Why Female Fruit Flies Behave Differently After Sex

A new study has mapped out in detail the physiolgical, biological, and neurological changes that affect the female fruit fly after sex.

Previously, studies largely ignored the female fruit fly and focused instead on the more conspicuous male fruit fly.

"The male fruit fly is a big show off, always trying to impress the female with his elegant courtship display," explained Dr Stephen Goodwin from the University of Oxford. 

"During courtship, the female is somewhat 'coy' and her behaviours are more enigmatic, so she has tended to be overlooked. But she behaves very differently after mating, and we have exploited this complex behavioural change to explore how chemical signals passed between the sexes can trigger complex behaviours." 

The female fruit fly's changes are triggered by a male 'sex-peptide' protein found in the fruit fly's semen. This peptide triggers the changes via female genital tract.

After having successfully mated, the female fruit fly alters her feeding and activity patterns while rejecting other males' advances.The researchers have mapped out the sensory neurons involved and the circuitry responsible for delivering these signals around the female's body

After identifying the peptide, the team was able to trigger the exact same responses in unmated females. These females rejected other males and changed their behaviors even though they had never mated successfully.  

"Mating-induced behaviours are important to ensure the propagation and survival of the species," says Dr Rezával, the lead post-doctoral researcher.

"In flies, once the female has mated, something about her demeanour changes to make her less attractive to the male and focus on more maternal activities. We have now identified more elements of the fly circuitry that underlie this change in behaviour and shown that it is more sophisticated than was previously thought."