Adaptation and Invasion Dynamics of Rhipicephalus microplus in South Africa: Ecology, Resistance, and Management Implications.

Rhipicephalus microplus, also known as the Asiatic blue tick, is an invasive ectoparasite of significant economic and animal health importance in South Africa. This review synthesises evidence on its ongoing range expansion, which is displacing the native R. decoloratus, driven by factors including climate suitability, livestock movement, and communal grazing practices. The tick's success is compounded by widespread, multi-class acaricide resistance, which has been documented across all major chemical classes. Molecular diagnostics are crucial for accurate surveillance, and population genetics reveal significant gene flow facilitated by livestock movement. Projections indicate that climate change will further expand the tick's suitable habitat. Current reliance on chemical control is unsustainable. We conclude that an integrated parasite management (IPM) approach combining strategic acaricide rotation, targeted selective treatments, pasture management, and strict biosecurity is critical for sustainable control. Key recommendations include establishing standardised, national resistance monitoring, validating molecular markers for resistance prediction, and developing farmer-facing decision-support tools. This synthesis provides a framework for research and policy to mitigate the impact of R. microplus at the wildlife-livestock interface in South Africa.