Static Electricity May Help Butterflies and Moths Pick Up Pollen

Butterflies and moths build up static electricity as they fly, and these charges could allow the insects to collect pollen without touching flowers, according to a new study in the Journal of the Royal Society Interface. 

This new research is a “really cool study,” Avery Russell, a behavioral ecologist at Missouri State University who did not contribute to the findings, tells Science’s Catherine Offord. “There haven’t been many studies on electrostatics of plant-pollinator interactions, and very little outside of bee-flower interactions.”

Previous studies have found that honeybees, bumblebees and hummingbirds could pull pollen from flowers through the air with their electric charges. In the new study, researchers wanted to see if butterflies and moths could pick up pollen via electricity, since their charges hadn't been measured, according to the paper. Some studies have suggested that butterflies aren’t good pollinators, and measuring their charges could provide insight into this debate.

The researchers looked at 11 different species from five different continents. For free-flying butterflies, the team measured their charges by setting up a ring electrode system outside their container exit. For other insects, the researchers measured their charge by tethering them and dropping them through the ring after they flew.

All of the butterflies and moths measured carried an electrical charge, and for the vast majority of them, this charge was positive. In computer simulations, their average charge was strong enough to lift 100 pollen grains at least six millimeters in less than a second.

These charges were stronger than those measured in other insects, according to the study authors, and would be strong enough to trigger pollination without touching flowers.

“A clearer picture is developing of how the influence of static electricity in pollination may be very powerful and widespread,” Sam England, a co-author of the study and an ecologist at the Berlin Natural History Museum, says in a statement.

The researchers also found that insects with larger surface areas had higher charges, since the extra space allows them to accumulate more charge.

They theorize that charge differences between species could be an evolutionary adaptation. The team found that tropical butterflies and moths had lower charges than those in temperate climates, which could be because tropical insects have more predators, and predators could be able to detect their charge. Similarly, nocturnal insects had lower charges, which could also be related to greater predation risks at night. 

“The fact that we are seeing these correlations with ecology points to the fact that it might be a trait that evolution is acting on,” England says to Science News’ Anna Gibbs.

The 11 species studied in the paper are too few to draw conclusions about ecological differences, since there are more than 100,000 butterfly and moth species in the world, Víctor Ortega Jiménez, an integrative biologist at the University of Maine who was not involved in the study, tells Science.

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.