Climate change could alter the elevation and latitudinal range limits of the mountain pine beetle in western Canada

The mountain pine beetle, Dendroctonus ponderosae Hopk. (Coleoptera: Curculionidae) is the most damaging insect of Canada’s pine forests. Temperature plays a key role in regulating the population levels of this insect in forest ecosystems. For example, cooler temperatures frequently prevent populations from reaching outbreak levels. Above the northern range limits of the beetle, lethal winter temperatures cause almost complete mortality of larvae. However, climate change could potentially transform these unsuitable habitats to favorable habitats for mountain pine beetle. According to the Intergovernmental Panel of Climate Change (IPCC), regional temperature increases could range from 2-5ºC by the end of the 21^st century. Such increases in temperatures could significantly alter the distribution of mountain pine beetle outbreaks in Canada. We studied the potential impacts of climate change on the distribution of mountain pine beetle outbreaks in a study area in western Canada using an autologistic model, which prominently included cold temperature terms, and simulated various climate change scenarios over outbreak data from the peak year of the current outbreak, 2005. We present the results of computer simulations of four scenarios of climate change that include increases in mean temperatures of 0ºC, 1ºC, 2ºC, and 4ºC under one climatic variability scenario of 1ºC². Our results indicate that a 1-2ºC increase in mean annual temperature could help support tree-killing populations of mountain pine beetle at elevations >1500 msl in the study area, and a 4ºC increase could additionally sustain populations in areas further north of the current geographic range of the insect in Canada.