Ecology and management of the Senegalese grasshopper Oedaleus senegalensis (Krauss 1877) (Orthoptera: Acrididae) in West Africa: review and prospects

Abstract

Following the droughts that occurred in the Sahel during the 1970s, the Senegalese grasshopper Oedaleus senegalensis (Krauss 1877) suddenly became the main pest grasshopper species in this region, where it regularly causes serious damage to crops, especially millet. The lifecycle of O. senegalensis reflects the precariousness of the Sahelian environment. The lifecycle and survival strategies of O. senegalensis have evolved to include migration following shifts in the intertropical convergence zone (ITCZ) and embryonic diapause in the dry season. It is thus able to cope with its natural hostile environment and remain in the most suitable ecological conditions for as long as possible. The alternation between outbreaks and recession periods seems to be related to the high spatiotemporal rainfall variability in the Sahel. Senegalese grasshopper outbreaks depend on the rainy season chronological pattern and on the initial quantity of diapaused eggs in the soil. Since the 1970s, many studies have been conducted on this species in the Sahel. Various models designed to monitor the population dynamics of this species have been published. However, some key factors that could explain the variability in outbreaks have not been seriously investigated. The present bibliographical review provides an overview on current knowledge while proposing some avenues for future research to enhance the sustainable management of this major Sahelian pest.