African armyworms (AAW) experiencing a resurgence in Tanzania

Having been in an apparent recession for several years, coinciding with the expansion of the range of the newly invasive fall armyworm (Spodoptera frugiperda), reports from Tanzania suggest that its cousin, the African armyworm (Spodoptera exempta) may be undergoing a resurgence.

Following outbreaks in KILOSA (Morogoro region) in January, and then further outbreaks in SIMANJIROS district (Manyara region) and Coastal region in February, pheromone traps in KISONGO district (Arusha region) are currently reporting large numbers of moths (in excess of 100-200 moths per trap night), resulting in forecasts of large outbreaks in the region in March.

This northward migration of AAW outbreaks, at approximately months intervals (see Figure), is fairly typical of this moth species during the rainy season in Tanzania (see Rose et al. 2000), as it follows the movement of the seasonal winds and rainstorms, driven by the Inter-tropical convergence zone (ITCZ).

Farmers in Arusha region are being warned to monitor their crops closely for AAW egg batches and young larvae to ensure timely control as the potential threat to crops is high.

Photos courtesy of Wilfred Mushobozi