Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
Centre for Health Informatics, Computing and Statistics, Lancaster Medical School, Lancaster University, Lancaster, UK.
Parasit Vectors. 2020 Oct 19;13(1):526. doi: 10.1186/s13071-020-04398-3.
Climate change is predicted to impact the transmission dynamics of vector-borne diseases. Tsetse flies (Glossina) transmit species of Trypanosoma that cause human and animal African trypanosomiasis. A previous modelling study showed that temperature increases between 1990 and 2017 can explain the observed decline in abundance of tsetse at a single site in the Mana Pools National Park of Zimbabwe. Here, we apply a mechanistic model of tsetse population dynamics to predict how increases in temperature may have changed the distribution and relative abundance of Glossina pallidipes across northern Zimbabwe.
Local weather station temperature measurements were previously used to fit the mechanistic model to longitudinal G. pallidipes catch data. To extend the use of the model, we converted MODIS land surface temperature to air temperature, compared the converted temperatures with available weather station data to confirm they aligned, and then re-fitted the mechanistic model using G. pallidipes catch data and air temperature estimates. We projected this fitted model across northern Zimbabwe, using simulations at a 1 km × 1 km spatial resolution, between 2000 to 2016.
We produced estimates of relative changes in G. pallidipes mortality, larviposition, emergence rates and abundance, for northern Zimbabwe. Our model predicts decreasing tsetse populations within low elevation areas in response to increasing temperature trends during 2000-2016. Conversely, we show that high elevation areas (> 1000 m above sea level), previously considered too cold to sustain tsetse, may now be climatically suitable.
To our knowledge, the results of this research represent the first regional-scale assessment of temperature related tsetse population dynamics, and the first high spatial-resolution estimates of this metric for northern Zimbabwe. Our results suggest that tsetse abundance may have declined across much of the Zambezi Valley in response to changing climatic conditions during the study period. Future research including empirical studies is planned to improve model accuracy and validate predictions for other field sites in Zimbabwe.
气候变化预计会影响媒介传播疾病的传播动态。采采蝇（ Glossina ）传播导致人和动物感染非洲锥虫病的种属。此前的一项建模研究表明，1990 年至 2017 年期间的温度升高可以解释津巴布韦马纳波尔斯国家公园（Mana Pools National Park ）一个地点采采蝇丰度下降的现象。在这里，我们应用采采蝇种群动态的机械模型来预测温度升高如何改变津巴布韦北部 Glossina pallidipes 的分布和相对丰度。
之前使用当地气象站的温度测量值来拟合机械模型，以获得 G. pallidipes 的纵向捕获数据。为了扩展模型的应用范围，我们将 MODIS 地表温度转换为空气温度，将转换后的温度与可用气象站数据进行比较以确认其一致性，然后使用 G. pallidipes 捕获数据和空气温度估算值重新拟合机械模型。我们将该拟合模型应用于津巴布韦北部，使用 2000 年至 2016 年的 1 公里×1 公里的空间分辨率进行模拟。
我们为津巴布韦北部地区 G. pallidipes 的死亡率、产卵量、出蛹率和丰度的相对变化做出了估计。我们的模型预测，2000 年至 2016 年期间，随着温度趋势的上升，低海拔地区的采采蝇数量将会减少。相反，我们表明，以前认为海拔高于 1000 米（3280.8 英尺）的地区过于寒冷而无法维持采采蝇的生存，现在可能在气候上是适宜的。
据我们所知，这项研究的结果代表了第一个关于温度相关采采蝇种群动态的区域规模评估，也是第一个针对津巴布韦北部地区的这种度量标准的高空间分辨率估计。我们的结果表明，在研究期间，由于气候条件的变化，赞比西河谷的大部分地区的采采蝇丰度可能已经下降。计划进行未来的研究，包括进行实证研究，以提高模型的准确性并验证津巴布韦其他实地站点的预测。
