Optimal Monitoring and Controlling of Invasive Species: The Case of Spotted Wing Drosophila in the United States

Spotted wing drosophila (SWD) is an invasive pest with devastating effects on soft-skinned fruits including blueberries, raspberries, blackberries, strawberries, and cherries. Due to zero tolerance of SWD infested fruit in both fresh and frozen markets, current SWD management strategies usually focus on preventive broad-spectrum insecticide sprays. Growers and extension educators across the United States are calling for management strategies that incorporate monitoring to reduce unnecessary insecticide sprays but little is known about the economic benefits of these strategies. To assist with this information gap, we develop a dynamic bioeconomic model to identify cost-minimizing SWD management strategies. Bayesian methods are applied in a dynamic simulation setting to evaluate the economic outcomes of alternative management strategies. We apply this model to a single blueberry grower faced with decisions to control a SWD infestation. We show that the economic impact of alternative SWD control strategies depends on the efficacy of the insecticide applied, the efficiency of monitoring traps, and the action threshold selected (i.e. the number of SWD trapped that triggers insecticide applications). Overall, we find that as the efficiency of monitoring traps improves, management strategies based on monitoring are superior to spray-only strategies. Our results also suggest that growers can choose more liberal action thresholds when monitoring traps are more efficient. Finally, we perform a sensitivity analysis to assess the impact of insecticide efficacy on the performance of alternative SWD control strategies. JEL codes: Q130, C63, D83