The Loh Down On Science

What female butterflies do with their antennae

Biologists use nail polish to study mating butterflies?

This is Sandra Tsing Loh with the Loh Down on Science.

Meet the tropical butterfly Bicyclus anyana. Scientists already knew that inbred males of this species have trouble finding mates.  This makes sense, since half of all inbred males are sterile.

What they didn't know was what tipped females off.  Was it the blanks stares?  The creepy banjo playing (or butterfly equivalent?).

In successful matings, males transfer a sexy-smelling chemical onto females' antennae. 

To find out if this was the key, biologists dusted the genitals of both inbred and normal males with powder.  One color was for inbreds, another for normals. 

They also painted the antennae of some females with nail polish, blocking their sense of smell.  Then they put everyone together and waited to see where the colored dust would settle.

And?  Females with glam, nail-polished antennae got dusted with both colors, meaning they mated wily-nily.  But "unpolished" females—who could still smell—only mated with normal males.

Thus, inbred males just don't smell as sexy.  And nail polish will only get a girl so far.

***** For more 90-SECOND SCIENCE FACTS, click here.*****

Thursday, from 2-3 p.m. on the LDOS blog: Sandra chats with author Ashley Merryman about her book (with Po Bronson) Top Dog: The Science of Winning and Losing.

The Loh Down on Science is produced by LDOS Media Lab, with 89.3 KPCC. And made possible by the generous support of the Gordon and Betty Moore Foundation.

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