The key to insect success may be their wings. That’s what West Virginia University researcher Terry Gullion, professor of chemistry in the WVU Eberly College of Arts and Sciences, has learned by studying the chemical composition of insect wings — something that has not been examined in detail until now.
His findings reveal wings are composed of an unusually strong and durable molecule that may help advance technology in fields like agriculture and drone development.
Gullion became curious about the chemical composition of insect wings when periodical cicadas emerged in West Virginia after 17 years underground.
“They were all over the place,” he said. “I was curious. I realized, since the wings on these things are quite large, it might be possible to look at the composition of the wing membrane. So we collected a bunch of the wings from the dead cicadas and separated the membranes from the veins with a razor blade.”
Though scientists have extensively studied insects’ exoskeletons, little attention has been paid to the chemical composition of their wings.
“We wanted to look at the wing because the whole success of insects has been attributed to the fact that most can fly,” Gullion said. “It allows them to move to new territory, find food and avoid predators. That’s really why they’re so successful.”
Gullion used his custom-made nuclear magnetic resonance spectrometers to obtain NMR spectra of the wings’ veins and membranes. Because he is not an entomologist, he consulted textbooks, which indicated the wings would be made of epicuticle — a thin, waxy layer composed of protein— but would lack chitin, which is the main component in the exoskeleton.
Nevertheless, Gullion found chitin.
“That’s when we realized maybe we were seeing something that has been overlooked,” he said. “This was counter to what the basic model of the insect wing should look like.”
Chitin is the second most abundant biomolecule on the planet, after cellulose, and it gives an insect’s exoskeleton its strength. Lobster and crab shells get their strength from chitin, as do butterfly wings, which must be strong enough to support monarchs on their annual pilgrimage from Canada to Mexico.
“Hydrogen bonding makes chitin very strong and impervious to chemical attack,” Gullion said. “It’s a wonder material.”
In order to determine whether the cicada wings were unique in the insect world, Gullion’s students dissected thousands of ladybug and honeybee wings for NMR spectroscopy. However, only minute amounts of the samples could be obtained, so with funding from the National Science Foundation, he utilized the more sophisticated and sensitive equipment at the National High Magnetic Field Laboratory in Florida. The results confirmed what Gullion had discovered at WVU.
“The spectra conclusively showed the wings do all have chitin,” he said. “It’s 100% clear.” He published these initial findings in the Journal of Physical Chemistry and Solid State Nuclear Magnetic Resonance.
Gullion will be seeking more funding for the next step: determining the wings’ molecular organization. He believes the answers may shed light on how insect wings endure tremendous amounts of force while remaining thin and flexible. The membranes are much thinner than a strand of human hair.
Once they have a clear picture of the molecular structure, the researchers envision a variety of potential applications.
“Nature’s had millions of years to perfect this material and can guide us on how to synthesize new ones,” he said. “If we understand how the insect wing works, then we can make lightweight materials like that.”
Gullion cited micro drone technology as one area in which his findings could be useful, as micro aerial vehicles need to be both lightweight and strong. He said one application might be search and rescue in situations like the February 2023 earthquake in Turkey and Syria. Rescuers currently rely on sound to locate victims, but a tiny drone could fly between the rubble and relay images.
The agricultural industry might also have applications for Gullion’s findings. Broad-spectrum pesticides kill all insects, not just problem ones, and this may include beneficial pollinators like bees. He said by studying the chemical compositions of insects, the agricultural industry may be able to design pesticides that target specific species, thereby preventing pests from moving among crops.
“You’d get better control,” he said. “But it wouldn’t target bee wings. You don’t even have to kill the insect. You’ve just got to weaken it. Then predators like birds and other insects will take care of them. This is one reason why we study the chemical compositions of insects, so we can make things to control pests and leave all the others.”
Gullion said the ultimate goal is to improve existing technology with nature as a guide for doing so.
“We can learn from the insects who have been flying for millions of years. They taught us this strategy a long time ago.”
