Lecture 3

• Ecology


  The study of organism and how they interact with the environment around them
• Ecosystem


  A geographic area where plants , animals, and other organism, as well as weather and landscape, work together to form a bubble of life
• Agroecosystem


  The interaction of living organisms with one another and their environment under a man-managed agricultural system
• Ecological Concepts


  • Species
  • Individual
  • Population
  • Community
  • Ecosystem
  • Landscape ecology
  • biosphere
• Species


  Groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups
• Individual


  A single organism (bacterium, weed, nematode, insect)
• Population


  A collection of individuals of one species that exists in some defined geographical area
• Community


  A group of populations occurring in the same geographical area
• Ecosystem


  A community of living organisms and the abiotic framework that supports them. Agroecosystem – An ecosystem dominated by humans that typically has few common or major species (crops) and numerous rare or minor species (some of which are pests)
• Landscape


  A cluster of interacting ecosystems
• Trophic Levels


  • Producers – 1st trophic level
  • Primary Consumers – 2nd trophic level
  • Secondary Consumers – 3rd trophic level
  • Tertiary Consumers – 4th tropic level
• Producers (Autotrophs)


  These are organisms that produce their own food through photosynthesis
• Primary Consumers (Herbivores)


  These are organisms that feed directly on producers. Consume plant materials for their energy
• Secondary Consumers (Carnivores)


  These are organisms that feed on primary consumers. They obtain their energy by consuming herbivores
• Tertiary Consumers (Top Carnivores)


  These are organisms that feed on secondary consumers. They are often apex predators at the top of the food chain
• Decomposers (Detritivores)


  These are organisms that break down dead organic matter and waste, releasing nutrients back into the ecosystem
• Each trophic level represents a transfer of energy and nutrients from one group of organisms to another within an ecosystem
• Energy is lost as heat at each trophic level, resulting in a pyramid-like structure of energy flow, where energy decreases as it moves up the food chain
• Trophic interactions are essential for maintaining the balance and stability of ecosystems
• Terminologies


  • Herbivore – organism that consumes plants or plant parts
  • Carnivore – organism that eats other animals
  • Omnivore – organism that feeds on plants and animals
  • Monophagous – eat only one or a few species in a genus or related genera
  • Oligophagous – eat a limited range of usually related species
  • Polyphagous – eat a range of unrelated species
  • Host – serve as both a food source and habitat for parasitic organisms
• Terminologies


  • Prey – serve as a food source for predators
  • Predators – eat all or part of their prey, resulting in death
  • Parasites – plant or animal that lives in or on another organisms; causes some damage; usually not lethal to its host
  • Parasitoid – arthropod parasite that kills its host
  • Hyperparasites/Hyperparasitoids – parasites of parasites; sometimes called secondary parasites
• Why do need to study ecology in IPM?

  • Provides insights into relationships between organisms and their environment
  • Helps in recognizing the factors that influence pest populations and their natural enemies
• Why do need to study ecology in IPM?

  • Understanding Ecosystem Dynamics
  • Biodiversity and Natural Controls
  • Ecosystem Services
  • Impacts of Pesticide Use
  • Population Dynamics
  • Habitat Management
  • Sustainable Agriculture
• Economic Threshold Level (ETL)


  The density of pests at which control measures should be taken to prevent the pest population from reaching the EIL
• Economic Injury Level (EIL)


  The lowest population density of pests that will cause economic damage
• Economic damage


  The amount of injury that will justify the cost of control
• How does the ETL and EIL affect the management decisions?

  • Timing of Control Measures
  • Selection and of Control Methods
  • Resource Allocation
  • Monitoring