Figure 2 | Scientific Reports

Figure 2

From: Predicting the spread of the Asian hornet (Vespa velutina) following its incursion into Great Britain

Figure 2

The likely spatial locations of nests in the years 2015, 2016 and 2017, and the sensitivity of results to the effect of latitude-on the numbers of nests. Given the two locations in which a nest and a hornet were found in 2016, map (A) shows the most likely positions of a common ancestor nest in 2015. Extrapolating forward from this probable location, maps (B and C) show the likely density of undiscovered nests in 2016 and new nests in 2017 respectively. The red contour is defined such that outside this (high-risk) region we would expect to find less than one nest. The inset histograms show the likely distribution of nests in each year, accounting for parameter uncertainty and stochastic variability. Graphs (DF) explore the sensitivity of these findings to our assumption about the effects of latitude; in particular, we vary the linear function of latitude and plot on the x-axis the realised reproductive ratio at the likely location of the founder nest in 2015 relative to that inferred from the Andernos-les-Bains data (Supplementary Material). We show the expected number of nests (D), the chance that the invasion naturally dies out (E) and the area within the high-risk red contour (F) – blue lines correspond to Year 1 (2016), red lines to Year 2 (2017). (All results are calculated explicitly from the probabilistic rates in the Supplementary Material without having to use stochastic simulations. Maps are generated from EEA Corine Land Cover data28 and displayed with bespoke software using Matlab29.)

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