[Pollinator] Spring forest flowers likely a key to bumble bee survival

[David Inouye]

Spring forest flowers likely a key to bumble bee survival, Illinois 
study finds | Illinois <https://news.illinois.edu/view/6367/1809224114>

Mola, J. M., et al. (2021). "Long-term surveys support declines in early 
season forest plants used by bumblebees." Journal of Applied Ecology 
n/a(n/a).
     Populations of bumblebees and other pollinators have declined over 
the past several decades due to numerous threats, including habitat loss 
and degradation. However, we can rarely investigate the role of resource 
loss due to a lack of detailed long-term records of forage plants and 
habitats. We used 22-year repeated surveys of more than 262 sites 
located in grassland, forest, and wetland habitats across Illinois, USA 
to explore how the abundance and richness of bumblebee food plants have 
changed over the period of decline of the endangered rusty patched 
bumblebee Bombus affinis. We documented a decline in abundance of 
bumblebee forage plants in forest understories, which our phenology 
analysis suggests provide the primary nectar and pollen sources for 
foundress queens in spring, a critical life stage in bumblebee 
demography. By contrast, the per-unit area abundance of food plants in 
primarily midsummer-flowering grassland and wetland habitats had not 
declined. However, the total area of grasslands had declined across the 
region resulting in a net loss of grassland resources. Synthesis and 
applications. Our results suggest a decline in spring-flowering forest 
understorey plants is a previously unappreciated bumblebee stressor, 
compounding factors like agricultural intensification, novel pathogen 
exposure and grassland habitat loss. These findings emphasize the need 
for greater consideration of habitat complementarity in bumblebee 
conservation. We conclude that the continued loss of early season floral 
resources may add additional stress to critical life stages of 
bumblebees and limit restoration efforts if not explicitly considered in 
pollinator conservation.


-- 
Dr. David W. Inouye
Professor Emeritus
Department of Biology
University of Maryland

Principal Investigator
Rocky Mountain Biological Laboratory

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