Faced with Deadly Bacteria, Butterflies Turn Promiscuous

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Blue moon butterfly

Biologist Sylvain Charlat studied how the female blue moon butterfly, or Hypolimnas bolina, has adapted to a male-killing bacteria by becoming more promiscuous. Sylvain Charlat hide caption

toggle caption Sylvain Charlat

Scroll down to read some of Olivia Judson's favorite examples of biological promiscuity.

Sylvain Charlat

Sylvain Charlat studies butterflies on the island of Tubuai in French Polynesia. Philippe Pacou hide caption

toggle caption Philippe Pacou

They were dropping like flies. Butterflies, that is. When a deadly, male-killing bacteria surfaced in a colony of blue moon butterflies, some wondered how the species would be able to sustain itself.

Sylvain Charlat, a biologist at University College London, has studied the way that insects are reacting to this virulent bacteria.

Charlat discovered that the butterflies, found in the South Pacific, have managed to survive, despite a shortage of males. The female blue moon butterfly, or, Hypolimnas bolina, has adapted by becoming more promiscuous.

In colonies where the bacteria is rampant, the male-to-female ratio can be as low as 1 to 90, says Charlat. Surviving males become fatigued and put less and less effort into mating, while females agressively increase their mating behavior.

Intrigued by Charlat's study, biologist Olivia Judson of London's Imperial College says it's possible that one-fifth of the insect species in the world have now been infected by the dreaded germ, Wolbachia.

Though nature has found a way to work around the bacteria, it still creates quite a spectacle: "When males are in short supply — as anyone who's been to a girl's school can tell you — things get pretty nasty," says Judson.

More Promiscuity in the Animal Kingdom

Olivia Judson is a research fellow at University College of London and author of Dr. Tatiana's Sex Advice To All Creation. Though she's hard-pressed to come up with a species that truly mates for life, Judson admits that promiscuity is an awkward term. "It implies a lack of discrimination," she says. Often, promiscuity depends on how many other 'offers' an insect gets.

Some of Judson's favorite promiscuous females:

The Harlequin Beetle-riding Pseudoscorpion

This arthropod rides on the wings of the harlequin beetle, and is a discerning female suitor. Lady pseudoscorpions will have sex with virtually any male that comes along, says Judson. However, they actively avoid mating with males with whom they have already had sex.

The Dunnock (Hedge Sparrow)

Once held up by biologists as a model of Victorian chastity, this sparrow is now one of the most common examples of promiscuity in the animal world. Males often find themselves rearing chicks that are not their own, a consequence of the female's penchance for mating with multiple partners.

The Honey Bee

A queen bee has sex with as many as 100 males over the course of a few days— whoever can catch her, says Judson. "When he does catch her, he explodes."

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Dr. Tatiana's Sex Advice to All Creation

by Olivia Judson

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