4 - The Eurasian spruce bark beetle in a warming climate: Phenology, behavior, and biotic interactions

Abstract

Outbreaks of the eruptive Eurasian spruce bark beetle (Ips typographus) have led to extensive mortality of European Norway spruce (Picea abies) forests causing severe economic losses, but also initiating forest succession and regeneration. Establishment and reproduction of I. typographus and its assemblage of microbial partners is initiated by pheromone-mediated mass attacks to circumvent the host's formidable chemical and anatomical defenses. However, in contrast to its host tree, which is poorly adapted to climatic conditions outside its natural habitat, I. typographus benefits from a warm and dry environment. Increasing temperatures promote multivoltine bark beetle populations; yet, their consequences for hibernation and diapause are still unclear. Existing knowledge of I. typographus has focused on individual aspects of the bark beetle development and host defense. To gain an improved understanding of climate-driven ecological changes in forest ecosystems, the complex interplay between climate change, beetle phenology, associated microbes, and tree physiology should be studied under natural field and laboratory conditions.