In social insects the tasks of workers and queens are typically so different that strong morphological differentiation should be favored by selection if the caste of an individual can be predicted early enough. To determine whether a cohort of pupae that would ordinarily become workers can become queens, we removed all the queens from one colony and all but one from another colony of Parachartergus colobopterus. A week later the colony with no queens had a new, young cohort of mated queens. Relatedness patterns confirmed that these new queens would normally have been workers and not queens. These new queens were pupae when we began the experiment and so could not have been fed any differently from female larvae destined to become workers. Worker aggression diminished after we had removed all the queens, indicating that it may usually have a role in inhibiting newly emerging females from becoming queens. Delaying queen replacement is in accord with the greater worker relatedness to old than to new queens, and with worker sex ratio interests. A behavioral mechanism for determining the queen caste thus meets the worker interests most closely, but at the cost of not having a morphologically optimized queen caste.
Species 1: Hymenoptera Vespidae Parachartergus colobopterus (Neotropical Swarm-Founding Wasp)
Keywords: kin selection, levels of selection
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA