Hawkmoths Reveal Their Slow-Processing Secrets For Life in the Dead of Night

In difficult situations between life and death, sometimes inaction is the same as making the wrong choice. Sometimes instead, using your brain less and doing more is the right answer. And it appears that for the hawkmoth Manduca sexta, slowing its thought process may just be the adaptation that it needs to feed in dark of night.

For years researchers have wondered exactly how it is that these hawkmoths are able to track their meal, hover, feed and adjust to changing light conditions in the dead of night. It's a confluence of very demanding tasks that, for the most part, we humans cannot fathom doing. In fact, the importance of such processes is one that researchers in robotics have investigated for years in hopes of developing future drone devices capable of sensing environments while hovering in mid-air. And now, courtesy of a new study published in the journal Science, researchers believe that they have revealed exactly how the moths are capable of feasibly completing such tasks, all by slowing down their central nervous system to best interpret the little information their brains are given to process.

"There has been a lot of interest in understanding how animals deal with challenging sensing environments, especially when they are also doing difficult tasks like hovering in mid-air" coauthor of the study and assistant professor at the Georgia Institute of Technology, Simon Sponberg says. "This is also a very significant challenge for micro air vehicles."

To investigate the natural phenomenon in a lab-setting, researchers with the Georgia Institute of Technology devised an experiment employing a 3-D printed robotic flower as their nectar source for the hawkmoths and high-speed infrared cameras to capture the action in all sorts of alternating light. Researchers had already established that this species is able to maximize the light it can see by using specialized structures in the eye, but they wanted to see how it was that the moths were able to function so efficiently and complexly using only limited light. 

"We expected to see a trade-off with the moths doing significantly worse at tracking flowers in low light conditions" Sponberg says. "What we saw was that while the moths did slow down, that only made a difference if the flower was moving rapidly-faster than they actually move in nature."

As an added hurdle, the researchers began oscillating the flowers slowly, but found that the hawkmoths were able to actively overcome this challenge as well. And with the ability to adjust to the wide range of lighting intensity, which changes more than 10 billion-fold from noon to the dead of night, these insects make the perfect natural system to study if we one day want to make robots capable of doing just the same.

"To maneuver like this is really quite challenging" Sponberg says. "It's an extreme behavior from both a sensory and motor control perspective"

"This is really an extreme behavior, though the moth makes it look simple and elegant."