Why does a colony replace its queen?
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A colony may replace its queen for several reasons: advanced age, insufficient egg-laying, poor fertilization, injury, or general weakness. But a recent study suggests that another factor may sometimes be at play: a severe viral infection in the queen could impair her reproductive function and alter her pheromonal signal, to the point of triggering supersedure.
A recent study proposes a plausible mechanism to explain, at least in certain cases, supersedure in the honey bee. The authors show that a high viral infection load in the queen is associated with a decrease in methyl oleate, a component of the queen's pheromonal signal, as well as a reduction in ovarian mass. They suggest that such a change in the signal may contribute to inducing workers to rear a new queen.
This finding is particularly notable because it connects three levels that are often discussed separately in beekeeping: the queen's health status, her reproductive physiology, and the colony's collective response. In their experiments, the researchers also show that a blend of queen mandibular gland pheromones supplemented with methyl oleate inhibits queen cell rearing more strongly than a blend without it. It should be noted, however, that this experiment was conducted in queenless colonies, which supports the biological relevance of the compound but limits direct generalisation to a colony still headed by a living, if weakened, queen.
Earlier work had already suggested that certain viral infections can impair the queen's reproductive function and be associated with premature supersedure, notably in Chapman et al. and Gauthier et al. The new study adds a more precisely defined candidate mechanism by linking this impairment to a decline in methyl oleate, a component of the queen's pheromonal signal. It also continues a line of recent research on queen pheromones and their relationship to reproductive status.
For the beekeeper, the value is clear, even if this study alone does not provide a simple method for predicting every supersedure event. It does, however, reinforce the view that rigorous varroa control remains central. If the viral pressure promoted by Varroa destructor can not only weaken the bees and the colony but also impair the queen's reproductive function and chemical signal, the health implications are broader than previously appreciated. In other words, controlling varroa also contributes to protecting the stability of the queen and the social organisation of the colony. This extension to practice remains, however, a cautious biological inference and not a direct demonstration that any particular treatment reduces the risk of supersedure.
Caution is nonetheless warranted in interpretation. The authors speak of a plausible mechanism, not a definitively closed causal chain. They also show that a restriction in ovarian investment is sufficient to lower methyl oleate levels, suggesting that workers may be responding to a deterioration in the queen's reproductive status rather than to the viral infection itself in isolation. The precise mechanism remains open: the site of methyl oleate production has not yet been established, and other pheromonal components may also be involved.
Original study
Bibliography
McAfee, A., Chapman, A., Alcazar Magaña, A., Marshall, K. E., Hoover, S. E., Tarpy, D. R., & Foster, L. J. (2025). Elevated virus infection of honey bee queens reduces methyl oleate production and destabilizes colony-level social structure. Proceedings of the National Academy of Sciences, 122(42), e2518975122.
Chapman, A., et al. (2024). Common viral infections inhibit egg laying in honey bee queens and are linked to premature supersedure. Scientific Reports, 14, 17285.
Gauthier, L., et al. (2011). Viruses associated with ovarian degeneration in Apis mellifera L. queens. PLoS ONE, 6, e16217.
McAfee, A., Magaña, A. A., Foster, L. J., & Hoover, S. E. (2024). Differences in honey bee queen pheromones revealed by LC-MS/MS: Reassessing the honest signal hypothesis. iScience, 27, 110906.