The Colony Environment, but Not Direct Contact with Conspecifics, Influences the Development of Circadian Rhythms in Honey Bees

Honey bee workers develop circadian rhythms later in life, contrasting with most insects that emerge with established rhythms.

• Newly emerged honey bees show no circadian rhythms in behavior or brain clock gene expression.
• Bees exposed to a colony environment for their first 48 hours have a similar percentage of rhythmic individuals as older foragers, but with weaker rhythms.
• Isolated bees in the laboratory for 48 hours are significantly less likely to exhibit circadian rhythms compared to those in a colony environment.
• Limited exposure to the colony environment (24 hours) or social isolation with 30 sister bees does not promote the development of circadian rhythms.
• Bees caged in single- or double-mesh enclosures inside a colony are as likely to show circadian rhythms as freely moving sisters, indicating isolation factors are not solely responsible.
• The influence of the colony environment on the development of circadian rhythms may be linked to volatile pheromones or the microenvironment.

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