Simulations of population dynamics of hemlock woolly adelgid and potential impact of biological control agents

The hemlock woolly adelgid (Adelges tsugae) is a small invasive Hemipteran herbivore that threatens the continued presence and abundance of hemlock in eastern North America. Efforts to control the adelgid have focused on the introduction of classical biological control agents. These biological controls include six different species of predatory beetles, two of which have established. Of these predatory beetle species, Laricobius nigrinus has the most potential to alter the dynamics of hemlock woolly adelgid, because it has been recovered in large numbers at multiple release sites in eastern North America. However, establishment does not guarantee the predators will maintain the density of the adelgid at levels sufficiently low to prevent hemlock damage and death. Here we present results of a simulation model in which the potential impact of the introduced predator L. nigrinus is explored in the context of what is known about the dynamics of hemlock woolly adelgid in the absence of predators.