Ecological Aspects of Pest Management

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Ecological Aspects of Pest Management

• Ecosystem Concept

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Ecosystem Concepts

• Individuals
• Population
• Community
• These are influenced by physical environment
• Complex of biotic/abiotic factors in an ecosystem

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Ecosystem Concepts

• Individual - primary importance to study
• Behavior, physiology, morphology, response to
  others of same species
• Population - also of primary importance
• Populations of different species coexist -
• Community Level - any given habitat seems to have
  a finite saturation level (K).

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Ecosystem Concepts

• Ecological Niche Concept -

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Ecosystem Concepts

• Ecological Niche Concept -
• Set of resources that provides a species with all
  of its requirements for existence and
  reproduction
• Individual requisites necessary for survival
• Population requisites - broad vs. narrow
• Limit to number of species that can occupy an
  area (K).

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Ecosystem Concepts

• Structural complexity - 2 components
• 1. Number of plant species, or species richness
• 2. Physical structure of system
• More plants than herbivores, more herbivores than
  natural enemies
• Different plant stages - different, new resources

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Ecosystem Concepts

• Colonization of Islands

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Ecosystem Concepts

• r versus K strategists
• r - early colonizers r based on reproduction
• r colonizers tolerate harsh conditions then they
  modify their conditions, which allows other
  colonizers.
• 2 phases of colonization 1) non-interactive
  phase 2) Interactive phase.

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Ecological Concepts

• 5 factors influencing the number of arthropod
  species
• 1) Plant species diversity
• 2) Plant Structural diversity
• 3) Distance of community from source of colonists
• 4) Length of contemporary time available for
  colonization
• 5) Evolutionary time available for coevolution
  between herbivores and host plants.

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Ecological Concepts

• Crop Islands - uncultivated areas can be
  overwintering/refuge sites for pests and
  beneficials - farmscaping, hedges/windrows.
• Crop fields are invaded by insects coming from
  various distances
• Matrix - crops, uncultivated fields, fallow
  fields, other crops.
• Nature of the Crop Island - short or long term
  broccoli versus orchard.
• Plant spp. diversity, plant structural diversity
  and length of time available

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Ecological Concepts

• Short season crops - create stability no
  equilibrium due to short time
• Humans moving pests/crops - Japanese beetle,
  Colorado potato beetle

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Ecological Concepts

• Community succession
• Initial dispersers - wind dispersed seed -
  dandylions, thistles, milkweed,
• Later - shrub seeds, tree seeds - carried by
  birds.
• r - reproductive strategy
• K - competitive strategy

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Agroecosystems

• Island Biogeography
• Community Succession

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Farmers Strategies

• 1) Mechanized and commercial preparation of seeds
  and planting to replace the natural dispersal
  system
• 2) Fertilizers - replace natural cycles
• 3) Chemical or power weeding
• 4) Soil preparation and treatment - replace
  natural systems
• 5) Application of controls - pesticides
• 6) New varieties - against insects, disease and
  weeds.