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Critter Chemistry

November 4, 2002

Ants' Chemical Costuming Deceives Rivals

Maureen Rouhi

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COURTESY OF SYLVIA CREMER

Through chemical mimicry, winged males of the ant species Cardiocondyla obscurior (top photo) avoid attack by their aggressive wingless rivals for virgin queens. The wingless males--called ergatoids--use their saber-shaped mandibles in deadly duels for mating supremacy (bottom). Winged males, with weak mandibles, leave the nest after about 10 days. But before leaving the colony, young winged males manage to mate with virgin queens, ergatoids notwithstanding, and they also sexually attract the ergatoids.

The behavior can be explained by the chemical similarity between winged males and virgin queens, according to biologist Sylvia Cremer and others at the University of Regensburg, Germany [Nature, 419, 897 (2002)]. They find that the hydrocarbon profiles of the cuticles of young winged males and of virgin queens are similar and distinct from those of ergatoids and worker ants. By wearing the chemical bouquet of virgin queens, young winged males deceive ergatoids into perceiving them as queens.

Chemical female mimicry usually occurs among different species, Cremer says. For example, some orchids lure male bees with compounds that attract males to female bees. Rare intraspecific cases had been restricted to males with physiological conditions that preclude mating success. This study shows that sexually active and highly attractive males also engage in chemical female mimicry. "Cheating ergatoids is part of the winged males' reproductive tactic and is necessary for their survival before emigration from the nest," she adds.

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