Author
Victoria Ayala
vmoreno@agcenter.lsu.edu
Louisiana State University
Baton Rouge
Coauthors
David Kinsler, Rhodes University, Grahamstown, South Africa
Ivan Grijalva, Louisiana State University, Baton Rouge, United States
Rodrigo Diaz, Louisiana State University, Baton Rouge, United States
Abstract
Invasive aquatic weeds such as giant salvinia (Salvinia molesta) pose a serious threat to wetland health and ecosystem services across the southern United States, particularly in coastal Louisiana. Infestations of S. molesta suppress native vegetation, block sunlight penetration, and disrupt navigation, fishing, and waterfowl hunting. Biological control using the salvinia weevil (Cyrtobagous salviniae) has proven effective in subtropical regions; however, successful management depends on early detection of infestation hotspots to guide weevil releases. To address this need, we developed a near-real-time, web-based monitoring tool that integrates satellite imagery to detect S. molesta across southern coastal Louisiana. The platform automatically generates coverage maps and time-series analyses as new satellite images become available. For instance, in Palm Lake (Slidell, LA), coverage reached 40.09% (23.48 ha) as of September 2025. Complementing this remote sensing tool, we established a controlled mesocosm experiment to evaluate physiological responses of S. molesta under varying densities of salvinia weevil herbivory. Using a multispectral camera mounted on an unmanned aerial vehicle (UAV), we collected near-infrared reflectance data to quantify plant stress. We hypothesise that higher weevil densities will result in significant declines in reflectance values, which can be correlated with field densities of natural weevil populations. This integrated approach, combining satellite-based monitoring with UAV-assisted stress detection, aims to enhance early detection of S. molesta, and optimise biological control efforts through more strategic weevil releases from rearing operations.
keywords
Biocontrol
Giant salvinia
Salvinia weevil
Remote Sensing
Real-time monitoring
Highlights
Early-detection of giant salvinia infestations is key for targeted salvinia weevil releases
Aerial and satellite remote sensing tools provide near-real-time monitoring of hotspot infestations
Open-source tools are crucial for rapid response of biocontrol interventions early in the season