Past, present and future of the two-spotted stink bug (Perillus bioculatus) in Europe revealed by citizen science.

The introduction of the Nearctic predaceous stink bug species, (Perillus bioculatus) was attempted multiple times in various countries throughout Europe to mitigate the damage caused by the invasive and harmful pest species, the Colorado potato beetle (Leptinotarsa decemlineata). Though these attempts were thought to be unsuccessful for decades, more recent data elucidated that the species have established small self-sustaining populations in the Balkans Peninsula, Southern Russia, and Türkiye and recently began to expand. In the past years, the European range of the species reached Eastern Europe. After the first individuals were found in Hungary in October 2023 a citizen science campaign was launched to investigate the distribution of the species in the country. By June 2024 it became evident that the species is established throughout the country. Furthermore, observations regarding beetle larvae and moth caterpillars as alternative prey were reported supporting the previous assumptions that the naturalization and expansion of the species in Europe is facilitated by dietary drift. Here, we summarize the knowledge on the European presence of the two-spotted stink bug and formulate hypotheses regarding its future distribution and the impact of the species on the insect communities of the newly colonized areas.