The researchers were able to do this by temporarily disrupting synaptic transmissions in the flies.
Previous research indicated that the sexual orientation of fruit flies is genetically determined, but the brain pathways for controlling sexual preference weren't clear.
In this new study, appearing in today's issue of the Proceedings of the National Academy of Sciences, researcher Toshihiro Kitamoto of the Beckman Research Institute of the City of Hope in California placed a temperature-sensitive mutant gene into a particular subset of fruit fly neurons. The mutant gene is flicked on at higher temperatures and disrupts synaptic transmission between neurons in the flies' brains.
When the male fruit flies with the mutant gene were warmed to 86 degrees Fahrenheit, they courted female fruit flies less vigorously. Instead, they began courting other males and responding to other male's sexual advances, the study found.
At cooler temperatures, the males with the mutant gene reverted back to heterosexual behavior.
The study notes that the mutant gene affects neurons that include taste-sensing nerves on the fruit flies' heads and legs. Those particular neurons may suppress male-male courtship by detecting or interpreting anti-aphrodisiac pheromones produced by male fruit flies.
This is a new way to examine how certain groups of neurons affect sexual orientation and other types of fruit fly behavior, the study says.
This piece from the National Institutes of Health explains why fruit flies and humans are closer than you think.