DNA barcoding of gut contents from the tiny sap-sucking insects provided insight that may help control spread of this destructive invasive species.
Lanternfly nymphs of in various stages of development.
Image Credit: William O. Lamp/ UMD
Among the most aggressive invasive insect pests in the Mid-Atlantic, spotted lanternflies damage fruit trees and grapevines, and pose serious economic threats to farmers. Efforts to control them have been hindered in part by a lack of knowledge about what they eat and what plant species might host them at different stages of their life-cycle.
University of Maryland researchers have just added 13 new species to the list of plants that may provide nutrition to the insects in the very early stages of their development (in the first of four nymph stages) and should be monitored for the presence of spotted lanternfly nymphs. The team developed a new method of identifying the recent meals of first-stage nymphs by extracting plant DNA from the gut contents of multiple individuals all at once. Their work was published in June, 2022, in the journal Insects.
“Very little was known about the host plants of these first-stage nymphs, known as first instars,” said Alina Avanesyan, an assistant research scientist from the University of Maryland’s Department of Entomology. “They are very small at this stage, and they consume sap, so the challenge was to be able to detect plant DNA in such small concentrations.”
Scientists had previously identified the food sources for adult spotted lanternflies and later stage nymphs, largely by observing the brightly colored insects feeding on plants and from DNA analyses of gut contents. Scientists believed first instars might have a much wider range of host plants, but at less than half-a centimeter long, they are more difficult to observe and contain too little gut contents for conventional DNA analyses.
Bulk DNA analysis, in which multiple individuals are combined to increase the total amount of plant DNA in a sample, has been used in other applications. But Avanesyan and her colleagues did not know if it could work for spotted lanternfly nymphs, because they are sap-feeders and do not eat leaves or stems, which contain the bits of DNA scientists use to identify plants.
Sap does not contain plant DNA, but Avanesyan and her colleagues thought perhaps the nymph’s piercing mouthparts might pick up some DNA from plant cells as they puncture through leaves and stems like tiny hypodermic needles. And they were right.
By combining samples from multiple individuals and modifying their methods to handle very small amounts of diluted DNA material, the team identified 27 different plant species, including 13 plants that were not previously known to host the spotted lanternfly.
“Ultimately, we are not interested in plants from one individual, but what kind of plants first instar can consume in general,” Avanesyan said. “Prior to this we knew almost nothing about what the spotted lanternflies at this stage of development consumed or what host plants they visited.”
Since they were first identified in the U.S. in 2014, spotted lanternflies have been detected in 15 states. Controlling further spread depends on reliable monitoring to catch new invasions early. This research will help guide efforts to discover early-stage nymphs in new territories.
Other UMD researchers on this paper include Professor of Entomology William Lamp and Research Assistant Cameron McPherson
