Background: The developmental fates of offspring have the potential to be influenced by the identity of their care-givers and by the nature of the care that they receive. In animals that exhibit both parental and alloparental care, such as the annually eusocial insects, the influence of care-giver identity can be directly assessed to yield mechanistic and evolutionary insights into the origins and elaboration of brood care. Here, we performed a comparative investigation of maternal and worker brood care in bumble bees, a pollinator group where mothers (queens) rear the first offspring in the nest, and then daughters (workers) assume this role upon their emergence. Specifically, we compared the effects of queen and worker brood care on offspring development and also offspring performance, for a set of traits related to sensory biology, learning, and stress resistance. Results: We found that queen-reared workers were smaller-bodied than worker-reared offspring, suggesting that bumble bee queens influence body size determination in their offspring. We also found that queen-reared workers were more resistant to starvation, which might be beneficial for early nesting success. These maternal influences could not be explained by feeding rate, given that we detected a similar offspring feeding frequency in both queens and workers. Conclusion: Bumble bee queens have a unique influence on the development of the first offspring in the nest, which they rear, relative to worker-reared workers. We propose that bumble bee brood care has been shaped by a suite of evolutionary and ecological factors, which might include a maternal influence on traits that promote survival of incipient colonies.
Bibliographical noteFunding Information:
This work was supported by the National Institute of Food and Agriculture (2017-06558 to SHW and NY), the US-Israel Binational Agricultural Research and Development Fund (IS-5077-18 R to SHW and GB), and the US-Israel Binational Science Foundation (2017188 to SHW, GB, and NY).
We thank Felicity Muth and Laura Leger for providing feedback on the learning assay, Kristal Watrous for statistical assistance, Yadira Diaz for assistance with carrying out the experiment, Christie Miranda for assistance with analysis of brood-feeding behavior, and Leif Richardson for providing feedback on the manuscript.?We also thank Koppert Biological Systems, Inc. for providing bee colonies.
© 2021, The Author(s).
- Bumble bees
- Maternal influence
- Offspring development