Adult diapause of the spruce bark beetle. The spruce beetle, Dendroctonus rufipennis, is an important mortality agent in the Southern Rocky Mountain spruce forests and their populations are expected to increase. While other bark beetles like the mountain pine beetle, Dentroctonus ponderosae, have a primarily univoltine life cycle (1 generation per year), the spruce beetle is interesting in that its life cycle varies from one to three years. The spruce beetle has a two-year life cycle (semivoltine) throughout much of its range, which requires two separate dormancy events, a prepupal and an adult diapause. My research aims to understand the different overwintering patterns to help develop population models.
Spruce beetle attacking a tree. Photo credit: Gregory Ragland