Simulating the Potential Distribution and Abundance of the Brown Marmorated Stink Bug (Halyomorpha halys) under Future Climate Scenarios in Switzerland

The climate in Switzerland is changing. Depending on the emission scenario and time period, the projected increase in temperature is 2.7-4.8°C and the projected decrease in precipitation is 18-28%. There is scientific evidence that climate change will increase economic damage by agricultural pests. The prevention and management options of alien species are cost and time intensive. Climate change will improve the long-term suitability of potential new areas and amplify the need for action. Therefore it is highly important to assess the risk of alien species under future climate conditions and to plan an efficient monitoring and to develop management strategies. The brown marmorated stink bug (Halyomorpha halys) is an extremely polyphagous insect and has invaded North America and Europe around 2004. Especially in Italy it has become a relevant fruit pest. In Switzerland fruit damage have been reported from the canton Ticino and since 2017 also from the canton Zurich. Climate Impact studies are of great importance to develop adaptation strategies. In this work we used high-resolution, gridded climate change scenarios for Switzerland to simulate the distribution and abundance of H. halys under present and future climate conditions. The simulations were performed with the software package CLIMEX (© CSIRO), a process-based bioclimatic niche model that simulates the mechanisms that limits species’ geographical distributions and determine their seasonal phenology, and to some extend their relative abundance. A recently published CLIMEX model for H. halys (Kriticos et al. 2017, J Pest Sci) was validated and calibrated for Switzerland considering adult trap catch data. The potential distribution and abundance under present and future climates was compared by means of the number of generations per year and the annual growth index (suitability of the climate for the growth of insects). Today H. halys is univoltine in Switzerland. Our results indicate that under future climate conditions a multivoltine behavior will be possible. Furthermore our simulations demonstrate an enhancement of the overall suitability for the growth of H. halys. Our results help to define regions and time periods at greatest risk and to design management strategies for H. halys under future climate conditions