A single mom caring for her nest. Illustration by Erin Walsh, created in association with an article by Rachael M. Heuer in Conservation Physiology (https://academic.oup.com/conphys/article/8/1/coaa007/582578).
Bumble bees are eusocial insects, in which females are divided into the queen and worker castes. Although the overwhelming majority of bumble bee research has focused on workers, the queen caste is unique in several ways. Queens live longer (up to ~1 year) and go through several life history stages that workers do not, such as an overwintering stage and a solitary nest-founding stage. Whereas queens can mate and produce female offspring, workers cannot. Queen fitness is also more fundamentally connected to bumble bee population dynamics: the death of a single queen early enough in the nesting season precludes the production of a nest that can contain up to hundreds of workers and new reproductives.
Our work on queen bumble bees falls into several interrelated categories. First, we are examining the underlying drivers of life history transitions in queens, including transitions associated with nest-founding and entry into diapause. The former is funded in part by an NSF CAREER grant that is focused on identifying what causes queens to change their investment in brood care around the time that they initiate nests and become social. At this time in their lives, queens essentially transition from being solitary, to subsocial, to eusocial, all in the span of a few weeks. The CAREER project is coupling experiments that cause changes in brood care with analyses of gene expression in the brain, to identify the molecular basis of brood care in bumble bees. This work is being led by Postdoctoral Researcher Dr. Claudinéia Costa and PhD student Blanca Peto. PhD student Meghan Moore is currently expanding on this work to explore the underlying sensory mechanisms through which workers impact queens.
We are also examining how nutritional status influences the preparation for (or entry into) diapause. We have found that queens with more sugar-rich diets appear to enter diapause earlier (Costa et al. 2020). Further, although queens can recuperate their nutrient stores during the pre-diapause period after short-term starvation (Watrous et al., 2021), they are less likely to survive diapause if fully deprived of food at this stage (Woodard et al. 2019). This work is being led by Postdoctoral Researcher Dr. Claudinéia Costa and also PhD student Blanca Guillén, who is examining how mating status impacts feeding and nutrition in the period preceding diapause.
Our other line of research on queen bumble bees is focused on the consequences of queen reproduction and brood care, for larval development, individual nesting success, and bumble bee population dynamics. Working in collaboration with Guy Bloch (The Hebrew University of Jerusalem) and Naoki Yamanaka (UC Riverside), we are exploring social influences on larval development. Thus far, we have found that queens influence larvae such that they ultimately develop into smaller-bodied workers that are more resistant to starvation (Costa et al. 2021). This work is supported by funding from the US-Israel Binational Science Foundation and the US-Israel Binational Agricultural Research and Development Fund. Postdoctoral researcher Dr. Claudinéia Costa and PhD candidate Natalie Fisher are building on this work to also examine the downstream consequences of maternal and sibling care, specifically for nutritional and feeding-related traits in workers.
Lastly, we are extending our work into field studies with wild bees. In an NSF-funded project in collaboration with Shalene Jha (UT Austin) and Neal Williams (UC Davis), we are exploring how nutritional landscapes impact early nesting success and wild bumble bee population dynamics. PhD candidate Natalie Fisher is also using transcriptomic approaches to examine relationships between the regulation of nutritional pathways and foraging strategies in wild bumble bees (B. bifarius) at the Rocky Mountain Biological Laboratory.
Our work on queen bumble bees falls into several interrelated categories. First, we are examining the underlying drivers of life history transitions in queens, including transitions associated with nest-founding and entry into diapause. The former is funded in part by an NSF CAREER grant that is focused on identifying what causes queens to change their investment in brood care around the time that they initiate nests and become social. At this time in their lives, queens essentially transition from being solitary, to subsocial, to eusocial, all in the span of a few weeks. The CAREER project is coupling experiments that cause changes in brood care with analyses of gene expression in the brain, to identify the molecular basis of brood care in bumble bees. This work is being led by Postdoctoral Researcher Dr. Claudinéia Costa and PhD student Blanca Peto. PhD student Meghan Moore is currently expanding on this work to explore the underlying sensory mechanisms through which workers impact queens.
We are also examining how nutritional status influences the preparation for (or entry into) diapause. We have found that queens with more sugar-rich diets appear to enter diapause earlier (Costa et al. 2020). Further, although queens can recuperate their nutrient stores during the pre-diapause period after short-term starvation (Watrous et al., 2021), they are less likely to survive diapause if fully deprived of food at this stage (Woodard et al. 2019). This work is being led by Postdoctoral Researcher Dr. Claudinéia Costa and also PhD student Blanca Guillén, who is examining how mating status impacts feeding and nutrition in the period preceding diapause.
Our other line of research on queen bumble bees is focused on the consequences of queen reproduction and brood care, for larval development, individual nesting success, and bumble bee population dynamics. Working in collaboration with Guy Bloch (The Hebrew University of Jerusalem) and Naoki Yamanaka (UC Riverside), we are exploring social influences on larval development. Thus far, we have found that queens influence larvae such that they ultimately develop into smaller-bodied workers that are more resistant to starvation (Costa et al. 2021). This work is supported by funding from the US-Israel Binational Science Foundation and the US-Israel Binational Agricultural Research and Development Fund. Postdoctoral researcher Dr. Claudinéia Costa and PhD candidate Natalie Fisher are building on this work to also examine the downstream consequences of maternal and sibling care, specifically for nutritional and feeding-related traits in workers.
Lastly, we are extending our work into field studies with wild bees. In an NSF-funded project in collaboration with Shalene Jha (UT Austin) and Neal Williams (UC Davis), we are exploring how nutritional landscapes impact early nesting success and wild bumble bee population dynamics. PhD candidate Natalie Fisher is also using transcriptomic approaches to examine relationships between the regulation of nutritional pathways and foraging strategies in wild bumble bees (B. bifarius) at the Rocky Mountain Biological Laboratory.