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SUMMARYThe present study is focused on the potential occurrence of the Colorado potato beetle (Leptinotarsa decemlineata, Say 1824), an important potato pest, and the European corn borer (Ostrinia nubilalis, Hübner 1796), the most important maize pest, during climate change. Estimates of the current potential distribution of both pest species as well as their distribution in the expected climate conditions are based on the CLIMEX model. The study covers central Europe, including Austria, the Czech Republic, Hungary, and parts of Germany, Poland, Romania, Slovakia, Switzerland, Ukraine, Slovenia, the northern parts of Serbia, parts of Croatia and northern Italy. The validated model of the pests’ geographical distribution was applied within the domain of the regional climate model (RCM) ALADIN, at a resolution of 10 km. The weather series that was the input for the CLIMEX model was prepared by a weather generator (WG) which was calibrated with the RCM-simulated weather series (for the period of 1961–90). To generate a weather series for two future time periods (2021–50 and 2071–2100), the WG parameters were modified according to 12 climate change scenarios produced by the pattern scaling method. The standardized scenarios derived from three global climate models (HadCM, NCAR-PCM and ECHAM) were scaled by low, middle and high values of global temperature change estimated by the Model for the Assessment of Greenhouse-gas Induced Climate Change (MAGICC) model (assuming three combinations of climatic sensitivity and emission scenarios). The results of present study suggest the likely widening of the pests’ habitats and an increase in the number of generations per year. According to the HadCM-high scenario, the area of arable land affected by a third generation per season of Colorado potato beetle in 2050 is c. 45% higher, and by a second generation of the European corn borer is nearly 61% higher, compared to present levels.

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The intensity and area of occurrence of pest species are strongly determined by the overall climate conditions of a locality and the weather pattern within a given season in combination with other factors (e.g. host plant abundance). While inter-seasonal weather variability and consequent fluctuations of individual pest species are well-known phenomena, changes in overall climate conditions and associated range shifts of particular species have likewise become important areas of research, especially during the last decade. The present study demonstrates the methodology and benefits of climate-driven modelling tools using the European corn borer (ECB) Ostrinia nubilalis (Hübner, 1796) and Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say, 1824) as examples. CLIMEX models of the potential geographical distributions of each species were created and validated under present climate conditions. Both models were then used to study the effects of climate change on ECB and CPB by estimating changes in population dynamics and/or infestation pressure during the first half of the 21st century. Simulations were conducted using 3 global circulation models (HadCM3, NCAR-PCM, and ECHAM4) and scaled by low and high values of global temperature change. The results predict an increase in newly established areas and in the number of pest generations per year. The ratio of arable land affected by a particular number of generations is also expected to increase. Under the HadCM3-high 2050 scenario, this ratio increases by about 43 and 48% for the second generations of CPB and ECB, respectively. Another significant result is shown for higher altitudes currently unoccupied by pests. We recorded rapid generation increase (from 0 to 2), which supports the hypothesis that these areas are more affected by increased temperatures.

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