managing pests often relies on exploiting a pest’s ecological weaknesses.

• Alternatively, one may manage the ecology in order to make a crop less vulnerable to pests.

• Future of IPM lies in increasingly sophisticated ecological manipulations.

Ecosystems & Pest Organisms

1. Ecosystem Organization & Succession

2. Definitions & Terminology

3. Trophic Dynamics

4. Limiting Resources & Competition

1. Ecosystem Organization & Succession1. Species : "groups of actually or potentially interbreeding natural populations that

are reproductively isolated from other such groups" (Ernst Mayr)

2. Individual: A single organism (bacterium, weed, nematode, insect); not always obvious.

3. Population : a collection of individuals of one species that exists in some defined geographical area

4. Guild: a group of species that exploit the same resource in a similar manner

5. Community: a group of populations occurring in the same geographical area

6. Ecosystem: a community of living organisms and the abiotic framework that supports them. Agroecosystem – An ecosystem dominated by humans that typically has few common or major species (crops) and numerous rare or minor species (some of which are pests).

7. Landscape: a cluster of interacting ecosystems

Landscape Ecology

Crop Field

Crop Field

Crop Field

Crop Field

Crop Field

Extinction

Surrounding Ecosystem(s)

Migration

Landscape Ecology

• Involves multiple populations interacting in time and space between several different ecosystems.

• “Blinking Lights” Theory

• Often presented as an application of “Island Biogeography” -- Concentrates on local population/species extinctions.

Island Biogeography & Landscape Ecology

• When one species goes extinct, it is replaced so that there’s an equilibrium

• Replacement species is not necessarily the same as the extinct population…may be another from the same guild.

• Smaller islands have higher extinction rates than larger islands.

• Extinction rates increase with increasing distance between islands

Wilson & MacArthur studied species extinction rates on small islands & found:

Lesson: Size AND distance both affect species equilibrium

Which is better?

Lesson: Agroecosystems can fragment landscapes

• Some species are stranded on their islands – increasing the chance that they might go locally extinct.

• Reduction in biodiversity is good for pests which thrive in the agroecosystem anyway.

• Note that reduction is in species diversity – includes number of spp. AND number of individuals.

Green Network Concept

• Maintain a network of contiguous patches & corridors that are not part of the agroecosystem.

• Specific Things to do can be found at:– http://

www.dal.ca/~dp/reports/zkidston/kidstonst.html#guidelines

– http://www.dal.ca/~dp/reports/zkidston/guidelines.html

• Enforcement/implementation?

Ecological Succession

• An orderly, directional and therefore predictable process of development that involves changes in species structure and community processes over time.

• Results from a modification of the physical environment by the community and culminates in a stabilized ecosystem in which maximum biomass and symbiotic functions are maintained.

Succession Sequence

Agriculture typically keeps the ecosystem at this end.

Natural tendency is to go to the right (cf Fig. 4-1 in text, p. 69)

Fig. 4-1, p. 69

Implications of Early Succession Systems

1. Trophic cycles are disrupted (adds to the biodiversity problem)

2. Species good at invasion are favored

3. Nutrient cycles are altered, biomass does not accumulate/cycle

4. Energy flow is not webbed but, instead, directed toward one commodity

5. Ecology “resets” each cropping season

2. Definitions and Terminology

• Carnivores and Omnivores can be monophagous, oligophagous, or polyphagous

• Host organisms do not necessarily host parasites, herbivorous insects also feed on “hosts”

• Note distinction between parasites and parasitoids. Both can be internal or external (ectoparasites).

• Add “Pathogen – A microbial parasite that causes disease. Primary – attacks a healthy host, secondary – attacks an injured/weakened host.”

Refer to pp. 71 – 72 in text. Notes on those definitions:

3. Trophic Dynamics

Large subject that is central to pest injury and pest management.

