LIGHTS OUT!
Parasitic wasps, vibrating traps and other ways to destroy spotted lanternflies
Science is catching up with the spotted lanternfly as researchers experiment with parasitic wasps, vibrating traps and other strategies to stop the colorful pest.
Before the bug reached the United States, federal funding was already flowing to science labs conducting mitigation research and news media were calling its imminent arrival a plague. When spotty spotted lanternfly infestations were proven to be caused mostly by adults and their egg masses hitching rides on motor vehicles, their spread was called an invasion.
Recent international research has found that while a lanternfly infestation can have dire regional economic consequences, their population centers are somewhat temporary, more like wartime beachheads that launch more contained but potentially devastating incursions.
Lycorma delicatula is native to Southeast Asia and its impact on Chinese agriculture was initially studied in the early 2000s.
Analysis of research conducted in 2019-21 by private industry and universities in China and South Korea said much could be learned by tracking the bug’s migration out of China.
“Biological invasion has been a serious global threat due to increasing international trade and population movements,” said the National Institutes of Health in an overview of the research. “Tracking the source and route of invasive species and evaluating the genetic differences in their native regions have great significance for effective monitoring and management, and further resolving the invasive mechanism.”
More than 390 complete genome sequences from the DNA of female lanternflies captured in four countries were studied to ascertain their origin, dispersal and migration history. The lineage was followed from the late Pleistocene Era to current inhabitations, following the insect’s ancient expansion northward across the Yangtze River. South Korean populations were the result of multiple invasions from two separate regions of China.
Spotted lanternflies currently infesting agriculture in Japan and the United States came from a single lineage, which has been called “a bridgehead of invasion.”
The U.S. population, now in 13 states mostly east of the Mississippi River, is the result of a single invasive event. When South Korean produce was unloaded at a Berks County shipping yard in 2014, the stowaway lanternflies found their favorite food – Ailanthus trees, commonly called Tree of Heaven – growing wild and prospering in suburban yards. Being not particularly picky at meal time, the adaptive pests also sucked the sap from more than 70 species of New World vegetation and by 2017 had spread across Eastern Pennsylvania.
“The environmental conditions, especially the distribution of host Ailanthus trees, and adaptability possibly account for the rapid spread of the spotted lanternfly in the native and introduced regions,” said the report.
Lanternfly eradication efforts in the research realm have included the investigation of various insecticides, oils and other host tree treatments; chemicals released into the air by plants; development of a lethal fungus; traps and detection technologies; skewing the lanternfly sex ratio; impacts of potential biocontrol species on American forests; and deeper dives into the distribution, survival and life cycle of the insect.
Chickens and praying mantises were once considered among likely lanternfly predators. Aerosol solutions for lanternfly infestations were found to kill beneficial backyard critters as well, including ladybugs, praying mantises, spiders and pollinators such as honey bees and butterflies.
In addition, the sprayed toxins would kill a promising biological bulwark against spotted lanternfly expansion.
From 2018-21, the U.S. Department of Conservation and Natural Resources, Department of Agriculture, National Institute of Agricultural Sciences and Chinese Academy of Forestry separately researched the mass production of insects that eat spotted lanternflies from the inside out. Young “parasitoids” develop on or inside another organism, eating its host until it is dead before emerging.
Researchers found the most promising parasitoids were the young of two wasp species that target spotted lanternflies and occur naturally in China. One wasp preys on spotted lanternfly eggs; the other targets lanternfly nymphs. An overview published by Entomological Society of America said the biocontrol would work when monthly temperatures and photoperiod were the same as in the wasps’ home region near Beijing.
More recently, the USDA explored ways to exploit one of spotted lanternflies’ greatest weaknesses: an attraction to vibration.
Richard Mankin, an entomologist with the USDA Agricultural Research Service in Florida, said he and colleagues found a way to potentially corral and control lanternflies.
“There were rumors that lanternflies are attracted to vibrations of buzzing electrical power lines, so we did a laboratory study of nymph and adult responses to [60Hz] vibrations,” Mankin said. “The rumor proved to be correct. Both nymphs and adults walked towards the source of [the] vibrations.”
Maybe the bugs confused the artificial vibrations with the low hum emanating from trees infested with hundreds of thousands of sap-sucking, “honeydew”-excreting lanternflies.
Mankin noted that most power lines in North America transmit alternating current at a rate of 60Hz. Artificial vibrations could be used to entice lanternflies toward control devices, he said. Further USDA research is expected to focus on traps and disrupting spotted lanternfly mating behaviors.
New long-term research from Penn State has shown that hardwood trees such as maple, willow and birch may be less vulnerable to spotted lanternflies than initially thought. The grapevines of Erie County remain vulnerable.
Another study of sorts is currently underway across Pennsylvania. Commercial vehicles are required to have state permits when traveling into and out of 52 counties placed under spotted lanternfly quarantine.
“I wouldn’t characterize the business permits as commercial travel restrictions,” said Shannon Powers, a spokeswoman for the Pennsylvania Department of Agriculture. “The permits … are an effective tool for educating business travelers on how to recognize lanternflies and not take them to a new home when they travel.”
The permits also give the state a database of potential travel routes that could unintentionally import lanternflies. Currently, more than 32,000 businesses across the U.S. and Canada carry 1.36 million lanternfly quarantine permits.