A New Spectral Index for Estimating the Oriental Migratory Locust Density.

It is very important to acquire timely information on the spatial distribution of locust populations in order to bring a locust outbreak under control quickly. In this study, we propose a new method for estimating the Oriental migratory locust density using a Locust Density Index (LDI). This index is based on the change in vegetation before an outbreak and shortly after the outbreak, taking into account the pre-outbreak vegetation conditions as well. This method was applied to study three locust-infested sites in Huanghua City, Hebei Province in China during a 2002 outbreak. NDVI images were derived from radiometrically corrected multi-temporal Landsat TM/ETM+ data recorded during and after the outbreak. After radiometry of the post-outbreak NDVI image was standardized to that of its during-outbreak counterpart, their difference multiplied by the pre-outbreak NDVI (termed LDI) was used to map the density of locusts at five levels of no locust, low, moderate, high, and very high. Nearly 90 percent of the study sites had a low to moderate locust density. Results produced with the proposed ml method are similar to those observed on the ground with an accuracy of 88.9 percent. This proposed LDI method is easy to implement. It allows quick and accurate mapping of locust density from satellite data. [ABSTRACT FROM AUTHOR]