Ecology and migration patterns of solitary red locusts,Nomadacris septemfasciata (Serville) (Orthoptera: Acrididae) in southwestern Madagascar

Red locusts frequently cause crop damage in Madagascar. This problem has worsened in recent years, likely due to the intensive deforestation that is under way. Little is known about this locust In Madagascar, contrary to continental Africa. Several studies have been carried out in southwestern Madagascar, where locust damage is regularly reported, with the aim of determining the cause of recent outbreaks and improving control strategies—they included surveys of rural inhabitants and an analysis of over 25 years of archival data at the Centre national antiacridien (Malagasy locust control centre). The results revealed several zones between which the red locust—a single-generation species that undergoes imaginal diapause in the dry season—seasonally migrates on a northeast to southwest track, and vice versa, depending on rainfall and wind patterns. The migration dynamics and interannual variations associated with rainfall irregularity certainly partially account for the recurrence of red locust outbreaks in Madagascar.