It鈥檚 tempting to call them lords of the flies. For the first time, researchers have controlled the movements of free-flying insects from afar, as if they were tiny remote-controlled aircraft.
By connecting electrodes and radio antennas to the nervous systems of beetles, the researchers were able to make them take off, dive and turn on command. The cyborg insects were created at the University of California, Berkeley, by engineers led by Hirotaka Sato and as part of a programme funded by the Pentagon鈥檚 Defence Advanced Research Projects Agency (DARPA).
The project鈥檚 goal is to create fully remote-controlled insects able to perform tasks such as looking for survivors after a disaster, or acting as the ultimate spy.
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Green beetles
The Berkeley team implanted electrodes into the brain and muscles of two species: , and the much larger African species . Both responded to stimulation in much the same way, but the weight of the electronics and their battery meant that only Mecynorrhina 鈥� which can grow to the size of a human palm 鈥� was strong enough to fly freely under radio control.
A particular series of electrical pulses to the brain causes the beetle to take off. No further stimulation is needed to maintain the flight. Though the average length of flights during trials was just 45 seconds, one lasted for more than 30 minutes. A single pulse causes a beetle to land again.
The insects鈥� flight can also be directed. Pulses sent to the brain trigger a descent, on average by 60 centimetres. The beetles can be steered by stimulating the wing muscle on the opposite side from the direction they are required to turn, though this works only three-quarters of the time. After each manoeuvre, the beetles quickly right themselves and continue flying parallel to the ground.
Brain insights
, a biomechanist at the University of North Carolina, Chapel Hill, who was not involved in the research, says he is surprised at the level of control achieved, because the controlling impulses were delivered to comparatively large regions of the insect brain.
Precisely stimulating individual neurons or circuits may harness the beetles more precisely, he told New 杏吧原创, but don鈥檛 expect aerial acrobatics. 鈥淚t鈥檚 not entirely clear how much control a beetle has over its own flight,鈥� Hedrick says. 鈥淚f you鈥檝e ever seen a beetle flying in the wild, they鈥檙e not the most graceful insects.鈥�
The research may be more successful in revealing just how the brain, nerves and muscles of insects coordinate flight and other behaviours than at bringing six-legged cyborg spies into service, Hedrick adds. 鈥淚t may end up helping biologists more than it will help DARPA.鈥�
Brain-recording backpacks
It鈥檚 a view echoed by , an electrical engineer at the University of Utah, Salt Lake City, who has designed brain-recording backpacks for insects. 鈥淚鈥檓 sceptical about their ability to do surveillance for the following reason: no one has solved the power issue.鈥�
Batteries, solar cells and piezoelectrics that harvest energy from movement cannot provide enough power to run electrodes and radio transmitters for very long, Harrison says. 鈥淢aybe we鈥檒l have some advances in those technologies in the near future, but based on what you can get off the shelf now it鈥檚 not even close.鈥�
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