UW Today

January 17, 2012

Fruit flies watch the sky to stay on course — with video

News and Information



A fruit fly suspended in a magnetic field alters its flight path depending on cues it receives from light polarization.Peter Weir

“If you go out in a field, lie on your back and look up at the sky, thats pretty much what an insect sees,” said Michael Dickinson, a University of Washington biology professor. “Insects have been looking up at this view forever.”

Dickinson is the senior author of a paper providing details on the findings, published Jan. 10 in the journal Current Biology. The lead author is Peter Weir, a doctoral student at the California Institute of Technology.

The researchers noted that insects such as monarch butterflies and locusts maintain a constant heading while migrating thousands of miles across continents, while bees and ants hunting for food successfully find their way hundreds of feet back to the nest without a problem. That has led scientists to believe that the animals must possess a compass of sorts.

To assess how insects orient themselves, Weir and Dickinson examined the behavior of Drosophila melanogaster, a species commonly referred to as a fruit fly, in outdoor lighting conditions in a specially designed “arena” atop a building tall enough to be higher than treetops and other visual landmarks.

The researchers used a light-cured glue to attach the insects to a metal pin, which was then placed within a magnetic field that allowed the flies to move and rotate naturally but held them in place. Digital cameras tracked flight headings.


A fruit fly is tethered in a light-emitting diode, or LED, flight arena. The arena is one of the researchersFloris van Breugel





“Its been very hard to study these processes because animals such as butterflies and locusts used in previous studies are not standard lab models,” Dickinson said. “We know something about the processes, but not that much.”


For millennia, seafarers have depended on the sun to know their position in the world, but often the sun is not visible. Polarization vision solves that problem, Dickinson said, because if theres even a small patch of clear sky in a fruit flys very broad range of view then the natural light patterns can provide location information.

He noted that fruit flies “achieve remarkable functionality” with limited resources in their brains. There are 300,000 neurons in a fruit flys brain, and it would take 300,000 fruit flies to reach the equivalent number of neurons in the human brain.

“A lot of our research is focusing on how the fruit fly brain is multitasking in space and time to achieve remarkable effects,” Dickinson said.

The research is funded by the National Science Foundation and the National Institutes of Health.



The paper is available at http://www.cell.com/current-biology/abstract/S0960-9822(11)01305-4.