Researchers from the University of Massachusetts and the University of Washington (UW) have found a way to unlock the secret of how monarch butterflies are able to navigate through vast distances during their annual migration.

In a study featured in the journal Cell Reports, Eli Shlizerman, a professor at UW, led a team of scientists in developing a model circuit capable of mimicking the internal compass used by monarch butterflies to find their way from Canada to Mexico.

Shlizerman pointed out that as a mathematician, he is fascinated at how various neurobiological systems — such as those seen on the monarch — work. He also wants to find out what people can learn from such systems.

He said that the butterflies are able to complete their great migration in such a predetermined and efficient way that they seem to always end up in a specific spot in Mexico after only two months of flying.

Despite traveling long distances, the creatures seem to know how to conserve their energy and depend on only a few cues along the way.

Developing The Model Circuit

Scientists have long suspected that monarch butterflies use the location of the sun in the sky as well as their antennae's built-in mechanism for molecular timekeeping to help them navigate through the long journey.

The creatures tend to fly with the sun on their left when they have to go southwest in the morning, while they tend to leave the sun to their right when they need to fly toward the same direction in the afternoon. They make slight adjustments to their flight path if needed throughout the day.

Study co-author Steven Reppert said they wanted to find out how the placement of the sun and the monarchs' internal clock are able to influence each other in order to let the creatures know the correct flight path.

To solve this question, Shlizerman and his fellow mathematicians developed a series of equations based on the monarchs' neural activity. They estimated the firing rates of neurons found in the creatures' eyes and antennae, after which they determined how these neurons react to each other when triggered in a simplified model.

The researchers then developed equations that would let them know if the monarchs are traveling on the right flight path or if the needed to steer from right to left so that the creatures can travel toward the southwest.

Shlizerman and his colleagues' final model successfully predicted how the monarch butterflies orient themselves in real life when the creatures were placed in a flight simulator.

The researchers now plan to use this new model circuit to develop artificial versions of the monarch's internal navigation system. These can then be placed on robotic butterflies, which could follow the creatures and monitor them during their annual journey.

"It's a very interesting application that could follow the butterflies and even help maintain them," Shlizerman said.

"Their numbers are decreasing, so we want to keep this insect - the only one that migrates these huge distances - with us for many years."

Photo: Lori Branham | Flickr