The role of the parliamentary arena and members of parliament (MPs) therein for both mainstreaming and cross-sectoral policy integration is largely unknown. Studying the case of Switzerland, this paper analyzes the integration of the biodiversity issue into policies of 20 different policy sectors over a period of 19 years to assess how two specific actor attributes—issue and sector specialization—increase the chances of MPs of engaging in both biodiversity mainstreaming and its cross-sectoral integration. The results based on a comprehensive collection of political documents from the parliamentary arena, and multilevel regression models show that an increase in MPs' sector specialization is associated with both a decrease in mainstreaming and a decrease in cross-sectoral integration activities. By contrast, an increase in issue specialization typically translates into biodiversity-related activity in a larger number of sectors. In the parliamentary arena, therefore, it is primarily a small group of “issue specialists” who take responsibility for the integration of crosscutting issues, such as biodiversity, into critical sectoral policies.

议会舞台和议会成员 (MP) 在主流化和跨部门政策整合方面的作用在很大程度上是未知的。本文研究了瑞士的案例，分析了 19 年来将生物多样性问题纳入 20 个不同政策部门的政策，以评估两个特定的行为者属性——问题和部门专业化——如何增加国会议员参与这两个领域的机会生物多样性主流化及其跨部门整合。基于议会领域全面收集的政治文件和多层次回归模型得出的结果表明，国会议员部门专业化程度的提高与主流化和跨部门整合活动的减少有关。相比之下，问题专业化的增加通常转化为更多部门的生物多样性相关活动。因此，在议会领域，主要是一小群“问题专家”负责将生物多样性等交叉问题纳入关键部门政策。