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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. Ecosystem Concepts. Individual - primary importance to study
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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
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).
Ecosystem Concepts • 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).
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
Ecosystem Concepts • 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.
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.
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
Ecological Concepts • Short season crops - create stablility; no equilibrium due to short time • Humans moving pests/crops - Japanese beetle, Colorado potato beetle
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
Agroecosystems • Island Biogeography • Community Succession
Farmer’s 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.