Tuesday, September 25, 2007
Bat Bugs Evolved Fake Genitals to Avoid Sex Injuries
For African bat bugs, the battle of the sexes is quite literally a violent struggle—and now it appears that the bugs are using gender-bending tactics to defend themselves.
Bat bugs are small, reddish-brown parasites related to bed bugs that suck the blood of bats and sometimes bite humans.
Researchers have long known that male bat bugs ignore females' conventional parts and instead use their sharp penises to stab the females' abdomens, injecting sperm directly into the bloodstream.
So the females evolved a defense: structures called paragenitals that guide a male's needle-like member into a spongy reservoir of immune cells.
But the females aren't the only ones in need of protection. Observers documented males performing the same injurious sexual acts on other males.
Now evolutionary biologist Klaus Reinhardt of the University of Sheffield in England has discovered that male bat bugs have developed their own versions of female paragenitals to avoid the assaults.
And some female bat bugs are mimicking the paragenitals of the more successful males to improve their defenses.
Reinhardt calls the interactions a "hotbed of deception" with no known analogies in the animal kingdom.
The results, based on studies of bat bugs from a cave in Kenya, are being prepared for publication in an upcoming issue of the journal the American Naturalist.