Alien species costly for African farmers

Invasive alien species are costing Africa’s agricultural sector an estimated $3.6 trillion a year, according to scientists.

Boffins from the international not-for-profit organisation CABI conducted the first comprehensive study on the economic impact of a range of invasive alien species (IAS).

The team, comprising scientists from CABI centres in Africa and Europe, conducted a thorough literature review and online survey of 110 respondents – largely working in government or research – and established that Tuta (Phthorimaea) absoluta caused the highest annual yield losses at $11.45 billion, followed by the fall armyworm (Spodoptera frugiperda) at $9.4 billion.

The research took account of yield losses of major crops, including maize, tomato, cassava, mango and banana ($82.2 billion), as well as labour costs – through weeding ($3.63 trillion) – and loss of income derived from livestock ($173 million).

The annual impact of IAS – that also included Prostephanus truncatus, Bactrocera dorsalis and Banana bunchy top virus (BBTV) – was highest on cassava ($21.8 billion), followed by citrus fruits ($14.6 billion), tomato ($10.1 billion), maize ($9.8 billion) and banana ($7.1 billion).

Lead author Dr René Eschen said: “This study reveals the extent and scale of the economic impacts of invasive alien species in the agricultural sector in one of the least studied continents.

“The results highlight the need for measures that prevent new species from arriving and established species from spreading, and that reduce management costs for widely present and impactful species through methods such as biocontrol.”