Climate Change and Predicting Geographical Forest Insect Distributions

Excerpt from: Régnière, J. 2009. Predicting insect continental distributions from species physiology. Unasylva. 60:37-42.

Global spread of harmful forest pest species is a possible consequence of climate change. However, because of the diverse and complex responses of insects to climatic factors, it is difficult to make general predictions. Generic modeling tools, such as BioSIM (Régnière and St-Amant 2008), use available knowledge about the responses of particular species (usually pests) to key climatic factors to predict their potential geographic range and performance. These models focus mainly on factors that determine the insect’s seasonality and those that affect its survival during the harshest season (usually winter). They are based on the idea that the insect’s most fundamental requirement to complete its life cycle is a well-adapted seasonal pattern, with adequate synchrony between essential resources, such as host plants for food and shelter, and the life stages that require them. If a species cannot satisfy this basic viability requirement generation after generation under a specific climate, it cannot persist in that environment.

Once a seasonality model is available for an insect species, its distribution can be predicted by mapping climates that produce viable seasonality with more or less certainty and overlaying the distribution of resources vital to (or most at risk from) that species. Predictions can be further refined by also considering the probability of survival under extreme climatic conditions (based, for example, on tolerance to cold or heat). This approach has been applied to three species of importance to North American forests (i.e., gypsy moth, mountain pine beetle, and spruce budworm), using climate norms (averages and variances measured over standard 30-year intervals) for the periods 1971 to 2000 and 2041 to 2070 using a conservative climate change scenario driven by a 1 percent per year increase in atmospheric CO2 (Logan et al. 2003).

Three North American examples:
The Effect of Climate Change on Mountain Pine Beetle
The Effect of Climate Change on Spruce Budworm
The Effect of Climate Change on Gypsy Moth

Adapted for by Tom DeGomez, University of Arizona

References cited:
Logan, J.A., J. Régnière, and J.A. Powell. 2003. Assessing the impact of global warming on forest pest dynamics. Frontiers of Ecology and the Environment. 1(3): 130–137.

Régnière, J. and R. St-Amant. 2008. BioSIM 9 user’s manual. Information Report LAU-X-134. Quebec, Canada, Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre.

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