Ormiscodes outbreaks dynamics: Impacts and perspectives in a warming world

Abstract

Changes in the frequency and magnitude of insect outbreak appear to be occurring worldwide, but research has been mainly focused on northern hemisphere forests. In the temperate forests of the southern Andes, Nothofagus tree species experience severe defoliation caused by Ormiscodes caterpillars (Lepidoptera: Saturniidae). Current impacts of defoliation on tree health are relatively low and short term. Although relationships between Ormiscodes outbreaks and climate proved to be complex, defoliation events are generally associated with drier and warmer than average growing seasons. However, these probable climatic influences on outbreak occurrence are contingent on the sensitivity of Nothofagus and Ormiscodes to temperature and precipitation along environmental gradients. Relationships between Ormiscodes outbreaks and climate suggest that under predicted warmer and drier climates in the twenty-first century, these defoliator outbreaks may become more frequent and contribute to future forest decline in Nothofagus forests.