Assessing the effects of volatile repellents on the invasive spotted lanternfly, Lycorma delicatula (White)

Spotted lanternfly [Lycorma delicatula (White)] (Hemiptera: Fulgoridae) (SLF) is a large piercing-sucking insect, native to Asia and newly invasive to the United States. Since its arrival in Pennsylvania in 2014, SLF has spread to an additional 10 states and has caused damage to a variety of ornamental plants, trees, and fruit crops, most notably, grapes. The insect is predicted to have devastating consequences to agroecosystems and forests, demanding a better understanding of its ecology. While classical insecticides kill nymphs and adults, the ability to repel SLF from crops is of greater importance to prevent initial infestations. Volatile secondary plant metabolites are used to repel arthropods in a variety of agricultural contexts. Recent studies in Asia suggest that lavender essential oil [Lavandula spp.] and its predominant monoterpene constituent, linalool, repel SLF nymphs and adults in field and laboratory settings. To corroborate these findings under field conditions in the U.S., we tested the efficacy of lavender oil in Virginia in August 2020. Retention of adult SLF was monitored on its preferred host plant, tree-of-heaven [Ailanthus altissima] in comparison to cultivated grape [Vitis rotundifolia ‘Carlos’]. Analysis showed significant repellent effects on SLF adults positioned on tree-of-heaven, while effects on grapes were less pronounced. Overall retention rates were higher on tree-of-heaven compared to grape, which may be due to prior experience of individuals feeding on tree-of-heaven. Additional laboratory and field assays are currently performed to determine host plant effects on the efficacy of lavender oil and to test the application of other plant-derived repellents.