The Senegalese grasshopper Oedaleus senegalensis (Krauss, 1877): Dynamics and socio-economic impact in Senegal

This study conducted in Senegal from July to October 2021 aims to study the population dynamics of the Senegalese grasshopper, Oedaleus senegalensis (Krauss), estimate its economic impact and evaluate the implementation of a community-based control strategy. Two hundred and fifty (250) farmers, each with a one-hectare fertilized field and a control field of the same size, were selected in the regions of Fatick, Kaffrine, Thies and Saint Louis. The millet variety souna III was sown in both types of fields, and the fertilized fields received 150 kg of Nitrogen, Phosphate, Potassium (NPK) fertilizer and 150 kg of urea. Larval development stages and generations are determined by repeated sampling in time and space. The density of O. senegalensis was assessed in the fields using the quadrat method and the pedestrian transect method. Damage was estimated by determining the percentage of attack on millet leaves and ears, and by comparing field harvests. The 500 hectares were surveyed 1,500 times. Three generations were identified with all developmental stages except in Saint Louis, where two generations were observed. Oedaleus senegalensis movements and densities decreased in Kaffrine, Fatick, Thies and Saint Louis, following the rainfall gradient. It is more present in control fields, with an average density of 20.25 insects/are and attack rates of 15%, than in fertilized fields, with 8.5 insects/are and attack rates of 2%. Harvests averaged 813.95 kg/ha in fertilized fields versus 435.30 kg/ha in control fields. Fertilization, which increases the protein content of millet, is a means of controlling the insect.