Heavy Adult Feeding by Spotted Lanternflies on Young Maple Trees Hinders Tree Growth by up to 50%

According to a new Penn State study, short-term, heavy feeding by adult spotted lanternflies on young maple trees inhibits photosynthesis, potentially reducing the tree's growth by up to 50%.

The findings, according to the researchers, can assist production nurseries and forest managers in making management decisions that will protect their inventories.

Feeding damage caused by spotted lanternflies

(Photo : Michael M. Santiago/Getty Images)

According to Kelli Hoover, professor of entomology in the College of Agricultural Sciences, the spotted lanternfly will feed on important ornamental and forest trees such as silver and red maple, which are used to make products and are abundant across urban, suburban, and rural landscapes throughout Pennsylvania.

Pennsylvania's forest products industry has a total economic impact of $36 billion.

This Asian planthopper was discovered for the first time in the United States in Berks County in 2014, and it has since spread to 45 Pennsylvania counties and neighboring states.

The pest feeds on sap from more than 100 plant species with its piercing-sucking mouthparts, with a significant affinity for tree-of-heaven, an invasive species, and wild and cultivated grapes.

While the spotted lanternfly most likely co-evolved with its favorite host, the consequences on the health and physiology of tree hosts native to the United States have not been studied, according to Hoover.

In 2019, the scientists began their two-year investigation in Blandon's common garden area.

They gathered spotted lanternflies at two stages of development: adults and fourth instar nymphs, the last stage before maturity.

The insects were then planted on silver maple, red maple, black walnut, and tree-of-heaven seedlings in varied "densities," or numbers of insects per plant.

They studied how feeding pressure on a single branch influenced tree physiology throughout the first year.

The scientists evaluated the effect of nymph and adult feeding using whole-tree cages in the second year of the trial when the trees were more established.

Heavy feeding was described by scientists as a large number of bugs covering the tree.

They looked at how insect density varied by life stage and how it affected physiological plant responses, particularly gas exchange properties such as photosynthesis (the process of turning carbon dioxide and water into oxygen and sugar).

The team's results, which were just published in the journal Frontiers in Insect Science, reveal that adult spotted lanternfly feeding inhibits photosynthesis, slowing the development of young saplings.

There was some variance, however, depending on the tree type, insect population, and period post-infestation.

The researchers discovered that various densities of nymphs on a single branch of red maple or silver maple had no influence on gas exchange.

In contrast, restricted to a single branch of red or silver maple, forty adults slowed photosynthesis and lowered nitrogen content in leaves.

Silver maple soluble sugars were lowered in the fall, while red maple soluble sugars were reduced the following spring.

Silver maples exposed to nymphs in entire tree cages showed dramatically stunted diameter development during the next growing season, and the reduction was related to spotted lanternfly density (0, 40, 80, or 120 insects per tree), as per ScienceDaily.

Treatments with the greatest spotted lanternfly density (120) decreased diameter development by 55% compared to controls with no lanternflies, whereas intermediate (80) and low (40) concentrations produced 42% and 38% reductions, respectively.

In contrast, instars in full tree cages exhibited no impact on black walnut.

After two weeks of feeding, spotted lanternflies trapped on a tree-of-heaven at a density of 80 individuals per tree reduced photosynthesis.

Nonetheless, it had no effect on nonstructural carbohydrates, nitrogen concentrations, or tree development.

The researchers also discovered that each year, as the tree of heaven begins to fall dormant, spotted lanternfly adults eat intensively on maples, which lasts until the pest is killed by a harsh frost.

As a result, they advise producing nurseries, forest managers, and homeowners to monitor and maintain maple and black walnut seedlings during this period.

Hoover directed visitors to the Penn State Extension spotted lanternfly website for information on control methods.

According to her, the basic line is that the older the insects are, the more destructive they are.

If the spotted lanternfly is feeding on your rosebush, particularly the nymphs, or if they are limited to the underside of the leaves of your maple trees, they are unlikely to do significant damage.

Read more: Spotted lanternflies found to be flyers, not gliders

How invasive are they?

Spotted lanternflies are invasive and can spread over vast areas when individuals transfer infected materials or products carrying egg masses, as per Michigan Invasive Species.

If permitted to grow in the US, this insect might have a significant impact on the country's wine, orchard, and timber sectors.

The spotted lanternfly feeds on over 70 plants, including grapes, apples, hops, and hardwood trees.

The insects cause direct damage by sucking sap from host plants and secreting vast volumes of honeydew, a sugary, sticky substance.

This honeydew, as well as the accompanying black sooty mold, can harm plants and contaminate surfaces.

Despite their inability to travel great distances, spotted lanternflies lay eggs on almost any surface, including automobiles, trailers, firewood, outdoor furniture, and more.

Check cars, firewood, and outdoor equipment for hitchhikers before leaving an affected region.

Related article: Spotted Lanternfly: Officials Are Begging Public to Kill This Invasive Pest on Sight