Modeling the interaction between the exotic invasive aquatic macrophyte <Emphasis Type="Italic">Myriophyllum spicatum</Emphasis> and the native biocontrol agent <Emphasis Type="Italic">Euhrychiopsis lecontei</Emphasis> to improve augmented management programs

Mathematical modeling is used to investigate control of the invasive aquatic plant Myriophyllum spicatum L. by the native watermilfoil weevil Euhrychiopsis lecontei Dietz. An age-structured population model with discrete development class is used to separate the destructive activity of Euhrychiopsis lecontei Dietz larvae from the relatively benign activity of the other developmental stages. Empirical model behavior is evaluated and agrees with expected system characteristics. Simulation results demonstrate diminishing returns in the control impact of E. lecontei Dietz as a function of population stocking density. These results indicate that predictive modeling of this type may be used to optimize the utilization of Euhrychiopsis lecontei Dietz as a biological control agent.