South African scientists near breakthrough in biological control of invasive brambles

Scientists working in South Africa say they are on the verge of securing a biological control solution for the invasive bramble shrubs that have spread across the country for more than a century. The research, carried out by a consortium of universities and the country's environmental agency, has identified several insect and fungal candidates that naturally suppress Rubus species in their native habitats. While formal approval and field trials remain pending, the team believes the findings bring the long‑standing weed management problem closer to a sustainable resolution.

The brambles, belonging to the genus Rubus, were unintentionally introduced from North America and Europe in the early 1900s. Since then they have proliferated in a variety of South African ecosystems, from the fynbos of the Western Cape to the highveld grasslands. Locally they are known by a range of vernacular names – braam in Afrikaans, ijingijolo in isiZulu and monoko‑metsi in seSotho – reflecting how widely they have become embedded in the landscape. Their aggressive growth habit allows them to out‑compete native shrubs, forming dense thickets that alter fire regimes and reduce biodiversity.

The ecological consequences of the Rubus invasion are well documented. Thick bramble stands shade out indigenous seedlings, disrupt pollinator networks, and provide shelter for pest species that affect crops and livestock. Land managers also report that the thorny canes impede access to grazing land and increase the cost of mechanical clearing. Because the plants spread both by seed and by rooting runners, conventional control methods such as herbicide application and manual removal often prove labor‑intensive and short‑lived.

Biological control offers a more enduring alternative by re‑introducing the natural enemies that keep Rubus populations in check within their original range. The South African team has been sampling insects and pathogens from bramble‑rich sites in the United States and Europe, focusing on agents that target foliage, stems or reproductive structures without harming non‑target species. Laboratory trials have shown promising levels of feeding damage and reduced seed set, and the most promising candidates are now undergoing host‑specificity testing required by the country's environmental regulations.

If the upcoming risk assessments confirm safety, the selected agents could be released in pilot sites later this year, providing a rare example of a successful, science‑based response to an invasive plant that has persisted for more than a hundred years. Authorities stress that biological control would complement, rather than replace, existing management practices, and that ongoing monitoring will be essential to gauge long‑term impacts. The potential rollout underscores the growing emphasis on ecological solutions that limit chemical use while restoring native habitats across South Africa.