How Moths Find Distant Mates: Pheromones Waft in Turbulent Winds
Scientists have long wondered how male moths locate females flying hundreds of meters away. Now, they may have their answer. It all has to do with air flow.
Researchers have long known that moths use pheromones to locate their mates. But when these chemical odors are widely dispersed in a windy, turbulent atmosphere, the insects still manage to fly in the right direction.
"The male moths are flying toward females integrating all of this information along the way and somehow getting to them," said Massimo Vergassola, one of the researchers, in a news release. "French naturalists reported this behavior over a century ago and it has continued to be a puzzle to entomologists, neuroscientists and physicists."
In order to find out why this is, the scientists decided to take a statistical approach. They first determined the intensity and duration of pheromone signals, and then validated the results with numerical simulations, controlled lab experiments and field data. In the end, they found that pheromones emitted by female moths can be perceived by males located within a "cone of detection," which extends downstream as far as 1,000 meters away. In addition, they found that pheromone signals are most commonly detected as intermittent "whiffs" that last only a few milliseconds.
"This is a general problem-how animals, including ourselves, search for things," said Vergassola. "A similar problem exists for flies that can detect garbage cans far away or for dogs that are guided by scents, although the difference is that their smells are generally on the ground, so their signals are much more stable. Insects face the most difficult problem as they rely on olfaction and detecting the volatile signals dispersed in the wind."
The findings reveal exactly how moths manage to find one another, despite turbulent conditions. In addition, the results could actually be applied widely in agriculture or robotics. By controlling the behaviors of insects exposed to pheromones, researchers can limit the ability of invasive or disease-carrying pests to mate.
The findings are published in the journal Physical Review X.