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Integrated-pest-management-2

  • Lecture outline/goals
    • Forest pest management tactics
      1. Biological control
      2. Silvicultural control
      3. Resistance breeding
      4. Exclusion and eradication
      5. Chemical control (not viable for North America)

Biological control​

  • The control or regulation of pest populations through the manipulation of natural enemies or competitors

Biological control approaches

  • Classical: importation and establishment of natural enemies for long-term, large-scale pest population suppression/regulation
  • Augmentation: mass rearing and release of large numbers of natural enemies for short-term control of pests in small areas
  • Conservation: facilitation/enhancement of existing natural enemies over variable spatial and temporal scales
  • Biological insecticides: isolation, culture and dissemination of pest-specific diseases
  • Semiochemicals (aggregation/anti-aggregation pheromones)

Classical​

examples:​

  • speculatory successes in agriculture (vedalia beetle vs. cuttony cushion scale on citrus)
  • Few successes against forest insects -- due to ecosystem complexity?
  • Out of favour due to large failures (e.g. cane toad australia), but reconsidered as a tactic due to frequency of invasive species intros

Pros:​

  • Non chemical
  • Usually specific to pest organisms
  • Potentially long term

Cons:​

  • Non target effects (rare high risk)
  • efficacy lags
  • public perception
  • Long term modification

Augmentation​

Examples:​

  • trichogramma (egg parasitoid)
  • Out of favour in forestry due to effort and expense

Pros:​

  • Non chemical
  • Specific to pest organism
  • Little or no efficacy lag

Cons:​

  • Short term
  • Expensive (rearing adn release)
  • Public perception

Conservation​

Examples​

  • Few examples in forestry (but see southern pine beetle)
  • Increasing interest

Pros:​

  • non chemical
  • Specific to pest organism
  • Enhanced biodiversity

Cons:​

  • efficacy lags
  • large knowledge gaps

Biological insecticides​

Examples:​

  • BTK

Pros:​

  • Mostly non chemical (chemical carriers)
  • Largely species specific
  • Little or no efficacy
  • Relatively inexpesnive
  • Ease of application (like pesticide)

Cons:​

  • Some non-target effects (esp. Btk)
  • Public perception

Semiochemicals​

Examples:​

  • Aggregation "baits" for many eruptive bark beetle species
  • Verbenone, MCH; anti-aggregants for mountain pine beetle, Douglas-fir beetle
  • Manipulate populations to better coincide with management objectives

Pros:​

  • Fast acting
  • Specific to target pests

Cons:​

Silvicultural control​

The control or regulation of pest populations through the manipulation of host tree availability and/or susceptibility

  • Control approaches TODO:

Planting schedules​

Examples:

  • Choice of tree species and timing of planting post harvest to reduce regeneration pest impacts
  • Warren's root collar weevil, Hylobius warreni -- avoid replanting lodgepole pine seedlings immediately adjacent recently killed mature stands
  • Post mountain pine beetle -- don't plant lodgepole pine?

Pros:​

  • non chemical
  • specific to pest organism
  • Long term

Cons:​

  • potential site degredation
  • Potential regeneration delays
  • Knowledge gaps - long-term effects

Thinning / fertilizing / hygiene​

Examples:

  • thinning, fertilizing; esp. to manage bark beetles
    • "Thin from below" removes background beetle populations from suppressed trees
    • Increases vigour of remaining trees - increases tree resistance
    • Alters microclimate, reduces beetle attack success
  • Hygiene
    • Removal of suppressed, damaged amterial to avoid pest population buildup; e.g. Douglas-fir beetle in downed tgrees and large debris

Pros:

  • Non-chemical (although fertilizier)
  • Optimize tree growth
  • Reduce wildfire risk

Cons:

  • reduces biodiversity
  • Labour intensive, expensive
  • Knowledge gaps - long-term effects

Harvest scheduling​

Examples:

  • Shortened rotations to extract trees before susceptible to pests; esp. many bark beetles, defoliators that are pests of mature trees

pros:

  • non chemical
  • long term

Cons:

  • reduces diversity; esp. of old growth specific species
  • Knowledge gaps - long-term effects

harvesting infectewd trees​

pros:

  • non chemical

cons:

  • expensive, labour intensive

resistance breeding​

Approaches:

  • natural variation: selective planting of resistant provenances
  • Artifical selection: controlled breeding to promote pest resistance
  • Genetic modification: transgenics (i.e., engineering of novel genes into plants to express pest resistance)

Natural variation​

Examples: Sita spruce provenance selection against spruce weevil, pissodes strobi

Pros:

  • non-chemical

Cons:

  • Long-term commitment
  • Limited deployment potential
  • Selection for pest resistance
  • Public perception
  • Knowledge gaps - long-term effects

Artificial selection​

Examples: Cottonwood hybrids resistance to various insects and pathogens

Pros:

  • non chemical
  • optimize tree growth/shorten rotations

Cons:

  • long term commitment
  • limited deployment potential
  • selection for pest resistance
  • non target effects

Genetic modification​

Examples

  • Expression of foreign insecticidal proteins; Btk toxins in poplars against various defoliators

Pros:

  • Non chemical
  • Optimize tree growth / shorten rotations

Cons:

  • long-term commitment
  • Stability of gene expression in long-lived trees
  • Limited deployment potential
  • Selection for pest resistance
  • Non target effects
  • Horizontal gene transfer to wild populations
  • Public perceptions
  • Knowledge gaps - long-term effects

Exclusion and eradication​

Minimization of the probability of introduction and establishment of alien invasive species

Pros:

  • proactive

Cons:

  • potential "knee-jerk" response*
    • We spend lots of resources that might be better spent elsewhere
    • We can't risk making the mistake
    • Place for lots of science to save money
  • non-target effects (during eradication)

*Precautionary principle -- "where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degredation"

Chemical Control​

Approaches:

  • Broadcast insecticides
  • Systemics ("internal" to trees)

Broadcast insecticides​

Do not use Pros:

  • fast acting
  • Inexpensive
  • effective

Cons:

  • hard to target
  • potential for massive damage

Systemic insecticides​

Examples

  • Neem (azadirachtin) against bark beetles, defoliators, emerald ash borer; "natural" product, largely experimental but promising
  • MSMA (monosodium methane arsenate) against mountain pine beetle

Pros:

  • fast acting no lag
  • specific to target pests
  • Limited amounts of active ingredient required

Cons:

  • expensive
  • Limited by scale
  • public perceptions

IPM in forestry​

  • Never a magic bullet -- avoid generalization
  • For a given IPM strategy, all tactics should be considered and applied (alone or in combination) as specific situations dictate
  • IPM is a comonent of forest management, and must complement FM objectives]