Biology of Business

The role of host plant resistance in the colonization behavior and ecology of bark beetles

Kenneth F. Raffa, Alan A. Berryman

Ecological Monographs (1983)

TL;DR

One beetle dies; forty beetles kill the tree. Aggregation pheromones solve the coordination problem of overwhelming host defenses through precisely-timed mass attack.

By Alex Denne

Established the critical attack density threshold in bark beetle ecology—showing how aggregation pheromones solve the coordination problem of overwhelming host tree defenses through precisely-timed mass attack.

Key Findings from Raffa & Berryman (1983)

  • At least 40 attacks per square meter required to overcome tree chemical defenses
  • Optimal attack density is ~60 attacks per square meter for successful reproduction
  • Aggregation pheromones create positive feedback loop recruiting nearby beetles
  • Anti-aggregation pheromones at high density redistribute attackers to adjacent trees
  • Beetles maintain near-optimal density regardless of population pressure

Related Mechanisms for The role of host plant resistance in the colonization behavior and ecology of bark beetles

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