The pattern and range of movement of a checkered beetle predator relative to its bark beetle prey

Theoretical studies of predator-prey population dynamics have increasingly centered on the role of space and the movement of organisms. Yet, empirical studies have been slow to follow suit. Herein, we quantified the long-rang e movement of a checkered beetle, Thanasimus dubius, which is an important predator of a pernicious forest pest, the southern pine beetle, Dendroctonu s frontalis. Adult checkered beetles were marked and released at five sites and subsequently recaptured at traps baited with pine and pine beetle semi ochemicals and located at distances up to 2 km away from the release point. While the pattern of recaptures-with-distance at each site provided a mode st fit to a simple random-diffusion model, there was a consistent discrepan cy between observed and expected recaptures: a higher than expected proport ion of beetles were recaptured at the more distant traps. To account for th is deviation, we developed a model of diffusion that allowed for simple het erogeneity in the population of marked beetles; i.e., a slow and fast movin g form of the checkered beetle. This model provided a significantly better fit to the data and formed the basis for out estimates of intra-forest move ment. We estimated that on average, one half of the checkered beetles dispe rsed at least 1.25 km, one third dispersed > 2 km, and 5% dispersed > 5 km. The source of the heterogeneous dispersal rates were partially due to diff erences in beetle size: smaller beetles (for both males and females) were m ore likely to be recaptured away from the release site than larger beetles. The southern pine beetle (prey for the checkered beetle) exhibited no sign ificant heterogeneity in dispersal ability and provided a very good fit to the simple diffusion model. The only difference in dispersal between these two species was that checkered beetles were undergoing greater long-distanc e dispersal than the pine beetles (thr radius containing 95% of the dispers ing individuals was 5.1 km for the checkered beetle and 2.3 km for the pine beetle). Data on the movement of these two species is used to evaluate a g eneral model of spatial pattern formation in a homogeneous environment, and the potential of the checkered beetle as a biological control agent for th e southern pine beetle.