CABI News

CABI-led research published in the journal Biological Invasions suggests that the invasive prickly pear pest Opuntia stricta could cost sub-Saharan Africa USD 307 billion in lost livestock production over the next 50 years.

The authors argue that current costs associated with the “loss” of forage growing under and near O. stricta plants, which is inaccessible to livestock in Laikipia County, Kenya, and eastern Africa, are USD 8.4 million and USD 244.6 million, respectively, and stress that this plant negatively impacts livelihoods and biodiversity. They believe that O. stricta alone could reduce access to forage valued at more than USD 31, USD 18 and USD 26 billion in the absence of control over the next 50 years in Ethiopia, Kenya and Tanzania respectively.

Detrimental effect on human and animal health as well as pasture production

Cacti have been introduced to many parts of the world for food, fodder, and ornamental purposes. But many of these have become invasive, also having a detrimental effect on human and animal health as well as pasture production.

When livestock eat cactus fruits, small spines on the fruits, called glochids, lodge in their mouths, throats, stomachs, and intestines. These spines often cause secondary infections, leading to ill health and death. Large spines on modified stems, called cladodes, can also harm livestock. They often pierce animals’ eyes as they try to access grass growing under and around cactus plants.

However, the introduction of the biological control agent Dactylopius opuntiae ‘stricta’ biotype – a sap-sucking bug also known as ‘dudu’ in Swahili, has already reduced these potential impacts significantly in South Africa and Kenya.

Preventing loss through biological control agent would be cost effective

Dr Arne Witt said, “The widespread use of biological control against O. stricta across Africa would go a long way to preventing the reduction of forage for livestock and wildlife estimated to be valued at a conservative USD 307 billion over the next 50 years.

“The cost of preventing this loss would be minuscule in comparison. Firstly, because an effective biological control agent has already been identified, screened, and found to be safe and effective, and secondly, the agent is likely to spread naturally from release sites in South Africa and Kenya at no real cost to neighbouring countries.”

He added that introducing the cochineal to countries or regions with isolated Opuntia stricta invasions may be the only cost, as the agent is unlikely to reach these areas through natural dispersal.

Dr Witt said, “The challenge is that those who will benefit from control often lack the financial resources to introduce, rear, release, and disseminate the cochineal. This situation highlights the need for governments, international development partners, and environmental agencies to fund such projects for significant livelihood and environmental benefits.”

Additional information

Main image: Opuntia stricta poses a risk to cattle pictured here in Laikipia, Kenya (Credit: Sarah Hilliar, CABI).

Full paper reference

Witt, A.B.R., van Wilgen, B.W., Wise, R.M. et al. Current and potential economic costs of Opuntia stricta invasions in Africa. Biol Invasions 28, 69 (2026). https://doi.org/10.1007/s10530-026-03778-7

Funding

This work was funded by the Foreign, Commonwealth and Development Office, the Chinese Ministry of Agriculture and Rural Affairs, the Australian Centre for International Agricultural Research, Agriculture and Agri-Food Canada, The Dutch Directorate-General for International Cooperation and the Swiss Agency for Development and Cooperation.

Data availability

Data on the distribution of Opuntia stricta in Africa are available at https://www.gbif.org/dataset/23ec2d04-c0eb-4ca4-afb8-a8710e38f641