Simulation studies of senegalese grasshopper ecosystem interactions III: Optimization of grasshopper control

Large tracts of millet fields in the Sahel are sprayed with chemical insecticides to control the grasshopper Oedaleus senegalensis, but it is difficult to assess the impact of these pesticide applications on the grasshopper's population dynamics due to its migratory behaviour. The grasshoppers migrate along a route which runs from south to north. Therefore, a simulation model that can simulate population development and migration on a simple south-north transect was used to assess the impact of treatment with pesticides, including the biopesticide Green Muscle®, in terms of grasshopper control on two south-north transects in the Sahel. The results indicate that the various actual pesticide treatments had a considerable overall impact on local grasshopper pressure but had little impact on sites further along the transect, because they were only carried out curatively in the millet fields themselves. The results however suggest that preventive treatment of both grassland and millet fields in the south would be more efficient, and thereby represents an alternative strategy. It would, moreover, appear that this could represent an environmentally sensitive alternative if carried out using Green Muscle, but even preventive use of a traditional chemical pesticide would be more environmentally sensitive than spraying pesticides solely on millet fields curatively and over a larger area.