Insect Outbreaks
Southwest Alaska Network. 2018. Insect Outbreaks. Southwest Alaska Network
Roughly 1.5 million hectares (3.7 million acres) of white spruce in southcentral Alaska has been killed by the spruce beetle (Dendroctonus rufipennis) over the last quarter century. The recent spruce beetle outbreaks, and the spread of the non-native spruce aphid (Elatobium abietinum) into southcentral Alaska, have been attributed to regional warming. Warm winters have resulted in lower overwinter mortality of both beetles and aphids. Warm summers accelerate larval development in the spruce beetle, reducing generation time from a two-year life cycle to a single year and supporting rapid population growth. Above-average spring and summer temperatures can also contribute to moisture stress in white spruce, weakening them and making them vulnerable to spruce beetle attack (Csank et al. 2016). These warming-related effects have resulted in extensive damage to spruce stands and changes in stand structure and composition. Long-term forest monitoring and tree-ring studies are helping us to better understand the timing, frequency, and ecological effects of these outbreaks.
- Type
- Resource Brief
- Authors
- Southwest Alaska Network
- Date of Issue
- 2018-03
- Publisher
- Southwest Alaska Network
- Units
- KATM , LACL , SWAN
- Keywords
- defoliation, spruce aphid, spruce beetle, vegetation
- Subjects
- Ecological Framework: Biological Integrity | Infestations and Disease | Insect Pests , Ecological Framework: Biological Integrity | Focal Species or Communities | Vegetation Complex