Comparison of the potential spread of pinewood nematode (Bursaphelenchus xylophilus) inFinland andIberia simulated with a cellular automaton model

Abstract

SummaryPinewood nematode (PWN) is one of the most threatening invasive pests in the pine forests ofEurope, and it has recently spread to theIberianPeninsula via import of timber and wooden packaging material fromEastAsia. A cellular automaton (CA) model was developed to simulate and compare the potential spread ofPWNby transportation and its vectors,Monochamusbeetles in the pine forests of Finland and Iberian Peninsula. The model assumes that all pines are equally sensitive toPWN. TheCAis a spatio‐temporal grid‐based model, which can easily be applied on different geographical scales. The effects of climate warming and number of entries from ports on the spread ofPWNwere studied. A sensitivity analysis was conducted on the most uncertain model parameters. Twenty years after hypothetical entries, the predicted area of symptomaticPWNinfection (pine wilt disease,PWD) was very low inFinland compared toIberia. This was because of the low probability of warmJuly inFinland. The increase in the meanJuly temperature increased the area ofPWD‐infected pine forest relatively more inFinland than inIberia. An increase in the number of entries also increased the area ofPWD‐infected pine forest relatively more in Finland than in Iberia. The probability ofPWDinfection was the highest in pine forests that were close to entry points and in areas with low elevation and high human population density.