Bumble bee (B. vosnesenskii) queen nest searching occurs independent of ovary developmental status

Studies on the physiological states of wild-caught organisms are essential
to uncovering the links between ecological and physiological
processes. Bumble bee queens emerge from overwintering in the
spring. At this time, queens develop their ovaries and search for a nest
site in which to start a colony. Whether these two processes, ovary
development and nest-searching, interact with or influence one another
remains an unresolved question in behavioral physiology. We explored the
hypothesis that ovary development and nest-searching might be
mechanistically connected, by testing whether (1) ovary development
precedes nest-searching behavior; (2) nest occupation precedes ovary
development; or (3) ovary development and nest-searching occur
independently, in bumble bee (Bombus vosnesenskii) queens.  We
collected queens either nest-searching (and thus prior to occupying a
nest) or pollen-collecting (and thus provisioning an occupied nest) and
measured their degree of ovary activation. We further screened these
queens for parasites or other symbionts, to identify additional factors
that may impact their reproductive success at this time. We found that
queens searched for and occupied nests at all stages of ovary development,
indicating that these processes occur independently in this system.
Nest-searching queens were more likely to have substantial mite loads than
pollen-collecting queens, who had already located and occupied a nest.
However, mite loads did not significantly predict ovary developmental
status. Collectively, our work shows that nesting status and symbionts
alone are insufficient to explain the variation in spring bumble bee queen
ovary development. We propose that ovary development and nest-searching
occur opportunistically, which may enable queens to begin laying eggs
earlier in the season than if these processes occurred in discrete
succession.