Climate Change and Rapidly Evolving Pests and Diseases in Southern Africa

Agriculture faces the huge challenge of meeting increasing food demands while simultaneously reducing its environmental footprint and meeting sustainability goals. Climate change is a major risk to sub-Saharan Africa and the southern Africa region. Pests are, and will continue to be responsible for crop losses which may amount to more than 40% worldwide. Climate change and weather patterns directly affect the distribution, development and population dynamics of insect pests and it may facilitate the spread of indigenous and exotic species. The aim of the study was to identify and evaluate major pests of vegetables in South Africa and Zimbabwe in relation to climate variability. Quantitative and qualitative research methods were used to solicit data from respondents. This was done across all nine provinces of South Africa and five agro-ecological zones in Zimbabwe. Key informants and focus groups were used to triangulate the data. Whiteflies and aphids collected from field and greenhouse sampling sites were phenotyped to determine the possible species present. In Zimbabwe, farmers perceived an increase in the abundance of insect pests such as aphids, whiteflies, stem borers, ball worms, red spider mite, termites and diamondback moths and the emergence of new pests. The increase in pest populations was perceived to be caused by short winters, higher temperatures and lengthy dry spells. In South Africa, the major pest outbreaks were aphids, whiteflies, red spider mites and thrips. Moreover, some of these pests are vectors of destructive viral pathogens. Emerging whitefly-transmitted torrado, crini, and begomoviruses were identified in major vegetable growing regions throughout South Africa. From this study, Tomato torrado virus (ToTV) was reported for the first time from continental Africa continent. In addition, several weed species significantly contributed to the epidemiology of vector-borne disease in commercial and smallholder farming communities. Preliminary risk maps for possible pest and disease outbreaks were produced for the two countries. The major policy directions require governments in Africa to start documenting new and emerging pests and diseases of major crops. Furthermore, surveillance systems should be initiated to monitor pest populations and extension programs that create awareness to farmers on new and existing pests and how to manage them. A collaborative effort is paramount for the development of appropriate integrated pest management systems to reduce the losses incurred by the agricultural pests in Africa and abroad.