Optimizing the establishment and impact of the Cyrtobagous salviniae through the manipulation of release points

Salvinia molesta is an invasive aquatic fern native to Brazil that impedes critical ecosystem services. Cyrtobagous salviniae is a host-specific weevil native to Brazil that has been successful at reducing S. molesta coverage in subtropical and tropical regions. This study aims to elucidate how propagule pressure, in this case C. salviniae release points, can influence population growth which is critical for the management recommendations for S. molesta. Currently, most land managers receive weevil-infested S. molesta from the LSU AgCenter and release them in one location. Using the ecological theory of propagule pressure, we hypothesized that increasing release points per area will increase population growth of the C. salviniae resulting in faster control of S. molesta. Replicated mesocosms and outdoor ponds were used to examine the impact that the number of releases (Control/0, 1, 2, 3, 4, and 5 release points) have on the colonization and population growth of C. salviniae. Plant performance and weevil population density were measured overtime for each release treatment. Results of the studies will be discussed in the context of management strategies for S. molesta in Louisiana.