Cheating workers with large activated ovaries avoid risky foraging

• Published in: Behavioral ecology Vol. 25; no. 3; pp. 668 - 674
• Main Authors: Roth, Katherine M., Beekman, Madeleine, Allsopp, Michael H., Goudie, Frances, Wossler, Theresa C., Oldroyd, Benjamin P.
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 01.05.2014
• Subjects: Reproductive Ground Plan hypothesis; foraging specialization; eusociality
• ISSN: 1045-2249; 1465-7279
• DOI: 10.1093/beheco/aru043

Lay summary If you were born a worker, but wanted to cheat and lay eggs, you would be well advised to stay in your hive and avoid foraging. Yet evidence from US honey bee populations shows that workers with large ovaries forage early in life. South African honey bee workers are different; the more reproductive ones stay at home. This shows that there is no causal link between ovary size and foraging behavior in honey bees. Eusocial insects undoubtedly evolved from solitary ancestors, but how this occurred is not well established. The Ground Plan hypothesis suggests that gene networks that once regulated the oviposition and foraging phases of an ancestral solitary insect’s life cycle have been co-opted to establish the queen–worker dimorphism in extant eusocial insects; queens permanently express genes that were once expressed during the oviposition phase, whereas workers express genes that were once associated with foraging. An extension of the Ground Plan hypothesis, the Reproductive Ground Plan-forager hypothesis, proposes that foraging specialization by worker honey bees for either pollen or nectar is controlled by the same reproductive gene networks. According to the Reproductive Ground Plan-forager hypothesis, workers with more ovarioles forage early in life and specialize in pollen collection. Here we find that among workers of a highly reproductive honey bee subspecies, Apis mellifera capensis, there is a positive correlation between ovariole number and age at onset of foraging, and no association between ovariole number and foraging preference, thus contradicting key aspects of the Reproductive Ground Plan-forager hypothesis. We also find a negative association between ovariole number and ovary activation, suggesting that high ovariole number is not directly related to reproductive potential as previously assumed.