A landmark biological control program is achieving remarkable success in controlling the invasive prickly pear cactus (Opuntia stricta) that has devastated rangelands across central and northern Kenya. The program, implemented by the Kenya Agricultural and Livestock Research Organization (KALRO) in partnership with international biocontrol experts, involves the carefully regulated release of the cochineal insect (Dactylopius opuntiae), a tiny scale insect that feeds exclusively on the targeted cactus species. After extensive host-specificity testing to ensure the insect would not damage native plants or crops, the cochineal was released at strategic infestation sites, where it has since spread naturally, sucking the sap from the cactus pads and gradually killing the plants without the use of chemicals or mechanical clearing.
The impact on the landscape and local livelihoods has been transformative. In Laikipia County, where dense stands of the invasive cactus had rendered thousands of hectares unusable for livestock and displaced native vegetation, the cochineal insects have reduced cactus coverage by over 80% within two years. The decomposing cactus plants are now making way for the return of native grasses, restoring grazing land for pastoralists and habitat for wildlife. The control method is particularly valuable because it is self-sustaining and cost-effective—once established, the insect population maintains itself and continues to spread to new infestations, requiring minimal further intervention compared to the repeated, expensive mechanical and chemical control methods previously used.
The long-term success of this program demonstrates the power of nature-based solutions for managing invasive species at scale. The restored rangelands are improving food security for pastoral communities and reducing human-wildlife conflict as animals return to their natural grazing patterns. Environmental managers are now exploring the application of similar biocontrol approaches for other problematic invasive species, such as the mathenge weed (Prosopis juliflora). This successful partnership between science, government, and local communities offers a sustainable model for ecological restoration across Africa, proving that sometimes the most effective way to combat an invasive species is not with heavy machinery or herbicides, but by reintroducing the natural checks and balances that existed in its native ecosystem.