Pws 331 Test 1

Front 1

Mechanisms of Resistance

Back 1

1) Antixenosis
2) Germination inhibition
3) Antibiosis
4) Hypersensitive response
5) Tolerance
6)Immunity

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Antixenosis

Back 2

pest behavior altered through chemical or physical means to deter or reduce colonization of the host plant

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Physical Antixenosis

Back 3

morphology of crop discourages attack. Ex. leaf characteristics such as hooks, hairs, glands and thicker cuticle

Front 4

Chemical Antixenosis

Back 4

secondary plant compounds inhibit or deter the pests

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Germination inhibation

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usually chemical in nature, affects spores of pathogens, eggs of nematodes, arthropods and weed seeds

Front 6

Antibiosis

Back 6

plant produces a toxin or reduces digestibility

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Hypersensitive response

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(very important for plant diseases)_ response – cells in immediate contact with the pest die, walling off the pathogen before it can spread into noninfected tissue. Common for pathogens and nematodes

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Tolerance

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supports feeding and reproduction of the pest with some damage, but without loss of product

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Immunity

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highest level of resistance to a pathogen, plant species are nonhosts to particular pests

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Horrizontal

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– usually incomplete resistance that extends across many pest races, controlled by many genes. Also called polygenic or durable resistance is not easily overcome, but may vary with environmental conditions

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Vertical

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gives complete resistance to a race, or several races of a pathogen but no impact on another race. Usually conferred by one or as many as three major genes, a new race of the pest can completely overcome this resistance

Front 12

Genetic Engineering

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Techniques that modify _genetic structure__ of the crop or pest genome, which is accomplished either by gene deletion or blocking, or by transferring genes from one organism to another.

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Nature Vector System

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uses the pathogenic bacterium Agrobacterium tumefaciens. Which uses plasmids (special DNA genes) that go into the host cell. Through the use of molecular biology, tumor-inducing genes can be deleted from the plasmids and cloned resistance genes can be inserted. The bacterium then inserts the plasmids carrying the resistance genes into the target host cells where they become incorporated into the host genome.

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Techniques Used to Transfer Genes

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1) Nature Vector System
2) Direct Plasmid fusion into protoplasts
3) Particle Bombardment

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Particle Bombardment

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shoots microscopic DNA-coated metal pellets at the target plant cells. Also called microinjection or biolistic injection.

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Direct Plasmid fusion into protoplasts

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protoplasts are naked plant cells (cell walls have been enzymatically removed). Also uses plasmids containing desired genes but they are developed in E. coli. The protoplasts are grown in a suspension culture that contains the plasmids, which can be taken up by the cells and integrated into the plant genome.

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Behavioral Control

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Actions of organisms or responses of organisms to their environment.

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Advantages of Behavioral Control

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1) Affect only the target pest and compatible with other control tactics
2) Resistance is not likely to develop

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Disadvantages of Behavioral Control

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1) Modify behavior by learning, avoid or bypass a control technique
2) Resistance

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Behavioral Control Tactics

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1) Vision based tactics
2) Auditory based tactics
3) Olfaction-based Tactics

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Vision-based tactics

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- to attract target arthropod, trap is typically covered with sticky material. Ex. yellow sticky traps for thrips, white flies, leaf minors, or red spheres to attract apple maggot flies

- inhibit some insects from landing on host plants

- attract and capture insects because of the phototactic response of insects

-Tactics for Vertebrate Pests (Vision-based)

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Tactics for Vertebrate Pests (Vision-based)

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1) Hanging dead animals in the crop area to deter birds
2) Scarecrows – recommended for discouraging sparrows
3) Reflective materials that move and glitter in the wind are used to deter birds

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Auditory-based Tactics

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1) Cannons, sound like a gun being discharged
2) Recordings of distress calls

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Olfaction-based Tactics

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- chemicals released to act as stimulants and/or mediate interactions among organisms. Ex. feeding attractants, repellants

- chemicals released by an individual and affect other individuals within the same species. Ex. aggregation, alarm, sex

- inorganic ions (K, Cs, Cl etc) repel pests

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Endoparasites and endoparasitoids

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consume their host from the inside. Ex wasps, some flies, fungi

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Ectoparasites

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attach to the outside of their host and suck the contents from the host.

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Facultative parasites

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obtain nutrition by feeding on nonliving decaying matter (saprotrophes)

Front 28

Obligate Arthropod Parasite Ex.

