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The next phase in the fight against invasive spotted lanternflies (Lycorma delicatula) in the United States might just involve man’s best friend. New research from Cornell University found that trained dogs were better than humans at detecting the lanternfly eggs that spend the winter in some landscapes, particularly forested areas. The findings are detailed in a study published December 26, 2024 in the journal Ecosphere.
Why are spotted lanternflies a problem?
The spotted lanternfly is native to China, and was first detected in Pennsylvania in 2014. Since then, it has spread to at least 17 other states primarily in the eastern United States. Roughly 61,000 of these winged insects were found in 2021 alone. While they may not bite or sting humans, they can be devastating to crops and are difficult to eradicate. The insect feeds on and kills several host plants including maple and walnut trees, apples, hops, and grapes.
“A spotted lanternfly infestation in a vineyard can cause 80% to 100% mortality of the vines in one growing season,” study co-author and Cornell University conservation ecologist Angela Fuller told the Cornell Chronicle.
[ Related: What’s going on with spotted lanternflies? ]
According to Fuller, these infestations can also increase the amount of insecticide that growers need to use on their plants. The added insecticide can increase costs by up to 170 percent in a single growing season.
Scientists have used pesticides, physical traps, and even robots and fungi to manage the insects at a local level. However, the pesticides and traps do have their downsides. Sticky traps can ensnare other animals and the lanternflies can eventually evolve resistance to certain current methods. A team at the United States Department of Agriculture is currently investigating a parasitoid wasp species as natural predators that could provide a potential solution. Using dogs and their keen sense of smell to find their eggs in the winter may be another possibility.
Enter the dogs
This new study was designed to compare how well dogs and humans can find the lanternfly’s eggs when they overwinter. Dogs typically rely on their noses to find things, while humans rely on visual cues and touch.
Professional dog trainers from the New York-New Jersey Trail Conference and Working Dogs for Conservation trained two dogs–a Labrador retriever and a Belgian Malinois–to track the scent of spotted lanternfly egg masses.
Fuller and colleagues selected 20 vineyards in Pennsylvania and New Jersey that are known to have lanternfly infestations. Next, the team used the various lines along vineyard rows called transects and the forests next to them. One day, humans surveyed the area for egg masses. Leashed dogs with a human handler scanned the same areas on different days, so that the scene of people did not influence the dogs.
In the vineyards, humans spotted 1.8 times more egg masses than the dogs. Here, adult female lanternflies will lay their eggs on support poles and vines.
Compared to the humans, the dogs searched more randomly in the vineyards, so their surveys were likely less systematic and effective. By comparison, humans found 31 egg masses per hour versus 24 egg masses per hour for dogs in vineyards.
However, in the adjacent forests, the dogs at 3.4 times more detections than humans. The forests are where many spotted lanternflies overwinter and then hatch to infect vineyards.
“The dogs find egg masses by smell,” Fuller said. “So, in a very complex environment, it’s easier for a dog to smell something than it is for a human to see something that is small and cryptic.”
In forests, the dogs found 7.6 egg masses per hour versus 6.7 per hour for humans. The dogs also did spend more time searching than the humans did.
“The extra time that dogs take to find them is not as important as it is to find them in the first place, because you need to detect the egg masses in order to eradicate them,” Fuller said.
No vacancy in the vineyard
The researchers also used a computer model to estimate the probability that a particular area has a spotted lanternfly–or occupancy rates. They models shows that occupancy was higher in
vineyards than in forests and higher on metal poles than on vines. The lines in the vineyards that were closest to the forest had a higher chance of having egg masses than those that were further away from the forest. The team believes that this is likely because lanternflies do not typically disperse very far, will often fall out of trees or are carried away by wind.
“If you’re searching in a vineyard close to the forest, that’s more likely where they’re going to be,” Fuller said.
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