More than 80% of all (multicellular) species on the planet are insects, but it’s not fully known how an insect is able to identify objects — be it flowers to pollinate, crops to feed on or arms to bite.
“Nothing humans have created to date has the computational prowess to navigate the world like a tiny little fly. Pretty humbling, isn’t it?” said Shannon Olsson, an associate professor of naturalist-inspired chemical ecology at the National Centre for Biological Sciences in Bangalore, India, and an author of a new study that published Monday in the journal Proceedings of the National Academy of Sciences of the United States of America.
“Understanding how an insect navigates in the world with only a few hundred thousand neurons in their brain (unlike our human 80 billion) can help us to create better technology that uses less computational power,” she said.
Olsson had long wondered how insects are so good at finding things several miles away, but given how tiny they are and how fast they duck and weave — something anyone who has tried to swat a fly can attest to — exploring this in their natural environment has proved difficult, she said.
“Because of their small size and speed, it is difficult to follow insects around in nature, and even more difficult to evaluate what an insect is seeing, smelling or feeling at any one point in time when it is flying around in the real world,” she said
“Our VR (virtual reality), which moves the world around the insect instead, allows us to measure what 3D sights, smells and air currents cause them to change direction.
Ready insect one
Olsson’s team built what they described as a “video game that is controlled by the fly using its wings as a joystick” and used a tiny needle to keep the fly tethered within the arena they created.
“The fly was not harmed, but was rather on a stiff ‘leash,'” Pavan Kumar Kaushik, a graduate student at the National Centre and the chief architect of the virtual fly world, said in an email. “It was surrounded by gaming monitors in all directions to provide visual input.”
Using monitors, they provided visuals that mimicked flying around in an open meadow with grass, sky and trees, while they used valves and a novel revolving mechanism to control exactly when and where the fly received air currents and odor,” Kaushik added.
They chose the apple fly, official name Rhagoletis pomonella, as their subject.
“Apple flies are specialists — they only like ripe apples on apple trees. This is where they mate, lay eggs and what their babies eat. They were therefore the ideal choice for our VR,” Olsson said.
“Since we knew we couldn’t replicate the world exactly, their attraction to apple trees was our way of verifying that the VR provided enough stimuli for them to approach virtual trees like they do in reality.”
Researchers were most amazed by the fact that the insects were able to handle the virtual reality even when they slowed down the frame rate and there was no pattern in the optical flow, Olsson said.
“These experiments really showed me how insects have been able to conquer almost every ecosystem on Earth — they are incredibly robust and adaptive.”
She said, however, that it wasn’t possible at the moment to represent the insect’s environment 100% precisely.
“We simply don’t know enough about how they see, smell and feel the world to be able to re-create their work accurately.”