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Gypsy Moth Risk Assessment in the Face of a Changing Environment: A Case History Application in Utah and the Greater Yellowstone Ecosystem
Jesse Logan, USDA Forest Service (ret.), Logan, UT, J. Régnière, Canadian Forest Service, Québec, Quebec, D.R. Gray, Canadian Forest Service, Fredericton, New Brunswick, and A.S. Munson, USDA Forest Service, Ogden, UT
Risk assessment for establishment of introduced pests is an important ecological and economic issue. Evaluation of climate is fundamental to determining the potential success of an introduced or invasive insect pest. However, evaluating climatic suitability poses substantial difficulties; climate can be measured and in a multitude of ways. Some physiological filter, in essence a lens that focuses climate through the requirements and constraints of a potential pest introduction, is required. Difficulties in assessing climate suitability are further exacerbated by the effects of climate change.
Gypsy moth (Lymantria dispar L.) is an exotic, tree-defoliating insect that is frequently introduced into the western United States. In spite of abundant host species, these introductions have yet to result in established populations. The success of eradication efforts and the unsuccessful establishment of introductions may be related to an inhospitable climate. Climatic suitability for gypsy moth in the western United States, however, is potentially improving, perhaps rapidly, due to a continuing general warming trend that began in the mid 1970s. In this presentation, we describe the application of a physiologically based climate suitability model for evaluating risk of gypsy moth establishment on a landscape level.
Development of this risk assessment system first required amassing databases that integrated a gypsy moth climatic assessment model with host species distributions and climate. This integrated system was then used to evaluate climate change scenarios for native host species (primarily aspen) in Utah, with the result that risk of establishment will dramatically increase during the remainder of the 21st century under reasonable climate change scenarios. We then applied the risk assessment system to several case histories of detected gypsy moth introductions in Utah and the Greater Yellowstone Ecosystem. These applications demonstrated the general utility of the system for predicting risk of establishment and for designing improved risk detection strategies.