Deciphering genome-wide transcriptomic changes in grapevines heavily infested by spotted lanternflies

The Spotted Lanternfly Contains High Concentrations of Plant Hormones in its Salivary Glands: Implications in Host Plant Interactions

The spotted lanternfly (SLF), Lycorma delicatula is an invasive species in the United States that has emerged as a significant pest in vineyards. This polyphagous insect causes significant damage to grapevines and tree of heaven (TOH). SLF feeds voraciously on plant tissues using its piercing and sucking mouthparts through which it injects saliva and uptakes plant sap. Despite its impact, research on fundamental mechanisms mediating SLF interactions with their predominant hosts is limited. This study documents the morphology of salivary glands and quantifies plant hormones in salivary glands of SLF adults fed on grapevines and TOH using Liquid Chromatography-Mass Spectrometry (LC/MS). SLF adults have one pair of large salivary glands, ranging from 10 to 15 mm in length that extend from the insect's head to the last sections of the abdomen. The salivary glands of SLF contain salicylic acid (89 ng/g), abscisic acid (6.5 ng/g), 12-oxo-phytodienoic acid (5.7 ng/g), indole-3-acetic acid (2 ng/g), jasmonic acid (0.6 ng/g), jasmonic acid isoleucine (0.037 ng/g), and the cytokinin ribosides trans-zeatin (0.6 ng/g) and cis-zeatin (0.1 ng/g). While the concentrations of these hormones were similar in insects fed on grapevines and TOH, abscisic acid was more abundant in insects fed on grapevines, and jasmonic acid isoleucine was only detected in insects fed on grape. These results are discussed in the context of the possible implications that these hormones may have on the regulation of plant defenses. This study contributes to our understanding of the composition of SLF saliva and its potential role in plant immunity.

Development and survivorship of Lycorma delicatula (Hemiptera: Fulgoridae) on cultivated and native Vitis spp. (Vitales: Vitaceae) of the Eastern United States

As Lycorma delicatula (White) continues to spread across the United States, more winegrapes are potentially susceptible to damage from this pest. Lycorma delicatula, spotted lanternfly, is primarily associated with Ailanthus altissima (Mill.) Swingle, a tree from its native range that is now globally distributed. While L. delicatula is a known pest of cultivated Vitis spp. in South Korea, its relationship with the specific grape species grown in the United States is unclear. This study assessed L. delicatula survivorship and development on 5 Vitis species, including 2 winegrape V. vinifera L. varieties, 'Pinot Noir' and 'Chardonnay', Concord grape, Vitis labrusca L., River grape, Vitis riparia Michx., and muscadine grape, Vitis rotundifolia Michx. var. 'Carlos'. A diet of A. altissima served as a positive control. Lycorma delicatula provided with a diet of V. riparia or V. vinifera 'Pinot Noir' yielded the highest survivorship and fastest rates of development among grape diets and were statistically equivalent to those provided with A. altissima. Vitis rotundifolia did not support L. delicatula growth past the third-instar life stage, indicating this species is a poor host for the early development of this pest. Our results indicate that both V. riparia and V. vinifera are favorable hosts for L. delicatula and may provide the means for this insect to invade and establish in new regions.

Impacts of short-term feeding by spotted lanternfly (Lycorma delicatula) on ecophysiology of young hardwood trees in a common garden

Spotted lanternfly (SLF; Lycorma delicatula White; Hemiptera: Fulgoridae) invaded the US from Asia and was first detected in 2014; currently, populations have established in 14 states primarily in the Northeast and Mid-Atlantic. It feeds voraciously on phloem sap from a broad range of host plants, with a preference for tree of heaven (Ailanthus altissima [Sapindales: Simaroubaceae]), grapevines (Vitis spp. [Vitales: Vitaceae]), and several common hardwood tree species. We evaluated the impacts of fourth instars and adults confined to a single branch or whole trees on gas exchange attributes (carbon assimilation [photosynthetic rate], transpiration and stomatal conductance), selected nutrients, and diameter growth using young saplings of four host tree species planted in a common garden. In general, the effects of adults on trees were greater than nymphs, although there was variation depending on tree species, pest density, and time post-infestation. Nymphs on a single branch of red maple (Acer rubrum [Sapindales: Sapindaceae]), or silver maple (Acer saccharinum [Sapindales: Sapindaceae]) at three densities (0, 15, or 30) had no significant effects on gas exchange. In contrast, 40 adults confined to a single branch of red or silver maple rapidly suppressed gas exchange and reduced nitrogen concentration in leaves; soluble sugars in branch wood were reduced in the fall for silver maple and in the following spring for red maple. Fourth instars confined to whole silver maple trees reduced soluble sugars in leaves and branch wood, and reduced tree diameter growth by >50% during the next growing season. In contrast, fourth instars in whole tree enclosures had no effects on black walnut (Juglans nigra [Fagales: Juglandaceae]). SLF enclosed on tree of heaven at 80 adults per tree suppressed gas exchange after two weeks of feeding, but did not alter non-structural carbohydrates, nitrogen concentrations, or tree growth. Results suggest that moderate to heavy feeding by SLF on young maple saplings may impair tree growth, which could have implications for production nurseries and forest managers.