Modeling for management of invasive species: Musk thistle (carduus nutans) in new zealand

Mathematical modeling is an important tool with which managers can understand, and hence plan to control, invasive species. A matrix model for the invasive musk thistle, derived from demographic studies in New Zealand, is used to conduct a retrospective analysis of the relative merits of three biological control agents released to control this species: Rhinocyllus conicus, Urophora solstitialis, and Trichosirocalus horridus. The analysis of musk thistle illustrates the utility of modeling approaches in management and demonstrates how model-derived information could shift the focus of future management efforts. By placing management in an adaptive framework, where active learning is used to improve management decisions, existing management strategies can be further improved to cope in situations where optimal control methods may depend on local conditions.