Fabricating a playground for this precision hunter may provide the access scientists need to understand its neural circuitry.

Anthony Leonardo's indoor flight arena has all the elements that allow dragonflies to thrive: grass, water, food, colorful gardens, daily light cycles, and controlled heat and humidity.

For many animals, hunting can seem effortless. Frogs flick their tongues to catch flies. Whales swim with their mouths open to strain plankton from the sea.

But no matter how straightforward an animal's technique seems, behind each attempt to capture prey whirs an intricate choreography of sensory input, neuronal firing, and muscle response that scientists do not fully understand.

Curious to know more, Anthony Leonardo, a group leader at HHMI's Janelia Farm Research Campus who studies the neural basis of animal behavior, decided to focus on dragonflies, which hunt with incredible precision, rarely missing their prey. Using an advanced video camera, he has been able to capture the insects in action, shooting 1,000 frames per second.

Played back at a speed the human eye can follow, a clip shows a perched dragonfly turning its head as it tracks a fruit fly. With coordinated strokes of its four gossamer wings, the insect lifts off and adjusts its route to intercept its prey. The dragonfly then glides, its hairy legs coming together to create a basket to imprison the fly before devouring it midair.

		What's inside a dragonfly flight arena? Hear Anthony Leonardo describe the inside of his dragonfly habitat. Listen to Audio (running time: 3.17) How to catch a dragonfly Tips from a pro. Listen to Audio (running time: 1.37) All the species of dragonflies They're not all the same, says Leonardo. Listen to Audio (running time: 2.25) What does it take to study dragonflies? Hear how dragonflies are finicky when it comes to where they'll live. Listen to Audio (running time: 3.17) Why are dragonflies so cool? Hear why Leonardo is fascinated by these insects. Listen to Audio (running time: 1.32)

More important than their aerial grace, dragonflies are large and strong enough to carry a miniature, wireless system that will allow Leonardo to record their neurons firing in real time as they pursue their prey.

But first, he had to design and build an indoor “flight arena” that would encourage dragonflies to behave almost as they would in a natural setting.

“We don't want to reproduce the outside world—there's too much complexity. We want it to be just complex enough so the dragonflies act normally,” he says.

One of Leonardo's collaborators, Rob Olberg of Union College in Schenectady, New York, helped with the design. Olberg, who is a visiting scientist at Janelia Farm through this summer, has already identified 16 key neurons that deliver information to the muscles involved in flight and prey capture. These neurons are believed to tell the dragonfly's wings the location of the fruit fly for an accurate capture.

But these findings were based largely on studying dragonflies held in place by miniature restraints. Olberg says his subjects are no doubt more concerned about escaping than about catching a meal. “The nervous system probably works a whole lot differently when the dragonfly is actually flying,” he says.

With Leonardo's flight arena, a virtual meadow, understanding that difference might now be possible. Dragonflies are finicky creatures: they require far more space than the typical lab allows, special lighting that mimics the sun's ultraviolet spectrum, and visual cues to orient themselves.

Photo: Erik Johnson

	PAGE 1 2	Continue