In a new lab study, spotted lanternflies moved toward the source of a nearby 60-hertz vibration. Further field experiments could reveal whether “vibrational trapping” might be a new tool for managing the invasive pest. Spotted lanternflies are known for massing on tree trunks and other surfaces. Chemicals released by the insects’ honeydew may help trigger these conventions. The new research suggests that vibrations may also play a role. (Photo by Richard Gardner, Bugwood.org)

By Ed Ricciuti

Ed Ricciuti

The world of insects is filled with communicative vibrations, some good, some bad. The sound of a male cricket rubbing its wings together, carried through the night air, is good news to females in the mood to mate. Not so the vibrations of an ant struggling in the sandy trap of a hungry antlion larva—for the ant, at least. Like the antlion, an estimated 200,000 species of insects can sense vibrational messages traveling though the ground, water, plants, and other substrates. And, according to new research published in October in the Journal of Economic Entomology, the invasive spotted lanternfly (Lycorma delicatula) may also be one of them.

Researchers at the United States Department of Agriculture (USDA) have found that spotted lanternflies actively respond to substrate-borne vibrational signals broadcast during laboratory experiments. That may be good news for pest managers, who increasingly see acoustic signals as a way to control pests while reducing the use of chemical agents. Research into the role of substrate vibrations on behavior of lanternflies could enable scientists to “develop better tools that rely on modulating their behaviors (attraction, repulsion) for survey, detection, and control,” says Miriam F. Cooperband, Ph.D., entomologist at the USDA Forest Pest Methods Laboratory in Buzzards Bay, Massachusetts, who designed the experiment.

Some insects deliberately produce vibrations, like the cricket’s chirp. Others, like those from a trapped ant, are incidental. Either way, substrate-borne messages can trigger aspects of insect behavior such as mating, predation, avoiding predators, or foraging. Understudied, the role of vibrations that use substrates as a channel for insect communication is receiving increasing interest from researchers, including its potential to modify insect behavior for integrated pest management (IPM).

Pest control researchers are working feverishly to come up with effective IPM for the spotted lanternfly. Since its arrival in Pennsylvania in 2014, the lanternfly (really a planthopper in the infraorder Fulgoromorpha) has spread to more than a dozen other states. With its piecing-sucking mouthparts, it can reach and swill the sap out of more than 100 different plant species, from grapes to hardwoods. The feeding damage significantly stresses the plants, which can lead to decreased health and potentially death.

As the lanternfly feeds, it excretes sugary glop called honeydew, which makes a gooey mess, attracts bees and wasps, and promotes the growth of sooty mold, a gross blanket over ornamental plants, patio furniture, cars, and anything else on which it grows. The honeydew problem is aggravated when lanternflies congregate, as they commonly do.

In a study of how spotted lanternflies (Lycorma delicatula) respond to acoustic stimuli, individuals were placed at the center of a circular surface with a 60-hertz tone broadcast nearby. In these charts, open circles show where the individual lanternflies moved and reached the edge of the circle, and red lines indicate the average direction of all individuals observed. (Length of the red lines indicates magnitude of the average direction as a proportion of the circle radius; the maximum magnitude of the full radius would be obtained if all insects exited the test circle at the same angle.) (Image originally published in Rohde et al 2022, Journal of Economic Entomology)

Spotted lanternflies are becoming famous—or, rather, infamous—for gathering like flash mobs, massing on tree trunks and backyard furniture, even ending up in people’s clothing and entering buildings. Chemicals released by honeydew may help trigger these lanternfly conventions. The new research suggests that vibrations may also play a role in these get-togethers, which occur prior to mating. Their egg masses, which adhere even to the tires of vehicles, enable the spotted lanternfly to travel well.

After hatching, a lanternfly goes through four instars, or stages in nymph development. Nymphs as well as adults attack plants. The USDA experiments were conducted on fourth instars and adults, both of which have receptors on their bodies that sense substrate vibration. Results showed that both were attracted to and walked purposefully toward broadcasts of 60-hertz (Hz) vibroacoustic stimulus. This frequency, the so-called “60-cycle hum,” can interfere with audio equipment. During the experiments, volume was set below the range of human hearing.

The nuts-and-bolts experiments were conducted by USDA technician Isaiah Canlas, alone in a room due to pandemic precautions, with equipment designed by Cooperband, who with the other authors analyzed the results. Lanternflies were placed in an arena floored by white paper atop a plywood platform covered by tulle fabric. The observer was hidden. When the vibrations were broadcast, the insects clustered toward the signal, dispersing when it stopped.

Based on their findings, the USDA team suggests next conducting field studies to monitor vibrations in trees where lanternflies are congregating and mating. Eventually, such studies could perhaps lead to development of what pest control managers call “vibrational trapping.”

Ed Ricciuti is a journalist, author, and naturalist who has been writing for more than a half century. His latest book is called Bears in the Backyard: Big Animals, Sprawling Suburbs, and the New Urban Jungle (Countryman Press, June 2014). His assignments have taken him around the world. He specializes in nature, science, conservation issues, and law enforcement. A former curator at the New York Zoological Society, and now at the Wildlife Conservation Society, he may be the only man ever bitten by a coatimundi on Manhattan’s 57th Street.