• General Concepts

• Bottom-up versus top-down processes

• Basic food chains – note the diagrams– Pathogens– Weeds– Webs (generalized and animal-based)

General Concepts of Trophic Dynamics

What is a trophic system?

Top-Down vs Bottom-up Trophic Systems

• Top-Down – Producers (plants) limit the growth of primary consumers (herbivores) which limit the growth of primary carnivores & so on.

• Bottom-up – Top consumers limit growth at the next lowest level throughout the chain.

• Note that “limit” can be an economic effect, not necessarily an ecological one

Top-Down vs Bottom-Up Trophic System

With bottom-up control, increased production results in greater productivity at all trophic levels. With top-down control, consumers depress the trophic level on which they feed, and this indirectly increases the next lower trophic level.

BottomUp

Top Down

Grazer vs. Decomposer Systems

Grazer food chains begin with algae and plants and end in a carnivore.

Decomposer chains are composed of waste and decomposing organisms such as fungi and bacteria

Food Webs

• Two or more trophic systems linked within a given ecosystem or landscape.

• Three main categories in agroecosystems:– Animal-based (animal production systems)– Above-ground, plant based (Crop Production

Systems [CPS])– Soil food web in CPS’s

• The two CPS webs interact but are usually managed separately

Components Soil Food Web

• Herbivores – Root feeders (arthropods, microbes)

• Pathogens – Microbes that attack underground organisms

• Shredders – Chew up organic matter, increasing surface area & decomposition rate

• Decomposers – Decompose organic matter• Predators – Maintain stability of above

populations

Pest/weed biocontrol components in red

Limiting Resources & Competition

• Populations can be limited in several ways– Food & water– Shelter/Reservoir

• Limitation can occur at any stage or time (e.g. overwintering)

• Effectiveness dependent on population ecology of individual pest. Life history strategy important part of that ecology.

r- vs. K-selected pestsCharacteristic r-Selected K-Selected

Reproductive Rate

High Lower

Longevity Short Long

Competitive? No Yes

Habitat Disturbed Stable

General Strategy

Invasive Domination

Examples Annual weeds, pathogens, nematodes

Perennials, mammals, some insects

Managing for one may help otherCharacteristic r-Selected K-Selected

Reproductive Rate

High Lower

Longevity Short Long

Competitive? No Yes

Habitat Disturbed Stable

General Strategy

Invasive Domination

Examples Annual weeds, pathogens, nematodes

Perennials, mammals, some insects

Interactions Between Pest Categories

Read Chapter 7, Ecosystem Biodiversity & IPM

Fig. 6-1, p. 129

Note: No crop, management, beneficial species, or environmental effect. Biological interactions between pests only.

Interactions Between Pest Categories

• Trophic Relationships• Environmental (Habitat) Modification Result• Mechanical Effects• Response to Control Tactics

– Non-pesticide– Pesticide-related

• “Interactions” may be:– Pest-pest or pest-crop– Measured in injury or damage

This subject excludes the direct effects of:

• Interactions within pest categories (i.e. – pathogen – pathogen). But note that viruses, bacteria, fungi, & nematodes are different “categories” for Norris et al.

• Interactions between pests and their natural enemies

Reading Assignment for Monday

1. Check the Reading Assignments page• Note the assignments that are covered in

the exam

2. Chapter 8, pp. 172 – 208

Direct vs. Indirect According to Brown

• Direct: (Pest A + Pest B) -> Outcome

– Outcome may be biological or economic– If Spp. A & B are present, outcome is realized

• Indirect: Pest A -> Affector -> Pest B -> Outcome

– “Affector” may be another pest, management action, environmental effect, etc.

– A & B & Affector must all be present for outcome to occur

Direct Interaction(A + B) -> Outcome

Four possibilities

1 – Together, one (or both) pest

2 – A helps B

3 – A needs B4 – A and/or B

are worse together

Not Crop Pest

Crop Pest

Not Crop Pest Crop Pest

A

B

Examples by Category

1. Green vegetable bug becomes a problem if provided with non-pest weeds.

2. Ants tending aphids.

3. Weeds as alternate hosts for pathogens.

Overwintering hosts for aphids.

