Biological Pest Management

Biological Control = Importation of exotic natural enemies to control an exotic pest, also includes the use of pathogens [classical biological control]

Natural Control = All biotic and abiotic factors limiting insect populations; excluding intervention by man

Natural Enemies = predators, parasitoids, and diseases attacking pests

Plant Resistance to Insects = the use of heritable plant traits to prevent or limit insect damage in crop plants

Biological Control

Types of Biological Control

Classical

• Definition 1, importation and colonization of natural enemies, to control exotic (usually) pest insects and weeds

Conservation

• Provide nesting sites, alternate hosts, foods, refugia, over wintering sites, and other needs for natural enemies

Examples of Biological Control Agents

An Adult Lacewing Predator of Aphids

Life Stages of the Convergent Ladybird Beetle

A Predator of Aphids

Periodic Releases

• Not dependent on colonization by natural enemies
• The release or application of natural enemies or pathogens with the expectation of either immediate or season-long control, not permanent control

Other Biological Methods

Plant Resistance

• First control factor a pest encounters is the host plant

Cultural Controls

• Agroecosystem changes that adversely affect the pest of favor natural enemies

Plant Resistance to Insects

Second Oldest Form of Insect Control

Practiced by the very first agriculturists

• Natural resistance
• Selected seeds of their best plants for replanting

Mechanisms of Resistance

• Antibiosis - Plant resistance with negative effects on insect biology
• Antixenosis (Non-preference) - Affects insect behavior so that the insect seeks an alternative host plant
  • feeding
  • oviposition
• Tolerance = Plant resistance with no effect on insects but which allows the host plant to withstand or recover from insect damage

Modes of Resistance

Plant traits causing insect resistance

Chemical Defenses

• Compounds that affect insect growth or cause increased mortality in insects (AB)
  • Toxins
  • Insect growth regulators
• Chemicals that affect insect behavior and result in reduced use by plant feeding insects of a plant for feeding or oviposition
  • Repellents - cause the insect to move away from the plant
  • Deterrents - prevents insect feeding or oviposition

Plant Morphology (Structural Defenses)

• Plant Hairs (antibiosis, antixenosis)
  • Simple - mechanical barrier to feeding or oviposition
  • Glandular - secrete chemicals affecting insect development or behavior; sticky material that entraps small insects
• Surface (Cuticle) (antixenosis)
  • Prevent insects from grasping the plant
• Tissue Thickness (antixenosis)
• Sap (antibiosis, antixenosis)
  • Traps insects in sticky exudate; forces tunneling insects out of tunnels
• Plant Vigor (tolerance)
  • Outgrow insect damage
  • Replace damaged tissues

How is Plant Resistance to Insects Obtained?

Sources of Resistance

• Different cultivars of the crop
• Less developed or primitive varieties of the crop
• Related species
• Unrelated species
• Mutation
• Transgenic methods

Cultural Insect Control

Planting Dates

• Time the planting of crops to avoid peak insect populations.

Rotation

• Plant crops in new areas each year to avoid a buildup on insect populations.

Trap Cropping

• Use an attractive crop to attract pest insects away from a more desirable crop.

Links to Related Entomological Sites

• Biological Control - A Guide to Natural Enemies in North America at the Cornell University , Jan. 4. 1999
• National Biological Control Institute, USDA - APHIS , Jan. 4. 1999

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Last updated Jan. 2, 2000
Gary Brewer