Growth-differentiation balance: a basis for understanding southern pine beetle - tree interactions
Abstract
Interrelationships between the southern pine beetle (SPB), Dendroctonus frontalis Zimm.) and its host pines are explained in terms of the growth-differentiation balance concept.A general hypothesis is proposed based on growth-differentiation balance in southern pines (radial growth of stems versus synthesis and yield of oleoresin) and seasonal activity of the SPB based on knowledge from experimentation and observations reported in the literature.The spring appears to be particularly favorable for successful SPB attack because of the strong demand for available photosynthates by growth processes at that time, whereas, in the summer, strong resin flow increases the potential resistance of trees to attack. Growth - differentiation balance provides a basis for understanding SPB-tree interactions, a rationale for commonly experienced problems in identifying consistent precursors to SPB outbreaks, and a philosophical basis for future research.The concept has potential application to other bark beetle-host conifer relationships.