Control of the weed ragwort Senecio jacobaea by the insects cinnabar moth Tyria jacobaea and ragwort flea beetle Longitarsus jacobaeae has emerged as a classic example of successful biological control. Past studies of regulation following experimental disturbance have demonstrated that abundant buried seed and localized disturbances combine to activate incipient weed outbreaks, and that interspecific plant competition and herbivory by the ragwort flea beetle and the cinnabar moth combine to inhibit the increase and spread of incipient outbreaks. To further investigate the nature of this balancing system, the P.I.s' propose to look across spatial scales to determine how the balance between activation and inhibition depends on spatial scale. They will conduct a field experiment that manipulates disturbances area and levels of cinnabar moth, flea beetle, and plant competition to test the response of biological control system to spatial variation in the disturbances regime. A regional survey that analyzes maps of ragwort flowering plants to discover how description of population fluctuations in space and time varies with scale of observation. The long term goal of this research is to aid development of ecological theory of species interactions and thereby provide a satisfactory general explanation for successes of biological weed control and a useful guide to achieving future successes. //