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Anagrus epos, parasite of the grape leafhopper, requires a suitable host at all times because it does not enter diapause. Grapes are deciduous and thus there are no grape leafhoppers to be parasitized in the winter. Anagrus survives by parasitizing a leafhopper on blackberries during the winter. In the spring, Anagrus returns to vineyards and grape leafhoppers. Vineyards near riparian areas where blackberries grow experience higher levels of biological control than do vineyards more remote from such areas

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Fundamental PrinciplesWhen Using Organism Biological Control

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1) Accurate Identification of the Target Pest
2) Source of beneficial organism
3) Specificity of agent
4)Culture, rearing, delivery of biocontrol agents
5)Ecosystem constraints
6) freedom from hyperparasites
7) Monitoring

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Freedom from Hyperparasites

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parasites or predators of the agent must not be introduced concomitantly or already be there. Ex. puncturevine seed weevil is limited by a parasite

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Monitoring

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an integral part of IPM, permits estimation of the proportion of the pest population that is under bio control. For parasites, such estimates are expressed as the percentage of the pest population that is attacked by a beneficial and the percentage that is not attacked. For predators the ratio of pest numbers to beneficial number is used.

Front 32

Ecosystem Constraints

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a beneficial agent will only succeed when the ecosystem conditions are suitable for its rapid population increase. Must evaluate environmental conditions and habitat suitability prior to introduction and release.

Front 33

Ecosystem Constraints :
Environment

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temperature range must be suitable. Example, Pediobius foveolatus, a parasitic wasp native to tropical India, was imported for the control of the Mexican bean beetle on soybean in temperate zones of North America. Pediobius is effective during the summer growing season but cannot survive the winter. Therefore, overwintering cultures are maintained in the lab and the wasps are re-released each year.

Front 34

Ecosystem Constraints:
Habitat suitability

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biological control agents require a relatively stable habitat for population growth and survival. Agroecosystems lack stability because of periodic tillage and harvesting.

Front 35

Culture, rearing, delivery of biocontrol agents

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if the natural enemy is to be released in large numbers it must be reared in artificial conditions, also for research purposes

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Specificity of agent

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beneficial organisms must not attack any nontarget organism useful to humans, or organisms native to natural ecosystems, ideally the beneficial has a very limited host range to the point it will die when the host is unavailable or go into a resting stage

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Source of Beneficial Organism

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suitable natural enemy must be used, which must either be exotic or endemic

Front 38

Source of Beneficial Organism: Exotic Agents

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brought in from outside the troubled area, foreign exploration is usually carried out in the geographic area where the pest originated

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Source of Beneficial Organism: Endemic agents

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beneficial organisms already present in the area, problem with endemic beneficials is they typically have their own natural enemies or higher-order organisms that feed on them

Front 40

Accurate Identification of the Target Pest

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correct taxonomic identification of the target pest is essential, otherwise the beneficial organisms selected for use may not feed on the target pest.

Examples of failures: Coffee Root Mealy bug in Kenya, herbivores against the wrong species of aquatic fern Salvinia

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Constraints To Organism Biocontrol

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1) Value to Humans
2) Ecosystem Stability
3) Lack of Adequate Control
4) Compatibility with other IPM Tactics
5)Contamination of Harvested Product
6) Agent Access to Pest Organism
7) Host Race Specificity
8) Host Specificity
9) Lack of Host Selectivity
10) Ecological Disturbance

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Ecological Disturbance

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nonnative agents must include consideration of possible nontarget effects. Ex. small Indian mongoose was introduced into the West Indies, Hawaiian Islands, Mauritius and Fiji to control rats in ag fields, rat control was not achieved because the mongoose is diurnal and rats are primarily nocturnal, mongoose is now considered a pest because it kills native birds.

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Lack of Host Selectivity

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beneficial agent may switch to another host

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Host Race Specificity

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beneficial agent exerts continuous selection pressure, thus host biotypes that best tolerate the natural enemy survive and reproduce. Ex. Skeleton weed in Australia, used a rust fungus (Puccinia chondrillina) for control, but control has decreased since first introduction, also Bt resistance in arthropods

Front 45

Host Specificity

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beneficial agent effectively induces replacement; especially in weeds, species-specific biological control may result in a secondary weed becoming dominant and does not resolve the overall weed management needs for a crop

Front 46

Contamination of Harvested Product

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residual biocontrol agents can themselves be a problem in the harvested product. Ex. lacewing eggs, damsel bugs, pest carcasses

