Expansion of the cassava brown streak pandemic in Uganda revealed by annual field survey data for 2004 to 2017

Funder: Uganda Government Association for Strengthening Agricultural Research in Eastern and Central AfricaFunder: Bill and Melinda Gates Foundation (Bill & Melinda Gates Foundation)Abstract: Cassava brown streak disease (CBSD) is currently the most devastating cassava disease in eastern, central and southern Africa affecting a staple crop for over 700 million people on the continent. A major outbreak of CBSD in 2004 near Kampala rapidly spread across Uganda. In the following years, similar CBSD outbreaks were noted in countries across eastern and central Africa, and now the disease poses a threat to West Africa including Nigeria - the biggest cassava producer in the world. A comprehensive dataset with 7,627 locations, annually and consistently sampled between 2004 and 2017 was collated from historic paper and electronic records stored in Uganda. The survey comprises multiple variables including data for incidence and symptom severity of CBSD and abundance of the whitefly vector (Bemisia tabaci). This dataset provides a unique basis to characterize the epidemiology and dynamics of CBSD spread in order to inform disease surveillance and management. We also describe methods used to integrate and verify extensive field records for surveys typical of emerging epidemics in subsistence crops

Occurrence data for <i>Ceratitis capitata</i> used in the study.

<p>Data with information about the month of occurrence is marked with red triangles. Countries/regions where Medfly is present are coloured with yellow and where it is eradicated are marked with green <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0111582#pone.0111582-IAEA1" target="_blank">[12]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0111582#pone.0111582-EPPO1" target="_blank">[13]</a>.</p

Global environmental suitability for <i>C. capitata</i> occurrence as predicted by MaxEnt model.

<p>Black triangles represent presence points used in the modeling. Blue, purple and red colors show high confidence in predicted suitability, while yellow represents low confidence and predicted absence.</p

Relative influence of the contribution of the variables to the model [%].

<p>Relative influence of the contribution of the variables to the model [%].</p

The list of the data sets used in the development of seasonal ecological niche models including source and the spatial resolution. Seasonal model 1: Jan–Apr, 2; May–Aug and 3: Sep–Dec.

<p>The list of the data sets used in the development of seasonal ecological niche models including source and the spatial resolution. Seasonal model 1: Jan–Apr, 2; May–Aug and 3: Sep–Dec.</p

Models were calibrated using training and test data (75% and 25% randomly selected occurrence points respectively).

<p>Area under the curve (AUC) was calculated as an average of 30 model replicate runs using subsample run type. Mean AUC and omission rate values were calculated both for test and training data. The mean omission rates are calculated at an arbitrarily chosen cumulative threshold of 10. All model omission results performed significantly better than random (<i>p</i><0.0001).</p><p>Models were calibrated using training and test data (75% and 25% randomly selected occurrence points respectively).</p

Data sets used in the development of ecological niche models, including source and spatial resolution.

<p>Data sets used in the development of ecological niche models, including source and spatial resolution.</p

3-panel seasonal maps showing the environmental suitability for <i>C. capitata</i> occurrence annually according to the MaxEnt model.

<p>Dots represent the seasonal presence points used in the seasonal potential niche modelling. Blue, purple and red colors show high confidence in predicted suitability, while yellow represents low confidence and predicted absence.</p

Evidence that recent climatic changes have expanded the potential geographical range of the Mediterranean fruit fly

Abstract The species distributions migration poleward and into higher altitudes in a warming climate is especially concerning for economically important insect pest species, as their introduction can potentially occur in places previously considered unsuitable for year-round survival. We explore the expansion of the climatically suitable areas for a horticultural pest, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera, Tephritidae), with an emphasis on Europe and California. We reviewed and refined a published CLIMEX model for C. capitata, taking into consideration new records in marginal locations, with a particular focus on Europe. To assess the model fit and to aid in interpreting the meaning of the new European distribution records, we used a time series climate dataset to explore the temporal patterns of climate suitability for C. capitata from 1970 to 2019. At selected bellwether sites in Europe, we found statistically significant trends in increasing climate suitability, as well as a substantial northward expansion in the modelled potential range. In California, we also found a significant trend of northward and altitudinal expansion of areas suitable for C. capitata establishment. These results provide further evidence of climate change impacts on species distributions and the need for innovative responses to increased invasion threats