Fantastic bees and where to find them: locating the cryptic overwintering queens of a western bumble bee

Abstract

Bumble bees are among the best-studied bee groups worldwide, yet surprisingly we know almost nothing about their overwintering habitats nor the microsite characteristics that govern selection of these sites. This gap represents a critical barrier for their conservation, especially if preferred overwintering habitats differ from foraging and nesting habitats. Current conservation plans focus on foraging habitat, potentially creating a problem of partial habitats where improved forage might fail to prevent population declines due to limited overwintering sites. We provide the first data on the overwintering habitat for any western North American bumble bee. Our data suggest that overwintering and foraging habitats are likely distinct, and queens' selection of overwintering sites may be shaped by environmental stressors of the year. In our study area, queens overwintered in litter beneath cypress trees, where no floral resources exist. Whether this separation of overwintering and foraging habitat holds for other bumble bee species remains to be discovered. Our data highlight the need to consider the whole life cycle for understanding population dynamics and conservation planning. This need is underscored by growing evidence for the decline of multiple North American bumble bee species.

Pursuing best practices for minimizing wild bee captures to support biological research

“…These are commonly used to estimate or survey population size and dynamics and are useful for long‐term monitoring and observing for trends while investigating factors that can influence population dynamics (Briggs et al, 2022; Pugesek & Crone, 2021). The information gained from recapture studies is not limited to population surveys but may also be useful in determining certain behaviors such as overwintering (Williams et al, 2019), nest searching (O'Connor et al, 2017) or flight and foraging ranges (Mola & Williams, 2019).…”

The effect of intrinsic physiological traits on diapause survival and their underlying mechanisms in an annual bee speciesBombus impatiens

“…soil type, moisture content) is necessary to ensure that queens can find suitable nesting sites and enter diapause in optimal physiological conditions. Yet, this relies on continued characterization of queen diapause habitats ( Williams et al , 2019 ), pre-diapause diet and life history of bumble bee species, especially those in decline. Through retention of late-season floral resources and integration of research on intrinsic physiological traits and extrinsic ecological factors, survival of the diapause life stage can be improved in annual bee species.…”

First field-based estimates of bumblebee diapause survival rates showcase high survivorship in the wild

“…Perhaps unsurprisingly, lab-based methodologies also play an essential role in studies of the biology of hibernating bumblebees. Bumblebees are some of the most important native pollinators of crops in the United States (Kleijn et al 2015 ), and recently there has been great interest in understanding their biology throughout the life cycle (Liczner and Colla 2019 ; Williams et al 2019a ). Multiple studies (> 10) have monitored diapausing bumblebees in the lab, relating survival rates to environmental factors like temperature or relative humidity (Gretenkord and Drescher 1997 ; Yoon et al 2013 ; Lindsay 2020 ) or to intrinsic physiological factors like body mass (Woodard et al 2019 ; Treanore and Amsalem 2020 ).…”