Fruit Flies Evade Danger by Using Fighter Jet Tactics, Study

Using high speed cameras, scientists at an international university found that fruit flies successfully evade danger by employing fighter jet tactics like quick banked turns.

Researchers at the University of Washington captured the wing and body movements of the fruit flies using high-speed cameras operating at 7,500 frames a second.  They observed that when these flies witnessed an approaching predator they made quick banked turns to evade danger.  To understand the mechanics of their flight, the team used robotic flies.

Due to its excellent flying ability, the fruit flies' (Drosophila hydei) flight is described as swimming through the air. But these tiny flies in reality roll their bodies similar to the fighter jet in a banked turn to move away from threats. They are seen changing direction in less than one-hundredth of a second i.e. 50 times faster than a human blink, much faster than earlier thought.

 Mid-air of a banked turn, these flies roll on the sides 90 degrees or more and fly upside down. "These flies normally flap their wings 200 times a second and, in almost a single wing beat, the animal can reorient its body to generate a force away from the threatening stimulus and then continues to accelerate," Florian Muijres, a UW postdoctoral researcher and lead author of the paper said in a statement.

In this study, the researchers worked on fruit flies that were the size of sesame seeds. These flies were placed in a cylindrical flight arena where they were free to buzz around.  The high speed cameras were synchronized to capture 7,500 frames every second or 40 frames every wing beat. The cameras were focused in the middle of the arena and as a fly buzzed through the intersection there were two laser beams aimed at the center of arena, which led to an expanding shadow that caused the fly to evade the danger.

To avoid blinding the fruit flies, the researchers used bright infrared light. 

"How can such a small brain generate so many remarkable behaviors? A fly with a brain the size of a salt grain has the behavioral repertoire nearly as complex as a much larger animal such as a mouse. That's a super interesting problem from an engineering perspective," Michael Dickinson, UW professor of biology and co-author of a paper said.

Next, the team plans to study how the brain and muscle of the flies control the fast and precise evasive maneuvers.

The finding was documented in Science.