4. cf. item 4 on p. 136 (cutworms & chinch bugs) & item 5 on p. 137 of text.

Read these sections closely

• Habitat Modification – Understand and be able to ‘compare & contrast’:– Altered Resource Concentration– Altered “Apparency”– Microenvironment Alteration

• Interactions Due to Physical Phenomena– Physical Damage to Host– External Transport– Internal Transport

Ecosystem and Biodiversity in IPM

• Why did monocultures become so widespread?

• Can we expect monocultures to continue?

• If so, how can we make biodiversity relevant? At what spatial scale will this relevancy be realized (cf. p. 157).

Frequent Disadvantages of Biodiversity in CPS

1. Increasing plant diversity decreases density of marketable commodities

2. Increased density/diversity of herbivores (cf. p. 136 – 137)

3. Increased alternative hosts for pathogens4. Larger complex of species to be managed5. More complex production system/equipment needed to

deal with mixed plantings6. Dilution of inputs (fertilizer, water)7. Decreases in commodity quality common (size, color,

texture, etc.)8. Increased cost of commodity as a result of the above

Contrast with benefits noted on p. 158

Two Issues Must Be Resolved in a Biodiversity & IPM Discussion

1. A. Does the discussion concern the use of biodiversity in IPM or B. does it concern the use of IPM to maintain biodiversity?

• If A, emphasis is biocontrol, if B, emphasis is pesticide reduction

2. A. Does the discussion concern managed biodiversity within crop fields or B. does it concern associated biodiversity in surrounding ecosystem?

• If A, emphasis is on tillage & cropping systems, if B, emphasis is on landscape ecology.

4. Applying Ecological Principles to Managing Pest Populations

• IPM is an implementation vehicle for ecological knowledge.

• Degree of implementation varies, recall the IPM continuum.

• Many examples available, see reading for “A Whole Farm Approach to Managing Pests.” In particular, note the sidebars.

Implementation of Ecological Principles in IPM

• Goal is preventative – keep pest populations from causing damage.

• Requires increased knowledge, observation, management – Increased costs not immediately offset

• Must return multiple benefits for adoption

• Usually helps, seldom adequate in itself

Two Approaches to Using Ecological Knowledge in IPM

• Ecologically-Based Pest Management (EBPM). Established in the NAS book of the same name.

• Farmscaping – Mostly for biological control.

• Widely used in organic production systems

Ecologically—Based Pest Management

• Basic Ideas:– Refocus pest management on maintaining ecological

balance– Change management emphasis from individual

species/components to processes, interactions between multiple species

• 3 Basic Principles– Safety– Durability– Profitability

EBPM Status

• Much research is funded annually

• Profitability issues remain, EBPM systems often not as profitable or are too risky compared to existing IPM systems

• EBPM generally relies on collective efforts (e.g. cooperatives, public oversight, etc.) which have yet to be accepted on a wide scale.

Farmscaping

• The practice of designing and maintaining habitats that attract and support beneficial organisms, used to improve crop pollination and to control pest species.

• Emphasis on landscape ecology for targeted objectives.

• Many examples are available. Here are a few.

Many similar themes along these lines

Here’s a small sample. Follow the links to read a little about each one & get the idea.

• Permaculture

• Biointensive Pest Management

• Regenerative Agriculture

• Biodynamic Agriculture

Notes on First Hour Exam

• Scheduled for Monday, Feb. 23• Covers everything through this point

– Chapters 1 – 7 in text– All assigned reading– Lecture notes– Be sure that you can do the exercises

• Structure will be short answer (~2/3 of grade), longer answer (most of the rest). Might be some matching.

• Note that the course has been re-organized since last time so old exams are helpful only for structure.

• Exam starts promptly at 8:00 & papers are collected at 8:50.