LIFE HISTORY TRAITS OF SIREX NOCTILIO F. (HYMENOPTERA: SIRICIDAE) CAN GENERATE OUTBREAKS INDEPENDENTLY OF ENVIRONMENTAL FACTORS

JUAN PABLO APARICIO, JUAN CORLEY, JORGE RABINOVICH

Santiago

Simposio; BIOMAT 2011: International Symposium on Mathematical and Computational Biology; 2011

BIOMAT Consortium

The woodwasp Sirex noctilio is an insect pest of conifers which may produce severe damage to pine plantations. We developed an individual based model for a wasp population developing in a pine plantation. We show that outbreaks may be the result of the characteristics of the insect’s life history, and in particular we show that limited dispersal may not only increase population persistence but also create the conditions for eruptive dynamics. When the probability of long distance dispersal is greater than zero, but relatively small (PLDD= 0.1) large outbreaks are the norm, with all of the suitable trees dead at the end of the simulation. For PLDD= 0 (only local dispersal allowed) outbreaks are smaller in size, and in some cases not well defined and spread over longer periods. For PLDD= 1 (wasps allowed only long distance dispersal), the frequency of extinction (without outbreaks) increases significantly. Aggregated attacks may induce physiological changes in the trees which allow other wasps to detect them. These changes may in turn trigger an outbreak. Healthy, vigorous trees are not suitable for wasp oviposition. In our model the density of suitable trees (healthy trees but more adequate for oviposition) are a key factor determining population persistence before outbreaks. Our results emphasize the importance of adequate plantation management in preventing woodwasp infestation.