Pick Thy Husband and Quench Thy Thirst On His Sperm

Desperation often pushes us to do things we do not normally do. For example cannibalize dead comrades during war time or eat your own feces when you're trapped in an inhospitable environment.

And that's exactly what a female picture-winged fly does; expels and then gobble up male sperm to quench its thirst. But only the sperms of males deemed unfit to father her offspring.

Christian Luis Rodriguez-Enriquez and colleagues at the Institute for Ecology in Vera Cruz, Mexico, watched 74 pairs of E. bilimeki court and mate. They discovered that all 37 females expelled and ate at least some of the sperms. Expelling the sperms means that those males don't get to celebrate Father's Day, but why mate if she's not going to utilize the sperms?

Image: www.newscientist.com

The researchers hypothesize that the females could have grown weary of evading aggressive males, and copulated unwillingly to stop further pursuits. Expelling the sperms means that she doesn't have to invest precious time and energy to deliver babies for unfit males.

But what's more interesting is what she does to the sperms. Why eat it?

Euxesta bilimeki lives in the deserts of Mexico and the U.S Southwest, where water and food are scarce. And as I've said earlier, desperation often pushes us to do some weird things. In the female picture-winged flies' case, ah-ha~ let's drink it.

To test this, the team placed the flies under several diet groups and observed the frequency of sperm-eating. They found that those that were given no food or water for two days did live longer if they consumed expelled sperm after mating.

But the starved and thirsty flies were no more likely than the well-fed flies to consume the ejaculate—showing that they don’t eat it for food.

Like I said, it's the desperation.

~Cheers~
Malcolm