bugs

• Pest Management


  • A variety of settings:
  • Crop plants
  • Livestock
  • Urban dwellings
  • Landscapes
  • Disease vectors
• Early pest management in crops

  Eliminating the pest
• Early pest management methods


  • 2500 B.C. - Ancient Sumerians used sulfur ("brimstone") to kill insects on crops
  • In the middle ages (1600s), arsenic was used to controls pests
  • In 1800s, U.S. farmers started using inorganic compounds and botanical extracts such as copper sulfate, nicotine, pyrethrum powder, and other chemicals
• Paris Green


  Highly toxic crystalline powder that is used as rodenticide and insecticide
• Mid-1900s pest management


  1. New synthetic pesticides; persistent organic pollutants (POPs)

  2. High toxicity

  3. Slow degradation

  4. Bioaccumulation
• Organochlorine pesticides


  • DDT
• Organophosphates are another highly toxic class of insecticides used widely until 21st century
• Organophosphate insecticides


  • Parathion (banned)
  • Chlorpyrifos (still debated)
• Environmental Movement


  • Published in 1962
  • DDT banned in 1972
  • EPA established in 1970
  • Clean Air Act (1970)
  • Clean Water Act (1972)
  • Endangered Species Act (1973)
• Toward "reduced risk" insecticides


  • Considerations:
  • Human health and safety
  • Persistence and bioaccumulation
  • Movement into water
  • Effects to other mammals
  • Effects on birds, fish, and other vertebrates
  • Effects on other insects, including bees
• Federal law related to pesticide regulation

  
• Insecticides


  • Have different modes of action, or how they cause physiological disruption
  • Categorized in various classes based on their target site and mode of action
  • Some may be "broad spectrum" in their toxicity, whereas and others are "narrow spectrum", and more specific to the target pest
• Integrated Pest Management (IPM)


  • An ecological and sustainable approach to managing pests by using a variety of common-sense tools that minimize economic, health, and environmental risks
  • Differs from "organic" in that organic generally does not allow for the use of synthetic pesticides and fertilizers, whereas IPM does

  
• IPM involves


  1. Knowing your pest, ecosystem, and plant health problems

  2. Knowing what is unacceptable pest damage for your crop

  3. Considering all available pest control options (integrated)

  
• Cultural controls


  • Modify the crop environment to make it less suitable for insect pests:
  • Reduce pest habitat in and around crop
  • Adjust crop planting to disrupt pest
  • Divert pest away from crop
  • Reduce yield loss from insect injury
• Reduce pest habitat in and around crop


  • Pests may thrive in crop residue, weedy field edges, and in the soil. Control options include:
  • Sanitation – removing weeds and residue
  • Destroying non-crop pest habitat near fields
  • Tillage to disrupt soil
• Adjust crop planting to disrupt pest


  • Consider spatial arrangement of crops. Dense plantings are less favorable to pests. Planting dissimilar crops near each other can limit pest movement from field to field.
  • Consider timing of planting. Adjust date of planting relative to pest's emergence/arrival (e.g., avoidance or tolerance). Rotate crops so that same crop isn't continuously planted in same location.
• Degree days can be calculated to determine when pests will emerge
• Monitoring and modeling can be used to know when migrating pests will arrive
• Divert pest away from crop

  Create spaces more attractive to pests than the primary crop to draw pests away. Trap cropping – planting preferred host plant of pest near the primary crop. Pest can then be killed in trap crop.
• Reduce yield loss from insect injury


  • Even when insect damage happens, yield loss can be reduced by:
  • Plant genetics (choosing tolerant varieties)
  • Improving plant vigor through proper irrigation, fertilization, and weed control

  
• Mechanical/Physical Controls


  • Remove pests or keep them from reaching host plant. Examples include:
  • Hand removal
  • Physical barriers
  • Traps
• Kaolin clay


  • Can provide a protective barrier between plants and insects
• Insect barrier fabrics


  • Can keep insects out while allowing for sufficient light and airflow to enter
• Biological Control


  • Using natural enemies to control or suppress pest populations:
  • Predators – ladybugs, syrphid fly larvae, lacewing larvae
  • Parasitoids – various wasp and fly species
  • Entomopathogenic nematodes
• Augmentation Biological Control


  Introducing natural enemies by releasing them in large numbers
• Conservation Biological Control


  • Supporting existing natural enemy populations. e.g., insectary plantings and beetle banks can support predators and parasitoids.
  • Cover cropping – i.e., planting of crops to cover the soil during normally fallow periods – can support predator populations (in addition to improving soil health and suppressing weeds)

  
• Integrating multiple tactics
• Semiochemicals


  • Chemical substances produced by organisms that elicit a behavioral or physiological response in another organisms (same or different species):
  • Pheromone - attractant
  • Allelochemicals - inhibitory
• Allelochemicals


  • Garlic and hot pepper-based materials (capsaicans) are low-toxicity botanicals used by some growers for their insect repellant properties, although their efficacy is uncertain.
• Pheromones


  May be used in mating disruption. Crop area is flooded with sex pheromones so male insects can't find female insects for mating.
• Sterile Insect Technique (SIT)


  Release of sterile male insects to mate with native females. Lowers reproductive potential, suppresses pest populations.
• Chemical Control


  • Pesticides are used in IPM programs but as a last resort
  • Before chemical control is used, growers must determine allowable thresholds for pests.
  • Pests are managed, not eliminated
  • Pesticides that have a narrow host range and lower environmental risk are prioritized.

  
• Economic injury level


  The smallest number of insects (amount of injury) that will cause yield losses equal to the insect management costs.
• Economic threshold


  The pest density at which management action should be taken to prevent an increasing pest population from reaching the economic injury level.

  
• Insecticides


  • First line of chemical defense includes "biorational" insecticides which are consider low risk and more environmentally friendly. Many are derived from natural sources, and thus qualify for organic certification:
  • Botanicals
  • Microbials
  • Mineral-based
  • Insect growth regulators

  
• Botanicals


  • Plant-derived materials. They are generally short-lived in the environment, as they are broken down rapidly in the presence of light and air, thus they do not provide pest control for very long, perhaps a day or several. Most botanicals are broad spectrum, so they kill beneficial insects, too.
  • Examples: Sabadilla, Rotenone, Pyrethrum
• Economic injury level


  The level of pest population at which management action should be taken to prevent further damage

  
• When to take action

  Insecticides

  
• Biorational insecticides


  • Low risk and more environmentally friendly
  • Derived from natural sources
  • Qualify for organic certification