Predicted regional and national distribution of Bactrocera dorsalis (syn. B. invadens) (Diptera: Tephritidae) in southern Africa and implications for its management.
Since its detection in Kenya in 2003, the exotic fruit fly, Bactrocera dorsalis, has rapidly spread throughout sub-Saharan Africa. This study was conducted to predict the potential distribution of B. dorsalis in the southern African region using suitable environmental variables and some feral host plants. Presence data from surveillance information carried out in Mozambique and Swaziland up to 2013 were used for niche modelling to predict the potential geographical distribution of the pest in the southern African region. Prediction for its national distribution within Swaziland was also carried out using distribution data for eight feral host plants. Although variable between countries, predicted habitat suitability for the pest was potentially greater in the eastern parts of southern Africa, with response curves suggesting higher probability of the pest's occurrence in low altitude areas with moderate diurnal temperature and high precipitation during the wettest month of the year. Of the host plants considered, the pest's distribution was associated mainly with Ficus sycomorus. The model's prediction also suggested that human-associated activities, such as irrigation, could influence the distribution and establishment of the pest even in areas of low host-plant richness. Since the presence of B. dorsalis causes restrictions in international trade of its host plants, it is imperative that countries within the region continue surveillance programmes and coordinated strategies to reduce the impact of the pest.