Abstract The invasive bumblebee Bombus terrestris has established widespread populations across northern Japan since its introduction in 1991 and has become dominant in some agricultural regions. This dominance has raised concerns about ecological impacts on native pollinators; however, the consequences of its removal for crop pollination and yield remain poorly understood. We conducted a field‐based case study in squash ( Cucurbita maxima ) fields to examine differences in pollination dynamics between a year without queen removal (2022) and a year with intensive queen removal (2024). We quantified floral visitation, stigmatic pollen deposition, fruit set, fruit weight and seed production. Queen abundance was also monitored in 2025 to document population reappearance following the removal period. The abundance of B. terrestris workers during flowering was markedly lower in 2024 than in 2022. Although native bumblebees and alternative visitors such as Vespula were observed, their visitation did not compensate for pollen transfer and fruit and seed production were reduced relative to the non‐removal year. In 2025, B. terrestris queens were again recorded, indicating recolonisation from surrounding areas. These results indicate that B. terrestris currently plays a dominant functional role in pollination at the study site and that its removal may be associated with reduced pollination services and crop production. Management of invasive pollinators in agroecosystems should therefore consider potential trade‐offs between biodiversity conservation and pollination services and integrate control efforts with measures that support native pollinator communities.
Kumano et al. (Sun,) studied this question.