Data Sheet 1_Informing African agricultural health: integrating human population dynamics and climate change into banana bunchy top disease risk assessment.docx

Introduction

Banana bunchy top disease (BBTD) is a major emerging viral disease of banana plants in Africa, threatening food security and economies. BBTD has spread to numerous (sub)tropical African countries, with new incursions in multiple countries confirmed even within the last few years.

Methods

We assessed the continent-wide risk of BBTD, to provide an informative tool of large-scale risk areas of BBTD introduction, establishment, and spread. Using published BBTD survey data across (sub)tropical Africa, a RandomForest model was developed incorporating both climatological suitability and socioeconomic drivers.

Results

Population density, which serves as a proxy for factors like road infrastructure and trade, dominates our model, along with maximum solar radiation and annual temperature range. Three main regions are identified as current high-risk areas, namely, East-Central Africa (around the African Great Lakes in Uganda, Rwanda, Burundi, eastern DR Congo, and northern Tanzania), western Central Africa (including Gabon and the Republic of the Congo), and southern regions of West Africa. Our projections for ~2055, driven by climate change and human population shifts, predict increased risks in East-Central Africa and along the 5-10°N latitude belt, while the risk in Central Africa is expected to decrease.

Discussion

We present these African risk maps as a complementary tool to national assessments, offering a broader spatial context to inform effective disease management and policy development. Specifically, we identify the critical need to address the unregulated banana seed system, where stakeholders are free to use and informally trade planting material across banana production regions and borders, to achieve effective prevention and disease management.