UNIVERSITY PARK, Pa. — Spotted lanternflies may season themselves to the distaste of potential bird predators, according to a new study led by entomologists in Penn State’s College of Agricultural Sciences.
The findings, which were published this week (Oct. 23) in the Journal of Chemical Ecology, showed that several species of birds were less likely to eat spotted lanternflies that had fed on the pest’s preferred host, Ailanthus altissima, commonly known as tree of heaven. This suggests the pest stores nasty-tasting chemicals when they feed on the invasive plant that birds can detect, according to the research team.
Further, they said, the extent to which birds may play a role in pecking away at spotted lanternfly populations remains up in the air and depends on various factors.
Led by postdoctoral researcher Anne Johnson, the team investigated whether birds could serve as natural predators of the spotted lanternfly. This Asian planthopper causes damage to vineyards, orchards and the nursery industry.
The entomologists theorized that when the spotted lanternfly feeds on the plant, it stores toxic chemicals called quassinoids, which make the insect less appetizing to birds. These compounds are bitter and have a pungent smell to mammals; it is unknown if this is the case with birds.
“Like the spotted lanternfly, tree of heaven is an invasive species that originated in the same region of Asia as the insect,” said Johnson, who worked on the project under the guidance of co-author Kelli Hoover, professor of entomology. “We found that birds, including nesting house wrens, preferred to eat spotted lanternflies that had not fed on tree of heaven, suggesting that the insects that consume this plant are less tasty, thereby providing some chemical defenses against avian predators.”
To investigate the possibility that birds are deterred from feeding on spotted lanternflies that had stored toxic chemicals from tree of heaven, Johnson and Hoover reared different life stages of spotted lanternflies in controlled environments — some with access to the tree of heaven and others without. Chemical analyses confirmed that spotted lanternflies accumulated quassinoids from the tree of heaven in their bodies, with the highest concentrations in adults.
The researchers presented the insects to birds in two experiments: one involving feeding tests with house wrens in nest boxes. The team worked with two groups of lanternflies — one reared with access to tree of heaven and another that had never fed on it. Johnson used adult insects from each group to create two batches of suet cakes: one containing pieces of lanternflies that had fed on tree of heaven and the other containing lanternflies that had not. These suet cakes then were offered to attract various bird species, which the researchers observed.
The most common species visiting the suet feeders included three types of woodpeckers, black-capped chickadees, white-breasted nuthatches and Carolina wrens.
Hoover said that most bird species in the tests preferred lanternflies that had not been exposed to the tree of heaven. Additionally, the nesting wrens ate — or fed to their young — larger quantities of the spotted lanternflies that were not exposed to the tree of heaven.
“Interestingly, we observed that, of the immature spotted lanternflies that were used by house wrens, the parents often ate both spotted lanternflies reared with and without access to tree of heaven but only fed their chicks nymphs reared without access to the tree of heaven,” Johnson said. “This could indicate that parent birds were less willing to tolerate quassinoids in spotted lanternfly prey for their offspring than they were for themselves.”
The researchers also found quassinoids in the eggs of the spotted lanternflies, indicating they likely inherited these toxins from the mothers. The scientists said this suggests that by passing these toxins to their eggs, adult lanternflies potentially are protecting the next generation.
The researchers noted that understanding the role of plant-derived toxins in the spotted lanternfly’s survival could help inform effective management strategies for this pest. While some birds may help control pest populations, their effectiveness may be limited by the insects’ toxic defenses. However, predation by birds does occur in the field; a community science project led by Johnson and Hoover in 2023 reported numerous observations of birds feeding on lanternflies in nature.
In addition to birds, other animals prey on the spotted lanternfly, and Johnson and Hoover have investigated how they might be impacted by lanternfly diet.
“Some insect predators show promise for this approach, as our previous research found that, unlike birds, they do not favor lanternflies that were raised on grapevines without ever feeding on tree of heaven,” Johnson said.
The researchers said the next step may be to explore whether birds or insect predators could help reduce populations of this serious pest.
Study collaborators included Allison Cornell, assistant professor of biology at Penn State Altoona; Fang Zhu, associate professor of entomology; Ashley Shay, director of the Metabolomics Core Facility at the Huck Institutes of Life Sciences; and Gabrielle Davis, a Penn State alumna who will be attending graduate school at the University of Michigan.
A U.S. Department of Agriculture McIntire-Stennis grant and the Pennsylvania Department of Agriculture supported this research.
For more information on spotted lanternfly research and management strategies, visit the Penn State Extension website.