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Ecological Aspects of Pest
Management
Ecosystem Concept
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
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Ecological Niche Concept -
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
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Colonization of Islands
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
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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.
Ecological Concepts
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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
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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Farmer’s Strategies
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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.