The preliminary findings indicate that foliar application of an insecticide containing dinotefuran timed to the spring egg-hatch period could be effective in reducing satellite populations of the pest, a tactic that could be useful in slowing its spread.

The study, which took place over the summer on six secluded acres in the Blue Marsh Lake Recreation Area, was an expansion and continuation of research that was carried out last year at Norristown Farm Park in Montgomery County.

The Blue Marsh experiments also suggest that the effectiveness of biopesticides containing Beauveria bassiana, a native, soilborne fungus that causes disease in insects, could be affected by the life stage of the spotted lanternfly and/or environmental conditions.

Rick Roush, dean of the College of Agricultural Sciences, said the most recent study highlights how the spotted lanternfly’s life cycle and the complexities of its preferred environments present challenges and barriers to gaining control over the destructive pest.

“As in our past research, we learned quite a lot about spotted lanternflies, including how to estimate their numbers after the various treatments used to try to control it, which is very difficult for this pest,” Roush said.

The spotted lanternfly, an invasive insect from Asia, feeds on the sap of critical agricultural commodities — including grapevines, fruit trees, nursery plants, and hardwood timber — as well as plants in natural habitats, parks, and backyards. Economists warn that this insect, if not contained, could have an annual economic impact of at least $324 million on Pennsylvania’s economy and cause the loss of about 2,800 jobs.

The overall goal of the Blue Marsh project was to explore the feasibility of controlling spotted lanternfly using area-wide spray application techniques, while minimizing negative impacts on nontarget organisms in the environment, noted Brian Walsh, an extension educator based in Berks County and a lead researcher on the project.

The study involved the evaluation of two biopesticides using ground and aerial applications over several weeks, in comparison to a single application early in the season of a synthetic insecticide containing the active ingredient dinotefuran, which is a systemic insecticide that is taken up by plants. Researchers hypothesized that dinotefuran’s early-season use and short surface persistence would maximize effectiveness against the pest with little impact on nonpest species.

The Blue Marsh investigation revealed that either aerial or ground-based spray application of dinotefuran reduced spotted lanternfly populations by up to 90% within 24 hours of application and remained effective for at least two weeks. Findings also showed that within the scope of this experiment, the insecticide had minimal to no measurable impact on nontarget species, including pollinators.

Measuring the effectiveness of the two biopesticide formulations containing Beauveria bassiana proved far more challenging, explained Nina Jenkins, senior research associate in entomology. Biopesticides typically take longer to work than chemical insecticides, requiring from three to 10 days to kill an insect.

The research team used additional methods to monitor the efficacy of the biopesticides, which included taking groups of live spotted lanternflies from the sprayed plots for mortality monitoring at the Penn State Berks campus. Mortality of these sampled populations reached up to 50% two weeks after spray application.

Unlike the dinotefuran treatments, the biopesticides were applied by ground or air three times at two-week intervals. Despite this, spotted lanternfly populations within the biopesticide plots did not differ significantly from the control groups.

“These results were disappointing, but several factors could have affected the results, including the life stage of the pest,” Jenkins said. “At Blue Marsh, the focus was on early-stage nymphs, which constantly move from place to place. This circumstance made it challenging to measure both initial populations and death rates in the plots treated with the slower-acting biopesticides.”

At the time of the study in Norristown, Walsh noted, the spotted lanternflies were late-stage nymphs and adults; both remain in the same place for days or weeks while feeding, making it easier to target applications and document mortality rates.

“We knew that nymphs are in near-constant motion, but it appears they are moving farther and faster than we thought,” he said. “We suspect that some of the infected nymphs left the research plot before their demise. That is one of the issues we are reviewing, as well as optimal environmental conditions and application timing.”

Roush said the scientists would apply the lessons learned at Blue Marsh to future research.

“We are striving for an organic form of spotted lanternfly control but need to have an enhanced understanding of circumstances under which it will be most effective,” he said. “In the meantime, our partners at the state Department of Agriculture and the U.S. Department of Agriculture have gained some valuable information that is guiding how they approach the problem, particularly in satellite populations.”

Among the more than 50 scientists involved with the study from Penn State were Dennis Calvin, associate dean and director of special programs in the College of Agricultural Sciences, David Biddinger, tree-fruit research entomologist based at the Fruit Research and Extension Center in Biglerville, John Rost, lab supervisor for biology and horticulture at the Center for the Agricultural Sciences and a Sustainable Environment at Penn State Berks, Kelli Hoover, professor of entomology, Joe Keller, postdoctoral scholar in entomology, Heather Leach, entomology extension associate, and scientists from Penn State’s Center for Pollinator Research.

Project partners also include the U.S. Army Corps of Engineers, Blue Marsh Lake Project; Pennsylvania Game Commission; Pennsylvania Department of Conservation and Natural Resources; U.S. Department of Agriculture; and the Pennsylvania Department of Agriculture.