What limits #bumblebee populations on farmland? Our new paper in @JAppliedEcology finds that bumblebee colony density is strongly limited by a late summer nectar gap and the cover of rural gardensRead more here: https://doi.org/10.1111/1365-2664.13826 and and in the thread below...

2/6: Bumblebees require floral resources throughout their whole flight period, but previous work ( https://doi.org/10.1111/1365-2664.13403) shows that these vary greatly through the year, with alternating periods of surplus and deficit. So when exactly are resources most limiting for bumblebees?

3/6: On 12 farms in W-England, we measured the supply of pollen and nectar during the 4 main flowering periods of the year to test which season had the strongest influence on colony density (estimated using microsatellite markers)

4/6: We found that the supply of nectar in September explained over half of the variation in colony density the following year, suggesting this may be a major resource bottleneck for bumblebees

5/6: Semi-natural habitat cover was NOT associated with colony density or even with the supply of floral resources. However, garden cover was positively associated with colony density, perhaps because of their more continuous resource supply @nicktew95

6/6: Using a modelling approach, we test the effect of different farmland management scenarios and find some promising strategies for plugging the late-summer nectar gap and supporting bumblebee populations on farmland.