Last month, it was reported that a single gene can determine whether voles are monogamous or prefer to play the field, and now the mating habits of fruit flies have come under the microscope. In a study reported in Nature, Devanand Manoli and Bruce Baker from Stanford University show that the key to successful courtship in Drosophila melanogaster lies in a cluster of 60 median bundle neurons in the male brain.

D. melanogaster males use an elaborate ritual to woo a female, as outlined in a handy step-by-step guide in CBC Health & Science News (Canada, 29 July 2004): “1. Find a female and follow her. 2. Tap female with foreleg, triggering pheromone cues. 3. Stretch out wing and vibrate it to serenade female. 4. Lick female's genitalia with proboscis. 5. Attempt copulation. 6. Copulate for 20 minutes.”

When Manoli and Baker disrupted the function of the 60-cell cluster by eliminating fruitless gene expression, they found that “the male essentially skips the tapping step and...he tries to copulate, lick her genitalia and play her a love song simultaneously. So what normally takes a total of four minutes is reduced to just 10 seconds”. According to Baker, the female flies take a dim view of this unsubtle approach: “it also took [the mutant males] longer to achieve copulation than normal males. We can well assume that, when the mutant males behave in this way, they are doing things that the female does not find attractive” (EurekAlert, 28 July).

Baker believes that the D. melanogaster courtship ritual mirrors some elements of human behaviour: “you tap them and get their attention, you play them a love song and so on. So the basic rudiments are pretty similar to what people do to get successful mating and produce an offspring” (Reuters, 28 July).