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Agent Access to Pest Organism

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can the beneficial agent find its prey. Ex rosy apple aphid injects a toxin into apples leaves which causes them to curl, the aphid lives inside and is hidden from parasitic wasps

Front 48

Lack of Adequate Control

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it is not ecologically likely that biological control can attain 100% suppression, with fresh market crops where cosmetic appearance is important, less than 100% may be unacceptable. The population of the beneficial can only increase after that of the pest has increased

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Compatibility with other IPM tactics

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pesticides/chemicals can disrupt development or kill the beneficial agents. Selective “soft” pesticides or biopesticides

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Value to Humans

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people working in different groups perceive weeds differently and assign different values. Ex. yellow starthistle is viewed as useful by beekeepers, but an enormous problem in the rangeland of western U.S.

Front 51

Ecosystem Stability

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agroecosystems experience regular disturbance which is a serious limitation to the success of biological control, can increase stability by establishing refuges on the borders and weed strips within fields

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Types of Biological Control Using Other Organisms

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1) Classical Biological Control
2) Inoculative Biological Control
3) Augmentative Biological Control
4) Inundative Biological Control
5) Conservation Biological Control
6) Competitive Exclusion
7) Induction of Suppressive Soils

Front 53

Augmentative Biological Control

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biological control – periodic release of a natural enemy, usually endemic, that is already present (ex. lady bugs) but does not build up its population sufficiently or quickly enough to control the pest

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Conservation Biological Control

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attempts to maintain endemic biocontrol, accomplished through maintenance of habitat that can sustain beneficial organisms

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Inundative Biological Control

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mass release of the biological control agent that cannot reproduce and thus cannot attain adequate population size without human intervention, considered and treated as a biotic pesticide

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Classical Biological Control

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natural enemy introduced from the region where the pest species is native, once the agent is introduced and established, classical biological control usually is self-sustaining

Front 57

Induction of Suppressive Soils

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increase in soil microorganisms that reduce nematodes and disease-causing pathogens leads to suppressive soil. They are typically identified as those in which the pathogen or nematode is present, but plant disease and crop losses do not occur. Suppressive soils may be induced by continuous monoculture of particular plants, or by cultivation of plant species that support antagonists.

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Competitive Exclusion

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– applies mainly to pathogens, interaction of organisms at the same feeding (trophic) level. Ex. root-gall-forming bacterial pathogen Agrobacterium tumefaciens can be controlled by dipping seedlings or cuttings in a suspension of an appropriate strain of A. radiobacter, which colonizes roots and produces an antibiotic, agrocin 84, which inhibits most pathogenic Agrobacteria that arrive at the root subsequently

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Inoculative Biological Control

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periodic releases and reestablishment of a biological control agent that dies out each year, but which can rapidly expand its population when conditions are suitable

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A Pest Is Anything That:

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1) Injures humans, animals, desirable plants, structures or man’s possessions
2) Spreads disease to humans, domestic animals, wildlife or desirable plants

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Pests

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Insects
Pathogens
Mites
Nematodes
Rodents
Birds
Weeds
Mammals

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Late Blight, Irish Potato Famine 1845

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a. 1 million people died
b. 2 million immigrated

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Dutch Elm Disease

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a. In US
b. Destroyed all American Elm trees 1930-current

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Chestnut Blight

Back 64

In the U.S.
Destroyed all American chestnut tress 1904-194

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Ergot of Rye and Wheat

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Worldwide
Poisonous to humans and animals

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Malaria

Back 66

Carried by mosquitoes
Found in tropical and subtropical countries
1.5 to 2.7 million people die / year

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Lyme Disease

Back 67

Transmitted by ticks
Important in North America, Europe and Asia

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Mormon Cricket Invasion

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a. 1848 nearly destroyed the crops of Utah's settlers
b. Continues to be a problem in Western US

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Agricultural vs. Urban Pest Problems:
Similarities

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1. Ecological relationships
2. Clear economic base
3. Pest control tools are the same
4. Pesticides used in agricultural settings then in urban environments

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Agricultural vs. Urban Pest Problems:
Differences

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1. Urban p.m. is often incidental
2. Agriculture it is an integral part of production
3. Urban emphasis is on management and or eradication
4. Ag applicators trained w/ licenses, urban maybe trained applicator or untrained home owner

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IPM

Back 71

is a decision support system for the selection and use of pest control tactics singly or harmoniously coordinated into a management strategy, based on cost-benefit analyses that take into account the interests of and impacts on producers, society, and the environment

IPM is applied ecology

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Ecology

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study of organisms, their relationships with each other and with their biotic and abiotic environments

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Diagram:
Society

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Laws and regulations:
for pests
for technology
Supermarket preferences; Misinformation, fear, and prejudices

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Diagram:
Ecosystem

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Pest resistance
Pollution
Weather
Interactions between pest types
Diversity

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Diagram:
Economics

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Pest losses
Control costs
Crop value
Consumer costs

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Diagram:
Control Tech.

