Worker age (days)

FIGURE 1 Temporal or age polyethism in the paper wasp Polybia aequatorialis. Data were collected on 130 individually marked, known-age workers. Two measures of worker activity at three task sets are plotted against worker age (solid lines: mean rate of task performance; dashed lines: number of workers performing the task). Note the typical centripetal developmental sequence: in-nest tasks (mostly nest cleaning) are followed by building on the nest exterior, and later by foraging (leaving the nest and returning with food and building materials).

through the sequence. Changes in hormone titers, such as juvenile hormone, have been implicated in determining the rate of temporal polyethism in Apis and Polybia.

Workers' relative age influences social status and task performance in some species. In the paper wasps P exclamans, the first-emerging (and consequently the oldest) workers in the nest tend to socially dominate their nestmates, a pattern referred to as gerontocracy, which is independent of body size variation. In this case, age influences workers' behavioral caste in a static way, rather than in a dynamic way as in temporal polyethism.

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