Locusts can destroy grain crops and pastures, threatening people’s livelihoods. In an international project, researchers from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have now developed methods to help detect locust outbreaks as early as possible and take action against them. Earth observation images acquired by satellites play a central role in this. These images enable the early detection of environmental parameters that favour the upsurge of the insects.
“Certain conditions are important for the development of locusts,” explains Igor Klein from DLR’s Earth Observation Center (EOC). “These include, for example, temperature, precipitation and soil moisture, but also the density and type of vegetation. Using Earth observation images, we can record these parameters and combine them in such a way that we can determine very precisely if a location exhibits the ideal conditions for locusts.” The researchers at the EOC use a variety of satellites for this purpose, including those of the European Copernicus Earth observation programme.
After evaluating the satellite data, the project participants determined where further analysis was needed. They then operated a drone over these areas. Its multispectral camera was used to observe the region in greater detail than is possible with the human eye. A healthy green meadow, for example, reflects strongly in the near-infrared range. If, on the other hand, the meadow is ‘stressed’ because locusts have begun to attack the blades of grass, healthy vegetation can be distinguished from damaged vegetation via infrared observations. This is because, while meadow may still appear unchanged to the human eye, the chlorophyll content has already begun to decrease.
Experts on site also entered their own observations into an app. This included measurements of the size of effected areas, the locust species present and the developmental stage and number of locusts per square metre. All of the data acquired via Earth observation, from the on-site specialists via the app and from the drone surveys converge within a geographic information system (GIS) and can be displayed on maps. Gradually, time series data will reveal how this monitoring and locust management complement one another.
