Fruit flies float into the humid air in a custom room dubbed the arena, and the main event draws near. Two high-speed video cameras are ready to catch the show. A dragonfly swoops and successfully collides with a fruit fly. Lunch.
The precise and swift movements of a dragonfly’s aerial assault are remarkable, especially given the small number of neurons that are responsible for guiding the insect. Paloma Gonzalez-Bellido, assistant professor in Ecology, Evolution and Behavior, leads the Fly Systems Laboratory (FLYSY) and is fascinated by this drama. Her lab aims to better understand how dragonflies — and a handful of other insects — are capable of such accurate mid-air maneuvers with such few neurons. They also are interested in whether dragonflies can adjust their attack if their line of sight changes, an indication of whether the insect can learn or adapt.
Researchers reconstruct the attack in 3D and closely examine the dragonfly’s trajectory, including acceleration and direction. With a better understanding of what the animal is doing, the researchers then go to the lab next door to figure out how. They show the animal a small moving object on a screen, and record electrical impulses of individual brain neurons. From this, they use a specialized microscope to image the whole brain and then determine where the neurons are located. This process allows researchers to pinpoint which neurons are responsible for which movements.
Gonzalez-Bellido’s lab studies the flight paths of three other insects as well. This allows the team to quickly compare and contrast flight paths and neural pathways, giving insight into how they evolved. Right now, though, dragonflies rule the flight arena. The researchers are working to tweak their approach so other insects can effectively hunt in the arena as well.
Whether or not the dragonflies can tweak their attack under different conditions is up for debate. To answer that question, the research team plans to fit insects with tiny glasses to shift their line of sight slightly.
By modifying their vision at different times during the dragonfly’s adult life, they’ll be able to nail down if critical neural connections form at a specific time, and whether they can be altered later on in the dragonfly’s life.
Fortunately the winter months will not halt flights in the arena. Equipped with specialized lighting and controlled humidity, the dragonflies experience a permanent summer. Researchers collected larvae in early fall in a nearby lake and they are now experiencing near winter conditions in the lab’s freezer. When the research team is ready for the next flight experiment, they increase temperatures and light, and trick the larvae into thinking it’s spring time.
With a steady supply of dragonflies, Gonzalez-Bellido and her team are eager to continue experimenting in the new arena. The shutters of the high-speed cameras and steady buzz of dragonfly wings will hum all winter long. - Claire Wilson