Back 76

Cultural/mechanical; Biological; Genetics and Plant Breeding; Pesticides

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Diagram:
Pests

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Identification; Biology; Ecology; Population dynamics; Population assessment

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Ergot of Grain

Back 78

As little as 0.3% of rye grain is ergotted, the flour made from such grain can cause illness or even death in humans when eaten
Causes hallucinations, gangrene, and other afflictions
1691 – 1692 ergot may have been a contributor to why people were thought of as witches in Salem, Massachusetts

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Goals of IPM

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1) Must Maintain economic reliability in managing pests.
2)IPM practices should reduce the risk of crop loss.
3)Designed to minimize selection pressure on pests to maintain the utility of the tactics in the future.
4)Maintain environmental quality, and must avoid use of tactics that are unnecessarily disruptive or damaging to ecosystems, especially those ecosystems that are not the target of the management.

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Key Aspects of IPM Programs

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1) Identify
2) Pest Biology and Ecology
3) Characteristics and Regional Crop Production System
4) Reliable Predictive Models
5) Cost Benefit Information on Control Tactics
6) Regional Management Components
7) Scouting and Monitoring System
8) Record Keeping
9) Resistance Management
10) Environmental and Social Constraints

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Regional Management Components

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Exclusion and detection, and role of regional control programs.

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Environmental and Social Constraints

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Consider all relevant ecological and sociological constraints.

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Resistance Management

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Development and implementation of resistance management strategies must be incorporated into the program.

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Record Keeping

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Determine the type of record keeping.

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Scouting and Monitoring System

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Determine the types and extent of population scouting and monitoring to support the decision making process. How will it be done and who will pay for it.

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Identify

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Pests likely to have a significant economic influence on the productivity of the system must be identified.

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Cost Benefit Information on Control Tactics

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Availability, benefits, and costs of all management strategies have to be evaluated. Incorporate costs and benefits to society and the environment when possible.

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Reliable Predictive Models

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Predict phenological events of both the crop and the pests, plus predict yield impacts and economics.

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Characteristics and Regional Crop Production System

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Know all aspects of the crop-production system, biology and ecology of all pests present in the system, advantages and disadvantages of different pest control strategies, environmental constraints, societal demands, and local, state, and federal regulations.

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Pest Biology and Ecology

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Know the life cycle, life history, reproductive habits, behaviors, feeding habits, host preference, activity patterns, dispersal mechanisms, sensitivity to environmental conditions, virulence, prey, predators, parasites, competitors, and aspects of density-dependent determinants.

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Sexual Reproduction

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Important to pest management, because it facilitates recombination of genes. Novel gene combinations may lead to the development of biotypes, races, or resistance to pest control tactics.
Genetic variability allows pests to evolve relative to the selection pressures of the environment, including management strategies

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Asexual Reproduction

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Offspring have the same genotype as the parent there is little or no genetic recombination. Progeny referred to as clones.
Beneficial by perpetuating exact copies of successful genotypes.

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Fertility

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actual number of viable offspring produced per adult

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Generation Time

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time required for a population to pass from birth to active reproductive status

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Short Generation Times

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Populations with short generation times increase rapidly

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Long Generation Time

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Populations with long generation times will increase more slowly

Example – most insect species usually have short generation times with many generations occurring in a year, but one brood of the periodical cicada has a generation time of 17 years

Front 97

Degree-Days

Back 97

In cold-blooded organisms, rates of metabolism and physiological processes are regulated primarily by environment temperature. For normal physiological processes to proceed, the ambient temperature must be above a critical lower limit and below a upper threshold, these are called lower and upper threshold temperatures, respectively.

Front 98

Calculating Degree-Days

Back 98

Degree-days = ([MAX + MIN] / 2) – TLOW

Ex. MAX 100°F, MIN 40°F, and TLOW 50°F
([100 + 40] / 2) – 50 = 20 degree-days for the 24-hour cycle