  Population dynamics with spatial information is applied to understand the
spread of pests. We introduce a model describing how pests spread in discrete
space. The number of pest descendants at each site is controlled by local
information such as temperature, precipitation, and the density of pine trees.
Our simulation leads to a pest spreading pattern comparable to the real data
for pine needle gall midge in the past. We also simulate the model in two
different climate conditions based on two different representative
concentration pathways scenarios for the future. We observe that after an
initial stage of a slow spread of pests, a sudden change in the spreading speed
occurs, which is soon followed by a large-scale outbreak. We found that a
future climate change causes the outbreak point to occur earlier and that the
detailed spatio-temporal pattern of the spread depends on the source position
from which the initial pest infection starts.
