Old developmental pathways spawn revolutionary evolutiona...( TEMPE Ariz. When the larvae of the ...)

TEMPE, Ariz. When the larvae of the primitive social insect Polistes metricus, a paper wasp, slips into the quiet pupal stage, she doesnt know if shell arise a worker or gyne (future queen) unless she consults with Arizona State Universitys social insect researcher Gro Amdam.

Amdams group is shedding new light on the development of colonial insects from solitary ancestors through study of a primitive social order of wasps. In a paper highlighted on the cover and published Aug. 28 in the Proceedings of the National Academy of Sciences (PNAS), ASUs Amdam and Florian Wolschin teamed up with Kari Norberg, from Amdams laboratory at the Norwegian University of Life Sciences, and James Hunt and others from the University of Missouri. They reveal that the Polistes larvae that can become future queens show signs of developmental diapause, a period of overt quiescence and a life history trait of many insect orders.

How can the larval environment determine future royal stature" The concept of environmental cues, things like weather, shorter day length, or food availability, determining destiny seems distinctly foreign in humans. However, Amdam, an associate professor in ASUs School of Life Sciences, has pioneered an understanding of how developmental programs underlying diapause and reproduction can be adopted in primitively social settings to result in the complex social behaviors and castes found in advanced insect societies.

Because the biology and physiology of the Polistes wasp is more transparent, instead of highly derived as is often the case of highly social insects, such as honey bees, we can more easily backtrack, follow the footprints of evolution and uncover the pathways that castes originally evolved from, says Amdam.

Many species of highly social insects have two distinct female castes, workers and queens, with traits set in larval life. However, Amdam points out that the primitive social Polistes wasp was origin
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