Female Flies Looking for a Mate Go with their 'Gut'

Female flies are flying around, surrounded by male flies performing an innate and impressive courtship dance, but how do they choose among all these suitors? New research shows that it's as simple as going with their "gut."

Researchers at Rockefeller University have determined that the Abdominal-B (Abd-B) gene, previously known as the gene that sculpts the posterior parts of the developing fly, is also an important part of this complex mating ritual.

Certain neurons help a female fly decide whether or not she will accept sexual advances from a male of her species, and the Abd-B gene is necessary for the development of these neurons.

"Female fly receptivity is hardwired into the nervous system by genetic programing, and we have identified a gene and neurons responsible for a major part of this behavior," lead author Jennifer J. Bussell said in a statement. "Our results provide an entry point into understanding the complex neural circuitry that drives courtship behavior on the female side of the equation."

Until recently, researchers have primarily focused on the showier behavior of the males, who actively court females through pursuit and song - extending a single wing and tapping out notes to woo potential mates. Once they turned their attention toward the females, they found that their receptivity to mating involved "pausing" - slowing down periodically to allow the pursuing male to catch up - and opening the "vaginal plates" of her exoskeleton to allow access to her genitalia.

Using a technique called RNA interference - which involves using small segments of RNA to silence individual genes throughout the entire fly genome - the research team was able to determine exactly which genes controlled this behavior in females.

Bussell and her colleagues were able to link Abd-B activation to a set of 150 neurons connected primarily to the genitalia and the abdominal ganglion.

"We found that silencing Abd-B neurons directly decreased the pausing behavior during courtship, but was a separate component from the opening of vaginal plates," Bussell explained.

So the male courtship song alone could not cause a female fly to stop dead in her tracks. The activity of Abd-B neurons depends on a female's gut feeling, or at least, a response from the abdominal ganglion.

The findings were published in the journal Current Biology.