Print Edition: March 5, 2014
Ever wanted to control the movement and mating habits of flies? Scientists have discovered the secret — a heat laser.
Using a technique called thermogenetics, the courtship of flies can be controlled with the flip of a mental switch.
“We used a warmth-activated cation channel … to activate [entire circuitries] via a temperature shift,” researchers said in “Turning Males on: Activation of Male Courtship Behaviour in Drosophila Melanogaster.”
Optogenetics — the science of triggering neurons with light — has been successful when tested on mice, and is not used on flies because of their size. The process works by implanting a fibre optic cable in the animal’s brain, and the flies are simply too small. In addition to their small size, most wavelengths of visible light are unable to penetrate the exoskeleton of a fly, which would impede the cable’s ability to function.
To get around the light inhibition, researchers began using heat, which has no problem getting through the exoskeleton. By adding a heat-activated protein to the neural circuits of flies, behaviours such as mating and decision-making can be controlled, therefore enabling humans to perform a kind of mind control.
Not only can flies be directed to become infatuated with other flies, but with inanimate objects as well. Some were directed toward a small ball of wax, to which they began performing typical courtship gestures.
“Courtship steps observed included unilateral wing extension and vibration, proboscis extension, abdomen bending and attempted copulation … and ejaculation,” researchers said.
To deliver the heat in an observable atmosphere, the scientists shone an infrared laser at a fly’s head while using a video camera to track its movement. The fly could therefore be triggered and its natural courtship behaviours could be monitored without interference.
Even after the laser was shut off, the fly continued to demonstrate the behaviours for another 15 minutes, which suggested to the scientists that the courtship was a complex and lasting behavioural state when initialized by heat.
By using lasers, it could be possible for researchers to control interactions between multiple flies or activate behaviours such as running backward or forward.