Fallen trees' last stand against bark beetles

Our results confirm that wind-felled trees are poorly defended, consistent with the hypothesis of the evolution of the tree-killing behavior from saprophagy in response to an overwhelming interspecific competition on undefended hosts. Wind-felled trees still represent a useful resource, exposing endemic populations of aggressive beetles to low defense levels while facilitating reproduction, growth and development. The constraint on the beetles' populations then becomes the ability to locate these scattered and unpredictable resources.