Light Sensitive Bumblebee Species Are Associated With Forest Habitat and Forest-Dominated Landscapes

We investigate whether the eye parameter of bumblebees-a visual trait measuring the tradeoff between light sensitivity and visual resolution-is associated with: (i) local habitats, (ii) forest cover at the landscape scale (1 km radius), and (iii) the shade tolerance of the plants they forage on. The association of bumblebee species with local habitat and forest cover at the landscape scale was analyzed using generalized linear mixed models. We combined data from the Norwegian national bumblebee monitoring program with Corine CLC+ land cover and bumblebee functional traits: eye parameter and intertegular distance. These analyses were done at the species and community level. To determine whether bumblebee light sensitivity correlated with the shade tolerance of the plant they forage on, we combined bumblebee-plant interactions from a British database with a Swedish plant trait database. Our findings showed that bumblebee species with high light sensitivity were more common and abundant in forest habitats and areas with greater forest cover, while species with high visual resolution showed the opposite trend. This pattern was reflected at the community level, as indicated by the community-weighted mean of the eye parameter, which increased with forest cover and was higher in forest habitats. Furthermore, bumblebees with higher light sensitivity tended to forage on plants with greater shade tolerance. These results suggest that visual adaptations for light sensitivity contribute to shaping bumblebee species distributions across different scales. Our study underscores the importance of pollinator vision in understanding species niches and its value for species distribution modeling. Moreover, by relating pollinator visual abilities to plant niches for the first time, this study provides an important basis for future modeling of plant-pollinator interactions and targeted conservation measures for plants and pollinators in forested landscapes.