Mon, Aug 02, 2021:On Demand
Background/Question/Methods
Upon emergence from diapause, bumble bee queens are not yet reproductively mature. In the early spring after they have emerged from diapause, queens feed on pollen and nectar to recuperate nutrient stores metabolized over the winter, develop their ovaries, and search for a suitable nest site. The nest searching and establishment period is a fundamental time in the bumble bee life cycle, yet little is known about the basic biology of queens at this time. Queens require both a suitable nest site and mature ovaries to lay eggs, but whether these two phenomena are interrelated or occur independent of one another remains unknown. In the spring of 2020, I collected Bombus vosnesenskii queens carrying out one of the following two behaviors: (1) nest searching (and thus prior to nest establishment) or (2) collecting pollen (and thus provisioning an established nest). I then measured the degree of ovary development and incidence of parasitism in these queens.
Results/Conclusions Queens exhibited a wide range of ovary developmental stages, and degree of ovary development was independent of queen behavior. These results suggest that queens establish and provision nests irrespective of their ability to lay eggs. Conversely, queens will also invest in ovary development irrespective of whether they have found a suitable nest in which to lay their eggs. Thus, queens accomplish these two milestones (ovary development and nest establishment) independently. Furthermore, we found external mites on nearly half of nest searching queens but not a single mite on pollen collecting queens. While this result could suggest that mites interfere with nest founding in B. vosnesenskii, we believe it is more likely that mites dismounted from queens after nest establishment and did not interfere with nest founding. Mite presence did not significantly predict ovary development.
Results/Conclusions Queens exhibited a wide range of ovary developmental stages, and degree of ovary development was independent of queen behavior. These results suggest that queens establish and provision nests irrespective of their ability to lay eggs. Conversely, queens will also invest in ovary development irrespective of whether they have found a suitable nest in which to lay their eggs. Thus, queens accomplish these two milestones (ovary development and nest establishment) independently. Furthermore, we found external mites on nearly half of nest searching queens but not a single mite on pollen collecting queens. While this result could suggest that mites interfere with nest founding in B. vosnesenskii, we believe it is more likely that mites dismounted from queens after nest establishment and did not interfere with nest founding. Mite presence did not significantly predict ovary development.