Ecological Aspects of Pest Management Ecosystem Concept Ecosystem

Ecological Aspects of Pest Management Ecosystem Concept

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

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

Ecosystem Concepts n Ecological Niche Concept -

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

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

Ecosystem Concepts n Colonization of Islands

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

Ecological Concepts n n n 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 n n n 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 n Humans moving pests/crops - Japanese beetle, Colorado potato beetle n

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

Agroecosystems Island Biogeography n Community Succession n

Farmer’s Strategies n n n 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.