Paper wasps object to dishonest face spots

If the spots on the face of a female paper wasp don’t look appropriate for her rank, another female gets extra aggressive, according to a new study of wasp fights.

SPOTS RULE. A high-ranking wasp (left) has more spots with wavy edges than a lowly wasp does. Tibbetts

“It’s the most conclusive evidence yet that honest visual signalers are accepted and cheaters are punished,” says Elizabeth Tibbetts of the University of Arizona in Tucson.

Biologists have linked various animal markings, such as a dark patch of bird feathers, to status. These badges signal winning or losing characteristics, such as dominance. But if such badges aren’t metabolically costly for animals to produce, why don’t fake badges evolve that give milquetoasts the appearance of higher status?

One theory has proposed that social demands make sure that only truly high-ranking animals can live up to their badges. However, evidence for this idea has been “equivocal,” comments Joan E. Strassmann of Rice University in Houston.

Now, Tibbetts and James Dale of Simon Fraser University in Burnaby, British Columbia, report that in Polistes dominulus wasps, a colony’s 10-or-so queens vary in facial-spot “brokenness,” an index combining the number of spots and the curviness of their edges. High brokenness correlates with bigger body size and higher rank. This is the first badge of status ever found in an insect, says Tibbetts.

To check for any social consequence of sporting lots of wavy spots, Tibbetts dabbed model-airplane paint onto wasp faces to increase or decrease spot brokenness. Paint jobs that preserved a wasp’s natural spots didn’t aggravate fights, the researchers report in the Nov. 11, 2004 Nature. However, the scientists found that regular wasps fought for an unusually long time when paired with a spot-altered wasp.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.

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