Fruit fly males prefer virgins to mate, after some pheromone lessons, reveals new research

Mating with a virgin female may be a preference among some human males, possibly decided by their cultural or social training background. But it is the most preferred option among the fruit fly (Drosophila melanogaster) males, and they make the choice based on a learning process, says recent research.  

It was earlier noticed that male fruit flies which try to court with already mated females are often rejected by them. However, a rejected male, more successfully spots virgin females later. It was a mystery that how the males were able to distinguish mated females from virgins. Now, the mystery has been unraveled.

cis-Vaccenyl Acetate (cVA) a.k.a the pheromone key to the mystery

As per the study, a pheromone (particular chemicals produced by insects to communicate between the members of the community) named cis-Vaccenyl Acetate (cVA) helps male fruit flies to identify mated females. cVA is usually deposited on female fruit flies while mating, thus making them different from other virgin females. 

Drosophila melanogaster

Image courtesy: Wikimedia Commons

To confirm this, the researchers have disabled the ability in certain fruit fly males to sense the presence of the pheromone. Later they found that such males selected already mated females as partners. Similarly, when they engineered the gens of a group of female fruit flies in such a way that they will produce cVA without engaging in mating, all other males in the experiment avoided them mistaking them for already mated.

While trying to unravel the mystery behind how the fruit flies successfully understood the pheromone signal, the researchers found that the dopamine levels in their brain have a direct connection to the phenomenon. 

Dopamine lessons for the fruit flies

The research has found that the dopamine level in the brain in a fruit fly male fluctuate when they come closer to a female for mating. According to the researchers, the dopamine fluctuation in the presence of cVA on a mated female and the subsequent rejection by her, function as a learning process in males. Thus an unsuccessful courtship increases the male fruit fly’s sensitivity towards the presence of the pheromone, decreasing the chances of it selecting an already mated female for courtship later. 

 “The learning experience can be mimicked by artificial activation of dopaminergic neurons, and we identify a specific class of dopaminergic neuron that is critical for courtship learning. These neurons provide input to the mushroom body (MB) γ lobe, and the DopR1 dopamine receptor is required in MBγ neurons for both natural and artificial courtship learning”, says the paper.

 Thus the study has revealed that learning triggered by dopaminergic neurons has a major role in deciding the mating strategies of the fruit flies, and possibly in other insects and organisms.