Agroecosystems

• Features of an agroecosystem?

  Limited duration

  Many changes, dominated by non-native species
• Features of an agroecosystem?

  NPK nutrients, uniform age structure

  Invasive outbreaks are common
• Pest?

  Organisms that occur in high numbers that is inconvenient to human health
• What allows a pest to flourish?

  lack of enemies, abundant resources, multivoltine, non-native
• What allows a pest to flourish?

  Parthenogenesis, high reproductive rates, genetic resistance
• How to manage insects?

  Reduce crop sustainability, reduce pest numbers
• Green Revolution?

  Focused on lower crop diversity for higher yields

  Focused on killing insects rather than protecting plants
• What was developed in 1967? (Norman Borlaug)

  Fast growing dwarf varieties of rice and wheat for the tropics and subtropics

  
• Insect Growth Regulators? (IGR)

  Interfere with development, little to no effects on humans or native fauna

  Nonspecific
• Microbial Insecticides?

  Bacterium (Bacillus thuringiensis)

  Attacks the midgut lining of the insect
• Cost of control?

  Cost to replace natural enemies and services of the food web + pollinators, side effect of broad spectrum pesticides

  
• Resistance?

  How effective a pesticide decreases over time as a pest adapts
• Resurgance?

  Pest population increases after pesticide use
• Replacement?

  A pest is replaced with another
• Integrated Pest Management? (IPM)

  Ecological approach, mixes biological methods, and cultivation methods

  
• What are some major ways to understand IPM?

  Pest species weakness

  How key pests affect other potential pests
• What are some major ways to understand IPM?

  How to sample major key pests

  Develop and promote the use of economic thresholds of key pests
• How to obtain an estimate of the pest population?

  In Situ counting

  Sweep netting

  Trapping (pheromones + blacklights)
• General equilibrium position? (GEP)

  average pest density
• Economic injury level? (EIL)

  level of injury (pest abundance) that is equal to the cost of management action
• Economic threshold?

  pest density, trigger management action
• Limitation of EIL/ET?

  Few cost-effective tools are available
• Limitation of EIL/ET?

  Difficult to calculate a crop value
• Limitation of EIL/ET?

  Tolerance and may be difficult to implement
• IPM tactics?

  Preventative: Applied before injury occurs

  Therapeutic: Applied while injury occurs
• Non-pesticide strategies?

  Antixenosis

  Augmentation: encourage natural enemies
• Non-pesticide strategies?

  Genetic resistance

  Biocontrol: Natural enemies, alter reproductive biology, pheromone traps, hormone disruptions