Climate and atmospheric carbon dioxide are significant factors in ecological risk assessments, suggesting their consideration is required in predicting potential distribution of a invasive species. CLIMEX model is one of species distribution models (SDMs) and provides potential geographical distribution by focusing on climatic effect on species inhabitation. Most SDMs, such as Bioclim, Domain, GARP and MaxEnt, focus on relationship between the occurrences of the species and static environmental covariates, whereas CLIMEX model depends on limitations of species' geographical distribution and reactions to climatic variables at an appropriate temporal scale (called seasonal phenology). In this study, we described the basic concept of CLIMEX and reviewed previous applications. Also, we demonstrated the various utilization of CLIMEX differed by study purposes and methodology for analyzing the model.

Invasive pests have posed an ecological threat as climate change has been accelerated, suggesting early prediction ofinvasive pests is required to minimize damages by them. As one of predictive tools, CLIMEX has been effectively usedin a few regions, including US, Australia, and Europe. It allows us to predict a species distribution on a local area inresponse to climatic conditions: and thus, potential distribution of invasive species, risk assessment of agricultural pests,and suitability of biological control agents have been tested by CLIMEX. In this study, we introduced how to use CLIMEXfor predicting a species distribution differed by climate change in terms of its functions, required data, and examplesof its application.

The establishment of insect population in certain region is affected by three major characteristics, the host spectrum, the phenological plasticity and the overwintering strategy. The geographical distribution of insect population is directly affected by their successful establishment in local environment, thus, in case of development of potential geographical distribution models, three major characteristics should be considered carefully. In this study, we developed geographical distribution model using CLIMEX system with well-known insect species, Carposina sasakii. Its geographical distribution is limited to northeast Asia including Korea, Japan, China and the Soviet Far East. C. sasakii overwinters as a full-grown larva within spherical and compactly woven larval-cocoons in the soil. We calculated Diapause Index (DI) then incorporated DI into CLIMEX system to simulate Ecoclimatic Index (EI), which stands for ability of establishment in a certain area for further studies of geographical distribution of insect populations which have overwintering strategy in their life history.

Thrips palmi Karny was introduced and first recorded in 1993 in Korea. This species has become a serious pest of vegetable and ornamental crops. CLIMEX simulation was applied to T. palmi to predict the potential geographic distribution in Korea under the Representative Concentration Pathway (RCP) 8.5 climate change scenario. In the CLIMEX simulation, ecoclimatic index (EI) was calculated, and compared in each simulated year and each simulated location. The map comparisons showed a good agreement between simulated and present distributions of T. palmi, indicating that the CLIMEX model was well explained and appropriate for prediction of future distributions of this species in Korea. In near future, until a year of 2020, all the western and eastern parts of Korea showed favorable to marginal suitability for T. palmi populations in fields. After the year of 2040, the potential distributions are shifted from no persistent to favorable for establishment and persistence from coastal to interior of the Korean peninsula except a north-eastern interior region which is the northernmost part of high mountains (Baekdu-Daegan) area in South Korea. Based on simulation results, T. palmi would overcome its weather restriction in near future under a severe climate change scenario, thus, pest management measures and strategies should be re-constructed in Korea, with further studies including interspecific competition and understanding ecosystem change due to climate change.

Light brown apple moth, Epiphyas postvittana, is a significant horticultural pest native to Australia, and currently with a limited global distribution. However it can tolerate very heterogeneous climatic and vegetation conditions and has recently invaded California with considerable consequences for US international and domestic trade. By comparing the climatic conditions of its native (Australia) and long-established (New Zealand) ranges to the rest of the world using CLIMEX, it was suggested that E. postvittana has potential to establish mainly in countries in Central and South America, southern Africa, west Europe and South-east Asia. However, the predicted global distribution of E. postvittana using a new multiple-species-distribution model system suggested that there are additional climatically suitable areas around the world where this species could potentially survive and establish. Our study provides basic but important information for further assessment of the establishment capacity of this species in new habitats, wihch will provide the knowledge required to make science-based decisions in biosecurity.