Math models predict mysterious monarch navigation

Monarch butterflies (Danaus plexippus) use their internal clock and the sun to guide them 4,000 kilometers south on their annual fall migration from eastern North America to central Mexico. Scientists have struggled to determine how butterfly brains combine visual cues from the sun with molecular timekeeping in their antennae to make the epic journey.

A new mathematical model can effectively mimic monarch flight navigation, researchers argue April 14 in Cell Reports. Their equations for neuron firing rates in the antennae and eyes point to a two-part circuit that orients the insect as the sun’s position changes. As the angle of the butterfly’s body to the sun narrows, it becomes harder for the insect to right itself, the model predicts. While slightly simplistic, the model successfully predicted the movement of live butterflies in the lab.