Can we improve invasive species management by using biological control?
Drone image of a wetland invaded with giant salvinia. We use different tools to measure the impact of biological control and restoration of ecological services.
We study invasive species impact on managed and natural ecosystems
...and consider biological control the cornerstone of invasive species management.
Biological control could happen in a matter of months.
Drastic reduction of cover and biomass of giant salvinia due to action of the salvinia weevil, Cameron Parish, Louisiana. Image before was taken in June, and after was taken in September.
WHAT WE DO
INVASIVE SPECIES IMPACTS
Our laboratory is involved in research on invasive species which are in different stages of the invasion process. We have worked on detection techniques adapted to the life history of a range of species including emerald ash borer, crape myrtle bark scale, and roseau cane scale. We document the distribution and dispersal mechanisms of invasive species using field surveys, remote sensing, and citizen science.
Sampling methodologies are implemented to assess the impact of invasive species and they vary a lot. For example, we use drones to measure the coverage of aquatic weeds, and record the changes in dissolved oxygen, leaf chlorophyll content and photosynthesis, plant metabolites, among others. Due to the large diversity of species, we had worked in different habitats such as coastal wetlands, freshwater marshes, roadside disturbed habitats, forests, and urban settings.
Working with invasive species involves direct cooperation with our stakeholders including land managers of state parks, homeowners, farmers, aquatic weed managers, foresters, scientists, plant health regulators, conservationists, among others.
IMPROVING BIOLOGICAL CONTROL
Biological control is the use of natural enemies to reduce pest populations. Our laboratory is actively involved in classical biological control which is the use of host-specific natural enemies from the native range of the pest. International cooperation is at the core of our efforts. We enjoy facilitating the explorations of natural enemies of pests in USA, as welll as traveling to the native range of the organisms to find natural enemies! Because some invasive species occur over large regions, we have developed collaborative projects with several institutions in Southeastern U.S.A.
A new challenge on classical biological control is the climatic mismatch between agents and pests. Specifically, we work with subtropical weeds that are invading temperate regions such as water hyacinth, alligatorweed, giant salvinia, and parrot feather. We seek to understand the underlying problems of poor population growth of agents in the laboratory and in the field. We explore variation in life-history traits of existing populations by measuring thermal limits of agents, and search for new populations with desirable traits in the native range. Other approaches include habitat manipution to enhance overwintering survival, increase releases efforts early in the growing season, and integration with other control tactics based on site conditions.
Understanding fortuitous biological control has been fascinating. We discovered three non-native parasitoids of the roseau cane scale, native weevils attacking parrot feather and a non-native delphacid associated with a dieback of elephant ear. In next few years, we will be studying the relevance of these findings from an applied perspective.
Wahl,C., Diaz, R. and J. Ortiz. 2020. Aquatic Invasions In Press.