Modelling the potential distribution of the box tree moth Cydalima perspectalis in North America using CLIMEX

The box tree moth (BTM), Cydalima perspectalis (Lepidoptera: Crambidae), is an insect of Asian origin that has invaded most of Europe, Turkey, and the Caucasus since 2005. It has become a major pest of ornamental box trees (i.e., boxwood) in gardens, while also representing a serious threat to native Buxus spp. in Europe and elsewhere. In 2018, BTM was found in Toronto, Canada and has since been reported in the adjacent Niagara region of Canada and the US. Given that C. perspectalis is a new invasive species in North America, the question arises as to its potential for spread on the continent. In 2013, we developed a bioclimatic (CLIMEX) model for BTM based on climatic, ecological, and developmental parameters to predict potential distribution of BTM in Europe. Current biological and distribution data were used to update the existing CLIMEX model. Our work suggests that BTM is likely to spread south through the US and into Mexico. To the west, the Rocky Mountains and more southern mountain ranges build a natural limit, however, the coastal climate is also suitable, at least up to the northern limit of Vancouver, Canada. In the east, BTM has the potential to spread from its current location in southern Ontario to reach parts of southern Quebec and New Brunswick, as well as to the west reaching Manitoba and Saskatchewan. However, because the northern climate only supports one generation of the moth, its impact in these northern regions is likely to be rather limited.