Tamarisk leaf beetle (Diorhabda sp.) has been a biological control agent used to combat the spread of the invasive, non-native riparian shrub tamarisk (Tamarix sp.) in the southwestern United States since 2001. Tamarisk is detrimental to riparian habitats as it consumes water sources that native vegetation relies on. Host specific tamarisk leaf beetle defoliates the shrub, reducing water consumption and ultimately killing the plant. However, initial estimates of tamarisk leaf beetle efficacy underestimated how quickly it would spread, resulting in faster tamarisk defoliation than previously expected. Many riparian birds rely on vegetation—native or not—for nesting sites. The rapid decline of tamarisk in riparian habitats threatens the reproduction of these birds, including endangered species such as the least Bell’s vireo in southern California. We developed an agent-based model for tamarisk leaf beetle that will help habitat managers determine how current and potential tamarisk leaf beetle invasions will impact their system over the next thirty-five years, and determine whether habitats will remain suitable for nesting. Agent-based models offer a way to simulate these systems by programming stochastic agents that are parameterized to interact and respond to environmental conditions as well as other agents. The behaviors of tamarisk leaf beetle under different habitat conditions can be used to make decisions on management strategies.
.png)
