POSTER: Long-term data shows increasing dominance of Bombus terrestris with climate warming

Description

While many bumblebee species decline due to climate and land-use changes, others cope well with contemporary conditions. One example is Bombus terrestris, which is common in intensively managed agricultural landscapes. During the 20th century its subgenus, which includes the B. lucorum complex (B. lucorum, B. cryptarum and B. magnus) came to dominate Scandinavian bumblebee communities, but the specific contribution of B. terrestris remains to be understood.

Using historical data on males, from the Biological Museum collections, we assessed how the relative abundances of B. terrestris and the B. lucorum complex changed over the past 150 years in southernmost Sweden. We tested if these changes differed between landscape types and whether the relative abundance of B. terrestris was related to annual mean temperatures. We also tested if the activity period of males had advanced and whether the advancement differed between taxa. The relative abundance of B. terrestris increased similarly in both landscapes, from 21% to 79% over the period, and this was largely explained by increasing temperature. Male activity period advanced with
41 days between 1900 and 2015 in both taxa. Although the dominance of B. terrestris correlates clearly with annual mean temperature, it remains to disentangle why.

Period	2022 May 16
Event title	Swedish Climate Symposium 2022
Event type	Conference
Location	Norrköping, SwedenShow on map