Developing novel remote sensing techniques to accurately detect the impact of biological control on water hyacinth, Pontederia crassipes Mart

Pontederia crassipes Mart. Solms (water hyacinth) is an invasive aquatic plant that was introduced into the United States in 1884. It causes extensive damage by covering large water bodies, altering aquatic habitat by reducing dissolved oxygen and light penetration and blocking access to agricultural and recreational activities. Two weevils, Neochetina spp (Coleoptera: Curculionidae), and a planthopper, Megamelus scutellaris (Hemiptera: Delphacidae) were released into Florida in 1970s and 2010 respectively, to control water hyacinth and mitigate its effect on freshwater ecosystems. Assessing the impact of biocontrol on water hyacinth is essential to maintain support, demonstrate efficacy, and inform additional control activities. Methods of accessing aquatic habitats for assessment are cumbersome, costly, and can be dangerous. Unmanned Aerial Systems (UAS) based remote sensing can provide a safe, quick, and efficient survey in areas where access is difficult and dangerous for traditional survey methods. In this study we developed methods that accurately detect the impact of biocontrol on water hyacinth using UAS. Hyperspectral data were collected in the lab on water hyacinth plants with varying levels of biocontrol agent pressure. Results showed that Megamelus scutellaris and Neochetina spp. treatments exhibit higher spectral reflectance than the control treatment at the blue, green, and red region of the spectrum, after 4 weeks of exposure. However, the control and M. scutellaris treatment exhibits higher reflectance value than Neochetina spp. at the NIR-band. Overall, the results of this study illustrate the potential of UAS based remote sensing and classification algorithms in detecting and classifying biocontrol damage.